NC State
BioResources
  • Editorialpp 8116-8118Hubbe, M. A. (2016). "My production facility, my laboratory of discovery," BioRes. 11(4), 8116-8118.AbstractArticlePDF

    By exercising of one’s curiosity, in combination with a lot of persistence, it is possible to solve some seemingly intractable problems. Many readers of this journal will have spent much, if not all of their careers, in university laboratories. In such settings there is an understandable emphasis on understanding underlying reasons. In other words, one is expected to focus on “why things happen” rather than just getting results. But if such an approach works well at the university, how about applying it at the production facility? This editorial features the stories of a man who was brave enough to spend his career asking “why” questions while working to improve the operations of paper mills.

  • Editorialpp 8119-8122Zhang, A., and Shen, J. (2016). "Adding growth-promoting ingredients in activated sludge process as a troubleshooting strategy for pulp and paper mill wastewater treatment," BioRes. 11(4), 8119-8122.AbstractPDF
    The activated sludge process is a well-established technology in the secondary treatment of pulp and paper mill wastewater. Maintaining the activities of microorganisms and allowing them to thrive, metabolize, and grow robustly is essential for efficient biological reactions. To this end, a scientific formulation of growth-promoting ingredients (containing stimulants, buffers, micronutrients, etc) provides a useful strategy for addressing the impact of fluctuations in process conditions involved in the pulp and paper production. Lots of potential exists in terms of the use of these “smart” ingredients to meet stricter discharge limits.
  • Researchpp 8123-8138Balea, A., Blanco, Á., Concepción Monte, M., Merayo, N., and Negro, C. (2016). "Effect of bleached eucalyptus and pine cellulose nanofibers on the physico-mechanical properties of cartonboard," BioRes.11(4), 8123-8138.AbstractPDF
    Extending the limits of paper recycling by increasing the number of recycling cycles results in decreased mechanical properties due to the irreversible hornification of cellulose fibers. This process alters the fiber structure and properties because of the repeated chemical and mechanical treatments that occur during wetting and drying. As a result, poor tensile strength is the main source of customer complaints to paper manufacturers. Cellulose nanofibers (CNF) from bleached eucalyptus and pine pulps were investigated as potential strength additives because of their proven contribution to interfiber bonding. These results were compared to the results obtained using different families of strength additives. The effects on the mechanical properties of recycled old corrugated containers were studied by measuring bursting, tensile, and short span compressive strength. Cellulose nanofibers and cationic polyacrylamide (cPAM) improved the mechanical strength properties when they were added at doses around 4 wt.%. A combination of CNF and cPAM was also tested. The effects of the combined additives were not as high as expected compared to the results achieved individually. The CNF from pine pulp resulted in the highest increase in bursting index when combined with cPAM, achieving an increase of over 93%. The combination of CNF from eucalyptus pulp and cPAM increased the bursting index over 60%.
  • Researchpp 8139-8154Pereira-Ferraz, G., Frear, C., Pelaez-Samaniego, M. R., Englund, K., and Garcia-Perez , M. (2016). "Hot water extraction of anaerobic digested dairy fiber for wood plastic composite manufacturing," BioRes.11(4), 8139-8154.AbstractPDF
    Dairy farmers worldwide are facing the difficulty of managing or disposing of dairy manure. Anaerobic digestion (AD) is an option for treating dairy manure and producing biogas. A byproduct of AD is fiber, which is only partially being used despite its potential for different products, including wood plastic composites (WPCs). However, some properties of WPCs need to be improved to use them in high moisture content environments. This work evaluates the effect of hot water extraction (HWE) (at 160 °C for 60 min) of the AD dairy fiber on properties of WPCs. WPCs were produced using AD fiber via extrusion and tested for mechanical properties and water affinity. The WPCs produced with HWE fiber exhibited increased mechanical strength (36%) and stiffness (30%), and reduced strain at break (15%) compared to composites produced with untreated fiber. Water sorption and thickness swelling were reduced by 39% and 36%, respectively, after immersion in water for 98 days. The diffusion constant of WPCs produced with HWE fiber was also reduced by 64%. These results show that HWE is an effective method for enhancing mechanical properties and reducing hydrophilicity of WPCs produced from AD fiber.
  • Researchpp 8155-8165Luján-Rhenals , D. E., and Morawicki, R. O. (2016). "Production of fermentable sugars and a high protein meal by dilute acid hydrolysis of soybean meal at high temperatures," BioRes. 11(4), 8155-8165.AbstractPDF
    The objective was to produce fermentable sugars with low levels of fermentation inhibitors and a high-protein meal, with acceptable color, by treating defatted soybean meal with dilute sulphuric acid at temperatures between 105 and 135 oC and durations up to 45 min. The conditions that maximized the amount of protein were 120 °C, 0.5% H2SO4, and 45 min, which increased protein from 48.1% to 58.6% d.b. The highest amount of fermentable sugars (32.2% d.b.), without regard for the protein content, was for the treatment at 135 °C, 2% H2SO4, and 45 min; such treatment generated relatively low 5-HMF and furfural levels (0.0018 g/L and 0.32 g/L, respectively), and 0.87 g/L, of acetic acid. The treatment at 120 °C, 1.5% H2SO4, and 30 min had the best balance between a high concentration of fermentable sugars (21.3% d.b.) in the liquid fraction and crude protein (52.1% d.b.) in the solid fraction without a significant change in the original color of the solid fraction.
  • Researchpp 8166-8177Gu, R., Mu, B., and Yang, Y. (2016). "Bond performance and structural characterization of polysaccharide wood adhesive made from konjac glucomannan/chitosan/polyvinyl alcohol," BioRes. 11(4), 8166-8177.AbstractPDF

    The bond performance and bonding mechanism were evaluated for a Konjac glucomannan (KGM), Chitosan (CS), and polyvinyl alcohol (PVOH) blended wood adhesive. An optimized experimental strategy was used to investigate the effects of the formula parameters of adhesives on the bonding strength of plywood using a Box-Behnken design and response surface methodology (RSM). The microstructure of the blended adhesives was analyzed by Fourier transform infrared spectroscopy (FTIR) and scanning electron microscopy (SEM). An optimum bonding strength (3.42 ± 0.31 MPa) was achieved with concentrations of KGM, CS, and 10% PVOH of 2.3%, 2.3%, and 5.0%, respectively. There was strong hydrogen bonding between the KGM, CS, and 10% PVOH adhesives and the interface. SEM observations indicated that the blended adhesive exhibited a net-like structure that increased the overall bonding strength. These results provided the scientific basis for the continual development of environmentally friendly wood adhesives and the improvement of processing conditions.

  • Researchpp 8178-8199Boran, S., Kiziltas, A., Kiziltas, E. E., and Gardner, D. J. (2016). "Characterization of ultrafine cellulose-filled high-density polyethylene composites prepared using different compounding methods," BioRes.11(4), 8178-8199.AbstractPDF

    An extensional flow mixture (EFM) system was studied, with the goal of achieving better distributive and dispersive mixing. The effects of different mixing strategies (masterbatch method (MB), polyethylene-grafted maleic anhydride (PE-g-MA) as a compatibilizer, and compounding devices, such as a single screw extruder (SSE), a twin screw extruder (TSE), and an extensional flow mixer (EFM)) on the mechanical, thermal, rheological, and morphological properties of ultrafine cellulose (UFC)-filled high-density polyethylene (HDPE) composites were investigated. Maximum tensile strength (17.7 MPa), tensile modulus (0.88 GPa), flexural strength (18.8 MPa), and flexural modulus (0.63 GPa) were obtained from the MB compounding method. The maximum stress-strain (13.8%) was obtained with EFM compounding. Polymer composites from SSE and SSE/EFM compounding methods with PE-g-MA exhibited slightly higher crystallinity compared with other compounding methods. The storage modulus of the samples prepared with the MB method was higher than those prepared with the SSE compounding method. The UFC-filled HDPE composites from the EFM compounding process exhibited lower melt viscosities than the other composites at high shear rates. Scanning electron microscopy (SEM) images showed the cellulose to be distributed and dispersed reasonably well in the HDPE matrix when using a coupling agent in combination with the MB and EFM compounding methods.

  • Researchpp 8200-8214Verdet, M., Salenikovich, A., Cointe, A., Coureau, J. L., Galimard, P., Toro, W. M., Blanchet, P., and Delisee, C. (2016). "Mechanical performance of polyurethane and epoxy adhesives in connections with glued-in rods at elevated temperatures," BioRes. 11(4), 8200-8214.AbstractPDF

    Glued-in rods have successfully been used for connections or reinforcement of timber structures due to their high strength and stiffness. However, their performance is potentially sensitive to temperature. This paper deals with an experimental investigation of the connections and adhesives in elevated temperatures. First, dynamic mechanical analysis (DMA) tests were performed to characterize an epoxy (EPX) and a polyurethane (PUR) adhesive. The evolution of the stiffness and the glass transition temperature, Tg, were measured in the range of 30 °C to 120 °C. Then, a total of 66 specimens with glued-in rods and the same adhesives were tested under a static tensile load at 20 °C, 40 °C, 50 °C, 60 °C, and 70 °C. In both types of tests, the EPX outperformed PUR due to its higher stiffness at temperatures of up to 40 °C; however, it showed a more rapid degradation of the stiffness and strength than the PUR at higher temperatures. No direct correlation was established between the Tg and the performance of the connections. The test results suggest that timber structures with glued-in rods may be vulnerable in service at temperatures above 40 °C.

  • Researchpp 8215-8225Yang, C., Zhu, X., Kim, N. H., Lee, S. H., Qi, Y., Bai, Y., Guo, M., and Ma, Y. (2016). "Experimental design and study of micro-nano wood fiber processed by nanosecond pulse laser," BioRes. 11(4), 8215-8225.AbstractPDF

    A new processing technology using a nanosecond pulse laser to process micro-nano wood fiber is proposed in this paper. A test bench was designed and manufactured for the technology. The digital design process, experimental methods, and general layout principle of the test bench are introduced. When the factors that affected the results of the experiment were analyzed, it was found that cutting width and cutting depth were affected by cutting direction, cutting speed, and cutting power. The wood underwent thermal degradation near the point of processing. The results of the experiment showed that the technology is feasible.

  • Researchpp 8226-8238Zheng, S., Song, K., Zhao, J., and Dong, C. (2016). "Inverse estimation of effective moisture diffusivity in lumber during drying using genetic algorithms," BioRes. 11(4), 8226-8238.AbstractPDF

    This article presents a methodology based on genetic algorithms (GA) optimization with a three-dimensional numerical solution to the diffusion model obtained by using the finite volume method (FVM) for determining the effective moisture diffusivity in lumber. The objective or error function between measured and simulated drying curves was obtained, and the effective moisture diffusivity parameters with greatest correspondence between measured and estimated values were obtained. As a result, a new equation for effective moisture diffusivity was proposed, which depends on lumber moisture content and drying temperature. Effective moisture diffusivities ranged from 1.120 × 10-9 to 1.277 × 10-8 m2/s. Finally, the proposed coefficients were validated by experiments. The drying kinetics were successfully simulated with the optimized effective moisture diffusivity model.

  • Researchpp 8239-8256Li, M., Li, W., Liu, Q., Jameel, H., Chang, H. M., An, S., and Ma, L. (2016). "A two-step conversion of corn stover into furfural and levulinic acid in a water/gamma-valerolactone system," BioRes. 11(4), 8239-8256.AbstractPDF

    A two-step hydrolysis method was evaluated as a potential means of obtaining high yields of furfural and levulinic acid from corn stover using sulfuric acid as catalyst in a water/gamma-valerolactone (GVL) system. The corn stover underwent a high-temperature hydrolysis process to produce levulinic acid, followed by a low-temperature hydrolysis process to produce furfural. A series of experiments were conducted to explore the relationship between the different reaction parameters and the final yields of furfural and levulinic acid. Scanning electron microscopy (SEM) pictures together with X-ray diffraction (XRD) analysis were used to further elaborate on the hydrolysis results. Molar yields of about 70.65% furfural and 57.7% levulinic acid were obtained by applying this method with a low temperature of 140 °C and a high temperature of 190 °C, together with 0.2 M of sulfuric acid used as the catalyst. These results indicated that this was an effective way to obtain satisfactory yields of furfural and levulinic acid from corn stover.

  • Researchpp 8257-8268Khosravani, A., Asadollahzadeh, M., Rahmaninia, M., Bahramifar, N., and Azadfallah, M. (2016). "The effect of external and internal application of organosilicon compounds on the hydrophobicity of recycled OCC paper," BioRes. 11(4), 8257-8268.AbstractPDF

    There are various applications of organosilicon compounds in papermaking. Additionally, organosilicons have been applied to improve the water resistance of some lignocellulosic materials. The performance, however, of such compounds for the hydrophobation of paperboard is unclear. In this study, an organosilicon solution was internally and externally applied to old corrugated container (OCC) paperboard at ambient temperature. Examination of the infrared spectra of treated paperboard confirmed the presence of CH2 groups and hydrophobic organic chains of organosilicon in the treated paperboard. Both internal and external treatment of the paperboard helped its resistance to water, though external treatment was more successful in the late reduction of the contact angle of water droplets and also in reducing water uptake.

  • Researchpp 8269-8276Maan, P., Bharti, A. K., Gautam, S., and Dutt, D. (2016). "Screening of important factors for xylanase and cellulase production from the fungus C. cinerea RM-1 NFCCI-3086 through Plackett-Burman experimental design," BioRes. 11(4), 8269-8276.AbstractPDF

    A Plackett-Burman design was employed to evaluate the effect of different culture conditions associated with xylanase and cellulase production by the fungus C. cinerea RM-1 NFCCI 3086 using agro-residues as substrate. Eight variables were assessed for their significance on xylanase and cellulase production under solid state fermentation. The optimal culture conditions for xylanase production were developed by maintaining the variables of temperature, incubation period, substrate concentration, particle size, inoculum size, and inoculum age at their higher levels, while keeping pH and moisture ratio at their lower levels. For cellulase production, temperature, incubation period, substrate concentration, inoculum size, and inoculum age were fixed at their higher levels, and pH, particle size, and moisture level were kept at their lower levels. Of the eight variables, temperature, incubation period, and pH had significant influence on xylanase and cellulase production. These three variables can be further optimized for increased enzyme production.

  • Researchpp 8277-8284Pérez, N., Segovia, F., Salinas, C., and Ananías, R. (2016). "Perpendicular mechano-sorptive strains during moisture desorption from Eucalyptus nitens specimens," BioRes. 11(4), 8277-8284.AbstractPDF

    The purpose of this paper was to determine the mechano-sorptive strains produced during desorption of moisture from Eucalyptus nitens specimens, from a perspective of modeling wood drying stresses. Eucalyptus nitens samples were tested in the radial and tangential directions. The mechano-sorptive strain was measured by cantilever bending during desorption. The runs were performed in a conditioning chamber at constant low temperature and variable equilibrium moisture content. Four load levels were considered for testing. The results showed that the mechano-sorptive strain during desorption of moisture was proportional to applied stress and reached the maximum value in the tangential direction. Also, the mechano-sorption coefficient depended on wood orientation and reached the maximum value of 5.46 × 10-2 in the tangential direction.

  • Researchpp 8285-8296Turkoglu, T., Baysal, E., Yuksel, M., Peker, H., Sacli, C., Kureli, I., and Toker, H. (2016). "Mechanical properties of impregnated and heat treated Oriental beech wood," BioRes. 11(4), 8285-8296.AbstractPDF

    The main purpose of this study was to investigate mechanical properties such as the modulus of rupture (MOR) and compression strength parallel to grain (CSPG) of impregnated and heat-treated Oriental beech (Fagus orientalis L.) wood. Some copper and boron containing impregnation chemicals such as Wolmanit CX-8 (WCX-8) and Celcure AC-500 (CAC-500) were used. Wood specimens were impregnated 2% aqueous solution of the chemicals according to ASTM D1413-07e1 standard. The wood specimens were heated at 150 and 175 °C for 4 and 8 h, respectively. Results showed that both impregnation and heat treatment decreased the MOR and CSPG of Oriental beech wood. The MOR losses of Oriental beech after both treatments were higher than CSPG losses. The largest reduction of MOR and CSPG were observed with 51.5% and 15.5% for CAC-500 impregnated and heated at 175 °C for 8 h. Except for WCX-8 impregnation and heat treatment at 150 °C for 4 and 8 h, the MOR values of impregnated and heat-treated Oriental beech wood were lower than only heat-treated Oriental beech wood. It was also found that the CSPG values of impregnated and heat-treated Oriental beech wood were higher than only heat-treated Oriental beech wood, except for impregnation and heat treatment at 175 °C for 8 h.

  • Researchpp 8297-8306Ratnasingam, J., Choon Liat, L., Ramasamy, G., Mohamed, S., and Senin, A. L. (2016). "Attributes of sawn timber important for the manufacturers of value-added wood products in Malaysia," BioRes. 11(4), 8297-8306.AbstractPDF
    The objective of this study was to assess the attributes of selected sawn timber species for door, flooring, and furniture manufacturing in Malaysia. Sawn timber attributes are important for value-added wood products manufacturing in terms of market opportunities and consumer preferences. A questionnaire was distributed to 30 value-added wood products manufacturers, in which there were 10 manufacturers in each category: door, flooring, and furniture. The study evaluated three aspects: the choice of sawn timber species for particular types of wood products, the source of origin of sawn timber, and the attributes that determined the choice of the sawn timber species for a particular product. The common local sawn timber species include rubberwood, meranti, merpauh, merbau, and kempas species, while poplar, oak, cherry, and pine represent imported species. It was found that cost, supply/availability, product specification, and market/buyer preferences were among the most important factors influencing the selection of sawn timber species for the manufacture of value-added wood products. However, these attributes were not statistically significant among the group of manufacturers and source of origin, respectively.
  • Researchpp 8307-8324Yan, F., Xu, K., Li, D., and Zhang, X. (2016). "Hazard assessment for biomass gasification station using general set pair analysis," BioRes. 11(4), 8307-8324.AbstractPDF
    Hazard assessment is critical for a biomass gasification station because it includes various hazardous factors. Set pair analysis (SPA) is a convenient and effective method for hazard assessment, but it has limitations, including (1) the inability to reflect the difference when the data belong to the same hazard grade and (2) the assessment results lack precision and accuracy. This study proposes an improved method designated as general set pair analysis (GSPA). Connection measure degree (CMD), which is based on the cosine function, as well as weighting deviation degree (WDD), relative membership degree (RMD), and comprehensive index (CI) were proposed in GSPA, and the algorithms were generated. The calculated results of these different methods can be utilized to overcome the shortcomings of SPA during hazard assessment. A case study of two biomass gasification stations in Shenyang City, Liaoning Province, Northeast China, was performed. The hazard assessment results of the GSPA were compared with those of SPA. The results showed that GSPA is a more effective, precise, and accurate method for hazard assessment of a biomass gasification station.
  • Researchpp 8325-8343Timar, M. C., Varodi, A., Hacibektasoglu, M., and Campean, M. (2016). "Color and FTIR analysis of chemical changes in beech wood (Fagus sylvatica L.) after light streaming and heat treatment in two different environments," BioRes. 11(4), 8325-8343.AbstractPDF
    Color and chemical changes were investigated in beech wood (Fagus sylvatica L.) following light steaming and further heat treatment for 2.5 h at 200 °C by two techniques (industrial ThermoWood versus a laboratory procedure in the presence of air). Colour changes were evaluated in the CIE Lab system, while Fourier transform infrared spectroscopy with attenuated total reflection (FTIR-ATR) investigation was employed to highlight and compare the associated chemical changes. Light steaming caused only minor chemical changes (limited hydrolysis of hemicelluloses) not ready detectable by FTIR. In contrast, heat treatments caused visible changes in the FTIR spectra, especially in the region 1800 to 1500 cm-1, consisting mainly in a clear decrease of the absorption band for conjugated carbonyls at 1643 cm-1 and a slight apparent increase of the absorption bands for lignin at 1506 and 1595 cm-1. A significant variation of the ratios of relevant absorption bands indicated complex chemical changes, including hydrolytic, oxidative, and condensation reactions. FTIR ratios and the mass loss values in the two heat treatments relate, both indicating a more advanced modification in the case of the ThermoWood process.
  • Researchpp 8344-8354Mirski, R., Dziurka, D., and Derkowski, A. (2016). "Properties of oriented strand boards with external layers made of non-strand chips," BioRes. 11(4), 8344-8354.AbstractPDF
    This study evaluated the possibility of producing oriented strand boards (OSB) from non-strand chips. Properties of the produced boards were compared with commercially available OSB/3. Research has shown that replacing the strand chips of external layers with smaller chips allowed for the manufacturing of OSB/3 using chips up to four times shorter than standard strand chips. Oriented strand board manufacturers should consider preparing a new standard and introducing the market to a new type of OSB with very good mechanical properties and made of selected strand chips comprising one of the fractions obtained during screening.
  • Researchpp 8355-8363Sánchez, J. H., Fajardo, M. E., and Quintana, G. C. (2016). "Viscoelastic properties of pulp suspensions of bleached sugarcane bagasse: Effects of consistency and temperature," BioRes. 11(4), 8355-8363.AbstractPDF
    The viscoelasticity of pulp suspensions of bleached sugarcane bagasse was studied in a stress/shear rate-controlled rheometer using concentric cylinders geometry. Results for the elastic (G’) and viscous (G”) modulus, as well as complex viscosity (n*), are presented as a function of the suspension consistency (1.0 wt% ≤ Cm ≤ 6.0 wt%) and temperature (20, 40, and 60 °C). The results show an effect of the concentration and temperature on the viscoelastic moduli and cross-over point. A power law model was fitted to the experimental results for elastic modulus, It was found that the complex viscosity exhibited shear-thinning behavior for all the suspensions. Only the pulp concentration had an influence on this material function.
  • Researchpp 8364-8385Cerbu, C., and Cosereanu, C. (2016). "Moisture effects on the mechanical behavior of fir wood flour/glass reinforced epoxy composite," BioRes. 11(4), 8364-8385.AbstractPDF
    Fir wood flour may be used as filler in glass reinforced composites due to the lower content of tannins in comparison with oak wood flour (Cerbu et al. 2010). This work focuses on the behavior of E-glass / fir wood flour / epoxy hybrid composites in mechanical tests (three-point bending tests, and Charpy impact tests) after immersion in water for 1177, 3048, and 6572 hours. Alternating layers were reinforced either with glass fabric or with fir wood flour. After 3048 hours of immersion, the flexural properties decreased: the modulus of elasticity (MOE) in bending and maximum flexural stress σ decreased by 13.16% and 37.54% respectively, with respect to the values recorded in the case of the dried specimens. The properties recovered a little after saturation because they increased after 6572 hours of immersion: MOE was greater (4.36%), while maximum flexural stress was greater (6.78%) with respect to the values corresponding to the specimens tested after 3048 hours of immersion. In the Charpy test, the impact strength K was measured. The damage (cracks developed at matrix-glass interface) caused by water absorption is discussed in order to explain the degradation of the mechanical properties. The adding of the wood flour led to the increasing of the modulus of rigidity EI in bending and it is proved by comparing with the results obtained in case of glass / epoxy composite without wood flour. Components for outdoor furniture (gardens) could be an application of the hybrid composite analyzed in this paper.
  • Researchpp 8386-8395Wei, J., Du, C., Liu, H., Chen, Y., Yu, H., and Zhou, Z. (2016). "Preparation and characterization of aldehyde-functionalized cellulosic fibers through periodate oxidization of bamboo pulp," BioRes. 11(4), 8386-8395.AbstractPDF
    Cellulosic fibers were efficiently disintegrated from bamboo pulp as raw material and then oxidized using sodium periodate to introduce dialdehyde groups on their surfaces. The resultant fibers were characterized using Fourier transform infrared spectroscopy (FT-IR), X-ray diffraction (XRD), and thermogravimetric analysis (TGA). FT-IR spectra demonstrated that the characteristic absorption band of aldehyde groups was present at 1735 cm-1, confirming that aldehyde groups were successfully introduced. XRD showed that the nature of bamboo pulp fibers changed slightly after oxidation, except in the reduction of crystallinity. The aldehyde content increased with the sodium periodate content and reached a maximum of 1.41 mmol/g. The yield loss maximum was 32.4 wt%. TGA results showed that the temperature at the initial and final decomposition of the oxidized fibers was subject to the periodate dosage and that the thermal stability decreased to some extent.
  • Researchpp 8396-8408He, S., Li, J., Xu, J., and Mo, L. (2016). "Enhanced removal of COD and color in paper-making wastewater by ozonation catalyzed by Fe supported on activated carbon," BioRes. 11(4), 8396-8408.AbstractPDF
    After biological treatment, pulp and paper mill effluent still may contain large amounts of recalcitrant organic pollutants that need to be further treated. In this study, Fe supported on activated carbon (Fe@AC) was prepared and used as a catalyst in the catalytic ozonation of pulp and paper mill effluent. The activity of this catalyst was studied in terms of color and chemical oxygen demand (COD) removal efficiencies. Results showed that the COD removal rate was increased by 21% in the presence of the Fe@AC catalyst. After 60 min of ozonation (3g/h ozone flow rate) of the pulp and paper mill effluent (initial COD 360 mg/L), COD removal rates reached 56% in the presence of Fe@AC, 43% using AC as catalyst, and only 35% with ozonation alone. Ozone alone can achieve satisfactory color removal results. Owing to the scavenging effect of carbonate and bicarbonate ions towards hydroxyl radicals, the COD removal rate in Fe/AC catalytic ozonation of the effluent was strongly inhibited in the presence of these two ions. The COD removal rate followed the pseudo-second-order kinetics model well. The COD removal rate constant in the Fe@AC/O3 process was about 1.6 times higher than that of the AC/O3 process, and approximately 2.1 times higher than that of ozone alone.
  • Researchpp 8409-8418Kerdtongmee, P., Saleh, A., Eadkhong, T., and Danworaphong, S. (2016). "Investigating sound absorption of oil palm trunk panels using one-microphone impedance tube," BioRes. 11(4), 8409-8418.AbstractPDF

    Sound absorption coefficient of oil palm trunk was explored using an impedance tube. Palm samples were taken from the central part of oil palm trunks with cut directions parallel and perpendicular to vascular bundles. Sound absorption was evaluated for palm panels with blind-holes with multiple radii and depths, as well as perforated and grooved panels and a panel with perforated holes at different distances from a solid backing. Measurements of sound absorption within the frequency range of 300-2000 Hz indicated that the sound absorption coefficient of the cross-cut biomass, ~0.15, was slightly greater than that of the parallel-cut panel, ~0.10. Samples with different depths of blind holes showed slight improvements in sound absorption coefficients as compared to the unmodified cross-cut panel. There was a significant improvement for 5-mm hole diameter with 10-mm depth, ~25% improvement as compared to that of 5-mm depth. The combination of the through-hole panel and grooved board allowed ~80% of sound to be absorbed for 1750 to 2000 Hz. Finally, the grooved board was removed and an air cavity backing was introduced by placing the through-hole panel 2-, 4-, and 6-mm away from the tube end. The sound absorption coefficients were then measured to be greater than 80% near the resonance frequencies, as calculated using the distributed Helmholtz resonator model.

     

  • Researchpp 8419-8424Choi, C., Lee, C. G., Yoo, J. C., Yang, S. M., Ha, S. Y., Yang, J. K., and Kang, S. G. (2016). "Effect of torrefied wood powder extract as a plant growth retardant," BioRes. 11(4), 8419-8424.AbstractPDF
    The effect of filtered torrefied wood powder as a plant growth retardant was evaluated. The filtered extract was manufactured using torrefied wood powder (Quercus serrata Thunb. Ex. Murray) and distilled water. The filtered extracts were used to create four solutions of varying concentration (1%, 5%, 10%, and 20%). Each solution was applied to various seedlings (Amaranthus retroflexus, Plantago asiatica, Echinochloa crus-galli var.) over the course of six days. Additionally, gas chromatography-mass spectrometry (GC/MS) was performed to investigate how plant growth was affected. The results indicated that higher concentrations of filtered extract delayed seed growth more than solutions of lower concentration. Additionally, the GC/MS analysis of the filtered extract of torrefied wood revealed one phenolic compound and two different types of furan compounds. This study investigated the active components of torrefied wood as plant growth regulators.
  • Researchpp 8425-8434Lin, L. D., Chang, F. C., Ko, C. H., Wang, C. T. (2016). "Bamboo-derived fuel from Dendrocalamus latiflorus, Phyllostachys makinoi, and Phyllostachys pubescens waste," BioRes. 11(4), 8425-8434.AbstractPDF

    Bamboo is used as a raw material for producing chopsticks, artifacts, utensils, plywood, fiberboard, and decorated multi-layered panels. The manufacturing process generates a large amount of bamboo residual waste. In this study, bamboo-derived fuels were prepared from the residual waste of Dendrocalamus latiflorus, Phyllostachys makinoi, and Phyllostachys pubescens. The combustion behaviors of bamboo-derived fuels were also investigated. The characteristics of derived fuels made from bamboo waste with engine oil waste showed that the ash content was less than 5% and that the calorific value reached 5,000 kcal/kg, which was higher than derived fuels standards. Additionally, the derived fuel of bamboo waste had a high combustion efficiency and low nitrogen, sulfur, and chlorine emission levels, which were lower than the derived fuels standards. Thus, bamboo-derived fuel prepared from Dendrocalamus latiflorus, Phyllostachys makinoi, and Phyllostachys pubescens waste mixed with engine oil waste is a suitable fuel alternative.

  • Researchpp 8435-8456Sameni, J., Krigstin, S., and Sain, M. (2016). "Characterization of lignins isolated from industrial residues and their beneficial uses," BioRes. 11(4), 8435-8456.AbstractPDF

    The physico-chemical properties of lignin isolated from lignocellulosic bioethanol residues and hardwood kraft black liquor were compared with two commercial lignins, kraft softwood lignin, and soda non-wood lignin. Lignin from the industrial residues was isolated through the acid precipitation method. The amount of lignin isolated was approximately 38% of the dry weight of lignocellulosic bioethanol residues and approximately 27% of the black liquor solids. The numbers of methoxyl groups and phenolic and aliphatic hydroxyls were determined to derive a molecular formula for each of the four lignins. The molecular weights of the lignins were measured by high performance size exclusion chromatography. Potential value-added applications of the lignins were summarized based on their molecular weights and physico-chemical characteristics.

  • Researchpp 8457-8469Ren, H., Chen, C., Guo, S., Zhao, D., and Wang, Q. (2016). "Synthesis of a novel allyl-functionalized deep eutectic solvent to promote dissolution of cellulose," BioRes. 11(4), 8457-8469.AbstractPDF

    Deep eutectic solvents (DESs) offer attractive options for the “green” dissolution of cellulose. However, the protic hydroxyl group causes weak dissolving ability of DESs, requiring the substitution of hydroxyl groups in the cation. In this study, a novel allyl-functionalized DES was synthesized and characterized, and its possible effect on improved dissolution of cellulose was investigated. The DES was synthesized by a eutectic mixture of allyl triethyl ammonium chloride ([ATEAm]Cl) and oxalic acid (Oxa) at a molar ratio of 1:1 and a freezing point of 49 °C. The [ATEAm]Cl-Oxa exhibited high polarity (56.40 kcal/mol), dipolarity/polarizability effects (1.10), hydrogen-bond donating acidity (0.41), hydrogen-bond basicity (0.89), and low viscosity (76 cP at 120 °C) owing to the π-π conjugative effect induced by the allyl group. The correlation between temperature and viscosity on the [ATEAm]Cl-Oxa fit the Arrhenius equation well. The [ATEAm]Cl-Oxa showed low pseudo activation energy for viscous flow (44.56 kJ/mol). The improved properties of the [ATEAm]Cl-Oxa noticeably promoted the solubility (6.48 wt.%) of cellulose.

  • Researchpp 8470-8482Chen, R. S., Ahmad, S., and Gan, A. (2016). "Characterization of rice husk-incorporated recycled thermoplastic blend composites," BioRes. 11(4), 8470-8482.AbstractPDF

    High-fiber-content composites made from rice husk (RH) (from 50 up to 80 wt%) as well as a recycled thermoplastic blend (rTPB) were fabricated using a two-step extrusion and hot/cold press molding technique. The temperature dependency of the thermal degradation and dynamic-mechanical behavior was investigated using thermogravimetric analysis (TGA) and dynamic mechanical analysis (DMA). The long-term water absorption and orthotropic swelling were analyzed following immersion in distilled, tap, and sea water for 15 weeks. Improvements in the thermal stability, storage, and loss modulus, as well as reductions in dimensional stability, were observed as the alkali content of the RH in the rTPB composites was increased. The composites immersed in sea water showed the lowest water absorption, followed by those in distilled and then tap water. The thickness dimension of the composite specimens exhibited the highest swelling values, followed by width and then length dimensions. The tensile strength and elastic modulus showed the maximum values at 70 wt% RH (21.2 MPa and 1.6 GPa, respectively). The surface morphology, interfacial adherence, and bonding between the matrix-fiber phases in the composites were characterized using a scanning electron microscope (SEM).

  • Researchpp 8483-8495Lu, P., Tian, X., Liu, Y., and Wang, Z. (2016). "Effects of cellulosic base sheet pore structure and soybean oil-based polymer layer on cellulosic packaging performance as a barrier for water and water vapor," BioRes. 11(4), 8483-8495.AbstractPDF

    Cellulose-based materials are good alternatives to petroleum-based materials in the packaging industry, considering their sufficient mechanical properties and sustainability; however, the barrier performances of cellulosic packaging materials against water and water vapor are generally poor due to the hydrophilic nature of cellulose. In this study, a soybean oil-based polymer was synthesized on the surface of several cellulosic materials through an acrylated-epoxidized soybean oil (AESO) reactive coating. The best conversion of the reaction was observed when a suitable reaction temperature, curing time, initiator dosing, and monomer content were selected. Five different types of cellulosic packaging materials were used as substrates for the reactive coating, and their barrier performances were investigated. The improvement in water barrier properties was indicated by the change in water droplet contact angle (CA). The water vapor permeability (WVP) of the substrates was reduced significantly after coating. The water vapor barrier properties of the coating were highly dependent on the tested substrate. A comparison of CA and WVP showed that the change in water vapor barrier did not correspond to surface hydrophobicity.

  • Researchpp 8496-8508Fabisiak, E., and Mania, P. (2016). "Variation in the microfibril angles in resonance and non-resonance spruce wood (Picea abies [L.] Karst.)," BioRes. 11(4), 8496-8508.AbstractPDF

    Variation in microfibril angle (MFA) in the S2 of the tangent cell walls of resonance and non-resonance spruce wood (Picea abies [L.] Karst.) used in the manufacture of musical instruments was studied. MFA was measured directly after preliminary visualisation of microfibrils in the cell walls. In the tested samples the position of an annual ring in the samples had no significant influence on the MFA. In the resonance wood, MFA values were between two and three times smaller than in the non-resonance wood. In the resonance wood, the differences in the MFA between earlywood and latewood were smaller, and the MFA fluctuations were also smaller.

  • Researchpp 8509-8521Muzamal, M., Bååth, J. A., Olsson, L., and Rasmuson, A. (2016). "Contribution of structural modification to enhanced enzymatic hydrolysis and 3-D structural analysis of steam-exploded wood using X-ray tomography," BioRes. 11(4), 8509-8521.AbstractPDF
    Steam explosion pretreatment modifies both the chemical and physical structures of a biomass. Chemical modifications are generated during the treatment of biomass with steam at high temperature. Physical modifications are created during the explosion step, which produces disintegrated and defibrillated biomass. In this study, the contribution of each modification to an increase in enzymatic hydrolysis has been studied. It was found that both physical and chemical modifications contributed to an increase in enzymatic hydrolysability. Additionally, high resolution X-ray tomography was performed to identify the structural modification created during the steam explosion process. Comparison of the 3-D micro-structure of a steam-exploded wood sample with an untreated wood sample revealed that several kinds of cracks were created during the explosion step, and the micro-structure of the wood sample was vigorously destroyed.
  • Researchpp 8522-8534Hýsek, Š., Wimmer, R., and Böhm, M. (2016). "Optimal processing of flax and hemp fibre nonwovens," BioRes. 11(4), 8522-8534.AbstractPDF

    Processing was studied for air-laid nonwovens from natural hemp and flax fibres using SPIKE® air-laying technology (Formfiber Denmark ApS Company). The process of web-formation and the properties of the fibre-webs before needle-punching and reinforced fibre-mats were evaluated. The settings of the air-laying machine were found to influence the web-formation process and nonwoven properties. In order to monitor web-formation processes and evaluate the fibre-web or fibre-mat quality, several machine settings were defined that enhanced the productivity of the machine or favoured fabrication of nonwovens with high density or great tensile properties.

  • Researchpp 8535-8547He, W., Tian, J., Li, J., Jin, H., and Li, Y. (2016). "Characterization and properties of cellulose nanofiber/polyaniline film composites synthesized through in situ polymerization," BioRes. 11(4), 8535-8547.AbstractPDF
    Cellulose nanofiber/polyaniline (CNF/PANI) composites films were synthesized through in situ polymerization of aniline in a nanocellulose suspension that was isolated from bamboo (Phyllostachys nidularia Munro). The PANI contents were 5 wt.%, 15 wt.%, or 30 wt.%. Scanning electron microscopy (SEM) and transmission electron microscopy (TEM) showed that the CNF nanofibril surfaces were uniformly coated by PANI particles. Moreover, Fourier transform infrared (FTIR) spectroscopy analysis indicated the formation of hydrogen bonds between the amine groups of aniline and the hydroxyl groups of cellulose. X-ray diffraction (XRD) analysis demonstrated that the cellulose I structure of CNF in the composites did not change, while the crystallinity of CNF was affected. Thermogravimetric analysis (TGA) showed that the thermal stability of CNF was increased due to the addition of PANI. Meanwhile, the obtained electrical conductivity and mechanical properties of the CNF/PANI composites indicated that the composites could be used potentially in anti-static materials, for shielding of electromagnetic radiation, and in biological sensors.
  • Researchpp 8548-8557Zhai, M., Guo, L., Zhang, Y., Dong, P., Qi, G., and Huang, Y. (2016). "Kinetic parameters of biomass pyrolysis by TGA," BioRes. 11(4), 8548-8557.AbstractPDF

    Pyrolysis processes of typical biomass, such as corn stalk and birch chips, were investigated by thermogravimetric analysis (TGA). The apparent activation energy and pre-exponential factor were calculated with the adoption of the improved Coats-Redfern integral method, 46 types of common mechanism functions, and the least square and iterative methods. By applying basic parameters of biomass pyrolysis, a reaction rate constant, activation entropy and activation enthalpy, activation Gibbs free energy, and the steric-hindrance factor were all calculated. Results showed that biomass pyrolysis can be divided into two primary reaction zones (Event 3 and Event 4). Event 3 is focused by cellulose and hemicellulose. Event 4 is oriented by lignin and cellulose. The thermogravimetric curves of the two biomass types under carbon dioxide and nitrogen atmospheres were roughly similar. The reaction mechanism function is 1 – alpha. It is possible to use activation entropy to represent the pre-exponential factor and to use the steric hindrance factor to predict the reaction rate.

  • Researchpp 8558-8569Chen, T., Xie, Y., Wei, Q., Wang, X., Hagman, O., Karlsson, O., Liu, J., and Lin, M. (2016). "Improving the mechanical properties of ultra-low density plant fiber composite (ULD_PFC) by refining treatment," BioRes. 11(4), 8558-8569.AbstractPDF

    To improve the mechanical properties of ultra-low density plant fiber composite (ULD_PFC), a suitable beating process to improve the fibrillation of cellulose fibers and maintain their length was investigated. The physical properties of cellulose fibers and papers, surface chemical bonds, and internal bond strength (IB) of ULD_PFCs were analyzed. The results showed that the beating degrees, degree of fibrillation, and fiber fines increased with the decreasing of beating gap, except for the fiber weight-average length, width, kink index, and curl index. The tensile index and burst index of paper showed an increasing trend with an increase in beating degree, while the tear index showed a decreasing trend. FTIR results showed that intermolecular and intramolecular hydrogen bonds in ULDF were broken. A suitable beating gap of 30 μm with a beating degree of 35 °SR was obtained. The corresponding IB was 50.9 kPa, which represented an increase of 73.1% over fibers with a beating degree of 13 °SR.

  • Researchpp 8570-8588Duan, R., Westerlind, B. S., Norgren, M., Anugwom, I., Virtanen, P., and Mikkola, J. P. (2016). "Fibre stress-strain response of high temperature chemi-thermomechanical pulp treated with switchable ionic liquids," BioRes. 11(4), 8570-8588.AbstractPDF

    The removal of lignin from a high-temperature chemi-thermomechanical pulp (HT-CTMP) using a switchable ionic liquid prepared from an organic superbase (1,8-diazabicyclo-[5.4.0]-undec-7-ene (DBU)), monoethanol amine (MEA), and SO2 was investigated. The objective was to measure the fibre properties before and after removal of the lignin to analyse the contributions from lignin in the HT-CTMP fibre to the tensile properties. It was found that the fibre displacement at break – measured in zero span, which is related to fibre strain at break – was not influenced by the lignin removal in this ionic liquid system when tested dry. There was a small increase in displacement at break and a reduction in tensile strength at zero span when tested after rewetting. At short span, the displacement at break decreased slightly when lignin was removed, while tensile strength was almost unaffected when tested dry. Under rewetted conditions, the displacement at break increased and tensile strength decreased after lignin removal. Nevertheless, no dramatic differences in the pulp properties could be observed. Under the experimental conditions, treatment with the ionic liquid reduced the lignin content from 37.4 to 15.5 wt%.

  • Researchpp 8589-8614Chen, F. X., Gong, P., Zhang, H. K., Bai, X. H., Gao, Y. F., and Zhou, A. N. (2016). "Biomass pyrolysis of Helianthus annuus stems: qualitative and quantitative study based on Py-GC/MS," BioRes. 11(4), 8589-8614.AbstractPDF

    The pyrolytic product vapor of Helianthus annuus stems was analyzed by Pyrolysis–gas chromatography–mass spectrometry (Py-GC/MS) using the internal standard (ISTD) method with different pyrolysis temperatures and times. 1,3,5-tri-tert-butylbenzene (TTBB) was found to be the best ISTD chemical in this study. Scanning electron microscopy (SEM) revealed that, for the solid-state product, the pores and mesh structure gradually increased along with the pyrolysis temperatures and time. Sintering and porous destruction were observed at a lower pyrolysis temperature (600 °C) with longer time (0.5 min). The pyrolysis vapors contained small gas molecules such as CO2 as well as complex organic compounds, mainly alcohols, esters, acids, aldehydes, ketones, aromatic compounds, etc. In these products, aldehyde, ketone, and aromatic compounds were the main biochemicals; the appropriate pyrolysis temperature to produce aldehydes and ketones was 700 °C, and 600 °C was suitable for aromatic compounds. The regularity of the distribution of products and pyrolytic conditions was explored through eight representative compounds. The relationship between the product contents and pyrolysis conditions were complex for Helianthus annuus stems, but partial least squares discriminant analysis (PLS-DA) methods were a powerful tool for screening biochemicals whose absolute contents were sensitive to the pyrolysis conditions.

  • Researchpp 8615-8626Indarti, E., Roslan, R., Marwan., and Wan Daud, W. R. (2016). "Polylactic acid bionanocomposites filled with nanocrystalline cellulose from TEMPO-oxidized oil palm lignocellulosic biomass," BioRes. 11(4), 8615-8626.AbstractPDF

    Bionanocomposites from polylactic acid (PLA) filled with unmodified nanocrystalline cellulose from TEMPO-oxidized oil palm empty fruit bunch (OPEFB-NCC) at various loading levels were fabricated using the solvent casting technique. Scanning electron microscopy (SEM), transmission electron microscopy (TEM), attenuated total reflectance Fourier transform infrared spectroscopy (ATF-FTIR), differential scanning calorimetry (DSC), and mechanical analyses were used to characterize the bionanocomposite films. FTIR suggested that the incorporation of the OPEFB-NCC was based on physical interaction. The melting temperature did not change markedly except at higher OPEFB-NCC additions, while the crystallization temperature shifted to lower temperatures and crystallinity increased with increasing OPEFB-NCC content.The SEM of cryo-fractured films indicated a rather weak compatibility between the OPEFB-NCC and PLA, resulting in the decrease of both the modulus and the tensile strength of the bionanocomposite.

  • Researchpp 8627-8637Tian, X., Wang, B., Li, J., Zeng, J., and Chen, K. (2016). "Surface grafting of paper with photochromic spiropyran ether methacrylate," BioRes. 11(4), 8627-8637.AbstractPDF
    It was demonstrated that a photochromic paper could be made through the atom transfer radical polymerization (ATRP) method by grafting spiropyran ether methacrylate (SPMA) onto the fiber surface. The surface composition and topography of the grafted paper were analyzed by Fourier Transform Infrared Spectroscopy (FTIR), X-ray photoelectron spectra (XPS), and scanning electron microscopy-energy dispersive spectrometer (SEM-EDS). Crystal structures of the cellulosic fibers were also examined after the grafting reaction. The characteristic absorption bands detected in the FTIR spectrum after grafting suggested that a new functional group was formed by the reaction. The XPS and SEM results confirmed that SPMA was grafted onto the surface of the fibers successfully. The grafted spiropyran groups exhibited reversible photochromic properties when exposed to UV light irradiation and visible light. The modified paper showed a purple color under UV light irradiation and changed back to its original color when exposed to visible light. This surface modification using ATRP was demonstrated to be a feasible way to prepare photochromic paper.
  • Researchpp 8638-8652Gašparík, M., Gaff, M., Šafaříková, L., Vallejo, C. R., and Svoboda, T. (2016). "Impact bending strength and Brinell hardness of densified hardwoods," BioRes. 11(4), 8638-8652.AbstractPDF

    The objective of this research was to determine the influence of wood species (Fagus sylvatica L. and Populus tremula L.), thickness (4, 6, 10, 18 mm), and degree of densification (0%, 10%, and 20%) on the impact bending strength (IBS) and Brinell hardness (BH) in the radial direction. Three-factor analysis of variance confirmed that the difference in IBS was significantly related to the wood species and wood thickness. Wood densification did not have a significant effect on IBS. In addition, beech wood exhibited higher IBS values than aspen wood. The IBS values increased proportionally with increasing thickness. All factors affecting Brinell hardness were statistically significant, although thickness had the smallest influence overall. The Brinell hardness values were substantially higher in beech wood than aspen wood, and in some cases were more than three times greater. On the other hand, densification exhibited a more positive effect on increasing Brinell hardness for aspen wood than beech wood.

  • Researchpp 8653-8663Wu, Z., Chen, T., Huang, D., Wang, W., Xie, Y., Wan, H., Wang, X. (2016). "Effect of PVDC on the fire performance of ultra-low density fiberboards (ULDFs)," BioRes. 11(4), 8653-8663.AbstractPDF

    Poly vinylidene chloride-vinyl chloride emulsions (PVDC) were added as a substitute for chlorinated paraffin (CP) in the preparation of ultra-low density fiberboards (ULDFs). The micromorphology and fire performance of ULDFs were investigated using a scanning electron microscope, limiting oxygen index instrument, and cone calorimeter. The results showed that PVDC specimens were coated with a regularly smooth film, while the distribution of CP inside CP specimens was uneven. The limiting oxygen index increased with the dosage of PVDC, then reached a plateau at 50 mL and 28%, slightly higher than CP specimens (27.3%). The peak of heat release rate, mean heat release rate, mean CO, and total smoke release of PVDC specimens was reduced 43.3%, 13.5%, 38.5%, and 51.5% lower than respective CP specimens, and with nearly the same total heat release (only 0.04 MJ/m2 higher). Thus, PVDC exhibited excellent heat-reducing and smoke-suppressing properties and could replace CP in ULDFs.

  • Researchpp 8664-8675Shi, S., Zhang, H., Huang, C., Lin, X., and Chen, X. (2016). "Purification of lignocellulose hydrolysate by org-attapulgite/ (divinyl benzene-styrene-methyl acrylate) composite adsorbent," BioRes. 11(4), 8664-8675.AbstractPDF
    The purification of lignocellulose hydrolysate is crucial for the efficient conversion of lignocellulose. In this study, weak polar poly(styrene-divinyl benzene-methyl acrylate) (PSDM) and composite absorbent org-attapulgite/poly(styrene-divinyl benzene-methyl acrylate) (PSDM-T) were prepared in situ by suspension polymerization for the detoxification of mixed hydrolysate. The org-attapulgite (O-A-T) used was functionalized with the silane coupling agent KH-570. The effect of O-A-T mass on PSDM-T was investigated. The results showed that the addition of a moderate mass of O-A-T improved the pores of PSDM-T and adsorption abilities. Furfural and 5-HMF (FS), total weak acids (WA), and soluble lignin (SL) were removed simultaneously. The adsorption capacities of PSDM-T for FS, WA and SL were 37.5 mg/g, 34.3 mg/g, and 87.7 mg/g, respectively. Correspondingly, their removal extents (R) were 72.6%, 18.1%, and 52.3%. The adsorption abilities of the PSDM-T for mixed hydrolysate was better than AB-8 (a commonly-used adsorption resin). The total decolorization rates (D) greater than 63%. The absorption property retains high adsorption activity after two cycles.
  • Researchpp 8676-8685Uzuner, S., and Cekmecelioglu, D. (2016). "Comparison of artificial neural networks (ANN) and adaptive neuro-fuzzy inference system (ANFIS) models in simulating polygalacturonase production," BioRes. 11(4), 8676-8685.AbstractPDF

    The artificial neural network (ANN) method was used in comparison with the adaptive neuro-fuzzy inference system (ANFIS) to describe polygalacturonase (PG) production by Bacillus subtilis in submerged fermentation. ANN was evaluated with five neurons in the input layer, one hidden layer with 7 neurons, and one neuron in the output layer. Five fermentation variables (pH, temperature, time, yeast extract concentration, and K2HPO4 concentration) served as the input of the ANN and ANFIS models, and the polygalacturonase activity was the output. Coefficient of determination (R2) and root mean square values (RMSE) were calculated as 0.978 and 0.060, respectively for the best ANFIS structure obtained in this study. The R2 and RMSE values were computed as 1.00 and 0.030, respectively for the best ANN model. The results showed that the ANN and ANFIS models performed similarly in terms of prediction accuracy.

  • Researchpp 8686-8702Daud, S., Ismail, H.,  and AbuBakar, A. (2016). "Soil burial study of palm kernel shell-filled natural rubber composites: The effect of filler loading and presence of silane coupling agent," BioRes. 11(4), 8686-8702.AbstractPDF

    Palm kernel shell (PKS) was incorporated into natural rubber composites at loadings ranging from 0 to 20 phr using a laboratory-size two-roll mill. A soil burial study of the PKS-filled NR composites as a function of filler loading and silane coupling agent incorporation was then conducted over a period of six months. The degraded composites were evaluated by means of tensile testing. To study the degradation of the composites after soil burial, their morphological properties were observed by scanning electron microscopy. Prior to the soil burial tests, as the PKS filler loading increased, the tensile strength and elongation at break of the composites both with and without the silane coupling agent decreased, while the tensile moduli (M100 and M300) increased. At identical filler loading values, the NR/PKS composites with the incorporated silane coupling agent exhibited better tensile properties than the NR/PKS composites without the silane. Following the soil burial tests, the tensile strength, elongation at break, and the tensile moduli (M100 and M300) all decreased because of microbial attacks on the composites. The addition of silane enhanced the retention of the tensile properties of the NR/PKS composites after soil burial because of the improved adhesion at the filler-rubber matrix interface.

  • Researchpp 8703-8719Zhai, R., Chi, F., and Zhou, X. (2016). "NaOH-thiourea aqueous solution treatment of cellulose fiber and its effects on bulk and softness," BioRes. 11(4), 8703-8719.AbstractPDF

    Bleached kraft pulp of hardwood was pretreated in a NaOH-thiourea aqueous solution to modify the bulk and softness of the cellulose fibers with minimal reduction in paper strength. The effects of soaking time, fiber concentration, alkali dosage, and freezing time were evaluated through single factor experiments. The optimal conditions were determined to be a soaking time of 15 min, fiber concentration of 15%, alkali dosage of 9%, and freezing time of 75 min. Under the optimal conditions, the bulk and softness of the treated cellulose fibers were increased by 28.7% and 21.6%, respectively, compared with those of untreated cellulose fibers. The tensile and burst indices were only reduced by 1.2% and 5.1%, respectively, under these conditions. Also, there were almost no effects on the polymerization degree, the thermostability, and the structure of the functional groups or crystalline regions.

  • Researchpp 8720-8738Marzbani, P., Resalati, H., Ghasemian, A., and Shakeri, A. (2016). "Surface modification of talc particles with phthalimide: Study of composite structure and consequences on physical, mechanical, and optical properties of deinked pulp," BioRes. 11(4), 8720-8738.AbstractPDF

    Commercial talc was modified with phthalimide to produce a composite filler, which was characterized by Fourier transform infrared spectroscopy (FTIR), X-ray diffraction spectroscopy (XRD), X-ray fluorescence spectroscopy (XRF), and scanning electron microscope (SEM). It was used as a papermaking filler, and its efficiency was compared with that of plain commercial talc and when mixed with additives (i.e., cationic polyacrylamide and alum-rosin size). The results showed that phthalimide could be linked appropriately to the surface of talc particles through forming ester bonds with the surface hydroxyl groups. The brightness of the composite filler was more than that of the commercial filler due to a reduction in the impurities and removal of the metal compounds. Unlike other treatments, the brightness of the papers filled with modified talc (MT) was enhanced with increases in filler loading. In spite of reducing the paper strength in all treatments, the reduction was significantly less in the MT treatment, which implies the enhancement in particle tendency to develop hydrogen bonds in the fiber network.

  • Researchpp 8739-8755Govindan, V., Husseinsyah, S., and Leng, T. P. (2016). "Treated Nypa fruticans husk-filled regenerated cellulose biocomposite films," BioRes. 11(4), 8739-8755.AbstractPDF

    The effects of filler content and methacrylate acid (MAA) treated Nypa fruticans husk (NFH) on the mechanical properties, X-ray diffraction (XRD), thermogravimetric analysis (TGA), and morphology of NFH regenerated cellulose (RC) biocomposite films were investigated. Ionic liquid containing 8 wt% of lithium chloride (LiCl)/N,N-dimethylacetamide (DMAc) was used to dissolve microcrystalline cellulose (MCC) and NFH to produce NFH RC biocomposite films. Methacrylate acid was used as a modifying agent on the NFH to promote better mechanical and thermal properties for the resulting NFH RC biocomposite films. The results showed that the tensile strength, Young’s modulus, crystallinity index (CrI), moisture content, and thermal stability of the untreated NFH RC biocomposite films increased with increasing NFH content up to 3 wt% and decreased with further increments. The MAA-treated NFH showed improved tensile strength and Young’s modulus compared with the untreated NFH RC biocomposite films. The presence of MAA enhanced the crystallinity index (CrI), moisture resistance, and thermal stability of the NFH RC biocomposite films. Good interfacial interaction between the NFH and RC matrix was proven by scanning electron microscopy (SEM).

  • Researchpp 8756-8776Moya, R., Berrocal, A., Rodríguez-Zúñiga, A., Rodriguez-Solis, M., Villalobos-Barquero, V., Starbird, R., and Vega-Baudrit, J. (2016). "Biopulp from pineapple leaf fiber produced by colonization with two white-rot fungi: Trametes versicolor and Pleurotus ostreatus," BioRes. 11(4), 8756-8776.AbstractPDF

    Trametes versicolor and Pleurotus ostreatus were used for the biopulping from pineapple leaf fiber (PALF). PALF substrate was subjected to T. versicolor for 2 to 6 weeks and to P. ostreatus for 4 to 8 weeks. The yields, holocellulose and lignin contents, and extractives in ethanol-toluene mixture and in sodium hydroxide (NaOH) solution were evaluated. Fourier transform infrared spectroscopy (FTIR) spectra, thermogravimetric analysis (TGA), and color studies by L*a*b* systems were used for sample analysis. The results showed that the pulp yield was 55% to 70% with P. ostreatus and 35% to 50% with T. versicolor. Longer colonization periods increased the amount of holocellulose and decreased the amount of lignin and extractives in ethanol-toluene and NaOH solution. TGA showed an increase in intensity associated with cellulose, and the observed inflexion was attributed to lignin, which showed a tendency to fade. The FTIR spectrum showed high intensity between 3100 cm-1 and 3600 cm-1 (cellulose) and decreased intensity at 1730 cm-1 (lignin). For both fungi, the pulp color produced an increase in L* color parameter and decreased in yellowness, while little variation was observed in redness. The most appropriate colonization period was 5 weeks for P. ostreatus and 4 weeks for T. versicolor.

  • Researchpp 8777-879Li, P., Liu, Y., Lu, J., Yang, R., Li, H., and Wang, H. (2016). "Structural characterization and effect on enzymatic hydrolysis of milled wood lignin isolated from reed straw and corn stover pretreated with liquid hot water," BioRes. 11(4), 8777-8790.AbstractPDF
    To assess the possible effects of lignin on enzymatic hydrolysis, the structural characteristics of milled wood lignin (MWL) isolated from reed straw and corn stover pretreated with liquid hot water (LHW) at different severities were investigated. The changes in the chemical structure of the MWL were characterized by gel permeation chromatography, elemental analysis, differential scanning calorimetry, thermogravimetric analysis, Fourier transform infrared spectroscopy, and 1H and 13C nuclear magnetic resonance. The results showed that the MWL isolated from reed straw and corn stover pretreated with LHW was more condensed. The non-conjugated and conjugated ketone groups, as well as the ether bonds of the MWL, disappeared after LHW pretreatment, while the phenolic hydroxyl and methoxy groups increased. The carboxyl groups of MWL from reed straw increased after LHW pretreatment, whereas the carboxyl groups of MWL from corn stover decreased. When MWL was added into the enzymatic hydrolysis system, the filter paper activity of cellulase, the protein content, and the conversion of cellulose to glucose all decreased.
  • Researchpp 8791-8805An, Q., Wu, X. J., Han, M. L., Cui, B. K., He, S. H., Dai, Y. C., and Si, J. (2016). "Sequential solid-state and submerged cultivation of the white rot fungus Pleurotus ostreatus on biomass and the activity of lignocellulolytic enzymes," BioRes. 11(4), 8791-8805.AbstractPDF

    Sequential solid-state and submerged cultivation with various lignocellulosic biomasses as a substrate for lignocellulolytic enzyme production by Pleurotus ostreatus were assessed by measuring endoglucanase, xylanase, and laccase activities. An unconventional pre-culture method was established by cultivating the P. ostreatus mycelia in a solid substrate medium for an initial fungal growth phase, followed by a transition to submerged fermentation through adding a liquid culture medium. The lignocellulolytic enzymes of P. ostreatus in different fermentation methods revealed wide differences. The higher yields of endoglucanase (3152 ± 139 U/L), xylanase (3064 ± 40 U/L), and laccase (543 ± 21 U/L) were achieved by using the sequential solid-state submerged method compared to conventional solid-state and submerged cultivation. Generally speaking, sequential solid-state and submerged fermentation of cottonseed hull is favorable for laccase secretion, whereas sequential solid-state and submerged fermentation of corncob provides better production of hydrolytic enzymes. These results revealed that the nature of the lignocellulosic biomass and the fermentation method play an important role in the expression of lignocellulolytic enzymes. This indication would be helpful in optimizing the production of integrated industrial lignocellulolytic enzymes.

  • Researchpp 8806-8819Liu, X., Hua, W., and Wu, S. (2016). "Characterization of thermo-chemical degradation and pyrolysis properties for three kinds of biomass residues," BioRes. 11(4), 8806-8819.AbstractPDF

    This study investigated the thermo-chemical degradation and fast pyrolysis of watermelon seed shells (WSS), pumpkin seed shells (PSS), and sunflower seed shells (SSS). The raw materials and pyrolysis products were analyzed. The results showed that the carbon content (52.96%), hydrogen content (7.38%) and higher heating value (HHV) (23.88 MJ/kg) of PSS were highest, and the bio-oil from the PSS pyrolysis had high amounts of phenolic compounds. For SSS, the content of holocellulose (83.47 wt.%) was the highest, but the lignin content (13.62 wt.%) was lower than the other samples. The gas yield from the SSS pyrolysis was the largest and the bio-oil content of acids (acetic acid 36.53%) and ketones (1-hydroxy-2-propanone 9.90%) were higher. For WSS, the yield of the biochar was 39.14 wt.%. Additionally, the raw materials’ structures were similar. The thermal decomposition process of all seed shells had three stages, i.e. dehydration, active pyrolysis, and passive pyrolysis. In all three kinds of bio-oil, the components were mainly guaiacol-type and phenol-type. The guaiacol-type in the bio-oils from PSS (43.78%) and WSS (32.33%) were higher than in the bio-oil from SSS.

  • Researchpp 8820-8830Zhu, H., Yao, S., Jiang, L., Wang, S., and Qin, C. (2016). "Kinetics of adsorbable organic halogen formation during the first chlorine dioxide bleaching stage of eucalyptus kraft pulp," BioRes. 11(4), 8820-8830.AbstractPDF

    The emission standard for adsorbable organic halogen (AOX) has been adjusted as a mandatory assessment indicator in the papermaking industrial pollutants emission standards of China. To provide a theoretical basis to reduce AOX formation, a kinetic model of the first chlorine dioxide bleaching stage (D0) is presented for elemental chlorine-free (ECF) bleaching of eucalyptus kraft pulp. The kinetics of the D0 stage can be expressed as dW/dt = 314.6e-20.53/RT[H+]0.21[ClO2]0.41K0.98, where the reaction series for lignin, chlorine dioxide dosage, and H+ concentration are 0.98, 0.41, and 0.21, respectively. The reaction activation energy was 20.53 kJ.mol-1. R2 was greater than 0.9, which means that the model was shown to have high prognostic ability and feasibility. In the D0 stage, mostly lignin was removed and the reaction was fast. Much AOX was formed at the beginning of bleaching, and the reaction rate was primarily determined by the lignin content and chlorine dioxide dosage. H+ existed primarily as a catalyst and had little influence on AOX formation. The AOX formation occurs easily, as the reaction activation energy is less than 30 kJ.mol-1.

  • Researchpp 8831-8843Li, X., Gu, X., Lai, C., Ouyang, J., and Yong, Q. (2016). "Production of fumaric acid by Rhizopus oryzae in simultaneous saccharification and fermentation using xylo-oligosaccharides manufacturing waste residue," BioRes. 11(4), 8831-8843. AbstractPDF
    Production of fumaric acid from xylo-oligosaccharides manufacturing waste residue (XOR) by Rhizopus oryzae CICC 40351 was investigated in a simultaneous saccharification and fermentation (SSF) process. The fermentation conditions for SSF were optimized by an orthogonal design method to maximize the fumaric acid concentration. The highest fumaric acid concentration (12.54 g/L) was reached with a substrate loading of 5% (w/v) XOR in the SSF process at 38 °C. The fumaric acid concentration of the SSF process was 1.8 times greater than that of the separate hydrolysis and fermentation (SHF) process under the same conditions. In addition, the SSF process yielded 0.34 g/g of glucose, whereas the SHF process yielded only 0.20 g/g of glucose. The results indicated that the SSF process notably improved the production of fumaric acid from lignocellulose by R. oryzae.
  • Researchpp 8844-8859Fu, Q., Cloutier, A., and Laghdir, A. (2016). "Optimization of the thermo-hygromechanical (THM) process for sugar maple wood densification," BioRes. 11(4), 8844-8859.AbstractPDF

    Densified wood is a promising engineered wood product, especially for heavy-duty applications. This study optimized the temperature and duration of the thermo-hygromechanical (THM) densification process applied to sugar maple (Acer saccharum Marsh.) wood. The response variables studied were compression set recovery and hardness. The THM densification process was performed at three temperatures (180°C, 200 °C, and 220 °C), densification times (450 s, 900 s, and 1350 s), and post-treatment times (900 s, 1350 s, and 1800 s). Response surface methodology was used to analyze the impact of the three parameters. The effect of temperature on the density profile across thickness was also determined. The results suggested that the optimum densification conditions resulting in high hardness and low compression set recovery were obtained at a temperature of 180 °C, a densification time of 1004 s, and a post-treatment time of 1445 s. Additionally, the density of the densified samples was relatively homogeneous across thickness, although it was dramatically increased compared with control samples. However, density did not increase linearly with temperature. A much higher weight loss occurred at 220 °C, resulting in a significant decrease in density and hardness, whereas little compression set recovery was observed for sugar maple densified at this temperature.

  • Researchpp 8860-8874Shi, R., and Li, B. (2016). "Preparation and characterization of corn starch and lignosulfonate blend film with a high content of lignosulfonate," BioRes. 11(4), 8860-8874.AbstractPDF

    A degradable starch/lignin blend film was prepared using corn starch and sodium lignosulfonate via a casting and solvent evaporation method. The effect of sorbitol content on the swelling properties of starch/lignosulfonate blend films was investigated. The effect of lignosulfonate content on the swelling and mechanical properties was also studied. The results showed that when the mass ratio of sorbitol to starch changed over a wide range, from 0:9 to 9:9, the water absorption of the blend films increased at first and then decreased. When the mass ratio of lignosulfonate to starch changed in the same range, the ultimate stress of the blend films decreased markedly, while the water absorption and elongation at break did not show any regular pattern. When the mass ratios of sorbitol to starch and lignosulfonate to starch were both 6:9, the resultant film presented good elasticity and improved hydrophobicity compared to those without lignosulfonate.

  • Researchpp 8875-8889Sun, J., Shi, S., Wu, J., Xie, R., Geng, A., and Zhu, D. C. (2016). "Characterization of a salt-tolerant and cold-adapted xylanase from Bacillus cellulosilyticus," BioRes. 11(4), 8875-8889. AbstractPDF

    A xylanase (Xyn10A) gene from the saline-alkali-tolerant microorganism Bacillus cellulosilyticus DSM 2522 was cloned and expressed in Escherichia coli BL21 (DE3). The open reading frame was composed of 1008 base pairs, and it encoded 335 amino acid residues belonging to glycosyl hydrolase family 10. The optimal temperature and pH of the purified Xyn10A were 40 °C and 8.0, respectively. The Xyn10A was sensitive to heat and showed obvious cold-adapted activity, retaining 38.3%, 55.7%, and 82.9% of the optimal activity at 4, 20, and 30 °C, respectively. Xyn10A also showed a high level of NaCl tolerance. The highest activity was observed with 1.5 M NaCl. The specific enzyme activity of Xyn10A was as much as 163.8 U/mg. Kinetic assays showed that Km, Vmax, and Kcat were 2.56 mg/mL, 202.5 μM/min/mg, and 132.6 /s, respectively. Additionally, the main hydrolysis products using birchwood xylan as substrate were xylobiose, xylotriose, and xylotetraose, as determined by thin layer chromatography analysis. As a cold-adapted and salt-tolerant enzyme, Xyn10A is an ideal candidate for further research and biotechnological applications.

  • Researchpp 8890-8899Björngrim, N., Hagman, O., and Wang, X. (2016). "Multivariate screening of the weather effect on timber bridge movements," BioRes. 11(4), 8890-8899.AbstractPDF

    Monitoring displacements and weather impact of complex structures, such as a large cable-stayed footbridge, generates a large amount of data. To extract, visualize, and classify health-monitoring data for better comprehension, multivariate statistical analysis is a powerful tool. This paper describes screening to evaluate if principal component analysis is useful for health monitoring data. Principal component analysis (PCA) and projections to latent structures by means of partial least squares (PLS) modeling were used to achieve a better understanding of the complex interaction between bridge dynamics and weather effects. The results show that PCA gives a good overview of the collected data, and PLS modeling shows that winds from east and west best explain bridge movements.

  • Researchpp 8900-8913Shamaiirani, S., and Roohnia, M. (2016). "Dynamic modulus of wood containing water-resistant glue finger joint after severe steaming," BioRes. 11(4), 8900-8913.AbstractPDF

    The effect of steaming treatment on the dynamic modulus of oak wood (Quercus castaneifolia, C. A. Mey.; Fagaceae) containing a water resistant glue-finger joint was investigated. Sample joints were made with two different types of waterproof adhesives, polyurethane (PU) and epoxy, and the samples were tested by a free flexural vibration method according to flexural and longitudinal free vibration modes. Compared with the epoxy joints, the PU finger-joints retained elastic moduli closer to their initial values. In all three vibration tests, finger-jointed oak wood specimens with either glue retained their moduli of elasticity, after the steaming treatments. In the case of longitudinal-tangential (LT) vibration, some increases were observed for the evaluated elastic moduli. After steaming, the obtained dynamic values decreased. For epoxy-bonded specimens, the correlation coefficient in terms of the elastic modulus before and after steaming were weak. There were some acceptable PU-bonded specimens, but there was a considerable decrease after steaming.

  • Researchpp 8914-8928Song, X., Zhang, K., Han, B., Liang, J., Zhai, Z., and Du, L. (2016). "Anaerobic co-digestion of pig manure with dried maize straw," BioRes. 11(4), 8914-8928.AbstractPDF
    The anaerobic co-digestion of pig manure (PM) with dried maize straw (DMS) was studied at 35 °C with a volatile solid (VS) ratio (VSPM/VSDMS) of 1:2 in a continuously stirred tank reactor, and the digestions of mono-PM and mono-DMS were evaluated under the same conditions. The organic loading rates (OLRs) of 2, 3, and 4 g VS/L/d were studied and found to correspond to hydraulic retention times (HRTs) of 60, 40, and 30 d, respectively. Under the condition of long HRT and low OLR, PM could be degraded completely. The co-digestion of PM with DMS showed the most stable performance in TAN, whereas TAN in mono-PM increased with the increase of OLR. The specific methane yield (SMY) did not have a linear correlation with OLR, since HRT changed with different OLR. The maximum average SMY in the co-digestion reactor was 272 mL/g VS-fed at an OLR of 3 g VS/L/d and an HRT of 40 d. The SMY in mono-DMS digestion was the lowest and it decreased with the increase of OLR.
  • Researchpp 8929-8940Irfan, M., Lin, Q., Yue, Y., Ruan, X., Chen, Q., Zhao, X., and Dong, X. (2016). "Co-production of biochar, bio-oil, and syngas from Tamarix chinensis biomass under three different pyrolysis temperatures," BioRes. 11(4), 8929-8940.AbstractPDF

    Pyrolysis of Tamarix chinensis feedstock was performed at 300, 500, and 700 °C to investigate the characteristics of biochar, bio-oil, and syngas. Biochar yield decreased and syngas yield increased as the pyrolysis temperature increased. The biochar was characterized for elemental composition, surface, and adsorption properties. Values of pH, electrical conductivity (EC), ash, C, K, Na, and basic functional group contents all increased as the pyrolysis temperature increased, whereas P, Ca, Mg, and acidic functional groups decreased. The methylene blue adsorption capacity values were 1.78, 2.08, and 1.96 (mg g-1) and iodine 256.48, 255.51 and 76.42 (mg g-1) for the biochars produced at 300, 500, and 700 °C, respectively. The C and H contents in bio-oil ranged from 66 to 62% and 8 to 7%, while O changed from 25 to 29% when temperature was increased from 300 to 700 °C. The concentration of hydrocarbon gases, such as ethane, ethylene, propane, and acetylene, increased as the pyrolysis temperature increased. The sum of CO and CO2 occupied great percentage of the total gas, while the H2 concentration increased markedly to a maximum of 16% at 500 °C. Thus, T. chinensis is a potential feedstock for biochar and bioenergy production.

  • Researchpp 8941-8952Sulaiman, S. A., Guangul, F. M., Konda, R. E., Atnaw, S. M., and Moni, M. N. (2016). "Estimation of moisture content of oil palm fronds through correlation with density for the process of gasification," BioRes. 11(4), 8941-8952. AbstractPDF

    In the gasification process, one prominent factor that affects the quality of the resulting syngas is the moisture content of the biomass feedstock. Determining the moisture content of a feedstock is considered to be one of the challenges of the process. The information about moisture content of a feedstock is required to decide the need for further drying prior to the gasification process. In this study, a novel method was developed for the evaluation of the moisture content from density of oil palm fronds (OPF) in a sufficiently accurate manner for gasification process. A total of 147 samples from different sections of freshly pruned fronds were prepared. The density of each of the samples was determined from its weight and volume. A fine sand displacement method, using fine sand and a graduated cylinder, determined the volume of OPF. The moisture content of the OPF was determined from the weight difference of the samples before and after the drying process. The experiment implied a good correlation between moisture content and density of the biomass, in which the square of the correlation coefficient (R2) value was found to be satisfactory.

  • Researchpp 8953-8967Soltani, A., Hosseinpourpia, R., Adamopoulos, S., Taghiyari, H. R., and Ghaffari, E. (2016). "Effects of heat-treatment and nano-wollastonite impregnation on fire properties of solid wood," BioRes. 11(4), 8953-8967.AbstractPDF

    The effects of nano-wollastonite (NW) suspension impregnation on the fire-retarding properties of heat-treated solid wood of three species (beech, poplar, fir) were studied. Heat treatment was performed at two temperatures of 180 °C and 200 °C. Impregnation was carried out at a pressure of 3 bars for 30 min. The fire properties included ignition time, glowing time, back-darkening, back-splitting, back-firing, and length and width of the burnt area. Both impregnation with NW and heat-treatment generally improved all fire-retarding properties, although not always to a significant level. As a mineral material, NW acted like a physical shield against fire penetration into the texture of wood specimens, thus improving fire properties. Moreover, the high thermal conductivity coefficient of wollastonite increased the thermal conductivity of wood, therefore preventing the accumulation of heat at the point nearest to a piloted flame and contributing to the improvement of fire properties. The chemical degradation of wood cell components caused by heat-treatment further improved the fire properties. Cluster analysis indicated the significant effect of species on fire properties. Significant R-square values were found amongst fire properties related to the spread of fire on the surface of specimens. The combination of thermal modification and impregnation with NW provides suitable fire properties for solid wood.

  • Researchpp 8968-8980Ibraheem, S. A., Sreenivasan, S. S., Abdan, K., Sulaiman, S. A., Ali, A., and Abdul Majid, D. (2016). "The effects of combined chemical treatments on the mechanical properties of three grades of sisal," BioRes. 11(4), 8968-8980. AbstractPDF
    Different grades of sisal fibres (S3, STOW, and SUG) were immersed in five different treatment solutions: sodium hydroxide (NaOH) for 24 h; silane for 24 h; and NaOH followed by silane for 6, 12, and 24 h. The treated fibres were tested for bonding strength using the micro-droplet method. It was established that NaOH and silane treatments improved bonding strength with the unsaturated polyester resin that was used. However, it can be concluded that NaOH followed by silane (each for 6 h) produced the highest bonding strength compared with the other combined treatments. This is most likely because of fibre erosion caused by the chemicals in the other treatments, which causes fibres to lose the ability to bond with the resin. Fibres treated with silane had the highest bonding strength. The tensile mechanical properties, characterised using the single-fibre test method according to the ASTM standard C1557-03 (2008), showed that the NaOH treatment improved ultimate tensile strength, while the silane treatment decreased ultimate tensile strength for all sisal grades. Nevertheless, the ultimate tensile strength was reduced when the duration of the combined treatments was increased. The highest results for the mechanical properties were obtained from the combined treatments of NaOH followed by silane (each for 6 h).
  • Researchpp 8981-9001Laurent, A. B., Menard, J. F., Lesage, P., and Beauregard, R. (2016). "Cradle-to-gate- life cycle assessment of the portfolio of an innovative forest products manufacturing unit," BioRes. 11(4), 8981-9001.AbstractPDF

    Manufacturing companies are under pressure from consumers and legislation to reduce their environmental impacts. In some sectors where competition is particularly fierce, the ability to offer a product with a lighter environmental impact than the competition can be useful in significantly increasing market share. The forest industry, which harvests and processes wood, a renewable resource, also aims at being part of this trend towards transparency. Life cycle assessment (LCA) is often used to quantify the environmental footprint of harvested wood products (HWP). Based on a primary data inventory of four years of activity, this study presents an LCA of the portfolio of an innovative forest products manufacturer. The functional unit of that assessment is a cubic meter. A sensitive analysis on an economic allocation was also conducted. Because of loops in the studied system and flow conservation constraint, results of the portfolio LCA was verified using an organizational footprint assessment. From the material flow and the half-life of products, a bottom-up accounting method is suggested for integrating HWP in national greenhouse gas (GHG) inventories.

  • Researchpp 9002-9016Zhu, H., Wang, X., Chen, X., and Yu, G. (2016). "Effect of biomass char additives on the hydrogasification behavior of a bituminous coal," BioRes. 11(4), 9002-9016.AbstractPDF
    The hydrogasification behavior of a Chinese bituminous coal with three different biomass char additives, i.e., sargassum char (SG char), saw dust char (SD char), and wheat straw char (WS char), was studied in a pressurized fixed bed reactor. The effects of the biomass char amount (0 to 30%), pressure (0.1 to 4 MPa), and temperature (973 K to 1073 K) on hydrogasification reactivity of coal were investigated. The results showed that the SD char and WS char improved the hydrogasification reactivity of coal noticeably, but for the SG char, the improvement at 973 K was not obvious because of the high content of chlorine. For all samples, the hydrogasification reactivity increased with increasing temperature and pressure. Moreover, experiments involving coal with different ash of biomass chars were conducted to verify the catalytic effects of alkali and alkaline earth metal (AAEM) species in the biomass char.
  • Researchpp 9017-9035Fu, B., Ge, C., Yue, L., Luo, J., Feng, D., Deng, H., and Yu, H. (2016). "Characterization of biochar derived from pineapple peel waste and its application for sorption of oxytetracycline from aqueous solution," BioRes. 11(4), 9017-9035.AbstractPDF

    Physicochemical characteristics of biochar and its sorption potential for oxytetracycline (OTC) were investigated. Biochars from pineapple peel waste were produced via pyrolysis under oxygen-depleted conditions at 350 °C (BL350), 500 °C (BL500), and 650 °C (BL650), as well as the characteristics and polycyclic aromatic hydrocarbons contents of the samples were compared. The sorption kinetics of OTC onto the biochars was completed in three stages, i.e., a fast stage, a slow stage, and an equilibrium stage after 24 h. The kinetics data were perfectly fitted by the pseudo-second-order model with high correlation coefficients (R2 > 0.999). All of the sorption isotherms were nonlinear and well described by the Langmuir model. The Langmuir maximum sorption capacity (qmax) increased in the order of BL650 > BL500 > BL350. The thermodynamic parameters revealed that the sorption of OTC onto the biochars was spontaneous and endothermic. Fourier transform infrared spectroscopy (FTIR) of the biochars before and after sorption of OTC confirmed that the H-bonding interaction was the dominant sorption mechanism. The results demonstrated that biochars obtained from inexpensive and renewable materials could be utilized as a highly effective and environmentally friendly adsorbent for removing organic contaminants from wastewater.

  • Researchpp 9036-9046Hou, Y., Liu, C., Xu, J., Li, Y., and Hu, S. (2016). "Application of alkaline ionic liquids in the pretreatment process of eucalyptus kraft pulp," BioRes. 11(4), 9036-9046.AbstractPDF
    In order to explore the potential application of green solvent ionic liquids (ILs) in the kraft pulping process, eucalyptus wood was pretreated by [Mmim]DMP before normal pulping. The results showed that materials pretreated shortly by the ionic liquid had a higher yield and viscosity coupled with a lower potassium permanganate value and residual lignin content in the pulp, as a result of the cooking process. It was also inferred that alkaline [Mmim]DMP pretreatment could dissolve lignin effectively from fiber to result in a stronger binding force and more entangled properties. Paper tensile and burst strength were improved by about 40% and 60%, respectively. These results provide a new way for eucalyptus to be utilized in the kraft pulping process.
  • Researchpp 9047-9058Li, X., Zheng, K., Lai, C., Ouyang, J., and Yong, Q. (2016). "Improved itaconic acid production from undetoxified enzymatic hydrolysate of steam-exploded corn stover using an Aspergillus terreus mutant generated by atmospheric and room temperature plasma," BioRes. 11(4), 9047-9058.AbstractPDF

    Itaconic acid production by Aspergillus terreus (A. terreus) was investigated using the undetoxified enzymatic hydrolysate of steam-exploded corn stover as the sole carbon source. The fermentation conditions for A. terreus were optimized based on glucose as the carbon source. Unfortunately, wild-type A. terreus did not grow in the undetoxified enzymatic hydrolysate. Therefore, atmospheric and room temperature plasma (ARTP) mutagenesis was applied to obtain A. terreus mutant AT-90. A. terreus mutant AT-90 grew and secreted itaconic acid in the undetoxified enzymatic hydrolysate. The highest itaconic acid concentration (19.30 g/L) with a yield of 36.01% was obtained from the undetoxified enzymatic hydrolysate of 10% (w/v) steam-exploded corn stover. This work demonstrated that the A. terreus mutant generated by ARTP efficiently improved itaconic acid production from lignocellulose-based carbon source.

  • Researchpp 9059-9067Seo, J., Jeong, S. G., (2016). "Improvement of thermal conductivity of underlay foam for laminate flooring to reduce heating energy," BioRes. 11(4), 9059-9067.AbstractPDF

    In recent years, research on low-energy building materials has actively progressed, with a growing interest in eco-friendly building. Strong interest has also been shown in the wooden flooring sector to improve the thermal conductivity of under floor heating systems. This study focused on improving the thermal transfer performance of radiant floor heating systems by enhancing the characteristics of the existing polyethylene underlay foam (PE foam). The thermal conductivity of the modified PE underlay foam (MPE foam) was increased by 48.1% compared with that of the PE foam. The theoretical heat flux was also calculated for the thermal conductivity, the results of which showed that the heat flux of the MPE foam was enhanced by 24.1%, compared with that of the underlay foam. To confirm the theoretical results, flooring systems were installed in the laboratory as a replica for the experiment. The velocity of thermal transfer for the laminated flooring used with the MPE foam was slower than the engineered flooring in which adhesive was used. However, the velocity of transfer was faster for the laminate flooring incorporating the PE foam. In addition, after the heating was switched off, the heat storage capacity of the laminate flooring with the modified PE foam was the highest among the tested samples.

  • Researchpp 9068-9078Zhu, C., Guo, F., Guo, X., and Li, X. (2016). "In situ saccharification of cellulose using a cellulase mixture and supplemental β-glucosidase in aqueous-ionic liquid media," BioRes. 11(4), 9068-9078.AbstractPDF
    In situ enzymatic saccharification is one promising approach to efficiently convert non-food biomass to glucose as a platform chemical. The goal of the present research was to illustrate the catalytic behaviors and deactivation mechanisms of cellulase and cellobiase in an aqueous-ionic liquid (IL) media. The hydrolysis reaction rate was considerably increased because of the increased porosity and reduced crystallinity of the substrate. To lower the inhibitory effect of accumulated cellobiose on cellulase, a multi-enzyme synergetic system was explored. Compared with the single cellulase saccharification, addition of cellobiase resulted in a substantial increase in total reducing sugars (TRS) yield (88.0% vs. 59.1%) and glucose yield (40.6% vs. 28.9%) when the activity unit ratio of cellobiase/cellulase was 0.95. Cellulase showed a higher stability in aqueous 1-ethyl-3-methylimidazolium acetate ([EMIM]Ac) media. However, the activity of cellobiase quickly decreased, by 66.5%, after 6 h of incubation.
  • Researchpp 9079-9094Kučerová, V., Lagaňa, R., Výbohová, E., and Hýrošová, T. (2016). "The effect of chemical changes during heat treatment on the color and mechanical properties of fir wood," BioRes. 11(4), 9079-9094.AbstractPDF

    European silver fir (Abies alba L.) wood was heat-treated in an oven for 60 min at seven different temperatures of 100 °C, 150 °C, 200 °C, 220 °C, 240 °C, 260 °C, and 280 °C under atmospheric pressure in the presence of air. The effect of thermal treatment on the chemical composition, mechanical, and color properties of the wood was studied, and the mutual correlations between the investigated properties were evaluated. The bending strength/modulus of rupture (MOR) and the modulus of elasticity (MOE) were positively correlated with the total saccharides, glucose, mannose, and xylose content, where R ranged from 0.942 to 0.984. For changes in the wood color, very strong positive correlations between the total color difference and the contents of lignin and extractives were determined, where R = 0.968 and 0.945 respectively. Additionally, the total color difference was negatively correlated with the total saccharides, mannose, and xylose content, where R ranged from 0.876 to 0.938. The obtained data were evaluated by principal component analysis (PCA), where the components explained 93.1% of the total variance.

  • Researchpp 9095-9111Ispas, M., Gurau, L., Campean, M., Hacibektasoglu, M., and Racasan, S. (2016). "Milling of heat-treated beech wood (Fagus sylvatica L.) and analysis of surface quality," BioRes. 11(4), 9095-9111.AbstractPDF

    Several previous studies have investigated the effects of heat treatment on the chemical composition, along with the physical and mechanical properties, of wood from various species. However, the effects of these property changes upon the machining properties and surface quality of machined wood have been studied much less. The main goal of this work was to investigate the comparative cutting power consumption during milling and the resulting surface roughness of heat-treated and untreated beech wood (Fagus sylvatica L.). Several cutting regimes were tested by combining different values of rotation speed, feed speed, and cutting depth. The cutting power and the processing roughness were assessed and compared. The results clearly showed that the cutting power involved in the milling of heat-treated beech wood was up to 50% lower than that of untreated wood, but the processing roughness was slightly higher.

  • Researchpp 9112-9125Bryn, O., Bekhta, P., Sedliačik, J., Forosz, V., and Galysh, V. (2016). "The effect of diffusive impregnation of birch veneers with fire retardant on plywood properties," BioRes. 11(4), 9112-9125.AbstractPDF
    Wood is a natural, organic material that cannot be exposed to high temperatures, fire, or heat, especially when wood or wood-based materials are used as construction elements. The fire-extinguishing composition of di-ammonium phosphate, ammonium sulfate, and ammonium bromide (DAB) was used to increase the fire-resistance of birch plywood. The effects of various parameters of diffusive impregnation of the veneer (temperature and concentration of impregnating solution, duration of impregnation) were investigated. Their dependence was linear for the temperature of impregnating solution, and logarithmic for concentration of impregnating solution and duration of impregnation. Increased retention of fire retardant improved plywood fire resistance. However, considering the quality of impregnation, energy costs, and plywood properties, the following parameters of wet veneer impregnation are recommended: a temperature of impregnating solution of 22 °C, concentration of 30%, and duration of impregnation of 8 min.
  • Researchpp 9126-9141Tajik, M., Resalati, H., Hamzeh, Y., Torshizi, H. J., Kermanian, H., and Kord, B. (2016). "Improving the properties of soda bagasse pulp by using cellulose nanofibers in the presence of cationic polyacrylamide," BioRes. 11(4), 9126-9141.AbstractPDF

    Cellulose nanofiber (CNF) was used to improve the optical and strength properties of soda bagasse pulp (500 CSF) in the presence of cationic polyacrylamide (CPAM). Cationic polyacrylamide was added at 0.05, 0.1, and 0.15%, and cellulose nanofiber was added at 0.1, 0.5, 1, and 2% based on pulp O.D. Laboratory handsheets were prepared (60 g/m2), and optical and strength properties were measured according to TAPPI standards. Scanning electron microscopy and atomic force microscopy images showed that empty spaces between fibers decreased under CPAM/CNF treatments. The effect of the additives and their addition level on all the measured paper properties was significant at the 99% confidence level. The light scattering coefficient, brightness, and whiteness increased with the addition of cellulose nanofibers, but the light absorption coefficient, yellowness, and opacity decreased. At the highest levels of the additives (2% CNF and 0.15% CPAM), the tensile and burst strengths of handsheets increased by 33% and 15%, respectively. Generally, cellulose nanofibers/cationic polyacrylamide complexes improved the optical and strength properties of bagasse pulp.

  • Researchpp 9142-9153Ali, A., Rassiah, K., Othman, F., Lee, H. P., Tay, T. E., Hazin, M. S., and Megat Ahmad, M. M. H. (2016). "Fatigue and fracture properties of laminated bamboo strips from Gigantochloa scortechinii polyester composites," BioRes. 11(4), 9142-9153.AbstractPDF

    The fatigue and fracture properties of bamboo fiber composites made of woven layers were investigated. This study utilized a specific type of bamboo species named Gigantochloa scortechinii (Buluh Semantan). In these experiments, unsaturated polyester (UP) and bamboo fiber (BF) strips were prepared through a hand lay-up technique using 3-mm thick aluminum mould. The composite bamboo strips had a thickness of 1.5 mm. The strips were woven together to make a single layer. The layer was then laminated into several thicknesses. The specimens were then characterized using fatigue and fracture tests. A fatigue limit of 30 MPa and fracture toughness of 5 to 8 MPa √m were obtained. These findings suggest that the bamboo strips, based on unsaturated polyester, provided relatively good fatigue and fracture properties and a good method of reinforcing fibers to combat fatigue and fracture failures.

  • Researchpp 9154-9161Tao, Y., and Li, P. (2016). "Analyzing the relationships between processing parameters and fractal dimension of void size on cross-sections of oriented strandboards," BioRes. 11(4), 9154-9161.AbstractPDF

    Oriented strandboards (OSB) having various properties were constructed by varying processing parameters including strand thickness, strand length, and panel density. A calculation method was developed for analyzing the fractal dimension of void size (FDVS) on the cross-section of OSB samples based on a computer image processing technique and the fractal geometry theory. The results showed that The FDVS on the cross-section of OSB varied with different processing parameters. The FDVS decreased with strand thickness and increased with panel density, whereas the FDVS irregularly changed with strand length. Especially for panels with the same overall porosity, the FDVS was dependent on the internal structure. Therefore, the FDVS could be a useful additional parameter for characterizing the internal structure of OSB.

  • Researchpp 9162-9174Li, G., Wang, Q., Lv, P., Ding, Z., Huang, F., Wei, Q., and Lucia, L. A. (2016). "Bioremediation of dyes using ultrafine membrane prepared from the waste culture of Ganoderma lucidum with in-situ immobilization of laccase," BioRes. 11(4), 9162-9174.AbstractPDF

    A one-step method for laccase production and immobilization using the waste culture of Ganoderma lucidum (G. lucidum) was developed, and the laccase was immobilized by the mycelium, which was in the form of a white membrane consisting of superfine fibers. This medical and edible membrane was characterized by scanning electron microscope (SEM), and the fiber diameter was found to be between 1 and 3 μm, with a porous structure formed in the membrane. Fourier transform infrared spectroscopy (FT-IR) and thermogravimetric analysis (TGA) showed that the membrane contained polysaccharide groups and had good thermal resistivity. The membrane was used for the decolorization of methyl violet and malachite green, while the MTT test showed that the membrane had good biocompatibility. The experimental results indicated that the membrane might be applicable for other environmental protection applications in the future.

  • Researchpp 9175-9189Mukri, B. D., Krushnamurty, K., Chowdhury, A., Suryakala, D., and Subrahmanyam, C. (2016). "Alkali-treated carbonized rice husk for the removal of aqueous Cr(IV)," BioRes. 11(4), 9175-9189.AbstractPDF

    Rice husk was chemically modified for the preparation of activated carbon. Rice husk was treated with nitric acid and carbonized at 700 C. After carbonization, the resulting rice husk char was treated with NaOH at room temperature. The 5 M NaOH-treated rice husk had the highest surface area (750 m2/g). Proximate analysis of activated carbon confirmed that NaOH treatment removed silica completely. Temperature programmed decomposition (TPD) graphs showed that the total gas contents (CO and CO2) liberated by CRH and H2O-treated CRH and CRH5M were 2l5 μmol/g, 390 μmol/g, and 970 μmol/g, respectively. The adsorption studies of the activated carbon during Cr(VI) removal from the aqueous medium indicated that CRH5M showed the highest rate of adsorption. The effect of adsorbent dosage, Cr(VI) concentration, pH, and temperature were studied to determine the best removal efficiency. With a decrease in pH from 4.4 to 2, the adsorption capacity increased from 3 mg/g to 25.2 mg/g. The adsorption of Cr(VI) followed pseudo-second-order behaviour. The changes in Gibbs free energy, enthalpy, and entropy affected by thermodynamic parameters were found to be negative, which confirmed that the adsorption of Cr(VI) on CRH5M is spontaneous, exothermic, and favours low temperatures.

  • Researchpp 9190-9204Xing, X., Fan, F., Shi, S., Xing, Y., Li, Y., Zhang, X., and Yang, J. (2016). "Fuel properties and combustion kinetics of hydrochar prepared by hydrothermal carbonization of corn straw," BioRes. 11(4), 9190-9204.AbstractPDF

    The potential of using hydrothermal carbonization (HTC) on corn straw (CS) was studied for the production of solid fuel. The effects of hydrothermal conditioning on the mass yield, energy yield, higher heating value (HHV), H/C and O/C atomic ratios, the morphology, and equilibrium moisture content (EMC) of hydrochars were examined by varying the reaction temperature (170 °C, 200 °C, 230 °C, and 260 °C) and the residence time (15 min and 30 min). The results demonstrated that the solid fuel properties of hydrochar produced at 230 °C for 30 min had an appropriate HHV of 20.51 MJ/kg, a mass yield of 64.80%, and an energy yield of 77.41%. The physical structure changed because of hydrothermal carbonization and the hydrophobicity of hydrochar increased in comparison to raw corn straw after hydrothermal carbonization. The combustion characteristics and kinetic parameters of raw corn straw and hydrochar were calculated based on the thermogravimetric curves according to Arrhenius equation. The activation energies of hydrochars were larger than that of raw corn straw. The comprehensive combustibility index (S) of raw corn straw was greater than that of hydrochar when the reaction temperature and residence time were 230 °C and 30 min, respectively.

  • Researchpp 9205-9218He, G., Xie, L., Wang, X., Yi, J., Peng, L., Chen, Z., Gustafsson, P. J., and Crocetti, R. (2016). "Shear behavior study on timber-concrete composite structures with bolts," BioRes. 11(4), 9205-9218.AbstractPDF

    The key point of design for timber-concrete composite structure is to ensure the reliability of shear connectors. This study examined the mechanical properties of bolt-type connectors in timber-concrete composite structures theoretically and experimentally. The theoretical study was based on the Johansen yield theory (European Yield Model). Push-out specimens with different bolt dimensions were tested to determine the shear capacity and slip modulus. According to the experimental results, bolts yielded without timber or concrete cracks when the stiffness of bolts was not very great. The shear capacity and slip modulus of the bolt connectors were directly proportional to the diameter of the bolt. The strength of concrete was found to significantly affect the shear capacity of bolt connectors. Comparison between the theoretical and the experimental shear strength results showed reasonable agreement.

  • Researchpp 9219-9230Serna-Diaz, M. G., Arana-Cuenca, A., Medina-Marin, J., Seck-Tuoh-Mora, J. C., Mercado-Flores, Y., Jiménez-González, A., Téllez-Jurado, A. (2016). "Modeling of sulfite concentration, particle size, and reaction time in lignosulfonate production from barley straw using response surface methodology and artificial neural network," BioRes. 11(4), 9219-9230.AbstractPDF
    Barley straw is a lignocellulosic biomass that can be used to obtain value-added products for industrial applications. Barley straw hydrolysis with sodium sulfite facilitates the production of lignosulfonates. In this work, the delignification process of barley straw by solubilizing lignin through sulfite method was studied. Response surface methodology and artificial neural network were used to develop predictive models for simulation and optimization of delignification process of barley straw. The influence of parameters over sulfite concentration (1.0 to 10.0%), particle size (8 to 20), and reaction time (30 to 90 min) on total percentage of solubilized material was investigated through a three level three factor (33) full factorial central composite design with the help of Matlab® ver. 8.1. The results show that particle size and sulfite concentration have the most significant effect on delignification process. Both techniques, response surface methodology and artificial neural networks, predicted the lignosulfonate yield adequately, although the artificial neural network technique produced a better fit (R2 = 0.9825) against the response surface methodology (R2 = 0.9290). Based on these findings, this study can be used as a guide to forecast the potential production of lignosulfonates from barley straw using different experimental conditions.
  • Researchpp 9231-9243Vetráková, M., Ďurian, J., Seková, M., and Kaščáková, A. (2016). "Employee retention and development in pulp and paper companies," BioRes. 11(4), 9231-9243.AbstractPDF

    The aim of this paper is to present the opinions of professionals from the pulp and paper industry about employee development, as well as the necessity of competent employee retention. These opinions are different as a result of different expectations of employees and managers. The methodology of the paper is based on the following axiom: managers prioritize the processes of human resources management closely related to key employee retention improvement. To achieve the aim of the study, the largest pulp and paper companies in Slovakia were selected. Human resource managers and other professionals were asked about their opinions and attitudes about developing and retaining employees. Results of the research established that pulp and paper companies in Slovakia are significantly reflecting changes in technology and organization of work in the process of employee development. These companies also adopt the values and impacts of an intercultural environment in human resource management systems. The most important process affecting the development of employees is the possibility of professional training and development of competencies improving the performance. Due to changes in the external and internal environment, it is necessary to periodically review and assess the effectiveness of the policies and procedures affecting the development and retention of the employees.

  • Researchpp 9244-9254Klarić, M., Oven, P., Gorišek, Ž., Španić, N., and Pervan, S. (2016). "Yield of cold stirred maceration and extraction of milled European black alder wood and bark using different solvents," BioRes. 11(4), 9244-9254.AbstractPDF

    Wood extractives, especially polyphenols, have great influence on the xylem colour of many wood species, which affects the success of hydrothermal wood processing, such as wood drying. One such wood species is European black alder (Alnus glutinosa (L.) Gaertn.), which is prone to forming intense and uneven reddish-orange or reddish-brown discolourations immediately upon harvesting and processing. However, there is lack of published scientific data on the wood and bark extractives of black alder, as well as the most suitable solvents to extract them. In this work, total soluble extractives, phenols, and flavonoids have been quantified in the wood and bark of black alder. Furthermore, the influence of four different polar organic solvents and deionized water on extractives removal yields has been measured. It was found that the bark has much higher levels of extractives as compared to the wood. Furthermore, it has been found that the highest extractive yields were obtained by using methanol as the extraction solvent for all observed compound group classifications.

  • Researchpp 9255-9272Li, Y., Huang, H., Wu, G., and Chang, Z. (2016). "Straw degradation behaviors under different conditions of relative air humidity and ultraviolet-A irradiation," BioRes. 11(4), 9255-9272.AbstractPDF

    In this study, straw was degraded continuously for 150 days under one of three levels of relative air humidity (RH) (90%, 60%, or 30%) to estimate the effect of humidity on straw biodegradation. Moreover, straw was treated with ultraviolet (UV)-A irradiation + 90% RH for 180 days to evaluate the interaction between photodegradation and biodegradation. The effects of 30% and 60% RH on straw degradation was inconspicuous. Straw mass losses at 90% RH and UV-A + 90% RH were 18.5% and 39.1%, respectively. BIOLOG analysis showed that filamentous fungi played a major role in straw biodegradation. Thermogravimetric analysis showed that treatment with UV-A + 90% RH tended to increase the maximum pyrolysis rate and decreased the initial pyrolysis temperature. Compared with 90% RH, infrared spectra analysis showed that functional groups of UV-A + 90% RH treatment, e.g., –CH, –C=O, and the benzene ring structure, clearly decreased. Straw-degrading bacteria were observed by scanning electron microscopy at the beginning and end of UV-A + 90% RH treatment. Results highlight the role of humidity in the degree of straw biodegradation by filamentous fungi. Straw degradation is accelerated by the combined action of photodegradation and biodegradation under high UV-A irradiation and high humidity.

  • Researchpp 9273-9279Mirski, R., Dziurka, D., and Czarnecki, R. (2016). "The possibility of replacing strands in the core layer of oriented strand board by particles from the stems of rape (Brassica napus L. var. napus)," BioRes. 11(4), 9273-9279.AbstractPDF

    In this study, reducing the density of oriented strand board (OSB) in the core layer where strands were replaced by rape straw particles was evaluated. The use of rape particles in the core layer did not significantly affect the mechanical properties of OSB. This type of board had only slightly deteriorated properties compared with conventional OSB. However, with a decreasing density, significant changes occurred in the modulus of rupture (MOR) and modulus of elasticity (MOE) determined for the shorter axis. The lowest possible density value was determined based on statistical analysis, allowing for the production of OSB that met the requirements of EN 300 (2006) for OSB type 3. The analysis showed that panels of this type can be produced at a density of 530 kg/m3.

  • Researchpp 9280-9289Yuan, J., Wang, T., Huang, X., and Wei, W. (2016). "Effect of wet-end additives on the results of alkyl ketene dimer sizing after adding bacterial cellulose," BioRes. 11(4), 9280-9289.AbstractPDF

    Bacterial cellulose is a common research additive in the paper industry because it has unique and favorable characteristics. In this study, the effect of adding bacterial cellulose to an alkyl ketene dimer (AKD) sizing agent was investigated to optimize the dosage of bacterial cellulose, the retention system (cationic starch (CS), cationic polyacrylamide (CPAM)), and the sizing enhancement agents (polyamideamine-epichlorohydrin (PAE) and chitosan). The results showed that the addition of bacterial cellulose had a negative effect on AKD sizing. Meanwhile, the addition of 5% bacterial fiber had a slight but negligible effect on paper sizing. The retention system improved AKD sizing and the dual retention system with CS, and CPAM improved sizing up to 60%. When 0.2% PAE and chitosan were added simultaneously, the sizing degree increased by 42.8% and 47.6%, respectively.

  • Researchpp 9290-9301Yuan, J., Wang, T., Huang, X., and Wei, W. (2016). "Dispersion and beating of bacterial cellulose and their influence on paper properties," BioRes. 11(4), 9290-9301.AbstractPDF

    Three dispersion instruments (a standard laboratory disintegrator, PFI beater, and ultrasonic cell disrupter) were tested to determine their effects on the dispersion of bacterial cellulose (BC) wet films. After treatment with a standard 10000 r disintegrator treatment, there was still a large number of undispersed fiber bundles in the BC suspension. The BC films were dispersed well after PFI beating revolution at 30000 r, and the cationic charge demand of the BC suspension reached 2.4 × 10-4 eq·g-1. The ultrasonic cell crusher was altogether unsuitable for BC dispersion. The ultrasonic cell crusher only separated the BC from the bundles. The properties of the resulting paper indicated that the physical strength of paper containing BC dispersed by the PFI beater was higher than that of the sample produced via standard laboratory disintegrator. Well-dispersed BC was distributed evenly among the plant fibers, which benefitted the combination of BC and plant fiber to improve the physical properties of the paper sheets.

  • Researchpp 9302-9310Pinkowski, G., Krauss, A., and Sydor, M. (2016). "The effect of spiral grain on energy requirement of plane milling of Scots pine (Pinus sylvestris L.) wood," BioRes. 11(4), 9302-9310.AbstractPDF

    The effect of spiral grain angle on the cutting power was tested during plane milling of Scots pine wood. It is known that cutting resistance depends on the arrangement of grain in relation to the direction of woodworking operations. In this work, up-milling (conventional cutting) was applied, as well as two woodworking techniques: with the grain and against the grain. Tests were conducted on samples differing in their position at the stem cross-section, one located closer to the circumference with the spiral grain angle of 11.5° and the other located closer to the pith, in which the spiral grain angle was 7.5°. This analysis confirmed significant differences in cutting power recorded for different values of spiral grain angle and depending on the applied cutting techniques. Cutting power at milling with the grain was greater than at milling against the grain. For samples with a smaller spiral grain angle a lower cutting power was recorded than for samples with a greater spiral grain angle. Differences in cutting power requirement between milling with the grain and against the grain increase with an increase in spiral grain angle.

  • Researchpp 9311-9324Sarip, H., Hossain, M. S., Negm, M., Mohamad Azemi, M. N., and Allaf, K. (2016). "In situ autohydrolysis for the glucose production from sago pith waste with DIC technology," BioRes. 11(4), 9311-9324.AbstractPDF
    Instant controlled pressure drop (DIC) technology was utilized in the production of glucose from sago pith waste (SPW). In situ autohydrolysis was conducted in a DIC reactor to obtain the maximum glucose production. The influence of pressure, acid concentration, and treatment time on the glucose yield from SPW subjected to DIC-assisted in situ autohydrolysis was determined, and the experimental conditions were optimized using the response surface method. The results showed that the linear term of acid concentration and the quadratic terms of pressure and time had a significant effect on the glucose yield. The optimized experimental conditions for maximum glucose production (48.21%) from SPW subjected to DIC-assisted autohydrolysis were a pressure of 0.1 MPa, acid concentration of 0.1 M, and time of 4 min. The findings demonstrated that DIC technology has the potential to be utilized for the commercial production of glucose from SPW.
  • Researchpp 9325-9339Razali, N., Sapuan, S. M., Jawaid, M., Ishak, M. R., and Lazim, Y. (2016). "Mechanical and thermal properties of roselle fibre reinforced vinyl ester composites," BioRes. 11(4), 9325-9339.AbstractPDF
    Roselle (Hibiscus sabdariffa L.) bast fibre reinforced vinyl ester (VE) was prepared using a hand lay-up method and an internal mixer. The composite samples were prepared under two different parameters: with various fibre contents; and without fibre (neat VE). The mechanical properties (tensile and impact strength) and thermal properties were investigated. The morphological properties of impact fracture samples were studied using a scanning electron microscope (SEM). Roselle fibre reinforced VE (RFVE) composites showed increased tensile strength and tensile modulus. The highest tensile strength and modulus were at 20vt% fibre loading. However, impact strength decreased as the fibre loading increased. SEM showed that there was good fibre/matrix adhesion and fibre dispersion for 20% fibre loading, which was reflected in the good tensile strength properties. However, fibre agglomeration was seen at higher fibre loads. The results from thermogravimetric analysis (TGA) and derivative thermogravimetric analysis (DTG) showed three major degradations of the RFVE, which were the loss of moisture content, degradation of hemicelluloses, and degradation of cellulose. The thermal analysis showed enhancements in the residual content of the composite materials, thereby improving the thermal stability. However, there was no major difference seen in the degradation temperature.
  • Researchpp 9340-9349Marques, A. F. S., Martins, C. E. J., Dias, A. M. P. G., Costa, R. J. T., and Morgado, T. F. M. (2016). "Assessment of reuse potential of maritime pine utility poles for structural applications after removal from service," BioRes. 11(4), 9340-9349.AbstractPDF

    There has been a strong recent effort to develop procedures that prevent the unnecessary replacement of timber utility poles. Even when assessments show that the utility pole needs to be replaced, there are many cases in which the removed utility poles can be reused. The aim of this study was to determine the mechanical properties of Maritime Pine (Pinus pinaster (Ait.)) utility poles removed from service (UPRFS) in order to assess their ability to be reused in structural applications. A sample of 51 UPRFS in Portugal was selected, and visual and mechanical properties were evaluated through non-destructive and destructive tests. Dynamic modulus of elasticity (MOEdyn) was correlated with bending strength (MOR) (r = 0.43) and modulus of elasticity (MOE) (r = 0.71). UPRFS showed a decrease of 14% and 6% in the mean values of MOR and MOE, respectively, when compared with new utility poles. A high variability and low values were obtained for MOR. These results highlight the reuse potential of the maritime pine utility poles for structural applications. Furthermore, the determined properties of UPRFS could be improved with a more stringent selection process that discards utility poles showing severe damage or by removing damaged areas in the utility poles.

  • Researchpp 9350-9358Villasante, A., Laina, R., and Vignote, S. (2016). "Effect of vacuum and pressure treatments on the mechanical properties and moisture balance of wood from Pinus sylvestris," BioRes. 11(4), 9350-9358.AbstractPDF

    Several works have analyzed the alteration in the mechanical strength of wood after the application of protective substances. However, it remains unclear whether the significant differences obtained are caused by the protective substances, the pressure and vacuum conditions used in the treatment, or the simultaneous effect of both. In this study, 123 wood samples from Pinus sylvestris were tested for bending, and 85 samples were tested for compression strength parallel to the grain. These samples were randomly distributed in three groups (treated with water pressure, water vacuum, and control samples simply submerged in water). The results indicated that there was no difference in mechanical properties between the treated and untreated samples. In contrast, significant differences were detected in equilibrium moisture after a prolonged drying process.

  • Researchpp 9359-9372Kasal, A., Kuşkun, T., Haviarova, E., and Erdil, Y. Z. (2016). "Static front to back loading capacity of wood chairs and relationship between chair strength and individual joint strength," BioRes. 11(4), 9359-9372.AbstractPDF
    The relationship between the static front to back loading capacity of chairs and the moment capacities of the joints used in their side frames was investigated. The secondary purpose of the study was to determine the effect of tenon sizes on front to back loading capacity of chairs. The moment capacities of round edge mortise and tenon L-shaped and T-shaped joints constructed of Turkish beech (Fagus orientalis L.) with cross sections and tenon sizes identical to those used in the chairs were first determined. Tenons varied from 30, 40, and 50 mm in width and 30, 40, and 50 mm in length. Joints were assembled with 65% solid polyvinylacetate (PVAc) adhesives. Front to back loading tests were then performed on the chairs according to the method adopted by the American Library Association (ALA). The results indicated that front to back loading capacity increases as either tenon width or length increases. Highest joint moment capacities were obtained when L-shaped joints were constructed with 50 mm wide by 50 mm long tenons and T-shaped joints were constructed with 40 mm wide by 50 mm long tenons. Finally, the strength of chairs could be reasonably predicted from the strength of joints.
  • Researchpp 9373-9385Zeidler, A., and Borůvka, V. (2016). "Wood density of northern red oak and pedunculate oak grown in former brown coal mine in the Czech Republic," BioRes. 11(4), 9373-9385.AbstractPDF

    This study deals with the characteristics of wood of two different species of oaks, the non-native northern red oak (Quercus rubra L.) and the native pedunculate oak (Quercus robur L.), growing in a reclaimed surface brown coal mine in the Czech Republic. The differences in the wood density of the aforementioned species, including the impact of position in the trunk, were examined. The impact of annual ring width and the proportion of latewood on density were also evaluated. The density of Q. robur wood reached 707 kg·m-3, which was significantly higher than that of the North American species, which reached 654 kg·m-3. Moreover, in the radial direction, the density increased in the direction from the pith toward the bark for both Q. rubra, and Q. robur. In the vertical direction, the density reached its highest value at the basal part of the trunk, but statistically, this assertion was only significant for Q. rubra. The effects of annual ring width and the proportion of latewood on density were shown to be statistically very low for both oak species.

  • Researchpp 9386-9399Olenska, S., Smardzewski, J., and Beer, P. (2016). "The stiffness of one-sided, asymmetrically veneered composites," BioRes. 11(4), 9386-9399.AbstractPDF

    The goal of the study was to analyse of the stiffness of one-sided, asymmetrical veneered boards by investigating the influence of glue type and board thickness on deflection and stress distribution on each composite layer. A specially designed stand that measured the whole area of the board was used to empirically measure the asymmetrically veneered elements. The theoretical measurements were taken using the Finite Elements Method in the Autodesk Mechanical Simulation 2015® program. All elements of composites including veneer (beech), glue-line (polyisocyanate and poly (vinyl acetate)), and the wood-based panel were simulated as elastic materials.

  • Researchpp 9400-9420Liu, X. Y., Timar, M. C., Varodi, A. M., and Yi, S. L. (2016). "Effects of ageing on the color and surface chemistry of Paulownia wood (P. elongata) from fast growing crops," BioRes. 11(4), 9400-9420.AbstractPDF

    The behavior of paulownia wood (Paulownia elongata) was investigated using three different ageing tests: simulated natural ageing under the influence of light under indoor conditions, temperature-induced ageing in the dark, and UV-induced ageing. Ageing effects were evaluated by color measurements in the CIE Lab system. Simulated natural ageing of wood in indoor conditions (6 months) and UV-accelerated ageing (72 h) are complex and dynamic processes, which resulted mostly in yellowing of the samples due to photo-degradation. Temperature-induced ageing (288 h at 100 C) resulted mostly in a rapid and visible darkening of the paulownia wood. Comparative in-time evolution of color changes during accelerated UV ageing testing and simulated natural ageing testing under indoor conditions allowed the estimation of an acceleration index of about 50X. Fourier transform infrared spectroscopy (FTIR) was used to examine specific chemistry changes occurring during these ageing tests. UV light from natural or artificial sources caused primarily lignin degradation followed by oxidative processes leading to carbonyl-containing chromophores. Temperature-induced partial degradation of hemicelluloses and oxidative processes resulted in the formation of chromophores containing mostly conjugated carbonyl groups. This research highlighted that paulownia wood (P. elongata) is quite sensitive to ageing under the action of light and temperature, which cause notable color and surface chemistry changes.

  • Researchpp 9421-9437Salem, M. Z. M., Elansary, H. O., Elkelish, A. A., Zeidler, A., Ali, H. M., Mervat, E. H., and Yessoufou, K. (2016). "In vitro bioactivity and antimicrobial activity of Picea abies and Larix decidua wood and bark extracts," BioRes. 11(4), 9421-9437.AbstractPDF
    Picea abies and Larix decidua were subjected to GC/MS analyses, and antimicrobial (fungi and bacteria) assays of their stem wood and bark extracts were investigated. L. decidua bark extract exhibited the highest antifungal and antibacterial activities against the microorganisms that were screened. The microbes Penecillium ochrochloron and Aspergillus ochraceus were the most sensitive to the extracts, whereas Candida albicans was the most resistant fungus. L. decidua wood and bark did not exhibit much variation in their antibacterial activities, except against Micrococcus flavus and Pseudomonas aeruginosa. The bacterium most sensitive to the extracts was Escherichia coli, whereas the most resistant was M. flavus. 13-epimanool and α-cedrol were the main components of P. abies wood extract. The main components in its bark were abietic acid, astringin, dehydroabietic acid, and α-terpineol. The main chemical compounds in L. decidua wood extract were abietic acid, oleanolic acid, duvatrienediol, and larixol. The main chemical compounds in its bark were (-)-2,9-dihydroxyverrucosane and larixol. The study revealed that P. abies and L. decidua stem wood and bark extracts contain several compounds that have antimicrobial activities towards diverse human pathogenic, food, and agricultural microbes. These results might guide in future searches for novel natural products with chemotherapeutic uses.
  • Researchpp 9438-9454Mohammed, A. A., Bachtiar, D., Siregar, J. P., Rejab, M. R. M., and Hasany, S. F. (2016). "Physicochemical study of eco-friendly sugar palm fiber thermoplastic polyurethane composites," BioRes. 11(4), 9438-9454.AbstractPDF
    The physicochemical properties of an innovative and environmentally friendly composite material based on sugar palm fiber (SPF) and thermoplastic polyurethane (TPU) were examined. The base material with short fibers was extruded and hot pressed to produce the TPU-SPF composites with different synthetic parameters. Operating parameters including temperature for extrusion (170 to 190 °C), rotational velocity (30 to 50 rpm), and fiber particle sizes (160, 250, and 425 µm) were investigated. The aims were to optimize rotational velocity, temperature, and fiber size of the TPU-SPF composites. Firstly, the influence of rotation of velocity and temperature on the tensile properties was investigated. Secondly, effects of different fiber sizes on tensile, flexural properties, and impact strength as per ASTM standards were tested. The morphological, thermal, and physicochemical properties of the synthesized TPU-SPF composites were ascertained with Fourier transform infrared spectroscopy (FT-IR), scanning electron microscopy (SEM), X-ray diffraction (XRD), and thermogravimetric analysis (TGA). The optimal results were observed with a temperature of 190°C and a rotational velocity of 40 rpm. Meanwhile, the strength and modulus for tensile and flexural were best for fiber size 250 µm. Moreover, the impact strength reached a peaking trend at 250 µm fiber size.
  • Researchpp 9455-9466Feng, Y., Lei, B., Liang, Y., Zhong, H., Yin, X., Qu, J., and He, H. (2016). "Changes in the microstructure and components of Eulaliopsis binata treated by continuous screw extrusion steam explosion," BioRes. 11(4), 9455-9466.AbstractPDF

    Eulaliopsis binata (EB) was pretreated by continuous screw extrusion steam explosion (SESE), with the aim of converting EB into useful materials on an industrial scale. The three main chemical components were characterized by component analysis using the Van Soest fiber detergent system, ultraviolet (UV) absorption spectrophotometry, gel permeation chromatography (GPC), and carbon-13 nuclear magnetic resonance (13C-NMR) spectroscopy. Changes in the contents of detergent soluble species in the Van Soest process revealed the partial degradation of hemicellulose and cellulose, and the partial removal of lignin. GPC indicated that the molecular weight of lignin decreased from 4194 to 3710 g/mol over the first three SESE pretreatment cycles, but then increased to 4592 g/mol following the fourth SESE pretreatment cycle. UV absorption and 13C-NMR results indicated the partial removal of lignin and the depolymerization and repolymerization of lignin during SESE pretreatment. Scanning electron microscopy (SEM) showed that the epidermis and parenchyma of EB were almost completely desquamated. X-ray diffraction (XRD) revealed that the crystallinity of EB initially increased and then subsequently decreased slightly, with increasing number of SESE pretreatment cycles. The varying physicochemical properties of EB resulting from different numbers of pretreatment cycles may find use in more diverse applications.

  • Researchpp 9467-9479Yasar, S. S., Fidan, M. S., Yaşar, M., Atar, M., and Alkan, E. (2016). "Determining the effect of seasonal variation in spruce (Picea orientalis L.) wood treated with various impregnations on combustion resistance," BioRes. 11(4), 9467-9479.AbstractPDF

    Prepared test specimens were surface treated and coated with synthetic and water-based outdoor varnishes after being chemically impregnated. The test specimens were left outdoors to determine the effects of impregnation and treatment on the wood during each of the four seasons. Caucasian spruce (Picea orientalis L.) test specimens were prepared and combustion analyses were performed. As a result of the combustion test, weight loss results, as compared with the control, were 89% lower in the spring specimens, 90% lower with impregnation, and 90% lower with the synthetic varnish coating. Furthermore, the O2 amount during combustion was found to be the highest in combustion with a flame source in the winter specimens (21%). The CO2 amount was the highest in combustion without a flame source for full-year specimens (20%). The CO amount was the highest in combustion without a flame source of full-year specimens (31,787 ppm), and the NO amount was the highest during glowing of full-year specimens (55 ppm). Final results showed impregnation with Tanalith-E and water-based varnish coating to be the most effective fire protective treatments.

  • Researchpp 9480-9495Shalbafan, A., Chaydarreh, K. C., and Welling, J. (2016). "Development of a one-step process for production of foam core particleboards using rigid polyurethane foam," BioRes. 11(4), 9480-9495.AbstractPDF

    A simulated one-step process has been developed for the production of foam core particleboards using rigid polyurethane as the core layer. The results showed that the different techniques used for surface layer separation (unresinated particles and sprayed water) and foam injections (open system and closed system) had no influences on panels’ characteristics. Mechanical properties (e.g., bending strength and internal bond strength) were mostly influenced by the surface layer thickness, while the water absorption and edge screw withdrawal were influenced by the foam cell structure. The use of sprayed water for surface layer separation doubled the formaldehyde emission (FE) of the panels. The addition of urea (based on 10% of the dry resin) to the sprayed water had a positive effect of reducing the final FE. Furthermore, increasing the surface layer thickness had a positive, linear relationship with FE.

  • Researchpp 9496-9505Kang, S., Zhang, G., Yang, Q., Tu, J., Guo, X., Qin, F. G. F., and Xu, Y. (2016). "A new technology for utilization of biomass hydrolysis residual humins for acetic acid production," BioRes. 11(4), 9496-9505.AbstractPDF

    Humins are a major byproduct formed from acid-catalyzed biomass hydrolysis and are usually considered as a low-value material. In this work, humins were completely degraded by a two-step technology, involving alkaline-catalytic hydrothermal treatment followed by wet oxidation. Using this technology, humins were converted to value-added acetic acid for first time. The highest acetic acid yield of 25.6% on a carbon basis or 37.2% on a mass basis was obtained with a purity of 46.2% based on the organic carbon in the aqueous product. This high-efficiency recovery of acetic acid is a new method for the effective utilization of humins, which is an important finding for biorefineries.

  • Researchpp 9506-9519Yao, Y., Tang, M., Yu, T., Liang, Y., and Hu, J. (2016). "Filtration performance of dual-layer filter paper with fibrillated nanofibers," BioRes. 11(4), 9506-9519.AbstractPDF
    Filter paper can be dramatically improved by the slip-flow effect and the huge specific surface area of nanofibers. Nanofibers can provide significant improvement in filtration efficiency with a relatively small reduction in permeability. In this study, nanofiber was prepared by fibrillation method using para-aramid fiber. A lab method was developed to laminate the nanofiber layer on a paper substrate by a wet-laid method. The filtration performance of dual-layer filter paper with fibrillated nanofibers was evaluated, and a theoretical model was developed to study the impact of nanofiber diameter on the filtration properties. It is found that in the fibrillation process, the number of trunk fibers decreased and nanofibers increased. With smaller fiber diameter, the pressure drop and filtration efficiency of dual-layer filter paper increased. Based on fibrous structure analysis, the dual-layer filter paper was able to perform well in self-cleaning filtration. The modeling results for pressure drop and filtration efficiency were close to the tested results, which provide a tool to understand the relationship between nanofiber diameter and filtration performance.
  • Researchpp 9520-9532Ma, Y., Jiang, J., Yan, W., Wang, K., Ying, H., and Xu, J. (2016). "Direct liquefaction of bamboo in ethanol-phenol co-solvent," BioRes. 11(4), 9520-9532.AbstractPDF

    Bamboo was converted into bio-oil via direct liquefaction with ethanol-phenol as solvent in a 250 mL Parr High-Pressure reactor. The influences of reaction parameters such as reaction time, liquefaction temperature, catalyst content, ratio of solvent/bamboo, and phenol concentration on the liquefaction yield were investigated. The highest liquefaction yield was 98.5 wt.% under the optimal conditions. The elemental analysis of the produced bio-oil revealed that the oil product had a higher heating value (HHV) of 29.5 MJ/kg, which was much higher than that of the raw material (16.4 MJ/kg). Gas chromatography mass spectrometry (GC-MS) and Fourier transform infrared spectrometry (FT-IR) measurements showed that the main volatile compounds in the crude bio-oil were phenolics and esters.

  • Researchpp 9533-9546Zhou, Z., Yin, J., Zhou, S., Zhou, H., and Zhang, Y. (2016). "Detection of knot defects on coniferous wood surface using near infrared spectroscopy and chemometrics," BioRes. 11(4), 9533-9546.AbstractPDF

    Lumber pieces usually contain defects such as knots, which strongly affect the strength and stiffness. To develop a model for rapid, accurate grading of lumbers based on knots, Douglas fir, spruce-pine-fir (SPF), Chinese hemlock, and Dragon spruce were used. The experiments explored the effects of modelling methods and spectral preprocess methods for knot detection, and investigated the feasibility of using a model built within one species to discriminate the samples from other species, using a novel variable selection method-random frog (RF)- to select effective wavelengths. The results showed that least squares-support vector machines coupled with first derivative preprocessed spectra achieved best performance for both single and mixed models. Models built within Dragon spruce could be used to classify knot samples from SPF and Chinese hemlock but not Douglas fir, and vice versa. Eight effective wavelengths (1314 nm, 1358 nm, 1409 nm, 1340 nm, 1260 nm, 1586 nm, 1288 nm, and 1402 nm) were selected by RF to build effective wavelengths based models. The sensitivity, specificity, and accuracy in the validation set were 98.49%, 93.42%, and 96.30%, respectively. Good results could be obtained when using data at just eight wavelengths, as an alternative to evaluating the whole spectrum.

  • Researchpp 9547-9559Hu, L., Lyu, S., Fu, F., and Huang, J. (2016). "Development of photochromic wood material by microcapsules," BioRes. 11(4), 9547-9559.AbstractPDF

    To develop a smart, colour-changing wood material, photochromic microcapsules were incorporated into coatings while painting veneered plywood. The properties of microcapsules and coatings were investigated. The colour-changing behaviour of the photochromic wood material in response to sunlight exposure was evaluated. The microcapsules exhibited sensitive colour-changing function and had good thermal stability. The prepared photochromic wood material spontaneously altered its appearance from the veneer colour to a blue colour following intensity changes of the sunlight exposure on the sample. The incorporation of microcapsules had no obvious effect on coating adhesion, but it obviously reduced coating wearability. With the microcapsule content increasing from 2.5% to 10% (of the coating weight), the colour difference (ΔE) of photochromic wood stimulated by sunlight linearly increased from 7.45 to 21.58. The performance of the prepared photochromic wood material can be adjusted by controlling the addition amount of microcapsules.

  • Researchpp 9560-9571Shenga, P. A., Bomark, P., Broman, O., and Sandberg, D. (2016). "The effect of log position accuracy on the volume yield in sawmilling of tropical hardwood," BioRes. 11(4), 9560-9571.AbstractPDF

    This study investigated the effect of the positioning of the log before sawing on the volume yield of sawn timber from tropical hardwood species. Three positioning parameters were studied, the offset, skew, and rotation, combined with two sawing patterns of cant-sawing and through-and-through sawing. A database consisting of two tropical hardwood species with very different outer shapes, jambirre (Millettia stuhllmannii Taub.) and umbila (Pterocarpus angolensis DC.), was used to simulate the sawing process. The result of the simulation revealed that, according to the combined effect of offset, skew, and rotation positioning, the positioning of the log before sawing is extremely important to achieve a high volume yield of sawn timber. The positioning parameter that has the highest effect on the volume yield is the rotation, and the variation in the volume yield associated with a deviation in the positioning can reduce the volume yield of sawn timber by between 7.7% and 12.5%.

  • Researchpp 9572-9583Jamberová, Z., Vančo, M., Barcík, S., Gaff, M., Čekovská, H., Kubš, J., and Kaplan, L. (2016). "Influence of processing factors and species of wood on granulometric composition of juvenile poplar wood chips," BioRes. 11(4), 9572-9583.AbstractPDF

    This article deals with the assessment of the influence of technical, processing, and material factors on selected mechanical properties and the granulometric composition of juvenile poplar wood chips. Individual analyses were made for two poplar species: naturally grown Populus tremula L. and the cultivated poplar clone Populus x euramericana “Serotina” for both juvenile and more mature wood. The main goal of this study was to evaluate the influence of the selected technical and processing parameters and of wood type (juvenile and more mature) on the chips’ granulometric composition during plane milling, its granulometric composition, and the sizes of the greatest and the smallest particles. Granulometric analysis (size test) was carried out to determine the share of the grain sizes for the individual wood fractions. While evaluating the granulometry, the influence of the milling process conditions as well as that of the wood’s physical and mechanical properties was taken into account.

  • Researchpp 9584-9595Park, J., Wang, Z., Lee, W. H., Jameel, H., Jin, Y. S., and Park, S. (2016). "Effect of the two-stage autohydrolysis of hardwood on the enzymatic saccharification and subsequent fermentation with an efficient xylose-utilizing Saccharomyces cerevisiae," BioRes. 11(4), 9584-9595.AbstractPDF
    To effectively utilize sugars during the fermentation process, it is important to develop a process that can minimize the generation of inhibiting compounds such as furans and acids, and a robust micro-organism that can co-ferment both glucose and xylose into products. In this study, the feasibility of efficient ethanol production was investigated using a combination of two approaches: two-stage autohydrolysis of biomass and fermentation using an engineered Saccharomyces cerevisiae to produce ethanol. When the hardwood chips were autohydrolyzed at 140 °C, followed by the second treatment at 180 °C, a higher yield of sugar conversion and fewer inhibitory effects on subsequent fermentation were achieved compared with the results from single-stage autohydrolysis. A higher overall yield of ethanol resulted by using an engineered yeast strain, SR8. This observation suggests the possibility of the feasible combination of two-stage autohydrolysis and the recombinant yeast.
  • Researchpp 9596-9610Ebner, T., Hirn, U., Fischer, W. J., Schmied, F. J., Schennach, R., and Ulz, M. H. (2016). "A proposed failure mechanism for pulp fiber-fiber joints," BioRes. 11(4), 9596-9610.AbstractPDF

    Due to stress concentration at the edges, fiber-fiber bonds under load are known to fail gradually inwards from the edges. In this paper, we propose a failure mechanism for fiber-fiber joints under load, based on the peak stresses occurring at the bond edges. We have modeled the mechanical testing of individual fiber-fiber joints using a finite element method (FEM) framework. The model is based on experimental results of fiber-fiber joint strength tests designed to induce each of the three modes in fracture mechanics: opening, sliding, and tearing. A parametric study of the peak load at the edges of the fibers was carried out in order to identify a failure mechanism. The peak stresses were not directly taken from the FEM models, as these values are highly discretization-dependent. Instead, the peak stresses were estimated from resultant forces and moments in the bond and an idealized geometry of the bonding region. The literature has, up to now, focused on shear load as a failure mechanism for fiber-fiber bonds. However, our findings indicate that pulp fiber joints are sensitive to normal stresses and insensitive to shear stresses. Hence, we suggest utilizing failure criteria related to normal stress in future work.

  • Researchpp 9611-9627Ajijolakewu, K. A., Leh, C. P., Wan Abdullah, W. N., and Lee, C. K. (2016). "Assessment of the effect of easily-metabolised carbon supplements on xylanase production by newly isolated Trichoderma asperellum USM SD4 cultivated on oil palm empty fruit bunches," BioRes. 11(4), 9611-9627.AbstractPDF

    Effect of lignocellulosic medium supplemented with selected easily-metabolised carbon sources on microbial xylanase production was assessed. A newly isolated oil-palm-waste-domesticated bio-agent-producing fungus, identified based on rRNA analysis as T. asperellum USM SD4 was used as a representative organism. The potential of T. asperellum for enhanced xylanase production was evaluated by the statistical optimization of important cultural parameters via response surface methodology (RSM). T. asperellum showed optimum xylanase activity at pH 7; temperature 27 °C; moisture content 4 mL growth medium (gm): 1 gram dried substrate (gds) and inoculum size 2 x 106 spores/mL. Xylanase activity (2,337 IU/gds) attained in this study was far higher than ever reported for T. asperellum. Using the set of optimum conditions, the mixture of supplementary sugars to the lignocellulosic medium initiated xylanase repression in a concentration-independent manner. However, the degree of repression depended on the nature and type of respectively added sugar. The repressive effect exerted by monosaccharides (xylose, glucose, and fructose) was greater than exerted by either of dimeric (cellobiose and sucrose) or polymeric (xylan) sugars. Of all added substrates, xylan exerted the least repressive effect. Using xylose as a representative sugar, mechanism of xylanase repression was decisively explained and supported with experimental data.

  • Researchpp 9628-9637Tong, R., Wu, C., Zhao, C., and Yu, D. (2016). "Effect of boric acid addition on the prehydrolysis of Whangee," BioRes. 11(4), 9628-9637.AbstractPDF

    Prehydrolysis is an important step in the kraft-based dissolving process for pulp production, as it helps remove as much hemicellulose as possible from cellulose fibers before the material is subjected to the main delignification operation, i.e., pulping. In this paper, a novel process concept was proposed by adding different dosages of boric acid (BA) based on the oven dry weight of Whangee, a genus of bamboo, in the prehydrolysis stage. The final yields of the prehydrolysis stage obviously increased and ferric ion contents in the hydrolyzed Whangee largely decreased with the addition of BA. Additionally, the highest α-cellulose retention occurred at a BA dosage of 0.5%. The results of acetic acid percent in the total sugars and furfural percent in xylose of the PHL showed that the addition of BA had an important impact on the structure of hemicelluloses in Whangee. Mass balance analysis of the PHL and Whangee indicated that the partly acid-insoluble lignin in Whangee was likely converted into acid-soluble lignin in the PHL.

  • Researchpp 9638-9648Wang, X., Björnberg, J., Hagman, O., Ahmed, S. A., Wan, H., and Niemz, P. (2016). "Effect of low temperatures on the block shear strength of Norway spruce glulam joints," BioRes. 11(4), 9638-9648.AbstractPDF

    The block shear strength of Norway spruce (Picea abies (L.) Karst.) glulam joints was tested under low temperatures. Glulam samples were glued with the three of the most common outdoor structural adhesives. The cold temperatures tested were 20, −20, −30, −40, −50, and −60 °C. Within the temperature test range, the block shear strength of the glulam joints was resistant to the effect of temperature. As the temperature decreased, the joints’ block shear strength did not show any significant change. In most cases, phenol-resorcinol-formaldehyde (PRF) adhesive yielded the strongest block shear strength, while melamine-formaldehyde (MF) adhesive yielded the weakest block shear strength. Melamine-urea-formaldehyde (MUF) adhesive yielded similar results to those of MF adhesives for all temperatures tested. The block shear strengths of the glulam joints with PRF, MUF, and MF adhesives were not sensitive to temperature change. The results indicated that PRF, MUF, and MF adhesives are stable for outdoor structural engineered wood construction in cold climates. The results also suggest that the SS-EN 14080 (2013) standard for the block shear method may not be the proper standard for testing differences in shear strength at different temperatures. The EN 302-1 (2011) standard could be more suitable for this purpose.

  • Researchpp 9649-9660Xu, Y., Liang, Q., Wang, Q., Liu, G., and Li, L. (2016). "Analysis and evaluation model for print mottle using wavelet image denoising method," BioRes. 11(4), 9649-9660.AbstractPDF

    Print mottle is problematic in the print and paper industry. In this report, a mathematical evaluation model of print mottle was generated after analyzing several methods. The print mottle images can be evaluated by the model based on the theory of wavelet image denoising analyses that use the wavelet multi-scale fast algorithm. The model was then applied to analyze print mottle on four business papers (inkjet papers, newsprint papers, art papers, and double-coated offset printing papers). The correlation between the results of this method and the human visual evaluation system (HVS) was calculated and evaluated. Experimental results showed that the model predictions agreed with HVS results. The correlation between the printed newsprint papers and the eight different wavelet base functions was over 0.76 (such as haar, sym4, bior3.7, etc.) and decomposed at the first, second, and third levels. The results of the three other papers were better matched with the analysis by human eyes, but the correlation of the art paper and visual model were not as strong as the others. The optimal parameters for the print mottle model were presented in the four kinds of papers presented.

  • Researchpp 9661-9675Revin, V. V., Novokuptsev, N. V., and Red'kin, N. A. (2016). "Optimization of cultivation conditions for Azotobacter vinelandii D-08, producer of polysaccharide levan, for obtaining biocomposite materials," BioRes. 11(4), 9661-9675.AbstractPDF

    A prospective binder composed of a microbial polysaccharide levan present in the culture fluid was obtained. The synthesis of levan was carried out by an Azotobacter vinelandii bacteria strain using molasses, distillery stillage, and milk whey as the nutrient medium. The maximum amount of levan produced in these experiments was 14.5 g/L. Composite materials were obtained based on wood waste and biological binder. Depending on the pressing behaviour, materials were obtained within a density range of 1083 to 1443 kg/m3 and a tensile strength of 7.2 to 32.4 MPa. Water absorption and thickness swelling were 7.2% and 14.9%, respectively. During hot pressing, the resulting materials changed in their attenuated total reflection-frustrated total reflection (ATR-FTR) spectra at frequencies of 930, 1000, and 1750 cm-1, indicating the occurrence of chemical and structural changes in individual components of the lignocellulosic raw materials and changes in the composition of biological binding agent. Analysis of the physico-mechanical properties and other results of the composite materials using scanning electron microscopy (SEM) and X-ray microtomography suggested that composite materials based on the microbial polysaccharide levan-containing binder are advanced, new, and eco-friendly substances.

  • Researchpp 9676-9685Cao, T., Jiang, B., Gu, F., Wu, W., and Jin, Y. (2016). "Characterization of lignin isolated from wheat leaf based on LiCl/DMSO dissolution and regeneration," BioRes. 11(4), 9676-9685.AbstractPDF

    The isolation of lignin is of great importance to understand its structural characteristics. A lithium chloride/dimethyl sulfoxide (LiCl/DMSO) solvent system has been developed for the dissolution of lignocellulose and for the isolation of lignin for this purpose. In this work, ball-milled wheat leaf (sheath included) was dissolved in the LiCl/DMSO solvent system and then regenerated in water. Two lignin preparations, cellulolytic enzyme lignin from the ball-milled leaf (CEL) and from the regenerated leaf (RCEL), were obtained through a cellulolytic enzyme lignin procedure. The RCEL and CEL were comparatively investigated by the use of wet chemistry and spectroscopic methods. The results indicate that the effects of ball milling and regeneration on the aromatic structure and β-O-4’ linkages of lignin were not significant. The RCEL had a higher isolation yield and purity, but a similar structure with the corresponding CEL. The RCEL can be used for structural analysis.

  • Researchpp 9686-9709Adebisi, G. A., Chowdhury, Z. Z., Abd Hamid, S. B., and Ali, E. (2016). "Hydrothermally treated banana empty fruit bunch fiber activated carbon for Pb(II) and Zn(II) removal," BioRes. 11(4), 9686-9709.AbstractPDF
    Activated carbon was produced by chemical activation of hydrothermally carbonized (HTC) banana empty fruit bunch (BEFB), using phosphoric acid (H3PO4) as the activating agent. The activation process was optimized using a Box-Behnken factorial design (BBD), with an outcome of 17 different experiments under the predefined conditions. Three different parameters (activation temperature (x1), activation time (x2), and the concentration of activating acid (x3)) were analyzed with respect to their influence on maximum adsorption percentage for divalent cations, Pb(II) (Y1) and Zn(II) (Y2), and carbon yield (Y3). All process parameters had strong positive effects on adsorption capacity up to a certain limit. The specific surface area of the hydrochar (HTC) was enhanced substantially after the activation process. Scanning electron microscopy (SEM) revealed that the morphology of the BEFB-based char changed noticeably after the acid impregnation and activation process. The Langmuir maximum monolayer adsorption capacity for Pb (II) and Zn (II) cations was 74.62 mg/g and 77.51 mg/g, respectively. Equilibrium isotherm data were in agreement with the Langmuir model. Thermodynamic characterization revealed that the equilibrium system was endothermic and spontaneous.
  • Researchpp 9710-9722Chen, T., Li, Y., Xu, J., and Hou, Y. (2016). "Dissolution of eucalyptus powder with alkaline ionic liquid [Mmim]DMP under microwave conditions," BioRes. 11(4), 9710-9722.AbstractPDF
    An orthogonal design was used to study three factors—melting temperature, time, and solid-liquid ratio—and how they affected the dissolution rate of eucalyptus powder. The optimum solution conditions were 170 °C, 20 min, and a solid-liquid ratio of 1:25. Composition analysis of the residue indicated that, in the dissolving process, acid-insoluble lignin was converted into acid-soluble lignin, and a part of the lignin was degraded or modified. After dissolution, the crystalline structure of cellulose deteriorated, the relative crystallinity decreased, and the crystal form changed from type I into amorphous. Wood powder degradation occurred during dissolution, and a higher dissolution rate led to greater degradation. In a low-temperature environment below 225 °C, the residue thermal stability decreased slightly with increasing dissolution rates, but it greatly improved in a high-temperature environment of 225 to 600 °C.
  • Researchpp 9723-9740Zhang, Y., Hong, M., Li, J., Chen, X., Zeng, Z., and Liu, H. (2016). "Benchmarking analysis of energy efficiency indicators in paper mill," BioRes. 11(4), 9723-9740.AbstractPDF
    Paper mills consume a large amount of energy, which is an important factor restricting their sustainable development. Benchmarking is a critical method for discovering the energy-savings potential of mills. To address problems such as the absence of indicators for energy efficiency benchmarking, the influence of different basis weights on energy efficiency levels and on the estimation of energy-saving potential, this paper makes use of production line-based and process-based benchmarking in coated paperboard production. The indicator system is constructed to collect data and quantify the energy efficiency. K-means clustering is used to classify the basis weight and energy efficiency data for seven months and obtain the benchmark values. The results showed that the specific energy consumption (SEC) decreased with the increase in basis weight. An analysis of production line-based benchmarking for a paper mill in China indicated that energy efficiency reached the level of 5.92 to 6.94 GJ/t, which was 10.8 to 23.91% lower compared with the European Union best available energy level (7.78 GJ/t) and 6.28 to 24.6% higher compared with the energy consumption of American paper products integrated production units (5.57 GJ/t). These energy-saving measures should be taken into account in order to raise the energy efficiency in paper mills.
  • Researchpp 9741-9755Bernardino-Nicanor, A., Montañéz-Soto, J. L., Vivar-Vera, M. A., Juárez-Goiz, J. M., Acosta-García, G., and González-Cruz , L. (2016). "Effect of drying on the antioxidant capacity and concentration of phenolic compounds in different parts of the Erythrina americana tree," BioRes. 11(4), 9741-9755.AbstractPDF

    The Erythrina americana tree has been widely studied for its antioxidant and antimicrobial activity, principally of the seeds. Few studies have focused on the other tree parts. This work evaluated the effect of drying on the proximate chemical composition, IC50, and total phenolic content (TPC) of different parts of the plant from Erythrina americana. Proximate chemical composition showed significant differences between parts of the plant. Tree bark (TB) exhibited higher protein content, crude fiber, and ash. The IC50 value was significantly different in all parts of the plant; the leaves exhibited lower amounts necessary to reach this value. The drying process had a positive influence on the antioxidant activity in all parts of the plant, with mature flowers (MF) and young flowers (YF) samples. These were the samples that required the lowest concentration of all dry samples to reach the IC50 value. The TPC values showed significant differences between fresh and dry samples except for MF, according the ANOVA and Tukey test (P≤0.05). In conclusion, the drying process has potential for retaining the antioxidant activity in YD and MF.

  • Researchpp 9756-9770Wang, C. J., Chen, C., Ren, H., Yang, Y., and Dai, H. (2016). "Polyethyleneimine addition for control of dissolved and colloidal substances: Effects on wet-end chemistry," BioRes. 11(4), 9756-9770.AbstractPDF

    Within the pulp and paper industry, the recycling of whitewater to reduce fresh water consumption and effluent volume leads to an accumulation of dissolved and colloidal substances (DCS) in the papermaking wet-end system. DCS interacts with certain electrolytes and polyelectrolytes to form non-ionic DCS interferents (pitch deposits and depositions), which adversely affect papermaking. Polyethyleneimine (PEI), a fixing agent with a low molecular weight and high cationic charge density, can control the DCS in the wet-end system. The fixation efficiency of DCS simulacra and the wet-end properties were explored under varying Ca2+ and PEI concentrations in pulp. The fixation and retention efficiency of DCS simulacra were improved, the zeta potential of pulp and drainage rate of pulp increased, and the cationic demand of pulp filtrate decreased with increasing PEI dosage. Ca2+ shielded the negatively charged ions on the surface of the fibers and DCS simulacra, influenced the fixation efficiency of PEI to DCS simulacra, and improved the drainage rate of pulp.

  • Researchpp 9771-9788Li, W., Xie, X., Tang, C. Z., Li, Y., Li, L., Wang, Y. L., Fan, D., and Wei, X. (2016). "The distribution of bio-oil components with the effects of sub/supercritical ethanol and free radicals during cellulose liquefaction," BioRes. 11(4), 9771-9788.AbstractPDF

    Hydroxyl radicals (HO•) and hydrogen radicals (H•) produced from sub/supercritical ethanol have an obvious contribution on cellulose liquefaction for bio-oil production. Salicylic acid was employed as the HO• trap and CCl4 was employed as the H• trap to investigate the role of HO• and H• on the formation pathways of dominant chemical components in bio-oil during cellulose liquefaction in sub/supercritical ethanol (mostly ketones and esters). The yield of bio-oil decreased from 24.7% to 20.7% with the addition of CCl4, while the bio-oil yield increased from 29.3% to 47.9% with the addition of salicylic acid. Gas chromatography/mass spectrometry results showed that the yields of ketones, esters, and phenols in the bio-oil were 22.3%, 8.8%, and 4.7%, respectively, without salicylic acid or CCl4. The highest yields of esters and phenols increased to 21.6% and 36.9%, respectively, in the presence of salicylic acid. The yield of ketones decreased to 14.1%. Experimental data indicated that the cleavage of C-O-C and C-C bonds in the cornstalk cellulose initially generated many active cellulose fragments. Then, platform chemicals were formed from these fragments through aromatization, isomerization, aldol condensation, Baeyer-Villiger oxidation, and trans-Diels-Alder ring-opening with the redox of HO• and H•.

  • Researchpp 9789-9802Matsushita, Y., Nakamura, A., Aoki, D., Yagami, S., and Fukushima, K. (2016). "Bio-based polymer from ferulic acid by electropolymerization," BioRes. 11(4), 9789-9802.AbstractPDF

    Electropolymerization was carried out in order to obtain a bio-based polymer by a simple procedure. Ferulic acid, a component of gramineous plants, was selected for this purpose. A thin polymer film was produced in an organic solvent medium (i.e., CH2Cl2/methanol (4:1 v/v) in the presence of 0.2 M LiClO4), whereas it was not obtained in a totally aqueous medium (0.2 M NaOH). Scanning electron microscopic analysis showed that the polymer film had a porous lamellar structure of ~10 μm thickness. Most of the carboxyl groups remained, and IR spectroscopy and time-of-flight secondary ion mass spectrometry (TOF-SIMS) analyses revealed that o-quinones existed in the polymer film. After electropolymerization, caffeic acid, sinapic acid, 3,6-bis(4-hydroxy-3-methoxyphenyl)tetrahydrofuro[3,4-c]furan-1,4-dione (1), and 4,4’-dihydroxy-3,3’-dimethoxy-β,β’-bicinnamic acid (2) were detected in the organic reaction medium; this suggested that demethylation, methoxyl group addition, and radical coupling reactions occurred at the electrode surface.

  • Researchpp 9803-9810Lee, C. G., Choi, C., Yoo, J. C., Kim, H. J., Yang, S. M., and Kang, S. G. (2016). "The combustion characteristics of self-igniting briquettes prepared with torrefied wood powder from a wood-roasting method," BioRes. 11(4), 9803-9810.AbstractPDF

    Agglomerated torrefied wood fuel was tested for its fuel properties and combustion characteristics. Torrefied wood was produced in a wood roaster, with three species (Pinus densiflora Siebold & Zucc., Quercus serrata Thumb. Ex Murray, Sinoarundinaria nigra var. henonis honda) that were torrefied at 220 °C for 180 s. After being torrefied, these powders were used as agglomerated torrefied wood-powder. Gelatin was used as binder, and linseed oil was spread on one side of each sample. All test samples were ignited and tested for carbon monoxide release and temperature variation. The agglomerated torrefied wood fuel showed 82% less carbon monoxide release in comparison to self-igniting briquettes. In particular, pine showed less CO release and mass loss. Also, pine and bamboo showed higher heat efficiency than the ignition coal. Therefore, using torrefied wood for agglomerated fuel reduced the carbon monoxide release and improved the heating efficiency of the ignition coal.

  • Researchpp 9811-9822Bariska, M., Börcsök, Z., Kantó, Z., Czimondor, D., and Pásztory, Z. (2016). "Forces acting on saw teeth during timber processing - a practical approach," BioRes. 11(4), 9811-9822.AbstractPDF
    Two oak cant timbers were sawn up to a total of 58 boards. As a dependent variable, the energy consumption while manufacturing a board was measured. As influencing variables, timber and saw blade characteristics were assessed, including density, moisture content, log feed speed, blade profile, and sawing sequence. Four types of forces acting in a saw-tooth were derived, namely, the dust particle shaving force, the particle accelerating force, the dust compressing force, and the frictional force as a consequence of blade wear. The experiment showed that the most prominent factor is the shaving force if the blade was newly sharpened, and that the dust accelerating and compressing forces were negligibly small. The frictional force grew from insignificant at the first board to more than one fourth of the force total at the 58th board. With each board, the saw tooth tips receded by more than 2 μm. With these data, the course of blades’ deterioration from wear was characterised.
  • Researchpp 9823-9841Yao, X., Xu, K., and Liang, Y. (2016). "Research on the thermo-physical properties of corncob residues as gasification feedstock and assessment for characterization of corncob ash from gasification," BioRes. 11(4), 9823-9841.AbstractPDF

    Harnessing energy from biomass is environmentally friendly because of the essentially zero net CO2 impact. As a common agricultural byproduct, corncobs are abundant in quantity. This study was carried out to examine the thermo-physical properties of corncobs and characterize the properties of corncob ash produced from gasification, in order to provide a basis for transforming it into value-added products. The results showed that the pyrolysis of corncobs followed a three-step, stepwise mechanism. Activation energies calculated by the Coats-Redfern method at heating rates of 5, 10, and 20 °C/min were 79.08, 76.73, and 75.78 kJ·mol-1, respectively, implying that the corncobs could be decomposed easily at high heating rates. The emissions of CO, CO2, CH4, H2, H2O, and O2 during pyrolysis corresponded well with thermal curves. Corncob ash could be a good fertilizer because of its high contents of K, P, and Ca. The high SiO2 content makes the corncob ash suitable for ceramics and blended cement concrete. Sylvite (KCl) and quartz (SiO2) were the two major crystal phases in the corncob ash. Relatively large particles of unburnt carbon residues in the ash indicated that low-cost adsorbent could be developed from these carbon residues.

  • Researchpp 9842-9855Segura, T. E. S., dos Santos, J. R. S., Sarto, C., and da Silva, Júnior , F. G. (2016). "Effect of kappa number variation on modified pulping of Eucalyptus," BioRes. 11(4), 9842-9855.AbstractPDF

    This work evaluated the impact of brownstock pulp kappa number variations on modified pulping process, oxygen delignification, bleaching, and the physical characteristics on bleached pulp. Wood chips of 6-year-old Eucalyptus grandis x Eucalyptus urophylla from Brazil were used. A modified pulping process was performed with the purpose of achieving two delignification levels on brownstock pulp: kappa 18 and kappa 15. Pulps were submitted to oxygen delignification and elemental chlorine-free (ECF) bleaching to achieve 89.5 ± 0.5% of ISO brightness. Subsequently, pulps were refined in four levels (0, 750, 1500, and 3000 rotations) for physical mechanical tests. Delignification increased after increasing the cooking H factor and alkali charge. As a result, delignification negatively impacted the pulping yields (from 56.1% to 55.0%) and the pulp viscosity (from 1,317 cm³/g to 1,227 cm³/g). Pulps with an initial kappa of 15 presented more efficient oxygen delignification and lower consumption of bleaching reagents. The final viscosity of these pulps were lower (899 cm³/g against 963 cm³/g), however, than that of the pulps with an initial kappa of 18. Furthermore, the pulps with a higher unbleached kappa demanded less refining energy and had lower capillarity. The other physical properties were not influenced by the brownstock delignification level.

  • Researchpp 9856-9868Jiménez, A. M., Espinach, F. X., Delgado-Aguilar, M., Reixach, R., Quintana, G., Fullana-i-Palmer, P., and Mutjè, P. (2016). "Starch-based biopolymer reinforced with high yield fibers from sugarcane bagasse as a technical and environmentally friendly alternative to high density polyethylene," BioRes. 11(4), 9856-9868.AbstractPDF
    Greener composites, as alternatives to more common materials, should also achieve technical and economic feasibility to be commercially competitive. This study presents the results obtained from using a biodegradable starch-based matrix, and a natural fiber reinforcement coming from sugarcane bagasse, currently an agro-waste. The sugarcane bagasse biomass was treated to obtain four kinds of fibers with different morphological and chemical properties. The fibers were used to obtain composite materials, which were then tested for tensile properties. The results showed that some of the composites were suitable to replace high density polyethylene, from a technical and environmental point of view. The comparatively higher cost of the biobased matrices hinders the substitution, but the higher the fiber content, the lower the economic disadvantage. A micromechanical test and a sensitivity analysis showed that the fiber orientation had the highest impact on the tensile strength, followed by the fibers mean length and the quality of the interphase between the fibers and the matrix.
  • Researchpp 9869-9879Kumar, H., Alén, R., and Sahoo, G. (2016). "Characterization of hardwood soda-AQ lignins precipitated from black liquor through selective acidification," BioRes. 11(4), 9869-9879.AbstractPDF

    In the development of integrated biorefinery process alternatives to produce value-added by-products, various black liquors from sulfur-free pulping processes offer potential feedstocks for recovering their main chemical constituents, lignin and aliphatic carboxylic acids. In this study, lignin fractions were obtained from silver birch (Betula pendula) soda-anthraquinone black liquor by carbonation (pH to about 8.5) or by acidification (pH to about 2) with H2SO4 after carbonation or directly. These fractions were characterized by Fourier transform infrared (FTIR), ultraviolet (UV), energy dispersive X-ray fluorescence (ED XRF), and 13C nuclear magnetic resonance (13C NMR) spectroscopy. In addition, the molecular weight distributions of these lignin fractions were determined. All the experimental data clearly suggested that only small differences between the precipitated lignins existed, and thus, their equal chemical utilization seems possible.

  • Researchpp 9880-9895Gaff, M., Ruman, D., Borůvka, V., and Záborský, V. (2016). "Impact bending strength as a function of selected factors," BioRes. 11(4), 9880-9895.AbstractPDF

    This article examines the influence of selected factors (wood species, densification, thickness, glue type, and number of cycles) on the impact bending strength (IBS) of solid and laminated wood. The evaluated properties were measured on samples of European beech (Fagus sylvatica L.) and common aspen (Populus tremula L.). Two types of glues were used for laminated wood: polyvinyl acetate (PVAc) and polyurethane (PUR). The highest IBS values were recorded in laminated beech specimens glued with polyvinyl acetate glue that were not subjected to cyclical loading.

  • Researchpp 9896-9911Hu, X. M., Wang, F. L., Ma, H. H., Zhang, B. X., Gao, Y. F., and Hu, B. A. (2016). "Factors governing the pretreatment process of lignocellulosic biomass in an acidic pyrrolidonium ionic liquid," BioRes. 11(4), 9896-9911.AbstractPDF
    Ionic liquid (IL)-assisted pretreatment is an important step in biochemical conversion of lignocellulosic biomass into biofuels. Design for low-cost ILs that efficiently work at a relatively low pretreatment temperature with a short processing time is of great interest. In this work, a functional acidic ionic liquid, 1-H-N-methyl-2-pyrrolidonium chloride ([Hnmp]Cl), was prepared by a simple synthetic procedure in a cost-effective manner and was then investigated for use in the pretreatment of lignocellulosic biomass. Factors including temperature, time, ratio of biomass to ionic liquid, and water content were studied to determine their impact on the pretreatment of lignocellulose; 91.39% of lignin content was recovered when the corn stalk was pretreated by pure [Hnmp]Cl at 100 °C for 45 min with a biomass loading of 5%. The highest glucose yield attained was 93.20% and the highest cellobiose yield was 18.76%, when the ratio of biomass to water was kept at 1:4. The pretreatment efficacy was dependent on the pretreatment temperature and processing time, which was more efficient for pure ionic liquid with respect to lignin recovery from lignocelluloses. However, more efficient enzymatic saccharification of cellulose-rich materials was achieved with aqueous ionic liquid.
  • Researchpp 9912-9921Sládková, A., Benedekov, M., Stopka, J., Šurina, I., Ház, A., Strižincová, P., Čižová, K., Škulcová, A., Burčová, Z., Kreps, F., Šima, J., and Jablonský, M. (2016). "Yield of polyphenolic substances extracted from spruce (Picea abies) bark by microwave-assisted extraction," BioRes. 11(4), 9912-9921.AbstractPDF

    Closed-system microwave-assisted extraction was applied to extract total phenolics from spruce (Picea abies) bark, using 96.6% ethanol as an extractant. The influence of particle size (0.3; 1.0; 2.5 mm), time (3 to 20 min), and temperature (60; 80; 100 °C) on polyphenol recovery was also studied. Higher extraction temperature and smaller particle size resulted in a higher yield of extracted polyphenols. However, the effect of extraction time on yield was more complicated. The effect of all three factors is tentatively explained.

  • Researchpp 9922-9939Enriquez, E., Mohanty, A. K., and Misra, M. (2016). "Alkali and peroxide bleach treatments on spring harvested switchgrass for potential composite application," BioRes. 11(4), 9922-9939.AbstractPDF

    Natural fibers are desirable in composite applications for their sustainability. However, improving upon the interfacial adhesion between the fiber and matrix is a major challenge. Chemical surface modification is a method used to improve compatibility of the fiber by exposing or adding functionalities to the surface, and removing non-cellulosic components in order to enhance mechanical and thermal properties. Switchgrass, an abundant natural fiber, has potential for use as a reinforcing material in composite applications. Surface modifications were conducted on switchgrass via alkali and peroxide bleaching treatments in order to remove surface impurities and create a rougher surface, as observed in scanning electron micrographs. Fourier transform infrared spectroscopy and compositional analysis showed that non-cellulosic components were reduced following the alkali and bleach treatments. Reduction of hemicellulose and lignin improved thermal stability by increasing the onset temperature of degradation from 258 °C to 289 and 281 °C for alkali and bleach treatments, respectively. The crystallinity index (CI) of untreated and treated fibers was calculated from x-ray diffraction analyses. An increase of 48% and 38% for the alkali and bleach treated fibers, respectively, was seen in the CI, compared to the untreated switchgrass. The surface of switchgrass was successfully modified using alkali and peroxide bleach treatments for composite applications.

  • Researchpp 9940-9955Liu, L., Li, P., Qin, G., Yan, Y., Li, Y., Yao, J., and Wang, H. (2016). "Conversion of corn stalk to ethanol by one-step process using an alcohol dehydrogenase mutant of Phanerochaete chrysosporium," BioRes. 11(4), 9940-9955.AbstractPDF

    The potential of Phanerochaete chrysosporium in ethanol fermentation was evaluated. During the initial submerged cultivation, 1.76 g/L ethanol was obtained using glucose as substrate. After mutation, the ethanol concentration of an alcohol dehydrogenase (ADH) mutant reached 5.02 g/L. Both base transition and nine-base frame shift mutation occurred in the ADH gene of the mutant, changing the secondary and tertiary structures of ADH, as well as increasing the ADH activity during cultivation. Moreover, P. chrysosporium converted corn stalk to ethanol by a one-step process. After statistical optimizations, 0.26 g/g•substrate of ethanol yield was obtained on day 10. During the fermentation, the maximum lignin peroxidase, Mn-dependent peroxidase, and cellulase activities were 29.0 U/L, 256.5 U/L, and 40 U/mL, respectively, thus explaining why the fungus directly ferments corn stalk to ethanol. This study is the first report of the conversion of corn stalk without pretreatment to ethanol using a white-rot fungus.

  • Researchpp 9956-9969Zhang, J., Du, M., and Hu, L. (2016). "Factors influencing polyol liquefaction of nut shells of different Camellia species," BioRes. 11(4), 9956-9969.AbstractPDF

    The liquefaction rates and kinetics of nut shells of different Camellia species in PEG400/glycerol/H2SO4 liquefying solvent were investigated. Changes in major components including cellulose, hemicellulose, and lignin as well as cellulose crystallinity of the nut shells were determined. The compositions of the liquefaction residues were analyzed. Results indicated that, under the same conditions, the liquefaction rates of nut shells of different Camellia species were noticeably different and the PEG400/glycerol/H2SO4 liquefaction agent was not suitable for the liquefaction of the nut shells of all Camellia species. The burst liquefaction of Camellia nut shells (CNSs) that occurred during the first stage was due to the rapid degradation of hemicellulose, acid-soluble lignin, and amorphous cellulose. The liquefaction during the second stage became very slow, mostly because the swelling and decomposition of crystalline cellulose was very difficult to achieve with the liquefying agent and the liquefaction products inhibited liquefaction at later stages. The liquefaction residues of CNSs were composed of crystalline cellulose, small amounts of hemicellulose, acid-insoluble lignin, and ash. Ash was partially dissolved in the liquefying agent. The liquefaction rates of all CNSs tested in this study showed linear relationships with time, with coefficients of determination (R2) greater than 0.7082, indicating that the liquefaction of CNS was a pseudo-first-order reaction.

  • Researchpp 9970-9985Fu, X., and Hu, Y. (2016). "Comparison of reactor configurations for biogas production from rapeseed straw," BioRes. 11(4), 9970-9985.AbstractPDF

    To investigate the effects of reactor configurations on the anaerobic digestion performance of agricultural residue rapeseed straw, semi-continuous, one-stage, continuously stirred tank reactors (CSTR) and batch, two-stage, leach bed-upflow anaerobic sludge blanket (UASB) reactors were operated at the same hydraulic retention time (HRT) (30 days) and target organic loading rate (OLR) (3.0 gVS/L.d). In the continuously loaded CSTR, the specific methane yields did not substantially change as the OLR increased from 1.5 gVS/L.d to 3.0 gVS/L.d during the four periods. Conversely, the specific methane yields in the batch-fed leach bed-UASB increased considerably with the increase in OLR. The leach bed reactor contributed 75% of the total yield, while the UASB reactor contributed only 25% of the total yield. The total specific methane yields were 108 mL/gVS and 160 mL/gVS for the leach bed-UASB and CSTR, respectively, while the volatile solid (VS) reductions of the rapeseed straw were 27.1% and 36.6%, respectively. The results indicated that the process performance was more efficient in the CSTR than in the leach bed-UASB for the digestion of rapeseed straw. Biogas production was clearly affected by the reactor configurations.

  • Researchpp 9986-10001Chen, Q., Zhang, R., Wang, Y., Wen, X., and Qin, D. (2016). "The effect of bamboo charcoal on water absorption, contact angle, and the physical-mechanical properties of bamboo/low-density polyethylene composites," BioRes. 11(4), 9986-10001.AbstractPDF

    The use of bamboo charcoal (BC) was investigated as a filler in bamboo-plastic composites (BPCs) to achieve improved water resistance, physical-mechanical properties, and reduced hydrophilicity. The influence of the BC content and size on the water absorption, contact angle, density, and mechanical properties of bamboo flour/low-density polyethylene (LDPE) composites was tested. Scanning electron microscopy was used to analyse fractured and flat composite surfaces. The results indicated that the BC increased water resistance, achieving optimal results at 8% content. The BC particles that ranged in size from 60 to 100 mesh were more water-resistant than other sized BC. The water contact angle increased with an increase in the BC content or a decrease in the particle size. These results indicated that BC reduced the composite hydrophilicity and that the smaller BC particles improved this effect. The BC strongly connected with the LDPE composites, and the BC contents below 12% improved the flexural properties and increased the density of the BPCs. Also, the impact strength of the BPCs decreased dramatically with a decrease in the BC particle size. These results demonstrated that the integration of BC with BPCs resulted in strengthened water resistance and physical-mechanical properties and reduced hydrophilicity.

  • Researchpp 10002-10013Stombock, L. B., Jeremic-Nikolic, D., Baldwin, B., Borazjani, H., and Diehl, S. V. (2016). "Bioremediation of oriented strand board (OSB) process wastewater," BioRes. 11(4), 10002-10013.AbstractPDF

    This study investigated the use of bioreactors and constructed wetlands to remediate oriented strand board (OSB) process wastewater. The first study evaluated the use of free cell bioreactors to reduce the biological oxygen demand (BOD). Control samples had significantly higher BOD levels than other treatments, and air+bacteria+nutrients treatment achieved significantly lower in BOD than air-only. Toxicity, total phenol, and total organic carbon concentrations decreased in all treatments. The initial constructed wetland was a screening study to determine which plants could acclimate to OSB process water. Plants that survived were placed into a floating constructed wetland (water hyacinth) or an emergent wetland (soft rush and Chinese water chestnut). A significant decrease in BOD occurred between days 15 and 30, with the emergent wetlands dropping by 51.7% and the floating wetlands by 52.7%. Toxicity, total phenol, and total organic carbon concentrations decreased in all treatments. This research suggests that an OSB facility may want to have an aerated pond that then feeds a constructed wetland. This could not only provide a means to treat and dispose of the wastewater in an environmentally favorable manner, but also provides the secondary benefits of a wetland and its associated land enrichment.

  • Researchpp 10014-10029Zhang, X., Tan, X., Xu, Y., Wang, W., Ma, L., and Qi, W. (2016). "Preparation of core shell structure magnetic carbon-based solid acid and its catalytic performance on hemicellulose in corncobs," BioRes. 11(4), 10014-10029.AbstractPDF

    Solid acid catalysts show good catalytic depolymerization behavior for lignocellulose. A stable core-shell structured magnetic solid acid catalyst (MSAC), Fe3O4/C-SO3H, was prepared from glucose, concentrated sulfuric acid, and modified magnetic particles of Fe3O4, which was used as the core. The effects of the carbonization and sulfonation processes on the activity of the catalyst were investigated. The results showed that preparation conditions had great influence on the quantity of the acidic groups (sulfonic, carboxyl, and hydroxyl groups) and the stability of magnetic catalysts. The best preparation conditions for MSAC were 3 h of carbonization time, 450 °C as the carbonization temperature, 9 h of sulfonation time, and 90 °C as the sulfonation temperature. Its surface topography, functional group, chemical composition, and magnetic properties were characterized by analysis instrument. Furthermore, the catalyst was stably dispersed in the reaction system, quickly separated from the reaction system using an external field, and reused many times; 44.3% of xylose yield was obtained at 160 °C for 16 h. The catalyst was used repeatedly more than 3 times, and the recovery over 89%. The depolymerization of corncobs was achieved by magnetic catalyst, representing the depolymerization characteristics of real lignocellulose. This data can be used as a reference for the subsequent use of biomass resource.

  • Researchpp 10030-10041Wong, L. Y., Saad, W. Z., Mohamad, R., and Md Tahir, P. (2016). "Efficacy of Aspergillus fumigatus R6 pectinase in enzymatic retting of kenaf," BioRes. 11(4), 10030-10041.AbstractPDF
    Enzyme retting can be a viable alternative to water retting, which is the currently utilised method for extracting fibres from kenaf. The advantages of enzyme retting are its greater environmental friendliness, shorter retting time, and more controllable fibre quality. The objective of this study was to determine the efficacy of pectinase produced from locally isolated Aspergillus fumigatus R6 in kenaf retting. A. fumigatus R6 pectinase effectively separated the fibres from non-fibre components. Scanning electron micrographs showed that the surface of pectinase-treated kenaf bast fibres appeared to be smoother and finer. The degree of retting increased with incubation time. A retting time of 32 h produced good-quality kenaf bast fibres with high tensile strength (459 MPa). No significant differences were found between the tensile properties of kenaf bast fibres treated with A. fumigatus R6 pectinase-containing culture filtrate and other sources of commercial pectinase enzyme. Hence, it was concluded that A. fumigatus R6 pectinase was capable of retting kenaf effectively.
  • Researchpp 10042-10056Hauptmann, M., Kaulfürst, S., and Majschak, J. P. (2016). "Advances on geometrical limits in the deep drawing process of paperboard," BioRes. 11(4), 10042-10056.AbstractPDF

    The geometrical limits of the deep drawing process of paper to advanced shapes are not known. This report examines the technological limits of convex elements of the base shape in relation to the drawing height and shows the material behavior in the bottom radius of 3D shapes with regard to special material properties. In the bottom radius, non-compressed wrinkles occurred due to the in-plane compression, but wrinkles were reduced by an increased blank holder force or tool temperatures and improved extensibility or in-plane compressive strain. The forming ratio during deep drawing (drawing height related to base diameter) was increased to a value of more than 1 by a blank holder force, which increased with the drawing height such that the initial blank holder force was reduced concurrently. Straight sections in the base shape reduced the risk for ruptures in the edge radii of rectangular shapes, producing a forming ratio in these radii of 2.5. The forming ratio was further supported by a pattern of creasing lines at the blanks with a radial orientation and a number near the expected maximum number of wrinkles. The spring-back at rectangular shapes mainly depended on the drawing height and edge radius.

  • Researchpp 10057-10069Oliveira, P. E., Cunha, A. G., Reyes, G., Gacitúa, W., and Petit-Breuilh, X. (2016). "Chusquea quila, a natural resource from Chile: Its chemical, physical, and nanomechanical properties," BioRes. 11(4), 10057-10069.AbstractPDF

    Chusquea quila or “quila”, is one of the most abundant lesser-known species from Chile, and for many years it has created problems for farmers in the southern part of this country. In this study, it was examined as a promising resource for high-tech materials. The chemical and physical properties were determined by ASTM standards. The extractives, ash content, lignin, and alpha-cellulose were 4.55%, 2.17%, 13.78%, and 54.65%, respectively. The higher heating value and basic density obtained were 5,106 kcal/kg and 290 kg/m3, respectively. The moisture content was studied during four seasons and found to be the highest in winter (73%). Regarding the nanomechanical profiles, hardness varied from 0.16 GPa in the cortex to 0.21 GPa in the nodule. The average elastic modulus in the nodule and internode was 12.5 GPa, while in the cortex it was 7.45 GPa. Considering the high cellulose content and structural features of the lignocellulosic matrix, it could be possible to extract cellulose fibers for commercial use and crude lignin for testing new applications. Thus, the entire quila structure is a potential biomass resource.

  • Researchpp 10070-10086Hidayat, W., Qi, Y., Jang, J. H., Febrianto, F., Lee, S. H., and Kim, N. H. (2016). "Effect of treatment duration and clamping on the properties of heat-treated okan wood," BioRes. 11(4), 10070-10086.AbstractPDF

    Effects of treatment duration and clamping during heat treatment were evaluated relative to the color and physical and mechanical properties of okan wood. Sapwood and heartwood boards from okan wood were treated with and without clamping for 1 to 4 h at 180 °C. Changes in color were mostly due to a reduction in lightness (L*) and yellow/blue chromaticity (b*). These values decreased more for longer treatment durations. Red/green chromaticity (a*) was not affected by the treatment duration. Weight loss and volume shrinkage increased with increased treatment duration. Density only slightly decreased because of a balanced reduction in weight and volume. Clamping during treatment prevented surfaces from having direct contact with the heated air, which resulted in lower weight loss and volume shrinkage than in the samples treated without clamping. Heat-treated wood absorbed less water than the control group, as suggested by the lower equilibrium moisture content and water absorption. Furthermore, the heartwood absorbed less water than the sapwood. An evaluation of the mechanical properties showed a reduction in both the modulus of rupture and modulus of elasticity after heat treatment. Clamping minimized strength reduction in both sapwood and heartwood, particularly for 1 and 2 h heat treatments.

  • Researchpp 10087-10098Cellatoğlu, N., and İlkan, M. (2016). "Solar torrefaction of solid olive mill residue," BioRes. 11(4), 10087-10098.AbstractPDF

    Torrefaction is a thermochemical pretreatment method for improving fuel characteristics of biomass. The process is conducted between 200 and 300 °C under inert atmosphere. The relatively low process temperature of torrefaction makes the use of solar energy suitable with low costs. In this study, solid olive mill residue (SOMR) was used to test the feasibility of using solar energy in the torrefaction process. SOMR is an agricultural waste obtained from olive oil extraction, and it is mainly produced in the Mediterranean region, which has high solar energy potential. In this study, the torrefaction of SOMR was conducted by concentrating solar energy with a parabolic dish concentrator, at 250 °C for 10 min. The fuel properties of solar torrefaction products were compared with raw SOMR. Solar torrefaction yielded a deoxygenated solid fuel with increased carbon content and higher heating value (HHV), similar to torrefaction.

  • Researchpp 10099-10111Peng, Y., Fu, S., liu, H., and Lucia, L. A. (2016). "Accurately determining esterase activity via the isosbestic point of p-nitrophenol," BioRes. 11(4), 10099-10111.AbstractPDF

    Esterase is an important enzyme for ester hydrolysis or synthesis. Its activity, however, has not been accurately ascertained due to a lack of accurate protocols. In this study, the isosbestic point of p-nitrophenol was found and used as the marker for its activity. The methodology avoided decomposition of the substrate, chromophore agents, and pH changes. The esterase activity was determined accurately and rapidly in a complex solution. In this protocol system, organic solvents were used for dissolving substrates, which influenced activity determination to some extent. Among the solvents tested, methanol exerted the least inhibitory influence. The results indicated that this modified method has potential to be applied for esterase activity determination on a large scale and in real time.

  • Researchpp 10112-10121Kaymakci, A., and Ayrilmis, N. (2016). "Influence of repeated injection molding processing on some mechanical and thermal properties of wood plastic composites," BioRes. 11(4), 10112-10121.AbstractPDF

    The influence of repeated cycles of injection molding on some mechanical and thermal properties of wood plastic composites (WPCs) was investigated. Pine wood flour (50 wt%) was mixed with HDPE (50 wt%) containing compatibilizing agent (MAPE, 3 wt%) in a co-rotating twin-screw extruder. The test specimens were produced by injection molding from the pellets dried to the moisture content (MC) of 1%. After the mechanical properties of the WPC test specimens were determined, the failed specimens were subsequently pelletized. These pellets were stored and dried for 4 to 6 h until the repeated injection was molded. These processes were repeated seven times. The results revealed that the flexural strength of WPCs increased by about 5.26% from the original granules to the third injection cycle, but further increments in the number of cycles decreased the flexural strength. The tensile strength and tensile modulus of the WPC specimens increased until the third cycle of injection molding while they tended to decrease after the third injection cycle.

  • Researchpp 10122-10139Sandak, A., Allegretti O., Cuccui, I., Sandak, J., Rosso, L., Castro, G., Negro, F., Cremonini, C., and Zanuttini, R. (2016). "Thermo-vacuum modification of poplar veneers and its quality control," BioRes. 11(4), 10122-10139.AbstractPDF

    Poplar wood is commonly used for many purposes due to its easy machinability, low density, uniform light colour, and relatively low cost. Here, vacuum thermal treatment is proposed for upgrading veneers in the manufacturing of plywood panels with resulting reduced hygroscopicity, improved durability, and dimensional stability. Thirty-eight batch processes with different treatment conditions (temperature ranging from 150 to 240 °C, time from 0.5 to 22.5 h and pressure from 100 to 1000 mbar) were performed to characterize the influence of process parameters on the product properties. Samples were characterized considering their appearance (colour) and their physical (mass loss and equilibrium moisture content), mechanical (bending strength), and chemical (investigated with near infrared spectroscopy (NIR)) properties. The darkening of poplar veneers and the reduction of mechanical strength were observed with increased treatment time and intensity. Mass loss closely correlated with colour change, resulting from chemical changes in wood components. Principal component analysis (PCA) and partial least squares (PLS) were used for evaluation of near infrared spectral data. Both were correlated with several technical properties, and thus NIR allowed the simultaneous prediction of several of these properties. Both colour change and NIR could be used to optimize the thermal treatment of poplar veneers at the industrial scale and for real-time statistical process control.

  • Researchpp 10140-10157Diaz, J. P. V., Silva, F. A., and d’Almeida, J. R. M. (2016). "Effect of peach palm fiber microstructure on its tensile behavior," BioRes. 11(4), 10140-10157.AbstractPDF
    This paper presents the results of an experimental investigation into the mechanical behavior and microstructural characteristics of peach palm fibers. The fiber morphology was studied using a scanning electron microscope (SEM), and the results of the mechanical tests were correlated with the fiber microstructure. The specimens were submitted to direct tensile tests in a state-of-the art microforce testing system using three different gauge lengths. The cross sectional areas of the fibers were measured using SEM micrographs and image analysis. The fiber microstructural characteristics were determined via thermogravimetric analysis and X-ray diffraction. The measured Young’s modulus was corrected for machine compliance. Weibull statistics were used to quantify the degree of variability in fiber strength at the different gauge lengths. The failure mechanisms were described and discussed in terms of the fiber microstructure, as well as defects in the fiber. The results showed that the fiber void content had a large influence on the fiber tensile strength and elastic modulus but the amount of main voids did not influence the fiber strength.
  • Researchpp 10158-10172Yen, S. H., and Chang, F. C. (2016). "Effects of fiber processing conditions on the yield, carbon content, and diameter of lignosulfonate-based carbon fibers," BioRes. 11(4), 10158-10172.AbstractPDF

    The use of a hardwood lignosulfonate (HLS) precursor along with electrospinning technology was studied to produce HLS-based carbon fibers. The production of the fibers helped to determine the appropriate processing parameters in the HLS carbon fiber production process. The processing parameters examined were the heating rate (POR) and the treatment temperature (POT) in the preoxidation process; the heating rate (C1R) and the treatment temperature (C1T) were in the low-temperature carbonization phase; and the carbonization temperature (C2T) and temperature holding period (C2t) were in the high-temperature carbonization phase. The results revealed that preoxidation with a POR of 1 °C/min and a POT of 250 °C generated favorable properties, particularly enhancing the fiber mat integrity and the fiber carbon content. The designed two-phase carbonization process was found to be satisfactory in increasing carbon fiber yields and enhancing fiber mat integrity. A C1R value of 1 °C/min and C1T of 400 °C facilitated favorable properties in the produced carbon fibers. Furthermore, a prolonged C2t increased the fiber carbon content but reduced the carbon fiber yield. The highest fiber carbon content occurred with a C2t of 3 h and a C2T of 1200 °C.

  • Researchpp 10173-10189Charisiou, N. D., Papageridis, K. N., Siakavelas, G., Tzounis, L., and Goula, M. A. (2016). "Effect of active metal supported on SiO2 for selective hydrogen production from the glycerol steam reforming reaction," BioRes. 11(4), 10173-10189.AbstractPDF

    The performance of nickel, cobalt, and copper supported on silica as catalysts was evaluated for the glycerol steam reforming (GSR) reaction. The samples were characterized by nitrogen-porosimetry according to Brunauer-Emmett-Teller (BET) method, X-ray diffraction (XRD), and inductively coupled plasma atomic emission spectroscopy (ICP-AES), while the deposited carbon on the catalytic surface was measured with a CHN-analyzer. Catalysts were studied in order to investigate the effect of the reaction temperature on (i) glycerol total conversion, (ii) glycerol conversion to gaseous products, (iii) hydrogen selectivity and yield, (iv) selectivity of gaseous products, and (v) selectivity of liquid products. The results showed that the Ni based on silica (Ni/Si) catalyst was more active and produced less liquid effluents than the catalysts that used an active metal such as Co or Cu. Moreover, the H2 yield from the Ni/Si catalyst was very close to the theoretical maximum predicted by thermodynamics, and the CO2 production was favoured in comparison to CO production, which is important for use in fuel cells.

  • Researchpp 10190-10200Ma, Q., Li, J., Xu, L., Sun, Q., Yong, B., and Wang, Y. (2016). "Biosynthesis of silver nanoparticles using wheat straw biomass under light radiation and their antibacterial activity," BioRes. 11(4), 10190-10200.AbstractPDF

    Silver nanoparticles (AgNPs) were synthesized with wheat straw biomass at room temperature using light irradiation. The reaction conditions were optimized, including the light intensity, biomass concentration, NaCl addition, and reaction time. The silver nanoparticles fabricated at the optimum conditions (light intensity 60,000 lx, biomass concentration 2 mg/mL, and reaction time 90 min) were characterized by UV-Vis spectroscopy, X-ray diffraction (XRD), transmission electron microscopy (TEM), Fourier transform infrared spectroscopy (FTIR), and zeta potential. The TEM results showed that the silver nanoparticles were mostly spherical, with an average diameter of 17.2 nm. The zeta potential of AgNPs reached -21.6 mV. The XRD spectra showed that the AgNPs were highly crystalline, with four characteristic peaks. The FTIR of nanoparticles implied that alcohols and proteins may have a vital role in the formation and stability of AgNPs. The silver nanoparticles synthesized by wheat straw biomass revealed antimicrobial activity against Escherichia coli and Bacillus subtilis strains.

  • Researchpp 10201-10212Yu, L., Tang, Z., Wei, D., Zhu, L., Zhu, J., Ma, X. (2016). "Evaluation of the dimensional stability and leaching performance of ACQ/wax treated southern pine," BioRes. 11(4), 10201-10212.AbstractPDF

    Southern pine (Pinus sp.) wood cubes were treated with ACQ solutions with wax modification and post-treated at 70 °C for 10 h with hot air circulation. The effects of wax concentrations in ACQ-treated southern pine on its dimensional stability and copper leaching performance were investigated. The ACQ/wax-treated wood exhibited improved water resistance during the water soak process. The testing of swelling and shrinkage performance of the treated wood showed that samples with a higher percentage of wax had higher resistance to water swelling and shrinkage. The samples with a lower percentage of wax addition had only a slight effect on the moisture swelling and shrinkage resistance. As a result, copper leaching from ACQ/wax-treated wood with a 2% wax concentration was reduced to a lower level compared to ACQ-treated wood. When the proportion of wax in ACQ preservative was less than 1%, a higher percentage of copper was leached from treated wood.

  • Researchpp 10213-10225Le, X., An, J., Zhang, G., Wang, L., Fan, J., Wang, P., and Xie, Y. (2016). "Investigation of the structural characteristics of corn stalk during hot-pressing," BioRes. 11(4), 10213-10225.AbstractPDF

    Corn stalk is one of the most abundant agricultural residues in China. In this experiment, corn stalks were hot-pressed to prepare formalin-free particleboard. Milled wood lignin (MWL) samples were isolated from original and hot-pressed corn stalks. To illuminate the self-bonding mechanism of binderless particleboard, the structural characteristics of original corn stalk, hot-pressed corn stalk, and MWL samples were thoroughly investigated by Fourier transform infrared spectroscopy (FT-IR), solid-state cross-polarization magic angle spinning carbon-13 nuclear magnetic resonance spectroscopy (CP-MAS 13C-NMR), X-ray diffraction (XRD), carbon-13 nuclear magnetic resonance spectroscopy (13C-NMR) and gel permeation chromatography(GPC). The degradation of hemicellulose and a portion of amorphous cellulose occurred during hot-pressing. Hot-pressing increased the crystallinity and crystallite size of cellulose in treated corn stalk. The analysis of MWL showed that hot-pressing resulted in corn stalk lignin depolymerization through cleavage of a substantial portion of the β-O-4 linkages in lignin, as well as the decrease of molecular weight of lignin in corn stalk. In addition, acid-catalyzed condensation occurred between lignin and xylose when liberated from hemicellulose. These results demonstrated that condensation between lignin and xylose may contribute to the self-bonding mechanism and improve board properties.

  • Researchpp 10226-10239Li, H., Li, K., Liu, H., Jing, T., Song, X., Xue, L., Li, C., and Shen, W. (2016). "The effect of VOCs from the branches and leaves of Pistacia chinensis Bunge and Juniperus chinensis cv. Kaizuka on mouse behavior," BioRes. 11(4), 10226-10239.AbstractPDF

    To meet both landscape aesthetics and health needs, the effects of different concentrations of volatile organic compounds (VOCs) from Pistacia chinensis Bunge (P. chinensis) and Juniperus chinensis cv. Kaizuka (J. chinensis) on mouse spontaneous behavior were studied during successive six-day experiments. The results were as follows: 1) The excitability of the mice and their total moving distance increased significantly upon exposure to low volatile concentrations of P. chinensis (P<0.05), whereas there was an opposite effect after exposure to J. chinensis. 2) The explorative capacity of mice was enhanced by J. chinensis; in contrast, P. chinensis treatment resulted in an opposite effect. 3) The scent of P. chinensis volatiles reduced mouse appetites while J. chinensis had the opposite effect. 4) P. chinensis volatiles helped enhance mouse tension. The number of fecal grains in the treatment group was always greater than that of the control group and increased with increasing volatile concentration to a number that was two times that of the controls when the volatile concentration reached a relatively high level. In contrast, in the J. chinensis environment, the mice were relatively relaxed, with overall numbers of fecal grains that were only 81.7% to 97.6% that of the controls. Overall, VOCs from J. chinensis had beneficial effects on mice. Therefore, more J. chinensis should be planted in urban green spaces. However, VOCs from P. chinensis could cause adverse effects on mice. Therefore, it is suggested to minimize their planting in city or repairing their branches to keep away from the smelling range of humans.

  • Researchpp 10240-10250Gong, Y., Wu, G., and Ren, H. (2016). "Block shear strength and delamination of crosslaminated timber fabricated with Japanese larch," BioRes. 11(4), 10240-10250.AbstractPDF

    Process parameters of cross-laminated timber (CLT) fabricated with Japanese larch were evaluated. The process parameters were designed by using an orthogonal test including pressure, glue consumption, and adhesive. Both delamination and block shear tests were conducted on CLT in accordance with GB/T 26899 (2011). The results showed that the optimum process parameters were A2B3C2 including pressure (1.2 MPa), glue consumption (200 g/m2), and amount of adhesive (one-component polyurethane). The weight loss and moisture absorption increased when the temperature increased, but the block shear strength decreased as the temperature was raised from 20 °C to 230 °C.

  • Researchpp 10251-10260Liu, Q., Bai, X., Feng, G., Tan, Z., Jiang, Q., and Guo, C. (2016). "Biomimetic conversion of glucose to organic acid facilitated by metalloporphyrin under mild conditions," BioRes. 11(4), 10251-10260.AbstractPDF
    Biomimetic catalytic conversion of carbohydrates to low-molecular weight (LWM) organic acids was investigated in the presence of sulfonated metalloporphyrins (MTSPP, M = Fe, Mn, Co, Cu), with dioxygen as the oxidant. The results showed that the selectivity of lactic acid reached 70%, starting from glucose with an iron complex of meso-tetra(4-sulfonato-phenyl)porphyrin (TSPPFeCl) as the catalyst at 433 K, and 0.6 MPa of O2 in 0.05 M NaOH aqueous solution. The effects of various metalloporphyrins on the selectivity of oxidative products were also considered. Experimental results show that TSPPFeCl exhibited the highest catalytic performance compared with TSPPMnCl, TSPPCo, and TSPPCu.
  • Researchpp 10261-10272Liu, J., Chen, T., Xie, Y., Wei, Q., Chen, Y., Rao, J., Niu, M., and Wang, X. (2016). "Fire performance of ultra-low density fiberboard (ULDF) with complex fire-retardants," BioRes. 11(4), 10261-10272.AbstractPDF

    To clarify how the fire performance of ultra-low density fiberboard (ULDF) can be improved by complex fire-retardants, the limiting oxygen index (LOI) and microstructure of ULDFs with different additive amounts of complex fire-retardants was analyzed. The char yield, chemical bonding, and thermostability of ULDFs treated by different temperatures were also tested. Results showed that the LOI values and compactness of ULDFs were increased with increased amounts of fire-retardants. Three steps of char yield curves in control fiberboard (CF) and mixed fiberboard (MF) were apparent. The preliminary degradation in lignin and cellulose of CF occurred at 300 °C. The cellulose had completely decomposed at 400 °C, but in the case of MF, the lignin and cellulose were not completely decomposed at 400 °C. It was shown that there are different ways to improve the fire resistance of ULDF using boron, nitrogen-phosphorus, silica, and halogen-based fire-retardants. The fiberboard with silicium compounds had the lowest mass loss in three stages and total mass loss. Compared with CF, MF had a lower mass loss. Furthermore, the exothermic peak for MF at around 400.0 °C was decreased, indicating that the fire resistance of ULDF was improved by the complex fire-retardants.

  • Researchpp 10273-10285Fu, Y., Liu, X., Cheng, F., Sun, J., and Qin, Z. (2016). "Modification of the wood surface properties of Tsoongiodendron odorum Chun with silicon dioxide by a sol-gel method," BioRes. 11(4), 10273-10285.AbstractPDF
    A sol-gel method was employed to improve wood surface properties by generating SiO2 with tetraethoxysilane and methyl triethoxysilane as co-precursors. The effect of SiO2 on the wood surface properties was studied by the analysis of size stability, ultraviolet radiation aging resistance, and contact angle of the modified wood. The improvement mechanism was explored using scanning electron microscopy (SEM), energy dispersive X-ray (EDAX), and Fourier transform infrared spectroscopy (FT-IR). The results showed that the water absorption and the hygroscopic expansion rate of the modified wood were less than those of the control samples. The discoloration resistant properties were improved 1.5 times more than that of the control samples. The thickness of SiO2 on the wood surface was approximately 60 μm, and the silicon content increased as the dipping time increased. The contact angle of modified wood showed that it was more hydrophobic than that of the control sample, and this increased as the dipping time increased. The variation in contact angle of the modified wood was less than that of the control sample before and after aging. The anti-aging performance of the modified wood surface was also improved.
  • Researchpp 10286-10295Tee, Y. B., Wong, J., Tan, M. C., and Talib, R. A. (2016). "Development of edible film from flaxseed mucilage," BioRes. 11(4), 10286-10295.AbstractPDF

    A flaxseed mucilage-based edible film was developed with the addition of glycerol as a plasticizer. Various concentrations of glycerol were blended into the extracted mucilage, and the developed films were studied in terms of physical, mechanical, and morphological properties. As the glycerol concentration was increased from 1 to 5 wt%, the elongation at break of the films prominently increased, whereas the tensile strength and Young’s modulus decreased. The film failed to form at 6 wt% glycerol inclusion. The developed film was slightly reddish and yellowish in color, with enhanced transparency as the glycerol concentration in the film increased. Overall, this work demonstrated that with the addition of glycerol as a plasticizer up to 5 wt%, a flaxseed mucilage-based edible film could be developed as a sustainable alternative for food and bioproduct coating or packaging.

  • Researchpp 10296-10313He, M., Cho, B. U., Lee, Y. K., Won, J. M. (2016). "Utilizing cellulose nanofibril as an eco-friendly flocculant for filler flocculation in papermaking," BioRes. 11(4), 10296-10313.AbstractPDF

    Cellulose nanofibril (CNF) is a type of nano-sized cellulosic material with a high aspect ratio and a large specific surface area, which makes it a promising additive to flocculate particles such as fillers. In this study, CNFs were prepared by wet disk-milling with three different degrees of fibrillation. The effect of the CNF on the flocculation of precipitated calcium carbonate (PCC) was elucidated. A photometric dispersion analyzer (PDA) investigated the flocculation phenomena resulting from the interactions between the PCC and the CNF, or polymers, in real-time. The results clearly showed that CNF could be used to control the flocculation behavior of the PCC particles. Scanning electron microscopy (SEM) images showed that the CNFs functioned as bridges between the two PCC particles. A significant reflocculation capability was observed in one- and two-component systems that consisted of CNFs. The addition of cationic starch (C-starch) could induce more efficient flocculation within a two-component system.

  • Researchpp 10314-10328Li, Y., Yu, M., Fan, Y., Li, R., Yang, T., Chi, Y. (2016). "Effects of metal salt catalysts on fluidized bed gasification characteristics of source-collected combustible solid waste," BioRes. 11(4), 10314-10328.AbstractPDF

    Effects of metal salt catalysts and gasification temperature on the gasification characteristics of combustible solid waste were studied, based on the source-classified waste in a fluidized bed gasifier, to provide guidance for utilizing the source-classified waste effectively. The results showed that the gasification characteristics of combustible solid waste, such as paper and sawdust, improved noticeably after adding NaCl, K2CO3, or sodium dodecyl benzene sulfonate (LAS). Adding NaCl to sawdust increased the yield of CO and CH4, while the gasification was inhibited gradually with increasing addition. Adding NaCl promoted the generation of H2 in paper gasification. NaCl played a catalytic role only when it exceeded a certain value. Adding K2CO3 increased the yield of H2 noticeably in sawdust and paper gasification. The catalytic effect of K2CO3 on sawdust was better than that on paper. Similar results were obtained for LAS in producing H2 in gasification. The carbon conversion efficiency and the gasification efficiency were increased with additional LAS. Moreover, the catalytic effect of K2CO3 was superior to that of LAS by comparison. As the temperature rises, the activity of the metal salt catalyst is enhanced, but it is inhibited if the temperature is too high.

  • Researchpp 10329-10338Yin, X., Xu, Y., Lin, T., Liang, Q., Yang, B., and Duan, C. (2016). "Further understanding of the silicon morphological fundamentals of bamboo culm," BioRes. 11(4), 10329-10338.AbstractPDF

    Bamboo is one of the most important non-wood raw materials for the pulp and paper industry in Asia and particularly in China. However, its high silicon content can cause challenges in the pulping and alkali recovery systems. Further understanding of the distribution, morphology, and composition of silicon in bamboo culm will be beneficial in solving these challenges. In this study, modern analytical tools such as scanning electron microscopy (SEM) and scanning electron microscopy equipped with an energy dispersive X-ray (SEM-EDX) were used to characterize the distribution, morphology, and composition of silicon in the bamboo culm. The results showed that silicon is mainly distributed in the outer skin and inner skin. The silicon deposits exist in a number of shapes, and sinuate is the most common one. Their sizes range from about 0.15 μm to 0.9 μm in the cell wall and between 0.3 μm to 1.5 μm in the cell lumen. Localized silicon deposits are present in the forms of its oxide, silica, monatomic silicon, and/or organosilicon. Based on the above results, two potential techniques are recommended for pulp mills to minimize silicon-related challenges.

  • Researchpp 10339-10348Lorincová, S., Hitka, M., Čambál, M., Szabó, P., and Javorčíková, J. (2016). "Motivational factors influencing senior managers in the forestry and wood-processing sector in Slovakia," BioRes. 11(4), 10339-10348.AbstractPDF

    Senior managers in the forestry and wood-processing sectors in the Slovak Republic were asked to complete questionnaires. The aim of the research was to identify the importance of certain factors that affect the process of their motivation. A total of 493 senior managers were surveyed. The respondents used a five-point rating scale to rate the significance of each motivation factor, where 5 was very important and 1 was unimportant. The importance of 36 motivation factors was studied for senior managers through the use of statistical methods. Based on the study, it was concluded that the base salary is the most important factor of motivation, followed by job security as the second most important motivation factor, and the third most important factor was the fair appraisal system.

  • Researchpp 10349-10377Wu, X., Jiao, W., Li, Y., Li, B. Z., Huang, Y., Zhang, H., Zhang, Y., Wang, Q., and Tang, Y. (2016). "Decomposition of β-O-4 linked lignin model compound in anhydrous ethanol without any added catalyst," BioRes. 11(4), 10349-10377.AbstractPDF
    The cleavage of a lignin model compound of 2-phenoxyacetophenone (2-PAP) was studied in an anhydrous ethanol solvent. A high conversion of 2-PAP (> 99%) to the desired products (> 80% for phenol) with impressive selectivity was achieved in a stainless steel (T316SS) autoclave without any added catalyst. The stainless steel was analyzed as being effective at catalyzing the decomposition of 2-PAP because of its hydrogen transfer activity and stabilization of reaction intermediates, while anhydrous ethanol served as both a solvent and hydrogen donator. An active hydrogen-promoted reaction network was proposed to explain these results. Further investigation demonstrated that the co-catalyst, Cs2.5H0.5PMo12O40, enhanced the cleavage efficiency, which resulted in high yields of the desired products (> 98% of phenol and > 91% of acetophenone). The proposed method in this study based on the stainless steel-promoted hydrogen transfer reaction, which had the merits of a high conversion efficiency and easy handling, can be expected to develop a promising process for further transformation of lignin to valuable multi-substituted aromatics.
  • Researchpp 10378-10390Missio, A. L., de Cademartori, P. H. G., Mattos, B. D., Santini, E. J., Haselein, C. R., and Gatto, D. A. (2016). "Physical and mechanical properties of fast-growing wood subjected to freeze-heat treatments," BioRes. 11(4), 10378-10390.AbstractPDF

    The physical and mechanical performance of wood from the rose gum (Eucalyptus grandis) and the Gympie messmate (Eucalyptus cloeziana) species were investigated. The wood samples were treated with a two-stage freeze-heat thermal process. Fast-growing trees were used for preparing test samples, which were subjected to thermal treatments. The freezing stage had the treatment temperature fixed at -22 °C for 72 h, while the temperature of the heat stage ranged from 180 to 200 °C for 3.5 h. The measurements of mass loss, density, and equilibrium moisture content were determined to better understand the mechanical properties. Static bending, compression parallel to grain, Janka hardness, and impact tests were applied to reveal changes in the mechanical behavior of the treated wood. In general, the freezing stage decreased the mass loss and increased the moisture content of wood (when combined with the heating stage), which showed the opposite trend for the heating stage. Modulus of elasticity and compression strength were increased only after the heating stage, while decrements were found for modulus of rupture, impact strength, and Janka hardness. The two-stage treatments did not prevent a decrease in the mechanical properties; however, they were helpful in preventing higher mechanical resistance losses in hardness (the Gympie messmate) and impact resistance (the rose gum).

  • Researchpp 10391-10403Han, K. M., and Cho, B. U. (2016). "Effect of surface sizing of black liquor on properties of corrugated medium," BioRes. 11(4), 10391-10403.AbstractPDF

    Spent cooking liquor from kraft pulping, known as black liquor, was applied to linerboard (corrugated medium) by surface sizing in order to increase strength properties. The influence of alum in black liquor on linerboard properties was also investigated. The surface application of black liquor improved the dry strength of linerboard. A slight addition of alum into black liquor (2.5% on black liquor solids) significantly improved strength properties such as tensile strength, TEA, compressive strength, and bursting strength. The results implied that black liquor with alum can be used for industrial grade papers that require high strength properties. The air permeability of corrugated medium increased after 5 g/m2 of dry pick-up. Black liquor appeared to penetrate the paper pores, and aggregates of lignin and carbohydrates in the black liquor increased bonds between fibers, which improved strength. The surface sizing of black liquor and alum addition also affected the hydrophobicity of linerboard.

  • Researchpp 10404-10418Keränen, J. Y., and Retulainen, E. (2016). "Changing quality of recycled fiber material. Part 1. Factors affecting the quality and an approach for characterisation of the strength potential," BioRes. 11(4), 10404-10418.AbstractPDF

    The paper recycling sector has undergone major changes in recent years, particularly regarding the quantity and quality of various materials processed. Material originating from board grades will increasingly dominate the recycling market as the use of printing papers decreases and the amount of non-fiber elements increases. Users of recycled fiber material have to overcome three main challenges: price, quality, and availability. This paper focuses on the quality dilemma in terms of measurement needs and possibilities from the user viewpoint. It includes a discussion of the factors causing deterioration in the quality of paper used for recycling. Today, the average fiber age is low compared to what the fibers can tolerate. Therefore, the characteristic phenomena in the paper recycling loop are not caused by the degradation of individual fibers, but by a blending process in which different fiber grades and non-fiber components are blended in a non-optimal way. A novel method is introduced in this article for evaluating the quality of recycled fiber material using a new parameter, the fiber integrity value. Part 2 of this paper will focus on the application of this new parameter and demonstrates its correlation with paper properties.

  • Researchpp 10419-10432Wang, S., Chen, M., Lu, L., Zhao, P., and Gong, C. (2016). "Investigation of the adaptability of paper sludge with wood fiber in cement-based insulation mortar," BioRes. 11(4), 10419-10432.AbstractPDF

    Paper sludge generated from the paper industry is classified as solid waste, comprising primarily wood fiber with excellent toughness and CaCO3 with low thermal conductivity. The purpose of this work was to investigate the adaptability of paper sludge with wood fiber into cement-based insulation mortar. The addition of paper sludge with wood fiber was found to be beneficial for optimizing the performance of cement-expanded polystyrene (EPS)/paper sludge (CEP) mortar. In detail, the addition of paper sludge with low fiber content in the range of 2.5% to 7.5% improved the toughness and softening coefficient of CEP mortar. In comparison, an increase of wood fiber content notably improved the properties of CEP mortar when its addition level reached 15%. Additionally, paper sludge with different fiber contents decreased the thermal conductivity of CEP mortar, ranging from 0.0897 to 0.0885 W/(m·K). In conclusion, paper sludge with wood fiber exhibited good adaptability in CEP mortar.

  • Researchpp 10433-10447Luo, Y., Street, J., Steele, P., Entsminger, E., and Guda, V. (2016). "Activated carbon derived from pyrolyzed pinewood char using elevated temperature, KOH, H3PO4, and H2O2," BioRes. 11(4), 10433-10447.AbstractPDF

    Activated carbon was prepared from pyrolyzed pinewood char using KOH, H3PO4, H2O2, and heat-only treatments. Activated carbon prepared by the heat-only treatment had a total surface area of 233.2 m2/g, a total pore volume of 0.138 cm3/g, a microporous surface area of 129.9 m2/g, and a microporous volume of 0.07 cm3/g. The most significant improvement of pore properties for the chemically treated pinewood char was obtained by the KOH treatment, which produced a total surface area of 1124.4 m2/g, a total pore volume of 0.723 cm3/g, a microporous surface area of 923.6 m2/g, and a microporous volume of 0.485 cm3/g. After the H3PO4 treatment, pinewood char had a total surface area of 455.5 m2/g, a total pore volume of 0.251 cm3/g, a microporous surface area of 393.3 m2/g, and a microporous volume of 0.211 cm3/g. The least significant improvement was obtained from the H2O2 treatment, which produced a total surface area of 363.0 m2/g, a total pore volume of 0.202 cm3/g, a microporous surface area of 271.5 m2/g, and a microporous volume of 0.141 cm3/g. Transmission electron microscopy (TEM), thermogravimetric analysis (TGA), and Fourier transform infrared spectroscopy (FTIR) were performed to compare separate treatment stabilities and functional group properties.

  • Researchpp 10448-10468Miranda, R., Nicu, R., Bobu, E., and Blanco, A. (2016). "Efficiency of chitosan and their combination with bentonite as retention aids in papermaking," BioRes. 11(4), 10448-10468.AbstractPDF

    In a previous work (Nicu et al. 2013), the flocculation efficiency of three chitosans differing by molecular weight and charge density were evaluated for their potential use as wet end additives in papermaking. According to the promising results obtained, chitosan (single system) and its combination with bentonite (dual system) were evaluated as retention aids, and their efficiency was compared with poly(diallyl dimethyl ammonium chloride) (PDADMAC) and polyethylenimine (PEI). In single systems, chitosan was clearly more efficient in drainage rate than PDADMAC and PEI, especially those with the lowest molecular weights; however, retention is considerably lower. This drawback can be overcome by using dual systems with anionic bentonite microparticles, with the optimum ratio of polymer:bentonite being 1:4 (wt./wt.). In dual systems, the differences in retention were almost negligible, and the difference in drainage rate was even higher, together with better floc reversibility. The most efficient chitosan in single systems was Ch.MMW, while Ch.LMW was the most efficient in dual systems. The flocculation mechanism of chitosan was a combination of patch formation, charge neutralization, and partial bridge formation, and the predominant mechanism depended on the molecular weight and charge density of the chitosan.

  • Researchpp 10469-10482Xu, Y., Li, X., Zhang, X., Wang, W., Liu, S., Qi, W., Zhuang, X., Luo, Y., and Yuan, Z. (2016). "Hydrolysis of corncob using a modified carbon-based solid acid catalyst," BioRes. 11(4), 10469-10482.AbstractPDF
    Lignocellulosic biomass is a very important renewable resource that can be used to produce biofuels and various platform chemicals. The conversion of biomass to reducing sugars is an important intermediate step that can impact the economic benefits of the process. Modified carbon-based solid acid is a novel catalyst used in the hydrolysis process of lignocellulosic materials. The catalyst material was prepared through the incomplete carbonization and subsequent sulfonation of a mixture of glucose and p-toluenesulfonic acid, followed by oxidation using 30% H2O2 to promote the acidity. The hydrolysis efficiency of the solid acid catalyst thus prepared was considerably increased. The effects of the carbonization temperature, time, and the glucose/p-toluene-sulfonic acid ratio on catalytic efficiency were investigated in this study. Under the appropriate preparation conditions, the catalyst could hydrolyze corncob to produce 78% xylose. The activity of the catalyst slightly declined after five cycles of application.
  • Researchpp 10483-10496Bian, H., Li, G., Jiao, L., Yu, Z., and Dai, H. (2016). "Enzyme-assisted mechanical fibrillation of bleached spruce kraft pulp to produce well-dispersed and uniform-sized cellulose nanofibrils," BioRes. 11(4), 10483-10496.AbstractPDF

    Cellulose nanofibrils, as a bionanomaterial with many promising properties, have great potential in composite applications. Herein, well-dispersed and uniform-sized cellulose nanofibrils (CNF) was successfully obtained from commercial bleached softwood kraft pulp, with yields of 79.15% via enzyme-assisted hydrolysis and a subsequent homogenization process. Field emission scanning electron microscope (FE-SEM) confirmed the fiber morphology. Water retention value (WRV) was increased from 107.32% of original pulp to 1383.92% of the resulting CNFs, while crystallinity had no significant changes. Fourier transform infrared (FTIR) spectroscopy indicated the addition of enzyme resulted in the removal of hemicelluloses and lignin. CNFs subjected to enzymatic treatment and homogenization had less entangled network, larger aspect ratio and higher transmittance than those from pure mechanical treatment. They exhibited well-dispersed in aqueous solution and uniform-sized in morphology. These advantages revealed enzyme-assisted process had a remarkable effect on the production of CNFs and made CNFs attractive for nanotechnology and nanomaterial.

  • Researchpp 10497-10510Li, H., Zhang, F., Ramaswamy, H. S., Zhu, S., and Yu, Y. (2016). "High-pressure treatment of Chinese fir wood: Effect on density, mechanical properties, humidity-related moisture migration, and dimensional stability," BioRes. 11(4), 10497-10510.AbstractPDF
    A new densification technique for industrial uses of plantation wood was studied. Chinese fir wood was treated by high pressure (HP) at 50 to 200 MPa for 5 min. The density and mechanical properties, moisture sorption isotherm (MSI), and dimensional changes of the pressure-treated wood under various relative humidity (RH) storage conditions were evaluated. The densities of HP-treated wood ranged from 0.79 ± 0.01 g/cm3 after treatment at 50 MPa to 0.92 ± 0.02 g/cm3 at 200 MPa, which was significantly higher (p < 0.05) than that of the control (0.35 ± 0.01 g/cm3). Hardness values in radial and tangential fiber alignment faces also significantly increased by 370% to 470% and 350% to 460%, respectively, as compared with the control. The modulus of elasticity and the modulus of rupture of pressure-treated wood increased by 48% to 88% and 89% to 170%, respectively. The equilibrium moisture content varied with RH, decreasing slightly at 33% and 52% while significantly increasing (p < 0.001) at 86% and 93% RH. Radial, tangential, and volumetric dimensions of densified wood were relatively stable at 33%, 52%, and 67% RH, while remarkable swelling occurred at 86% and 93% RH.
  • Researchpp 10511-10527Ahmad, Z., Asgher, M., Hussain, F., Randhawa, M. A. (2016). "A novel approach to delignify lignocellulosic materials by using ligninolytic enzyme consortium," BioRes. 11(4), 10511-10527.AbstractPDF
    Lignin biodegradation is an attractive approach for producing value-added products. These valuable products are produced by the processing and refining of lignocellulosic residues. A set of ligninolytic enzymes including lignin peroxidase (LiP), manganese-dependent peroxidase (MnP), and laccase (Lac) were individually produced from Ganoderma lucidum, Trametes versicolor, and Pleurotus ostreatus. Solid state fermentation under pre-optimized culture conditions with varying ratios of enzymes were used for the delignification of lignocellulosic biomass residues. The fungal enzymes were purified in four steps including ammonium sulfate precipitation, dialysis, ion exchange chromatography, and gel filtration chromatography. The purified enzymes were subsequently used in varying ratios (with each containing 200 U/mL) for the delignification of wheat straw, sugarcane bagasse, and rice straw. The consortium of enzymes caused the removal of 58.5%, 46%, and 52% of the lignin from the wheat straw, sugarcane bagasse, and rice straw, respectively, at LiP: MnP: Lac ratios of 1:2:2, 1:1:2, and 2:1:2. The best delignification was observed in wheat straw (58.5%), exposing 76.54% cellulose content. The results suggested that the ligninolytic enzymes are effective catalysts for the selective partial delignification of lignocellulosic biomass residues. After delignification these lignocellulosic residues could be utilized as cost-effective substrates for the production of enzymes, biofuels, and other industrially significant products.
  • Researchpp 10528-10539Kminiak, R., and Kubš, J. (2016). "Cutting power during cross-cutting of selected wood species with a circular saw," BioRes. 11(4), 10528-10539.AbstractPDF

    This study assessed the effect of selected factors, such as the feed force (Ff = 15, 20, and 25 N), wood species (beech (Fagus sylvatica L.), English oak (Quercus robur L.), and spruce (Picea abies L.)), and the number of saw blade teeth (z = 24, 40, and 60) on cutting power in the cross-cutting of lumber. The cutting was done using a circular saw with a rotating motion of the saw blade at a constant cutting speed (vc) of 62 m.s-1. The tangentially bucked lumber had a relative humidity (wr) of 12% ± 1% and a thickness (e) of 50 mm. For the experiment, four circular saw blades with SK plates, a uniform diameter (D = 250 mm), and identical angular geometry (angle of clearance (α) = 15°, wedge angle (β) = 60°, and rake angle (γ) = 15°) were used. The saw blades had a different number of teeth (z = 24, 40, and 60), and one saw blade had 24 teeth and a chip limiter. The aim of this study was to expand the knowledge about the resulting cutting performance with different combinations of technological process parameters.

  • Researchpp 10540-10548Büyüksarı, Ü., As, N., Dündar, T., and Sayan, E. (2016). "Comparison of micro- and standard-size specimens in evaluating the flexural properties of Scots pine wood," BioRes. 11(4), 10540-10548.AbstractPDF

    The aim of this study was to investigate the flexural properties (bending strength and modulus of elasticity) of Scots pine wood (Pinus sylvestris L.) using micro- and standard-size test specimens. In the standard- and micro-size specimens, the average bending strengths were evaluated as 72.8 and 62.4 MPa, and the bending modulus of elasticity was 9917 and 2884 MPa, respectively. These results showed that the bending strength and modulus of elasticity values of the micro-size specimens were lower than those of the standard-size specimens. The statistically significant effects included the specimen size, individual trees, and the interactions of the specimen size and trees on the bending strength and modulus of elasticity. Furthermore, regression analyses indicated a positive linear regression between the flexural properties of the micro- and standard-size specimens. The results indicated that micro-size specimens can be used to estimate the flexural properties of Scots pine wood when obtaining standard-size specimens is not possible.

  • Researchpp 10549-10564Yao, X., Xu, K., and Liang, Y. (2016). "Comparing the thermo-physical properties of rice husk and rice straw as feedstock for thermochemical conversion and characterization of their waste ashes from combustion," BioRes. 11(4), 10549-10564.AbstractPDF

    The thermogravimetric characterization and gas emission properties during the pyrolysis of rice husk (RH) and rice straw (RS) were compared, and the properties of waste rice husk ash (RHA) and rice straw ash (RSA) from the combustion process were investigated. The results showed that the pyrolysis of RH and RS followed a four-step mechanism. Comparing the emission properties of small molecule bio-syngas in the pyrolysis of these two biomass wastes implied that RS was more suitable for use as feedstock for thermochemical conversion. Chemical and phase analysis results indicated that the RSA was rich in K, Ca, and P and had good potential for use as a soil amendment or as a material for silicate ceramics. The RHA was rich in SiO2 and could be an ideal silica source for silicon compound preparation or a pozzolan source for blended cement concrete production. Morphology analysis on the ash samples revealed that the high content of alkali metals may cause the higher agglomeration tendency of RSA with respect to RHA. The contrast in pore properties of biomass char wastes isolated from the ashes indicated that the char wastes recovered from RHA would be better used as a low-cost precursor in activated carbon production.

  • Researchpp 10565-10574Gáborík, J., Gaff, M., Ruman, D., Záborský, V., Kašíčková, V., and Sikora, A. (2016). "Adhesive as a factor affecting the properties of laminated wood," BioRes. 11(4), 10565-10574.AbstractPDF

    This study focuses on changing wood’s bending properties using several types of adhesives. The strength, flexibility, and durability (service life) of laminated wood, glued with four types of adhesives, were examined. The results were compared with solid beech wood, conditioned to 9% moisture content. Depending on the adhesive used, the results indicate that laminated (layered) wood improved the strength and bending characteristics in comparison to the intact wood. Gained knowledge about materials properties have practical applications in the area of dynamic stress (e.g., as components of vibrating machinery mechanisms or in constructing beds, chairs, and sports equipment).

  • Researchpp 10575-10584Lomelí-Ramírez, M. G., Dávila-Soto, H., Silva-Guzmán, J. A., Ochoa Ruíz, H. G., and García-Enriquez, S. (2016). "Fungitoxic potential of extracts of four Pinus spp. bark to inhibit fungus Trametes versicolor (L. ex. Fr.) Pilát," BioRes. 11(4), 10575-10584.AbstractPDF

    Antifungal potential of bark crude extracts of Pinus strobus L., Pinus douglasiana Martinez, Pinus caribaea Morelet [var. Hondurensis (scheclauze) W. H. G. Barrett & Golfari] and Pinus leiophylla Schltdl. & Cham, for inhibiting mycelial growth to fungus Trametes versicolor (L. ex Fr.) Pilát was investigated. Pinus bark was extracted through a mixture of acetone-hexane-water 54:44:2 V. Bioassays were performed according to the agar dilution method (petri dish) using concentrations of 0.1, 0.5, and 1.0 mg mL-1 for each of the obtained extracts. All extracts showed some inhibition degree. Crude extracts of P. strobus bark showed the greatest inhibition degree. Antifungal potential of all tested extracts at a concentration of 1.0 mg mL-1 was classified as toxic. Through simple regression models, concentrations were calculated in order to achieve a 50% inhibition (IC50) and the minimal inhibition concentration (MIC). MIC values were 1.58, 1.72, 1.24, and 1.94 mg mL-1 for bark extracts of P. strobus, P. douglasiana, P. caribaea, and P. leiophylla, respectively.

  • Reviewpp 10585-10603Jin, J., Chen, S., and Wellwood, R. (2016). "Oriented strand board: Opportunities and potential products in China," BioRes. 11(4), 10585-10603.AbstractPDF
    North America’s first oriented strand board (OSB) mill was built in the early 1980’s. Twenty years later, the industry was thriving, with over 50 mills producing the product. China’s first OSB mill was built in 1990, and 25 years later, there are a few mills with a total capacity less than two large North America mills, most operating below capacity and struggling to identify domestic markets for the growing production. This paper briefly looks at the histories of OSB industries in North America and China, presents the current situation of China’s wood-based panels industry and its downstream industries, and identifies OSB opportunities and potential products in China. Opportunity for sheathing-grade OSB is very limited in the current Chinese market, whereas industrial opportunities for specialty OSB products to replace plywood have great potential. Those specialty products include materials for furniture, wood doors, wood flooring, container flooring, concrete form, etc. OSB producers must designate the right OSB products for the Chinese market and cost-effectively manufacture those differentiated products to meet specifications for various end-applications.
  • Reviewpp 10604-10624Kaur, P. J., Satya, S., Pant, K. K., and Naik, S. N. (2016). "Eco-friendly preservation of bamboo species: Traditional to modern techniques," BioRes. 11(4), 10604-10624.AbstractPDF
    The continuous depletion of forests calls for the astute usage of existing resources. Fungi and termites cause serious damage to biomass under storage and service conditions. Various protective treatments with high amounts of toxic chemicals are used by the wood and bamboo industry. Efforts are being made the world over to develop environmentally friendly preservatives for wood and bamboo species. Recent research highlights the potential and effectiveness of traditional practices and procedures, mainly water leaching technique and smoke treatment. Under laboratory conditions, the service life of treated blocks were found to be at a par with commercial chemical preservative treated blocks. Various plant extracts and oil-based formulations, such as organic acids, essential oils, and eco-friendly chemical-based preservatives, are in the stage of development. The bio-efficacy of such preservatives is measured in terms of the improvement in resistance to fungi and termites. However, much work still needs to be done to completely determine the efficacy of many of these newly developed preservatives and techniques. The present paper discusses an overview of the developments in the field of environment-friendly biomass preservatives.
  • Reviewpp 10625-10653Sarip, H., Sohrab Hossain, M., Azemi M. N., M., and Allaf, K. (2016). "A review of the thermal pretreatment of lignocellulosic biomass towards glucose production: Autohydrolysis with DIC technology," BioRes. 11(4), 10625-10653.AbstractPDF
    There is increasing demand for the production of biofuels from lignocellulosic biomass. Lignocellulosic biomass consists mainly of three polymeric components: cellulose, hemicelluloses, and lignin. The separation of these components requires an effective pretreatment process to ensure high quality glucose production, and is highly influenced by several factors, including moisture content, cellulose crystallinity, lignin content, and available surface area. Over time, numerous pretreatment methods have been utilized to change the lignocellulosic fiber structure and to enhance the enzymatic saccharification of cellulose to polysaccharides. This article reviews thermal-based pretreatment of lignocellulosic fiber used for glucose production. Based on the reviewed studies, autohydrolysis of lignocellusic biomass, followed by the “Instant pressure drop (DIC),” method can be regarded as an effective pretreatment process of lignocellusic biomass.
  • Reviewpp 10654-10676Md Shah, A. U., Sultan, M. T. H., Jawaid, M., Cardona, F., and Abu Talib, A. R. (2016). "A review on the tensile properties of bamboo fiber reinforced polymer composites," BioRes. 11(4), 10654-10676.AbstractPDF

    This paper reviews the tensile properties of bamboo fiber reinforced polymer composites (BFRP). Environmentally friendly bamboo fibers have good mechanical properties, which make them suitable replacements for conventional fibers, such as glass and carbon, in composite materials. Better fiber and matrix interaction results in good interfacial adhesion between fiber/matrix and fewer voids in the composite. Several important factors improve matrix-fiber bonding and enhance the tensile properties of BFRP. Coupling agents, such as maleic anhydride polypropylene (MAPP), improve the adhesion of bamboo fibers in the polypropylene (PP) matrix. A high percentage of lignin content in bamboo fibers limits fiber separation, which leads to less matrix absorption between fibers. Steam explosion is the best extraction method for bamboo fibers, although an additional mechanically rubbing process is required for fiber separation. Generally, high fiber content results in good composite performance, but at a certain limit, the matrix does not adhere well with a saturated amount of fibers, and the composite tensile strength decreases. However, the tensile modulus of BFRP is not affected by excess fiber content. Hybridization of bamboo with conventional fibers increases the tensile strength of BFRP. The addition of micro/nano-sized bamboo fibrils into the carbon fabric composites slightly enhances composite strength.

  • Reviewpp 10677-10710Johnson, M. A., and Hart, P. W. (2016). "Integrating a biorefinery into an operating kraft mill," BioRes. 11(4), 10677-10710.AbstractPDF

    Kraft pulp and paper mills have several advantages for serving the emerging biorefinery industry as a source of raw materials. This review examines technologies for producing liquid biofuels, chemicals, and advanced materials from woody feedstocks to generate new sources of revenue. Market pull comes in part from government policies that drive substitution of petroleum-based products with biobased equivalents. Kraft mills have ample networks to supply feedstocks, whether these are forest residues or byproduct side streams. Pulp mills are well suited to expand sufficiently to accommodate production of value added platform chemicals that are in demand because of brand owner sustainability commitments.

  • Reviewpp 10711-10755Veettil, S. I., Kumar, L., and Koukoulas, A. A. (2016). "Can microbially derived advanced biofuels ever compete with conventional bioethanol? A critical review," BioRes. 11(4), 10711-10755.AbstractPDF

    Microbially derived alkanes and their derivatives are recognized as promising alternatives to petroleum-based fuels and chemicals. We review recent developments in their production, assess progress, and their potential against conventional bioethanol fermentation pathways. The success rate of genetic engineering efforts and their commercialization prospects are assessed, as well as challenges for producing fuels and chemicals from lignocellulosic biomass. Although significant progress has been made in the genetic engineering of microbes used in the production of long-chain hydrocarbons and their derivatives, titer and yield of these biomolecules are currently too low to compete with petroleum-derived products. As for microbially derived isoprenoids or fatty acids, the inherent complexity of micro-organism development will continue to present formidable challenges, making it highly unlikely of any short-term commercial take off. Nonetheless, first generation bioethanol (starch/sugar based) production is commercially established and therefore continued advancements in chemical synthesis should enable broad-scale use of bio-ethanol as a chemical feedstock for the production of advanced biofuels including butanol and other long-chain hydrocarbons.

  • Reviewpp 10756-10782Mukhtar, I., Leman, Z., Ishak, M. R., and Zainudin, E. S. (2016). "Sugar palm fibre and its composites: A review of recent developments," BioRes. 11(4), 10756-10782.AbstractPDF
    The use of natural fibres as reinforcement in composite materials has increased over the years due to the rapid demand for renewable, cost-effective, and eco-friendly materials in many applications. The most common and adopted natural fibres used as reinforcements are flax, kenaf, hemp, jute, coir, sisal, and abaca. However, sugar palm fibre (SPF) as one of the natural fibres is gaining acceptance as a reinforcement in composites, though it has been known for decades in the rural communities for its multipurpose traditional uses. Sugar palm fibre (SPF) is extracted from sugar palm tree typically from its four morphological parts, namely, trunk, bunch, frond, and the surface of the trunk, which is known as Ijuk. In this paper, sugar palm tree, its fibre and composites, and biopolymers derived from its starch are discussed. Major challenges and the way forward for the use of sugar palm fibre and its composites are highlighted. This review also opens areas for further research on sugar palm fibre and its composites for academia and industries.