NC State
  • Editorialpp 5656-5657Hubbe, M. A. (2016)."Paper or plastic? Yes, but not as a mixture," BioRes. 11(3), 5656-5657.AbstractPDF

    As expressed by the chorus lyrics of a song by Dan Einbender, “it really isn’t garbage ‘til you mix it all together. It really isn’t garbage ‘til you throw it away. Separate your paper, plastic, compost, glass and metal. Then you get to use it all another day.” It’s worth paying attention to these lyrics once again in the face of yet another type of product that is starting to show up in stores. Extruded sheets of polyethylene (no. 2 plastic) with as much as 80% ground calcium carbonate content are being sold as “paper”. Calcium carbonate is widely used as a component of real paper. However, it rubs me the wrong way when the word “paper” is being used to refer to something that has no fibers in it and is not formed on a screen and dried. My more serious concern is that such materials, if they become widely used, have the potential to contaminate paper recycling operations.

  • Editorialpp 5658-5659Gangwar, A. K. (2016). "Benefits of polycups stock over other waste paper grades in paper recycling," BioRes. 11(3), 5658-5659.AbstractPDF

    It is never too late or too early to invent alternative processes for the betterment of our routine life. For paper production, trees are being cut in huge quantities each day, and this directly affects our day to day life by making atmospheric conditions less favorable. Waste paper can be recycled on average 4 to 6 times while maintaining acceptable qualities in recycled paper. To save forest resources, we should move ahead towards using more and more waste paper for paper production. A wasted resource can be recycled either to make the same product or by manufacturing new products, e.g. cardboard boxes, newspaper, writing and printing papers, and paper bags, etc. Several waste paper grades are not being fully utilized, and their use might allow increased paper recycling to produce new recovered paper with specified paper qualities. Polycup stock is an example of an under-utilized type of wastepaper that has the potential to substitute effectively for virgin pulp production.

  • Researchpp 5660-5675Jiang, W., Lyu, G., Wu, S., Lucia, L. A., Yang, G., and Liu, Y. (2016). "Supercritical water-induced lignin decomposition reactions: A structural and quantitative study," BioRes. 11(3), 5660-5675.AbstractPDF

    The use of supercritical water for the decomposition of lignin and evaluation of its influence on lignin decomposition and conversion to various products was the thrust of the current study. Poplar alkali lignin (AL), corncob-to-xylitol residue lignin (XRL), and cornstalk-to-ethanol residue lignin (ERL) were the lignin species studied because they constitute the main residual lignins available in the biomass refinery industry. The lignins were characterized by elementary analysis, Fourier transform infrared spectrometry (FT-IR), phosphorus nuclear magnetic resonance (31P-NMR), and X-ray diffraction (XRD), and their hydrothermal depolymerization products were analyzed by gas chromatography-mass spectrometer (GC–MS). The results showed that the residual lignin is a potential source for valuable aromatics. The XRL had the best total phenolics yield, 140 mg/g, while AL had the lowest, 90 mg/g. The maximum yields of phenol (28.94 mg/g) and 4-ethylphenol (36.21 mg/g) were obtained from XRL depolymerization at 375 °C for 30 min, and the optimal yields of guaiacol (14.34 mg/g) and 2,6-dimethoxyphenol (15.67 mg/g) were achieved by AL at 375 °C for 30 min. The information here provides some insights toward developing selective biorefinery methods for lignin-to-organic products conversion processes.

  • Researchpp 5676-5686Wang, F., Ai, M., Yang, G., Chen, J., Chen, X., and Huang, F. (2016). "Influence of carbon source on the production of extracellular ligninolytic enzymes by Phanerochaete chrysosporium," BioRes. 11(3), 5676-5686.AbstractPDF
    The effect of altering the carbon source in the growing environment was investigated relative to the production of ligninolytic enzymes by Phanerochaete chrysosporium. Glucose, cellobiose, and cellulose (or mixtures thereof) were used as the carbon sources. Glucose oxidase and glyoxal oxidase activities in all carbon sources were produced during cultivation. High peak levels (0.17 to 0.24 IU/mL) of manganese peroxidase activity were observed only in mediums containing oligosaccharides. Lignin peroxidase activity was high in glucose medium (0.21 IU/mL of peak value); however, minimal amounts were formed in the cellulose medium (0.01 IU/mL of peak value). High amounts of cellobiose:quinone oxidoreductase (3.33-3.99 IU/mL of peak value) and cellobiose dehydrogenase (0.04-0.2 IU/mL of peak value) were measured when P. chrysosporium was grown on a medium containing cellulose. This work discovered that the mixture of glucose and cellulose as a carbon source favored high co-production of ligninolytic enzymes by P. chrysosporium.
  • Researchpp 5687-5702Ethaib, S., Omar, R., Siti Mazlina, M. K., Dayang Radiah, A. B., and Syafiie, S. (2016). "Microwave-assisted dilute acid pretreatment and enzymatic hydrolysis of sago palm bark," BioRes. 11(3), 5687-5702.AbstractPDF

    Maximizing the amount of monomeric sugar yield from lignocellulosic materials requires an effective pretreatment process and identification of an optimal enzyme loading for cost-effectiveness. In this work, a microwave-diluted sulfuric acid pretreatment was applied prior to enzymatic hydrolysis of sago palm bark (SPB). Characterization of the solid fraction was completed before and after the pretreatment process. Analysis of SPB ash showed a presence of 6.8% silica. There was a 32% reduction in lignin content, an increased crystallinity from 29% to 47%, and clear damage and fragmentation to the surface structure of SPB after the pretreatment. Inhibitors were not detectable in the liquor after the microwave-acid pretreatment. The enzymatic hydrolysis of SPB was employed by adding 6 to 42 FPU/g of cellulase and 50 U/g of β-glucosidase to identify the optimal cellulase loading at fixed β-glucosidase loading. The maximum total monomeric sugar yield and total reducing sugar (using DNS method) at 77 mg/g and 378 mg/g were achieved using 24 FPU/g of cellulose, respectively. Thus, this enzyme loading can be recommended for further microwave-acid pretreatment and enzymatic hydrolysis of SPB.

  • Researchpp 5703-5721Gao, Z., Zhang, X., Wang, Y., Yang, R., Wang, G., and Wang, Z. (2016). "Measurement of the Poisson's ratio of materials based on the bending mode of the cantilever plate," BioRes. 11(3), 5703-5721.AbstractPDF

    Principles and methods to dynamically test the Poisson’s ratio of isotropic material and timber are proposed in this work. Five species of lumbers were processed into cantilever plates of tangential, radial, and cross sections with different length-width ratios of 6, 5, 4, and 3. The “Shell 63” element in ANSYS software was adopted to calculate strain and stress under the first-order bending mode. The paste position of the strain rosette for the Poisson’s ratio of timber was obtained through strain-stress relationship and regression analysis under states of stress, strain analysis, and plane stress. This method was also applied to steel, aluminum, and glass. For both isotropic and orthotropic materials such as timber, the paste positions of the strain rosette were determined by the position where transverse stress within the plate was zero during the first-order bending vibration. Meanwhile, the lateral and longitudinal strains of the spectrum were measured using the transient excitation method. In the spectrum, the ratio of linear amplitude between the lateral and longitudinal strain of the first-order bending frequency was taken as the measured value of the Poisson’s ratio of the material. The accuracy of the results was verified by axial tension and static four-point bending tests.

  • Researchpp 5722-5730Song, C. J., Lee, Y. S., and Lee, J. W. (2016). "Enhanced production of cellulase from the agricultural by-product rice bran by Escherichia coli JM109/LBH-10 with a shift in vessel pressure of a pilot-scale bioreactor," BioRes. 11(3), 5722-5730.AbstractPDF
    The optimal vessel pressure of the bioreactor for cell growth and the production of cellulase, as well as the effect of a shift in pressure within the reactor on cellulase production were investigated. The optimal vessel pressure for the cell growth of E. coli JM109/LBH-10 was 0.08 MPa, whereas that for the production of cellulase was 0.04 MPa. The maximal production of cellulase by E. coli JM109/LBH-10 with a shift in the vessel pressure from 0.08 to 0.04 MPa after 24 h was 636.8 U/mL, which was 1.2 times higher than that without a shift. The shift in vessel pressure optimized for cell growth to that for the production of cellulase after the mid-term log-phase resulted in higher cell growth and cellulase production. A simple process with a shift in the vessel pressure of bioreactors to enhance the production of cellulase from agricultural by-products has been developed and can be directly applied to the industrial-scale production of cellulases.
  • Researchpp 5731-5742Sun, Y., Ma, Y., Fang, G., Li, S., and Fu, Y. "Synthesis of acid hydrolysis lignin-g-poly-(acrylic acid) hydrogel superabsorbent composites and adsorption of lead ions," BioRes. 11(3), 5731-5742.AbstractPDF

    A series of acid hydrolysis lignin-g-poly-(acrylic acid) (AHL-g-PAA) composites was prepared by grafting acid hydrolysis lignin on the surface of the polyacrylic acid network. The results of structure analysis revealed that AHL-g-PAA had been grafted. The surface morphologies of the hydrogels were improved, as shown by scanning electron microscopy observation. The AHL-g-PAA hydrogel had high water absorption and it possessed sensitivity to external pH stimulus. This study also revealed that the adsorption capacity of AHL-g-PAA was 235 mg/g for Pb(II) ions. The adsorption kinetics data could be described by the pseudo-second-order model, and the adsorption isotherm agrees well with the Langmuir model.

  • Researchpp 5743-5750Wang, Z., Yang, X., Sun, B., Chai, Y., Liu, J., and Cao, J. "Effect of vacuum heat treatment on the chemical composition of larch wood," BioRes. 11(3), 5743-5750.AbstractPDF

    The effects of vacuum heat treatment were studied relative to the chemical composition of larch wood. The samples were heat-treated in vacuum at 160 °C, 200 °C, and 240 °C for 4 h, and the chemical changes were investigated by wet chemical analysis, elemental analysis, calorific value determination, and pyrolysis-gas chromatography-mass spectrometry (Py-GC-MS). The relative percentage contents of lignin and extractives increased after heat treatment. Additionally, the relative percentage contents of holocellulose, cellulose, and hemicelluloses decreased as a result of the thermo-vacuum treatment. Elemental analysis showed a slight reduction in the contents of hydrogen and oxygen. Vacuum heat treatment also increased the calorific value compared with untreated samples.

  • Researchpp 5751-5766Khandanlou, R., Ngoh, G. C., and Chong, W. T. "Feasibility study and structural analysis of cellulose isolated from rice husk: Microwave irradiation, optimization, and treatment process scheme," BioRes. 11(3), 5751-5766.AbstractPDF
    The goal of this study was to pretreat rice husk (RH) using a microwave-assisted pretreatment process coupled with chlorite delignification and alkaline treatment to facilitate the isolation of cellulose. The isolated cellulose was characterized and subjected to structural analysis and a thermal stability test to ascertain the efficiency of the isolation from a visual perspective. The optimum condition for the microwave-assisted pretreatment of RH was determined by response surface methodology (RSM). The effects of three independent variables—microwave power, irradiation time, and solvent ratio—were investigated based on the maximum content of the RH being pretreated. At the optimum parameters of microwave power of 400 w, a 10-min duration, and a solvent ratio of 80.0% v/v, the pretreatment efficiency of RH was 10.0%. Compared with the conventional Soxhlet technique, the microwave pretreatment was superior. The X-ray powder diffraction (PXRD) result for the isolated cellulose showed that cellulose was highly crystalline (CrI = 65.0%). Fourier transform infrared spectroscopy (FT-IR) verified that most of the lignin and hemicelluloses were removed from the isolated cellulose after the chemical treatment. Furthermore, the TGA study revealed that the thermal stability of RH cellulose was higher than the original RH.
  • Researchpp 5767-5779Wang, L., Shi, H., Xu, B., Li, X., Zhang, Y., and Wang, F. "Characterization of Thermotoga thermarum DSM 5069 α-glucuronidase and synergistic degradation of xylan," BioRes. 11(3), 5767-5779.AbstractPDF

    α-Glucuronidases are capable of breaking down the α-1,2-glycosidic bonds of 4-O-methyl-D-glucuronic acid residues. As an accessory enzyme, α-glucuronidase plays a vital role in xylan degradation. The recombinant α-glucuronidase from Thermotoga thermarum DSM 5069 was heterologously expressed in the Escherichia coli system, purified, and characterized. The purified enzyme exhibited optimal activity toward aldouronic acids at pH 6.5 and 80 °C. It was fairly thermostable and maintained 98% residual activity after incubation at 65 °C for 2.0 h. The kinetic parameters Km, Vmax, and kcat were 3.02 ± 0.16 mM, 88 ± 2 µmol min-1 mg-1, and 117 s-1, respectively. TtAguA had an apparent activation energy of 59.0 kJ/mol. By structure simulation and mutation analyses, Glu288 was identified as the catalytic proton donor, and Asp367 and Glu395 were likely nucleophile bases. The xylan degradation by endoxylanase Xyn10A was enhanced by approximately 10% in the presence of TtAguA.

  • Researchpp 5780-5796Mohd Warid, M., Ariffin, H., Hassan, M. A., and Shirai, Y. "Optimization of superheated steam treatment to improve surface modification of oil palm biomass fiber," BioRes. 11(3), 5780-5796.AbstractPDF

    Superheated steam (SHS) pretreatment is an effective method for hemicellulose removal from oil palm biomass (OPB) fiber, which leads to the surface modification of the fiber. However, the current SHS pretreatment is conducted at a high temperature and has a long retention time, which causes the removal of cellulose, which is an important component for biocomposite production. This study was conducted to optimize the SHS treatment temperature and retention time so that hemicellulose but not cellulose was removed. Three types of OPB fibers were used: oil palm mesocarp fiber (OPMF), oil palm empty fruit bunch (OPEFB), and oil palm frond (OPF). The chemical composition data was analyzed using a type of response surface methodology (RSM), i.e., central composite design (CCD). The optimal SHS treatment temperature and retention time were 265 °C/5 min, 280 °C/5 min, and 300 °C/9 min for OPMF, OPEFB, and OPF, respectively. The removal of hemicellulose at these temperatures was in the range of 60% to 70%, while the cellulose degradation was maintained below 5%. Statistical analysis showed that the optimal SHS treatment time can be shortened to 5 min to 9 min, which is 18 to 20 times shorter than previously reported methods.

  • Researchpp 5797-5815Tachon, N., Benjelloun-Mlayah, B., and Delmas, M. "Organosolv wheat straw lignin as a phenol substitute for green phenolic resins," BioRes. 11(3), 5797-5815.AbstractPDF

    Organosolv wheat straw lignin extracted using the CIMV processTM is a linear, low molecular weight, and natural phenolic oligomer. In this study, organosolv wheat straw lignin was tested as a substitute for 50% to 70% of the phenol in a phenol-formaldehyde-resol resin. The lignin was used without any chemical modification in a one-step synthesis reaction. Parameters such as reaction time and formaldehyde-to-phenol sources (phenol + lignin) mass ratios were optimized to achieve the requirements for industrial wood adhesives in terms of pH, viscosity, and dry matter. For the first time, the formaldehyde ratio was studied in order to reduce resin residual free formaldehyde below 1%. Lignin-phenol-formaldehyde resins were successfully synthesized up to a phenol substitution rate of 70% and showed physico-chemical properties close to standard phenol-formaldehyde resins. The thermo-mechanical properties analyzed in dynamic load thermo mechanical analysis were similar to those of the reference resins. Plywood panels manufactured using these lignin-based resins reached the specifications for industrial panels according to the French standard for exterior plywood panels. Moreover, the formaldehyde content of these plywoods was low enough to satisfy even the most rigorous legislation.

  • Researchpp 5816-5828Liu, Y., Liu, Y., Lyu, G., Ji, X., Yang, G., Chen, J., and Lucia, L. A. (2016). "Analytical pyrolysis pathways of guaiacyl glycerol-β-guaiacyl ether by Py-GC/MS," BioRes. 11(3), 5816-5828.AbstractPDF

    A synthetic method for obtaining a lignin model compound of β-O-4 structure, guaiacyl glycerol-β-guaiacyl ether, was researched through five reaction steps from guaiacol. The key step of this synthetic method was the condensation reaction between 4-(α-bromoacetyl)-guaiacol (III) and guaiacol (I). The compounds were characterized by 1H nuclear magnetic resonance spectroscopy (1H-NMR) and two-dimensional nuclear magnetic resonance (2D-NMR). Pyrolysis behaviors of guaiacyl glycerol-β-guaiacyl ether were investigated by pyrolysis-gas chromatography/mass spectrometry (Py-GC/MS). The thermal behavior and the evolution profiles of major volatile fragments from the guaiacyl glycerol-β-guaiacyl ether pyrolysis were evaluated. Guaiacol is the major product through Cβ-O homolysis at low temperatures. Cβ-O homolysis and Cβ-O concerted decomposition occurred at moderate temperatures, producing guaiacol, 2-hydroxybenzaldehyde, 2-methoxybenzaldehyde, and various phenolic compounds. At high temperatures, the products obtained from Cβ-O homolysis and Cβ-O concerted decomposition experienced secondary thermal cracking, generating a large number of small molecule products, which increased the complexity of the pyrolytic products.

  • Researchpp 5829-5838Rohumaa, A., Yamamoto, A., Hunt, C. G., Frihart, C. R., Hughes, M., and Kers, J. (2016). "Effect of log soaking and the temperature of peeling on the properties of rotary-cut birch (Betula pendula Roth veneer bonded with phenol-formaldehyde adhesive," BioRes. 11(3), 5829-5838.AbstractPDF

    Heating logs prior to peeling positively affects the surface properties of veneer as well as the wood-adhesive bond strength. However, the mechanism behind this increase in strength is not fully understood. The aim of the present study was to separate the influence of soaking temperature and peeling temperature on the physical surface properties and bonding quality. Rotary-cut birch (Betula pendula Roth) logs were soaked at 70 °C, and half of them were subsequently cooled to 20 °C prior to peeling. Surface roughness measurements, scanning electron microscopy (SEM), surface integrity testing, color measurements, and wood-adhesive bond testing were conducted with an automated bonding evaluation system. The results showed that logs soaked at 70 °C and peeled at 20 °C had roughness, color, integrity, bond strength, and wetting properties more similar to logs soaked and peeled at 70 °C than those soaked and peeled at 20 °C. In every test conducted, the effect of soaking temperature was greater than the effect of peeling temperature. High-temperature soaking not only caused softening of the material during the peeling process, but it also caused irreversible changes in the wood material, which affected the veneer surface characteristics and bond strength development.

  • Researchpp 5839-5853Li, W., Xu, Z., Zhang, T., Li, G., Jameel, H., Chang, H. M., and Ma, L. (2016). "Catalytic conversion of biomass-derived carbohydrates into 5-hydroxymethylfurfural using a strong solid acid catalyst in aqueous γ-valerolactone," BioRes. 11(3), 5839-5853.AbstractPDF

    Selective conversion of biomass-derived carbohydrates into 5-hydroxy-methylfurfural (HMF) is of great significance for biomass conversion. In this study, a novel solid Brønsted acid was prepared simply by the copolymerization of paraformaldehyde and p-toluenesulfonic acid and then used to catalyze the conversion of various carbohydrates into HMF in γ-valerolactone-water (GVL/H2O) reaction medium for the first time. The catalyst exhibited strong acidity, good water resistance, and high thermal stability. The present work focuses on the effects of various reaction parameters, including reaction temperature, time, water concentration, solvent, fructose level, and catalyst loading, on fructose dehydration. The catalyst exhibited excellent catalytic performance for HMF production from fructose in GVL and furnished a high HMF yield of 78.1% at 130 °C in 30 min. The recycling experiments suggested that the solid acid catalyst could be recycled at least seven times without a noticeable decrease in the catalytic activity. In addition, an attempt to study the one-step conversion of sucrose, glucose, and cellulose into HMF and furfural was performed using the same catalytic system.

  • Researchpp 5854-5869Oke, M. A., Mohamad Annuar, M. S., and Simarani, K. (2016). "Enhanced endoglucanase production by Bacillus aerius on mixed lignocellulosic substrates," BioRes. 11(3), 5854-5869.AbstractPDF

    Selected carbon sources including soluble carboxymethyl cellulose (CMC), insoluble microcrystalline cellulose (MCC), and single (SS)/mixed lignocellulosic substrates (MS), were evaluated for endoglucanase production by B. aerius S5.2. The lignocellulosic substrates of oil palm empty fruit bunch (EFB), oil palm frond (OPF), rice husk (RH), and their mixture (MS) supported growth of the strain better than CMC and MCC. The maximum endoglucanase activity on MS was 7.3-, 2.6-, 1.7-, and 1.2-fold higher than those recorded on MCC, CMC, EFB/OPF, and RH, respectively. While the reducing sugar concentration of the CMC medium was comparable to that of the EFB and MS media, wide variability was observed in the reducing sugar concentrations among the lignocellulosic substrates. Extremely low levels of sugar were detected in the MCC medium, reflecting its poor digestibility and hence unsuitability for growth and endoglucanase production. Endoglucanase production was predominantly extracellular when the strain was grown on CMC and MS. After seven days of fermentation, there was an approximately 25% reduction in MS dry weight. These findings show that the use of mixed lignocellulosics could potentially reduce the cost of cellulase production. Certain novel aspects of the cellulase system of B. aerius are reported in this study.

  • Researchpp 5870-5888López-Beceiro, J., Álvarez-García, A., Sebio-Puñal, T., Zaragoza-Fernández, S., Álvarez-García, B., Díaz-Díaz, A., Janeiro, J., and Artiaga, R. (2016). "Kinetics of thermal degradation of cellulose: Analysis based on isothermal and linear heating data," BioRes. 11(3), 5870-5888.AbstractPDF

    In spite of the many studies performed, there is not yet a kinetic model to predict the thermal degradation of cellulose in isothermal and non-isothermal conditions for the full extent of conversion. A model proposed by the authors was tested on non-oxidising thermogravimetric data. The method consisted of initially fitting several isothermal and non-isothermal curves, then obtaining a critical temperature and an energy barrier from the set of fittings that resulted from different experimental conditions. While the critical temperature, approximately 226 °C, represented the minimum temperature for the degradation process, the degradation rate at a given temperature was related to both the critical temperature and the energy barrier. These results were compared with those observed in other materials. The quality of fittings obtained was superior to any other reported to date, and the results obtained from each single curve were in line with each other.

  • Researchpp 5889-5904Pang, A. L., Ismail, H., and Abu Bakar, A. (2016). "Tensile properties, water resistance, and thermal properties of linear low-density polyethylene/polyvinyl alcohol/kenaf composites: Effect of 3-(trimethoxysilyl) propyl methacrylate (TMS) as a silane coupling agent," BioRes. 11(3), 5889-5904.AbstractPDF

    Composites containing linear low-density polyethylene/polyvinyl alcohol and various loadings of kenaf fiber were prepared using a Haake internal mixer. The loading of kenaf fiber varied from 10 to 40 parts per hundred resin (phr). The coupling agent 3-(trimethoxysilyl)propyl methacrylate (TMS) was evaluated for its effect on the processing torque, tensile properties, morphology, water resistance, and thermal properties of the composites. Composites without TMS were used as the control. The composites made from TMS-treated kenaf yielded higher stabilization torque, tensile strength, tensile modulus, water resistance, and thermal properties than the control composites. The improvements were attributed to the coupling effect of TMS.

  • Researchpp 5905-5917Rahman, M. R., Rahman, M. M., Hamdan, S., and Chang Hui Lai, J. (2016). "Impact of maleic anhydride, nanoclay, and silica on jute fiber-reinforced polyethylene biocomposites," BioRes. 11(3), 5905-5917.AbstractPDF

    Jute fiber/polyethylene biocomposites were prepared using a hot press molding technique. The effects of maleic anhydride, clay, and silica on the physical, mechanical, and thermal properties of jute fiber-reinforced polyethylene (PE) biocomposites with different fiber loadings (5, 10, 15, and 20 wt.%) were investigated. The biocomposites were characterized by Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), and thermogravimetric analysis (TGA). The mechanical properties were determined using a universal testing machine. The biocomposite specific surface area, pore volume, and pore size were investigated using the Brunauer-Emmett-Teller (BET) equation. Because of the Si-O-Si stretching vibration, the peak representing the O-H group significantly decreased in the range of 3200 to 3600 cm−1. Jute fiber/PE Maleic anhydride silica composite (JFPEMASC) showed smoother surfaces, which indicated good distribution and better interfacial bonding between the fibers and matrix. The jute fiber/polyethylene/silica composites had a higher surface area and pore volume, with a lower pore size. JFPEMASC was more thermally stable than the other composites, with higher activation energy. JFPEMASC had the highest Young’s modulus among all the biocomposites.

  • Researchpp 5918-5930Chen, K., Lv, W., Chen, W., Wang, Y., Zhang, Y., Zhang, X., and Yao, J. (2016). "2,3,6-tricarboxylate cellulose as a fully biodegradable flocculant: Efficient synthesis and flocculation performance," BioRes. 11(3), 5918-5930.AbstractPDF

    Cellulose-based flocculants have shown excellent performance for wastewater flocculation, being low-cost and eco-friendly. However, they are still disturbed by the problems of incomplete biodegradability and unstable chemical structure. In the present study, 2,3,6-tricarboxylate cellulose (TCC) was developed as a novel fully biodegradable flocculant to deal with the preceding problems. The key carboxymethylation of cellulose was first carried out to make the subsequent NaIO4 oxidation occur under homogeneous conditions, which greatly enhanced the carboxylate content of the final TCC products. The chemical structure and solution properties of the TCCs were characterized by Fourier transform infrared spectroscopy (FTIR), X-ray diffractometer system (XRD), field emission scanning electron microscopy (FESEM), charge density, particle size, and zeta potential. The flocculation performance of the TCCs was evaluated preliminarily by the turbidity removal of kaolin suspension. The positive results showed that all the TCC products had high carboxylate contents (more than 10 mmol/g) and zeta potentials. They exhibited excellent flocculation performance for the kaolin suspensions, in which the residual turbidities decreased from 610 to 14.9 NTU. Considering the degradation of cellulose caused by excessive NaIO4 oxidation, the TCC IV, together with its synthesis technology, could be used for practical applications in wastewater flocculation.

  • Researchpp 5931-5940Hua, J., Ju, L., Cai, L., and Shi, S. Q. (2016). "Modeling the air-drying rate of Chinese larch lumber," BioRes. 11(3), 5931-5940.AbstractPDF

    To help protect the environment and reduce energy consumption in the wood industry, air-drying has been used to pre-dry lumber to about 30% moisture content. An air-drying model based on the principle of diffusivity was developed to help estimate air-drying times more accurately. Because the moisture movement rate considerably differs from that which occurs during kiln drying, the effective diffusion coefficients were experimentally determined at different temperatures. A user-friendly computer program predicting air-drying times was developed using the control volume method. The model was experimentally confirmed by air-drying practices. This program is a powerful tool used to estimate the air-drying times for any final moisture content for larch lumber, at any time of the year, at any location where the historical meteorological data, such as temperature, relative humidity, and wind speed, is available. This tool enables mill managers to generate an optimal operation plan based on their kiln capacity, yard availability, inventory requirements, and weather conditions.

  • Researchpp 5941-5948Hamdan, S., Jusoh, I., Rahman, M. R., and de Juan, M. (2016). "Acoustic properties of Syzygium sp., Dialium sp., Gymnostoma sp., and Sindora sp. wood," BioRes. 11(3), 5941-5948.AbstractPDF

    Acoustic properties such as specific dynamic Young’s modulus (Ed/γ), internal friction (Q-1), and acoustic conversion efficiency (ACE) of wood are important properties frequently examined using free-free flexural vibration. This study determined the suitability for making musical instrument soundboards and frameboards from four tropical wood species; namely Syzygium, Dialium, Gymnostoma, and Sindora. The results show that (Ed/γ), (Q-1), and ACE were in the range of 20.0 to 28.9 GPa, 0.0031 to 0.0085, and 3.41×107 to 10.83×107, respectively. Based on the results, Syzygium was preferred for making the frameboard of violins and guitars. The outer sapwood (outer part) of Syzygium was the most suitable for making frameboard by considering the lowest ACE and highest Q-1. Based on Ed/γ, the inner sapwood (middle part) in Dialium was the most suitable for making soundboard, but based on Q-1 and ACE, heartwood (inner part) was the most preferred for making soundboard. Gymnostoma was also preferred for making soundboard of violins and guitars (inner sapwood) because it yields the highest mean value of Q-1 and ACE. Considering ACE and Q-1, the outer sapwood in Sindora was the best for making frameboard. When considering Ed/γ and Q-1, the heartwood is the most suitable for making the frameboard of violins and guitars.

  • Researchpp 5949-5960Hendrik, J., Hadi, Y. S., Massijaya, M. Y., and Santoso, A. (2016). "Properties of laminated composite panels made from fast-growing species glued with mangium tannin adhesive," BioRes. 11(3), 5949-5960.AbstractPDF

    Laminated composite is a wood panel constructed from timber pieces then are laminated together. Bio-adhesives such as tannin adhesive are a potential alternative to synthetic adhesives. The purposes of this study were to characterize the chemical makeup of tannin from mangium (Acacia mangium) bark extract and to determine the physical-mechanical properties of the panels made from jabon (Anthocephalus cadamba) and sengon (Falcataria moluccana), and adhesives based on either mangium tannin or methylene diphenyl diisocyanate (MDI). The panels made from five layers of lamina were 5 cm × 24 cm × 120 cm in thickness, width, and length, respectively. Based on results from gas chromatography–mass spectrometry, mangium tannin had 34.04% phenolic compounds. Both wood species were low density, 0.31 g/cm3 for sengon and 0.44 g/cm3 for jabon, with an average moisture content of 12.4%. The panels had better width shrinkage than solid wood, with an anti-shrink efficiency of 72.5%. With regard to mechanical properties, none of the panels met the standard for the MOE or shear strength; however, sengon panel with MDI met the standard for MOR. In the delamination test, sengon panel was resistant to cold water immersion. All panels had low formaldehyde emission and met the standard requirements.

  • Researchpp 5961-5973Deshpande, R., Sundvall, L., Grundberg, H., and Germgård, U. (2016). "The influence of different types of bisulfite cooking liquors on pine wood components," BioRes. 11(3), 5961-5973.AbstractPDF

    In this laboratory study, the initial phase of a single-stage sodium bisulfite cook was observed and analyzed. The experiments were carried out using either a lab- or a mill-prepared cooking acid, and the cooking temperature used in these experiments was 154 °C. Investigated parameters were the chemical consumption, the pH profile, and the pulp yield with respect to cellulose, lignin, glucomannan, xylan, and finally extractives. Cooking was extended down to approximately 60% pulp yield and the pulp composition during the cook, with respect to carbohydrates and lignin, was summarized in a kinetic model. The mill-prepared cooking acid had a higher COD (Chemical Oxygen Demand) and TOC (Total Organic Carbon) content than the lab-prepared cooking acid and this influenced the pH and the formation of thiosulfate during the cook. It was found that the presence of dissolved carbohydrates and lignin in the bisulfite cooking liquor affected the extractives removal and the thiosulfate formation.

  • Researchpp 5974-5986Ülker, O., and Burdurlu, E. (2016). "Effect of glass wool and stone wool additives on some mechanical properties of wood composites," BioRes. 11(3), 5974-5986.AbstractPDF

    Mechanical properties of wood composites made from multiple wood species (50% Crimean pine, 30% Eastern Black Sea oak, 15% quaking aspen, and 5% wood machining residues) were evaluated using various amount of glass wool (GW) and stone wool (SW) additives. A total of 70 experimental panels were produced with a target density of 640 kg/m3. The bending strength, modulus of elasticity, tensile strength parallel to the surface of boards, tensile strength perpendicular to the surface of boards (internal bond), and cutting (shear) strength parallel to the surface of boards were determined. After statistical analysis, the results indicated that the SW and GW additives decreased the bending strength and modulus of elasticity by 49% in almost all boards. The addition of SW resulted in a 6% reduction in the tensile strength parallel to the surface. Relative to SW, GW resulted in an additional 8% reduction in shear strength, a 3% reduction in the screw tensile strength perpendicular to the surface, and a 6% reduction in the tensile strength parallel to the surface. Thus, the SW and GW additives decreased all the selected mechanical properties of wood composites.

  • Researchpp 5987-5993Hamzaçebi, C. (2016). "Optimization of process parameters in oriented strand board manufacturing by Taguchi method," BioRes. 11(3), 5987-5993.AbstractPDF

    Optimization of process parameters in oriented strand board (OSB) manufacturing is a vital issue for improving product quality. In this study, the Taguchi method (TM) was applied to determine the effects of production factors such as adhesive ratio, press pressure, and pressing time on the thermal conductivity of OSB. Obtained results showed that adhesive ratio is the main factor affecting thermal conductivity. Press pressure and pressing time are the second and third most important factors influencing thermal conductivity, respectively. The study also identified the optimal values of factors that minimize thermal conductivity.

  • Researchpp 5994-6005Moradbak, A., Tahir, P. M., Mohamed, A. Z., Peng, L. C., and Halis, R. (2016). "Effects of alkaline sulfite anthraquinone and methanol pulping conditions on the mechanical and optical paper properties of bamboo (Gigantochloa scortechinii)," BioRes. 11(3), 5994-6005.AbstractPDF

    The objective of this study was to evaluate the mechanical and optical properties of paper made from alkaline sulfite anthraquinone and methanol (ASAM) unbleached pulp from bamboo (Gigantochloa scortechinii). The bamboo pulps were beaten using a PFI mill at 10,000 revolutions. To determine the properties of unbleached bamboo ASAM paper, handsheets with a density of 60 g/m2 were formed with 14 to 18% NaOH, 80/20 Na2SO3/ NaOH, 0.1% AQ, 0.5% EDTA, and 15% methanol pulping conditions. Pulping at 18% NaOH for 120 min cooking time produced paper with properties of 24.8 Nm/g and 43.02% for the tensile index and ISO brightness, respectively. Cooking at 16% sodium hydroxide for 90 min rendered the best results for mechanical and optical properties, with results of 20.86 Nm/g, 22.64 mN.m2/g, and 39.32% ISO value for the tensile, tear indices, and brightness, respectively. High quality bamboo paper produced by the ASAM pulping process was beneficial for producing highly durable paper and paperboard.

  • Researchpp 6006-6016Pexa, M., Čedík, J., Hönig, V., and Pražan, R. (2016). "Lignocellulosic biobutanol as fuel for diesel engines," BioRes. 11(3), 6006-6016.AbstractPDF

    Energy recovery of lignocellulosic waste material in the form of liquid fractions can yield alcohol-based fuels such as bioethanol or biobutanol. This study examined biobutanol derived from lignocellulosic material that was then used as an additive for diesel engines. Biobutanol was used in fuel mixtures with fatty acid methyl ester (FAME) obtained by esterification of animal fat (also a waste material) in the amounts of 10%, 30%, and 50% butanol. 100% diesel and 100% FAME were used as reference fuels. The evaluation concerned the fuel’s effect on the external speed characteristics, harmful exhaust emissions, and fuel consumption while using the Non-Road Steady Cycle test. When the percentage of butanol was increased, the torque and the power decreased and the brake specific fuel consumption increased. The main advantage of using biobutanol in fuel was its positive effect on reducing the fuel’s viscosity.

  • Researchpp 6017-6025Zhu, Y., Yang, L., Wu, W., Wang, Z., and Jin, Y. (2016). "Complete dissolution of ball-milled Masson pine using an aqueous sodium hydroxide solvent," BioRes. 11(3), 6017-6025.AbstractPDF

    An inorganic sodium hydroxide aqueous solution was developed for the dissolution of ball-milled softwood. Extractive-free Masson pine powder was prepared from the wood meal by planetary ball milling for various lengths of time. The effects of ball milling on the dissolution and regeneration of Masson pine powder were investigated. After 4 h of ball milling, the wood powder was completely dissolved in 6 wt% NaOH aqueous solution under vigorous magnetic stirring for 10 to 20 min at room temperature. The alkaline nitrobenzene oxidation products yield of 4 h ball-milled wood was very close to that of coarse wood meal without ball milling. Regeneration of the lignin fraction was easier than cellulose during the acid neutralization process, and the dialysis regeneration yield of total biomass was 91.1%. Therefore, the complete dissolution of the Masson pine in sodium hydroxide solution is of great potential for enhancing lignin isolation with a very little structural change.

  • Researchpp 6026-6039Wang, X., Li, Y., Deng, Y., Yu, W., Xie, X., and Wang, S. (2016). "Contributions of basic chemical components to the mechanical behavior of wood fiber cell walls as evaluated by nanoindentation," BioRes. 11(3), 6026-6039.AbstractPDF

    Selective chemical extraction was applied to gradually remove classes of chemical components from wood cell walls. Nanoindentation was performed on the control and treated wood cell walls to evaluate the contributions of the chemical components to the cell walls by measuring the elastic modulus, hardness, and creep compliance. Burger’s model was applied to simulate the process of nanoindentation and to gain insight into the response of visco-elastic properties to the chemical components. Wood extractives showed limited effects on the cell-wall mechanics; however, the removal of hemicelluloses and lignin resulted in reductions of 11.7% and 28.4%, respectively, in the elastic modulus and 14.8% and 30.4%, respectively, in the hardness. The extraction of hemicelluloses and lignin reduced the resistance of wood cell walls to creep. Furthermore, the extracted parameters from Burger’s modeling indicated that cellulose exhibited the greatest influence on the mechanical properties of wood cell wall, while hemicelluloses exhibited the greatest contribution to cell-wall viscosity, and lignin contributed extensively to cell-wall elasticity.

  • Researchpp 6040-6049Tian, S. Q., and Chen, Z. C. (2016). "Dynamic analysis of bioethanol production from corn stover and immobilized yeast," BioRes. 11(3), 6040-6049.AbstractPDF

    The use of low cost and abundant corn stover in yeast fermentation can reduce product costs. In this study, bioethanol was produced from a hydrolysate of corn stover using immobilized yeast. A kinetic model was established for the total reducing sugar consumption and the production of bioethanol. The parameter estimation for kinetic modeling considered the main process variables during bioethanol production from corn stover. Total reducing sugar concentrations decreased exponentially in the bioethanol fermentation for 6 h; consumption was more than 90%. To use kinetic modelling of yeast growth for bioethanol fermentation, the value of μmax reached 0.2891 h-1, and the matrix inhibition constant (KIS) and production inhibition constant (KIP) were 8.9154 g/dm3 and 0.00676 g/dm3, respectively. To use kinetic modelling of fermentation time on bioethanol, the maximum ratio of bioethanol production rate (qmax) reached 1.427 g/g•L. However, KIS was 2.813 g/dm3, and KIP was 0.0149 g/dm3.

  • Researchpp 6050-6061Kuutti, L., Pajari, H., Rovio, S., Kokkonen, J., and Nuopponen, M. (2016). "Chemical recovery in TEMPO oxidation," BioRes. 11(3), 6050-6061.AbstractPDF
    To be regarded as environmentally friendly and economical, an industrial process using 2,2,6,6-tetramethylpiperidine 1-oxyl (TEMPO) oxidation requires recycling and/or recovery of chemicals. In this work, hypochlorite recycling via electrolysis was evaluated and potential means for TEMPO recovery were explored. The most important variable affecting electrochemical hypochlorite conversion was the concentration of sodium chloride in the feed solution. With 30 g/L NaCl salt, a sufficient hypochlorite concentration of 0.8% could be obtained for pulp oxidation of up to 5% consistency. The regeneration of hypochlorite in the treated TEMPO solution was possible by electrolysis and further oxidation performed with only a small addition of make-up chemicals. During electrolysis, some TEMPO degradation took place; therefore, recovery of TEMPO should be done prior to electrolysis. For the recovery of TEMPO, solid phase extraction (SPE) was tested. The best recovery of TEMPO was obtained using a combination of hydrophobic SPE resin material and distillation (yields between 52% and 87%).
  • Researchpp 6062-6084Reeb, C. W., Venditti, R., Gonzalez, R., and Kelley, S. (2016). "Environmental LCA and financial analysis to evaluate the feasibility of bio-based sugar feedstock biomass supply globally: Part 2. Application of multi-criteria decision-making analysis as a method for biomass feedstock comparisons," BioRes. 11(3), 6062-6084.AbstractPDF
    Early-stage evaluation of biofuel and bioproduct technologies is extremely complicated and involves many disparate feasibility criteria, including technical, financial, environmental, logistic, legal, social, and other aspects. Problems can arise for decision-makers when evaluating renewable technologies at this early stage due to bias, shifting preferences or priorities, occurrence of trade-offs, and decision-making complexity. Thus, a method is needed for evaluating disparate, typically non-comparable criteria concurrently. In Part 1 of this research, cradle-to-grave environmental LCA was conducted for biomass delivery to a biosugar refinery using Ecoinvent v2.2 data and the TRACI 2 impact assessment method for midpoint impacts. Biomass availability, delivered cost, sugar yield, transportation distance, harvestable months per year, and other aspects of supply chain feasibility were measured for eighteen feedstock biomass types. In Part 2, stochastic multi-attribute analysis (SMAA) was used alongside LCA to develop an environmental preference single-score probability distribution function for feedstock alternatives. Weighted single-scoring and ranking, using multi-criteria decision-making analysis (MCDA), was conducted considering five criteria of biomass supply feasibility: biomass delivered cost, biosugar yield, harvestable months, transport distance, and environmental preference single-score. Corn was shown to cost the most, followed by switchgrass and U.S. primary forest products. Transport distance was found to be highest for residues due to low yield per acre and low covered area. Results of MCDA show that Brazilian eucalyptus and Malaysian empty fruit bunch biomass types were consistently preferred relative to other biomass types. In the U.S., Genera biomass sorghum is most holistically preferred. It is shown that SMAA is helpful for translating LCA data for decision science. It was shown that MCDA can be useful for early-stage biorefinery technology commercialization decision-making, using the novel decision science tool described herein.
  • Researchpp 6085-6096Yu, H., Chen, G., Xu, Y., and Chen, D. (2016). "Experimental study on the gasification characteristics of biomass with CO2/air in an entrained-flow gasifier," BioRes. 11(3), 6085-6096.AbstractPDF
    This study explored the gasification characteristics of pine sawdust and rice straw with CO2/air in a bench-scale entrained-flow gasifier. The effects of various gasification parameters, i.e., CO2/C, temperature, and biomass type, on the syngas composition, gasification index, and tar yield were investigated. When compared to air gasification, the CO2/air agent for gasification improved the yield of CO, and it decreased the tar yield and the yield of CO2 produced from biomass. The cold gas efficiency (CGE) of pine sawdust reached 87.06% at the CO2/C equivalence ratio of 0.25, whereas that of rice straw reached 73.35% at the CO2/C equivalence ratio of 0.50. When compared with air gasification, the CO2/air gasification increased the CGE of pine sawdust and rice straw by 4.20% and 9.17%, respectively. However, excessive CO2 was unfavorable to the gasification process. As the temperature increased, the yields of CO and H2 increased, and the tar yield decreased, thus improving the syngas quality. This study indicated that the addition of the proper level of CO2 for gasification improved the overall gasification efficiency. Moreover, the improvement for rice straw (herbaceous plant) was more noteworthy than for pine sawdust (woody plant).
  • Researchpp 6097-6109Qian, Y., Otsuka, Y., Sonoki, T., Mukhopadhyay, B., Nakamura, M., Jellison, J., and Goodell, B. (2016). "Engineered microbial production of 2-pyrone-4, 6-dicarboxylic acid from lignin residues for use as an industrial platform chemical," BioRes. 11(3), 6097-6109.AbstractPDF

    As one of the most abundant materials in nature, lignin has been used widely in co-generation operations and for fine chemicals and bio-fuels production. These uses, although important, are of relatively low value. Lignin contains many aromatic compounds with useful structures, and it is potentially more profitable to produce high-value fine chemicals from the low-molecular weight lignin fraction while using the high-molecular weight fraction for fuel or other applications. A transgenic P. putida bacterial strain PDHV85 was developed with the capability to convert vanillin, vanillic acid, and syringaldehyde to 2-pyrone-4,6-dicarboxylic acid (PDC), a novel platform chemical that can produce a variety of bio-based polymers. Initial testing with vanillin showed promise for lignin conversion. Testing for this, we used kraft lignin, Japanese cedar (Cryptomeria japonica), or birch (Betula platyphylla) to represent some of the most abundant industrial lignin sources from softwood and hardwood. Repeated manipulation of culture conditions and strain adaptation allowed conversion of these extracts to PDC by PDHV85, which has not previously been reported in a bacterial strain. No inhibition was observed at 0.14 mg/mL kraft lignin extract, 1.14 mg/mL Japanese cedar extract, nor 1.15 mg/mL birch extract when using the optimized growth conditions.

  • Researchpp 6110-6124Liou, T. H., Wang, P. Y., and Liou, Y. H. (2016). "An effective method to enhance adsorption capacity and mesoporosity of activated carbon by pre-pyrolysis and chemical activation procedures," BioRes. 11(3), 6110-6124.AbstractPDF

    Activated carbons with large adsorption capacity and high mesopore fraction were obtained from rice straw by a combination of pre-pyrolysis and NaOH activation procedures. The experiments varied the pre-pyrolysis procedure, impregnation ratio of activating agent, and activation temperature. Samples were examined by inductively coupled plasma-mass spectrometry (ICP-MS), X-ray diffractometry (XRD), field-emission scanning-electronic microscopy (FE-SEM), thermogravimetric analysis (TGA), and N2-adsorption analysis. The surface area and pore characteristics of the activated carbons were investigated by the Brunauer, Emmett, Teller (BET) method, Dubinin-Raduch (DR) model, and the t-plot method. The surface area, pore volume, and iodine adsorption capacity of the samples increased with increasing activation temperature and the impregnation ratio of the activating agent. A maximum surface area of 2093 m2/g was obtained at the activation temperature of 900 °C. The pore structure in the one-stage activation procedure was mainly microporous. Two-stage activation procedure efficiently enhanced mesopore volume, and therefore further increased the adsorption capacity of activated carbons. NaOH acted as both the activating agent in the reaction and as the cleaner to remove the ash. The results of this experiment will be useful in developing resource recovery systems from agricultural biomass.

  • Researchpp 6125-6136Wang, X., Qin, G., Chen, M., and Wang, J. (2016). "Microwave-assisted pyrolysis of cotton stalk with additives," BioRes. 11(3), 6125-6136.AbstractPDF

    The purpose of this study was to investigate the effects of microwave power and additives on the microwave-assisted pyrolysis of cotton stalk. Pyrolysis temperature profiles, product yields, and bio-oil components were analyzed. The results indicated that as the microwave power increased, so did the final temperature and heating rate. When microwave power increased from 800 to 1200 W, the yield of the solid residue decreased and gas yield increased, but the maximum bio-oil yield of 26.7% was achieved under a microwave power of 1000 W. All three of the additives (NaOH, Na2CO3, and H3PO4) increased the yields of solid residue and gas, while the yield of the bio-oil decreased. Gas chromatography-mass spectrometry (GC-MS) analysis indicated that the main components of bio-oil from microwave-assisted pyrolysis of pure sample were acetol, furfural, 2-methoxy-phenol, and 4-methyl-2-methoxy-phenol. Sodium hydroxide and sodium carbonate (NaOH and Na2CO3) greatly favor the formation of acetol. Phosphoric acid (H3PO4) remarkably promoted the formation of furfural and 4-methyl-2-methoxy-phenol, while H3PO4 inhibited the formation of acetol.

  • Researchpp 6137-6150Wang, F., Ai, M., and Huang, F. (2016). "Development of method to determine the concentration of alkali-soluble lignin using Coomassie brilliant blue G-250," BioRes. 11(3), 6137-6150.AbstractPDF

    A new method involving the non-covalent binding of Coomassie Brilliant Blue G-250 (CBBG) to alkali-soluble lignin was developed. The binding of the dye to alkali-soluble lignin caused an increase in visible absorption at the maximum wavelength of 630 nm or 640 nm. A linear correlation of the absorbance at their maximum absorbing peak with alkali-soluble lignin concentration was observed. Lignin estimation in black liquor showed that the result of the new method and the gravimetric methods after acidification were closer to quantitative information than that obtained from UV spectroscopy. The isothermal titration calorimetric experiments, and Fourier Transform Infrared (FTIR) spectroscopy comparative analysis of precipitates washed by water, 4% ethanol, and 95% ethanol indicated that CBBG was bound to alkali-soluble lignin, and the binding was non-covalent. This potential method is reproducible, rapid, and cheap, and there is little or no inference from carbohydrate degradation products.

  • Researchpp 6151-6161Zhang, L., Yang, Z., Zhang, Q., and Guo, H. (2016). "Tensile properties of maize stalk rind," BioRes. 11(3), 6151-6161.AbstractPDF
    Experiments were carried out to measure the tensile properties of maize stalk rind. Two varieties of maize stalk (SD 12 and SD 9) and two moisture contents (fresh and air-dried) were tested. From each maize stalk sample, nine specimens (test coupons) of stalk rind were prepared to represent nine internodes from the bottom to the top of the maize stalk. The rind specimens were subjected to uniaxial tensile loading at a slow rate of 3 mm/min. From the recorded load-elongation curves, tensile stresses, modulus of elasticity, and tensile energy were determined. It was found that maize stalk rind exhibited elastic-plastic behavior, i.e., stress initially increased with strain in a linear fashion, and then nonlinearly until rupture. The measured ultimate tensile stress ranged from 178.15 to 80.53 MPa (average 122.26 MPa), elastic modulus from 35.01 to 11.38 GPa (average 19.32 GPa), and tensile energy from 0.004 to 0.099 J (average 0.032 J). Tensile strength, elastic modulus, and tensile energy decreased from the bottom to the top of stalk. There was a significant difference in tensile strength, modulus of elasticity, and tensile energy among two varieties and two moisture contents.
  • Researchpp 6162-6173You, Y., Sun, X., Cui, Q., Wang, B., and Ma, J. (2016). "The retention and drainage behavior of cross-linked gelatin with glutaraldehyde in a papermaking system," BioRes. 11(3), 6162-6173.AbstractPDF
    A type of novel retention aid, cross-linked gelatin, was prepared using low-grade industrial gelatin as the raw material and glutaraldehyde as the crosslinking agent. The structure of cross-linked gelatin was characterized according to the crosslinking degree, isoelectric point, Fourier transform infrared spectroscopy, and ultraviolet-visible spectroscopy. The results indicated that the crosslinking reaction was successfully performed between the primary amine group of gelatin and the aldehyde group of glutaraldehyde, resulting in the formation of a Schiff base structure. The retention test showed that the addition of cross-linked gelatin remarkably improved the retention of filler. This effect was mainly attributed to the fact that cross-linked gelatin, with a high molecular weight and highly branched structure, exhibited favorable bridging flocculation and induced filler aggregation into the flocs, which were retained in the paper sheet. The drainage test showed that the cross-linked gelatin exhibited a poor drainage effect, which was attributed to the synergic effects of excellent hydrophilicity, film forming property, and sealing property.
  • Researchpp 6174-6184Múčka, M., Šedivka, P., Bomba, J., and Blažek, J. (2016). "Influence of spacer frames for wooden roof windows on the formation of surface condensation," BioRes. 11(3), 6174-6184.AbstractPDF
    This study reports the thermal characteristics of windows installed in the roof cladding of a block of flats in the second temperature zone of the Czech Republic, with boundary conditions for the design value θse = – 15 °C, according to the national standard ČSN 73 0540-3 (2005). The thermal behaviour of these elements was evaluated with regard to the condensation on roof windows, with four different types of spacer frames and the given boundary conditions, for maintenance of the thermal and technical humidity comfort of the interior. The tests of the surface temperatures of the diagnosed glazed roof units at the glazing of the wooden windows demonstrated that the SGG composite spacer was the best from a thermal perspective. The spacer frames based on aluminum, stainless steel, and a combination of stainless steel and plastic (TGI) did not provide adequate thermal insulation characteristics for usage in roof windows under the given climatic conditions, and condensation occurred on the glass surfaces.
  • Researchpp 6185-6192Liang, L., Li, J., Zeng, J., Ma, N., An, Y., Ju, R., and Wang, Q. (2016). "Effects of steam explosion on bagasse specific surface area and grafting degree of acrylamide-grafted bagasse," BioRes. 11(3), 6185-6192.AbstractPDF
    The effect of steam explosion pretreatment conditions, such as steam explosion pressure, maintained pressure time, and bagasse water content, on bagasse specific surface area were investigated through single-factor experiments. After determining the optimal pretreatment conditions, bagasse graft acrylamide was prepared by grafting polymerization reaction of the acrylamide monomer onto the pretreated bagasse. The effects of surface area on the grafting degree were analyzed. Results showed that the grafting degree increased with increasing specific surface area. The optimized steam explosion pretreatment conditions were as follows: steam explosion pressure, 2.0 MPa; pressure maintaining time, 60 s; and bagasse water content, 25%.
  • Researchpp 6193-6210Lin, P. Q., Zhou, J. H., Song, X., and Wang, S. (2016). "Kinetics of the formation of saccharides and fermentation inhibitors during the hot-compressed water pretreatment of cassava residue," BioRes. 11(3), 6193-6210.AbstractPDF

    A mathematical description was developed for production of saccharides and fermentation inhibitors during the hot-compressed water pretreatment of cassava residue. Pretreatment was conducted at 150 °C, 160 °C, 170 °C, and 180 °C, and reaction times ranged from 0 to 70 min. The formation of saccharides and four main inhibitors (furfural (F), hydroxymethylfurfural (HMF), acetic acid, and formic acid) were studied. A model for predicting the concentrations of F and HMF (CF and CHMF, respectively) as functions of H+ concentration was established. Furthermore, kinetic models were built after introducing the hydrogen ion concentration index mi. Hydrogen ion concentration had a dramatic effect on the dissolution of pentosan but did not greatly affect the dissolution of hexosan or the degradation of hexose or pentose. Additionally, the activation energies for the formation of pentose or hexose were lower than the degradation energies. The coefficients of determination (R2) of the kinetic models for predicting the yield of the four compounds (pentose, hexose, furfural, and HMF) were higher than 0.923. These kinetic models provided a theoretical foundation and technical support for controlling the production of the main carbohydrates and fermentation inhibitors.

  • Researchpp 6211-6231Barton-Pudlik, J., and Czaja, K. (2016). "Conifer needles as thermoplastic composite fillers: Structure and properties," BioRes. 11(3), 6211-6231.AbstractPDF

    This study describes the properties of thermoplastic polymer composites based on polyethylene (of low and high density) and ethylene-propylene copolymers using various types of conifer needles (pine, spruce, fir, and cedar) as fillers. For the needles, thermogravimetric analysis (TGA) and TGA/Fourier transform infrared spectroscopy (TGA/FTIR) were performed to investigate their structures and thermal resistance, as required for the composite processing methods. Moreover, structural differences were studied for the analyzed fillers and composite materials (FTIR). The results were compared with the values obtained for composites with conifer wood flour. Composites with conifer needles (pine) had increased water absorption and similar strength properties. However, irrespective of the degree of filling, composites with pine needles were positively characterized by the highest melt mass flow rate (MFR) values and showed a slightly better impact resistance than composites filled with other flours. Thus, shredded coniferous needles with sufficient thermal resistance could be successfully used as fillers in composites. This conclusion was based on thermoplastic polymers as an alternative and/or supplement to the wood flour used in the manufacture of wood-polymer composites.

  • Researchpp 6232-6243Jiang, X. Y., Lu, Q., Ye, X. N., Hu, B., and Dong, C. Q. (2016). "Experimental and theoretical studies on the pyrolysis mechanism of β-1-type lignin dimer model compound," BioRes. 11(3), 6232-6243.AbstractPDF
    A β-1-type lignin dimer, 1,2-bis(3,5-dimethoxyphenyl)propane-1,3-diol was employed as a model compound in this study. The pyrolysis mechanisms and formation pathways of the pyrolytic products were investigated by using density functional theory (DFT) calculations and analytical pyrolysis-gas chromatography/mass spectrometry (Py-GC/MS). Four possible initial pyrolysis mechanisms were proposed, including the Cα-Cβ homolysis mechanism and three concerted decomposition mechanisms (1, 2, and 3). Results indicated that the lignin dimer decomposed via two concerted decomposition mechanisms, forming 3,5-dimethoxybenzaldehyde, 1,3-dimethoxy-5-vinylbenzene, 3-hydroxy-5-methoxybenzaldehyde, and 3-methoxybenzaldehyde. 3,5-Dimethoxybenzaldehyde was the major product, accounting for greater than 50% of all pyrolytic products. In addition to the two concerted decomposition mechanisms, Cα-Cβ homolysis was a secondary pyrolysis mechanism during the lignin dimer pyrolysis process, and the pyrolytic products included 3,5-dimethoxybenzyl alcohol, 3,5-dimethoxyphenethyl alcohol, 1,3-dimethoxybenzene, and 1,3-dimethoxy-5-methylbenzene. A third concerted decomposition mechanism was judged to be the least likely pathway to occur because of the high activation energy requirement.
  • Researchpp 6244-6253Wei, G., Zuo, H. F., Guo, Y. R., and Pan, Q. J. (2016). "Synthesis of ZnO with enhanced photocatalytic activity: A novel approach using nanocellulose," BioRes. 11(3), 6244-6253.AbstractPDF

    Well-crystallized and hexagonal wurtzite ZnO was synthesized with nanocellulose using a facile hydrothermal method. Many highly active (001) facets were retained in the obtained ZnO nanocrystals, presumably due to interaction between the polar facet of ZnO and the nanocellulose. Given its effective surface area, the synthesized ZnO exhibited good photocatalytic activity of degrading methylene blue. Its degradation efficiency reached 94.4% within 30 min (UV irradiation power of 6 W), which was 34% higher than that of Degussa TiO2 P25. The ZnO photocatalyst also exhibited excellent reusability, confirmed by no obvious abatement after its being re-used for 8 cycles. These ZnO nanomaterials were synthesized using renewable nanocellulose derived from cotton. This environmentally friendly and cost-effective approach is anticipated to be applied in the future synthesis of small-sized ZnO photocatalysts.

  • Researchpp 6254-6266Chen, M. J., Feng, J., and Shi, Q. S. (2016). "Thermal stability of sugarcane bagasse derivatives bearing carboxyl groups synthesized in ionic liquid," BioRes. 11(3), 6254-6266.AbstractPDF

    To illuminate changes in the thermal stability of lignocellulosic biomass by homogeneous chemical modification in ionic liquids, sugarcane bagasse derivatives bearing carboxyl groups were prepared in ionic liquids. Fourier transform infrared (FT-IR) spectroscopy and solid-state nuclear magnetic resonance (NMR) confirmed the chemical structure of the derivatives. Sugarcane bagasse derivatives with degree of substituted OH as high as 9.93 mmol/g were achieved. The homogeneous esterification was demonstrated to be a more efficient approach than heterogeneous ones. Based on thermogravimetric analysis, the onset degradation temperature of sugarcane bagasse decreased dramatically to 185 °C, 160 °C and 140 °C, using succinic anhydride, maleic anhydride, and phthalic anhydride as reagent, respectively. A first-order degradation kinetic model was applied to obtain the degradation activation energies of sugarcane bagasse. The results showed that homogeneous chemical modification significantly decreased the thermal stability of sugarcane bagasse by reducing the onset degradation temperature and degradation activation energies.

  • Researchpp 6267-6285Mkhize, T., Mthembu, L. D., Gupta, R., Kaur, A., Kuhad, R. C., Reddy, P., and Deenadayalu, N. (2016). "Enzymatic saccharification of acid/alkali pre-treated, mill-run, and depithed sugarcane bagasse," BioRes. 11(3), 6267-6285.AbstractPDF

    In South Africa, approximately 3 × 106 tons of sugarcane bagasse is produced annually by 14 factories located on the north coast of KwaZulu-Natal. It is one of the most readily available lignocellulosic materials for ethanol production through enzymatic saccharification and hydrolysis. Pre-treatment enables disruption of the naturally resistant structure of lignocellulosic biomass to make the cellulose accessible to hydrolysis for conversion to biofuels. In this study, pre-treatment of depithed bagasse and mill-run bagasse was done using acid (3% H2SO4 v/v) followed by alkali (4% NaOH w/v), and the pre-treated solid was subjected to enzymatic hydrolysis. The effects of different conditions for enzymatic saccharification such as enzyme dose, reaction time, and amount of surfactant were studied in detail. The pre-treated substrate (10% w/v) when hydrolysed using 30 FPU/gds/40 FPU/g dry substrate (gds) with 0.4% (v/v) Tween® 80 for 20 h resulted in 608 mg/gds (depithed bagasse) and 604 mg/gds (mill-run bagasse) total reducing sugars.

  • Researchpp 6286-6298Cellatoğlu, N., and İlkan, M. (2016). "Effects of torrefaction on carbonization characteristics of solid olive mill residue," BioRes. 11(3), 6286-6298.AbstractPDF

    Torrefaction is an important biomass pretreatment method that impacts fuel characteristics of biomass, specifically during the torrefaction process. Besides improving the fuel characteristics of biomass, torrefaction also contributes to increased quality of liquid and gaseous energy carriers obtained from fast pyrolysis and gasification. In this study, the effect of torrefaction on the solid energy carrier biochar, produced by carbonization, was studied by using solid olive mill residue (SOMR) as raw biomass. The carbonization characteristics of SOMR and torrefied SOMR (tSOMR) were compared by using ultimate and proximate analysis results. The higher heating value (HHV) and energy yields of biochars produced from SOMR and tSOMR were compared. The results showed that torrefaction contributed to the reduction of energy given to the biomass during the carbonization process by decreasing the holding time.

  • Researchpp 6299-6308Bian, Y., He, B., and Li, J. (2016). "A one-step hydrothermal method of nitrogen-doped graphene quantum dots decorated graphene for fabrication of paper-based fluorescent composite," BioRes. 11(3), 6299-6308.AbstractPDF

    A facile approach for producing fluorescent composite paper containing nitrogen-doped graphene quantum dots (N-GQDs) and graphene on the surface of the modified fibers was implemented from the exfoliation of graphite oxide (GO) using a one-step hydrothermal method. The properties of the composite paper were characterized by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM), transmission electron microscopy (TEM), ultraviolet visible spectroscopy (UV), photoluminescence spectroscopy (PL), and confocal laser scanning microscopy (CLSM). The results indicated that the GO was reduced to graphene sheets, and the N-GQDs nanoparticles were deposited on the surface of these sheets. The composite paper remained undamaged, with a three-dimensional structure and smooth fibers during the hydrothermal process, and the average particle size of N-GQDs was less than 10 nm. Photoluminescence measurements showed that the composite paper had a strong ultraviolet absorption in the range of 200 to 340 nm, and the band edge emission occurred at 475 nm. The CLSM image of composite paper exhibited a well-defined excitonic emission feature with an excitation wavelength of 405 nm.

  • Researchpp 6309-6319Hideno, A. (2016). "Comparison of the thermal degradation properties of crystalline and amorphous cellulose, as well as treated lignocellulosic biomass,"BioRes. 11(3), 6309-6319.AbstractPDF

    Thermo-gravimetric analyses of three cellulosic substances, namely, microcrystalline and amorphous cellulose, and treated Japanese cypress (JC) sawdust were carried out in this study. The thermal degradation temperature of crystalline cellulose decreased with increasing ball-milling time, while that of amorphous cellulose barely changed. However, small differences in the derivative thermo-gravimetric (DTG) curves between crystalline cellulose (i.e., before ball milling) and amorphous cellulose (i.e., after ball milling) were observed. The DTG curves of high-crystalline cellulose were sharp and similar to those of low-crystalline samples. The thermal degradation temperature of JC was decreased by ball milling, and its DTG peak shape became broad and low. These effects could be caused by the denaturing of non-cellulosic substances such as hemicellulose and lignin. The thermal degradation behaviors revealed by the DTG curves may serve as indicators of crystalline cellulose purity and other physical properties of lignocellulosic biomass.

  • Researchpp 6320-6334Llovera, L., Benjelloun-Mlayah, B., and Delmas, M. (2016). "Organic acid lignin-based polyurethane films: Synthesis parameter optimization," BioRes. 11(3), 6320-6334.AbstractPDF

    Polyurethane (PU) films were prepared by solution casting using a three-component system, namely, a novel solvolytic lignin, polyethylene glycol (PEG), and tolylene 2,4-diisocyanate (TDI), with dibutyltin dilaurate as a catalyst. An important objective was to incorporate as much lignin as possible. To this end, PU film synthesis was optimized by varying the lignin content (30 to 70 wt.% with respect to PEG), isocyanate-to-hydroxyl (NCO/OH) stoichiometry (0.8, 1, 1.2, 1.5, and 1.8), and PEG molecular weight (400, 600, and 1000). The results showed that the films derived from PEG 600 and a NCO/OH ratio of 1.5 were synthesized with a maximum content of 70% lignin, with respect to PEG. The effects of lignin content on the tensile properties and the thermostability of the PU films were studied. The onset decomposition temperature (TOD) of the lignin PU films reached an average limit of 310 °C, regardless of the lignin content, and 260 °C for a PU film without lignin. Thus, the addition of lignin, as a PEG substitute in polyurethane films, leads to better thermal stability. Furthermore, breaking stress, Young’s modulus, and Shore hardness of PU films increased constantly with lignin content, without reaching a maximum.

  • Researchpp 6335-6345Novák, I., Sedliačik, J., Gajtanska, M., Schmidtová, J., Popelka, A., Bekhta, P., Krystofiak, T., Proszyk, S., and Žigo, O. (2016). "Effect of barrier plasma pre-treatment on polyester films and their adhesive properties on oak wood," BioRes. 11(3), 6335-6345.AbstractPDF

    A barrier plasma, created at atmospheric pressure, was used to improve the surface and adhesive properties of polyester (PES) film with respect to wood using polyurethane adhesives. The modification of PES film surfaces using barrier discharge plasma is attractive for various applications. Plasma pre-treatment initiates and participates in grafting, polymerization, or cross-linking reactions on the PES surface. This method of surface modification is clean, dry, ecological, and very efficient. The enhancement of the wettability of the polyester film was necessary for promoting higher adhesion to wood with water-based adhesives. The treatment of polyester films by barrier plasma led to a considerable increase in the surface free energy of the film and subsequently an increase in the peel strength of the adhesive joint of PES film-oak wood with polyurethane adhesive.

  • Researchpp 6346-6361Jiménez, A. M., Espinach, F. X., Granda, L. A., Delgado-Aguilar, M., Quintana, G., Fullana-i-Palmer, P., and Mutjè, P. (2016). "Tensile strength assessment of injection-molded high yield sugarcane bagasse-reinforced polypropyene," BioRes. 11(3), 6346-6361.AbstractPDF

    Sugarcane bagasse was treated to obtain sawdust, in addition to mechanical, thermomechanical, and chemical-thermomechanical pulps. The obtained fibers were used to obtain reinforced polypropylene composites prepared by injection molding. Coupling agent contents ranging from 2 to 10% w/w were added to the composite to obtain the highest tensile strength. All the composites included 30% w/w of reinforcing fibers. The tensile strength of the different sugarcane bagasse fiber composites were tested and discussed. The results were compared with that of other natural fiber- or glass fiber-reinforced polypropylene composites. Pulp-based composites showed higher tensile strength than sawdust-based composites. A micromechanical analysis showed the relationship of some micromechanical properties to the orientation angle, critical length, the intrinsic tensile strength, and the interfacial shear strength. The pulps showed similar intrinsic tensile strengths and were higher than that of sawdust. The properties of the sugarcane bagasse composites compared well with other natural fiber-reinforced composites.

  • Researchpp 6362-6377Salimi, M., Nejati, B., Karimi, A., and Tavasoli, A. (2016). "Hydrothermal gasification performance of Iranian rice straw in supercritical water media for hydrogen-rice gas production," BioRes. 11(3), 6362-6377.AbstractPDF

    As a clean and green alternative fuel to replace fossil fuels, hydrogen could be an ideal fuel for the future. Supercritical water gasification of lignocellulosic agricultural residues results in H2 production with zero CO2 emission, which makes this technique an attractive technology for hydrogen generation from biomass. Structural analyses were performed to determine the lignin, cellulose, and hemicellulose contents in feedstock. The effects of different process variables (temperature, reaction time, and feed concentration) on supercritical water gasification of Iranian rice straw (IRS) were evaluated. IRS, which has a high content of cellulose and hemicellulose, has significant potential for gaseous product generation under the supercritical water condition. The maximum H2 production of 5.56 mmol/gr of biomass was achieved at 440 °C (temperature), 20 min (reaction time), and 2 wt. % (feed concentration).

  • Researchpp 6378-6392Song, X., Chen, F., and Liu, S. (2016). "A lignin-containing hemicellulose-based hydrogel and its adsorption behavior," BioRes. 11(3), 6378-6392.AbstractPDF
    A lignin-containing hemicellulose-based hydrogel was prepared from acylated hemicellulose and acrylic acid by free radical polymerization reaction, initiated by ammonium persulfate and N,N,N’,N’-tetramethyl-ethane-1,2-diamine in the presence of sodium lignosulfonate. Sodium lignosulfonate present in the hydrogel, when grafted by poly(acrylic acid), was identified as an interpenetrating polymer network form, while that not grafted by poly(acrylic acid) was identified as a semi-interpenetrating polymer network form. Both the swelling ratio and the adsorption capacity were dependent on sodium lignosulfonate dosage. The adsorption behavior of the hydrogel was evaluated. The maximum adsorption capacity towards methylene blue, a model dye, was 2691 mg/g. The adsorption kinetics and isotherm were well fitted by pseudo-second-order kinetics and Langmuir isotherm model, respectively. The hydrogel reveals an approximately 80% adsorption efficiency after fourth recycle. This hydrogel is a promising material for dye wastewater treatment.
  • Researchpp 6393-6406Ahmed, I., Zia, M. A., and Iqbal, H. M. N. (2016). "Detergent-compatible purified endoglucanase from the agro-industrial residue by Trichoderma harzianumunder solid state fermentation," BioRes. 11(3), 6393-6406.AbstractPDF

    A robust process of purification, characterization, and application of endoglucanase from the agro-industrial waste was performed using solid state fermentation (SSF). Trichoderma harzianum as a micro-organism and wheat straw as a growth supportive substrate were used in SSF under pre-optimized conditions. The maximum activity of 480 ± 4.22 U/mL of endoglucanase was attained when a fermentation medium was inoculated using 10% inoculum size and 3% substrate concentration with pH = 5.5 at 35 °C for an optimized fermentation period. In comparison with crude extract, enzyme was 1.83-fold purified with a specific activity of 101.05 U/mg using Sephadex-G-100 column chromatography. Sodium dodecyl sulfate (SDS) poly-acrylamide gel electrophoresis revealed that the enzyme exhibited a low molecular weight of 43 kDa. The purified enzyme displayed maximum activity at pH = 6 and a temperature of 50 °C, respectively. The maximum activity (Vmax) of 156 U/mL and KM value of 63 µM were observed. Ethylenediaminetetraacetic acid (EDTA), SDS, and Hg2+ inhibited enzyme activity, while Co2+ and Mn2+ enhanced enzyme activity at 1 mM concentration. The maximum substrate affinity and specific activity of biosynthesized endoglucanase revealed that it can be potentially useful for industrial applications.

  • Researchpp 6407-6415Özdemir, F., and Tutuş, A. (2016). "Effects of coating with calcite together with various fire retardants on the fire properties of particleboard," BioRes. 11(3), 6407-6415.AbstractPDF

    The fire properties of particleboard coated with calcite and a variety of fire-retardants (FR) was investigated. Four different chemicals, boric acid (BA), borax (BX), dolomite (DOL), and melamine (MEL), were added at the concentration of 1.0%, 3.0%, and 5.0% by oven-dry weight of calcite. The particleboard panels were tested according to the ASTM-E 69 standard to investigate their fire-retardant properties. The determination of weight loss, temperature, and the release of O2, CO, and NO by the samples was measured and recorded over 30 s intervals during combustion of the materials. The results indicated that the BA coatings exhibited better thermal stability than the other chemicals. Consequently, the lowest weight loss and temperature was found for specimens treated with 5.0% BA. These chemicals were effective relative to the fire properties of coated particleboard surfaces, depending on the type and ratio of the chemicals to the calcite.

  • Researchpp 6416-6425Mitchell, P. H. (2016). "Modeling the cupping of lumber," BioRes. 11(3), 6416-6425.AbstractPDF

    Wood shrinks anisotropically as it loses hygroscopic moisture. While longitudinal shrinkage (parallel to the grain) is nearly negligible in normal wood, transverse shrinkage (across the grain) is significant and characterized as tangential and radial shrinkage. The application of average tangential shrinkage values to a rectangular cross section results in errors, especially for boards cut from near the center of the log. In addition, using a Cartesian coordinate system to calculate shrinkage cannot provide an estimate of cup. Calculating shrinkage and cup deformation using a previously developed model, this Excel model can provide a more realistic image of the final cross section and a more accurate estimate of shrinkage. The model is dependent on wood species, initial and final moisture contents, and location of the board within the log. This paper describes and illustrates uses of the model.

  • Researchpp 6426-6437Yoon, K., Takahashi, S., Nge, T. T., Nakagawa-izumi, A., Ohi, H., and Yamada, T. (2016). "Characterization of lignin derivatives in alkaline polyethylene glycol-treated soda cooking black liquor powder," BioRes. 11(3), 6426-6437.AbstractPDF

    To improve the thermal properties of softwood soda lignin, we studied a method of lignin modification using black liquor powder and polyethylene glycol (PEG). In this process, the black liquor powder was directly treated with PEG under alkaline conditions to produce a thermal melting material (alkaline PEG treatment). A model experiment was performed to determine the reaction of the lignin. The lignin in the black liquor powder consisted of 62.16% acid-insoluble lignin (purified lignin) and 37.84% acid-soluble lignin. After alkaline PEG treatment using purified lignin, the samples exhibited weak thermal melting during softening point analysis but did not exhibit appropriate thermal melting during thermal mechanical analysis (TMA). Nuclear magnetic resonance (NMR) data suggest that there was no linkage between lignin and PEG in the alkaline PEG-treated lignin prepared from the purified lignin. On the other hand, when using acid-soluble lignin, NMR data suggest that PEG was introduced to the lignin at its α-carbon position. Acid-soluble lignin PEG derivatives could work as plasticizers to induce the thermal melting of the alkaline PEG-treated lignin prepared from black liquor powder.

  • Researchpp 6438-6451Liu, Z., Lu, X., An, L., and Xu, C. (2016). "A novel cationic lignin-amine emulsifier with high performance reinforced via phenolation and Mannich reactions,"BioRes. 11(3), 6438-6451.AbstractPDF

    A novel cationic lignin-amine emulsifier with high surface activity was prepared from kraft lignin (KL) via the phenolation of KL to obtain phenolated kraft lignin (PKL) and improve reaction sites. The introduction of dehydroabietyl groups as hydrophobic groups and diethylenetriamino groups as hydrophilic groups in PKL, by Mannich reactions, enhanced the performance of the emulsifier. The results showed that the number of the hydroxyphenyl groups in PKL was 0.27/C9 unit when 1 mol lignin was treated with 10 mol phenol at 60 °C for 6 h under 60 wt% sulfuric acid. The numbers of dehydroabietyl groups and diethylenetriamino groups in PKL were 0.18/C9 and 0.13/C9 unit, respectively. The surface tension of the emulsifier was 30.03 mN·m-1 at a concentration of 0.03 M hydrochloric acid aqueous solution with a pH 2.0, which is close to the commercial surfactant cetyltrimethylammonium bromide (CTAB). The zeta potential of the emulsifier was 45.1 mV, and its emulsifiability was 72 min. In contrast, the surface tension of the emulsifier prepared by non-phenolated lignin at the same condition was 38.67 mN·m-1, where the maximum zeta potential was 40.03 mV and its emulsifiability was 53 min. As expected, the performance of the emulsifier was reinforced by the phenolation reaction.

  • Researchpp 6452-6463Wong, C., McGowan, T., Bajwa, S. G., and Bajwa, D. S. (2016). "Impact of fiber treatment on the oil absorption characteristics of plant fibers," BioRes.11(3), 6452-6463.AbstractPDF

    Most plant fibers are good sorbents of oil; however, synthetic sorbents have a much higher sorption capacity (SC) than plant fibers. This study evaluated the effect of fiber treatments, specifically hot-water treatment and mercerization, on the absorption characteristics of selected plant fibers. Five common plant fibers—corn residues, soybean residues, cotton burr and stem (CBS), cattail, and oak—were evaluated for their absorption characteristics in crude oil, motor oil, deionized (DO) water, and a 80:20 mix of DO water. The fiber treatments included ground fiber (control), hot-water treatment at 80 °C for 4 h and 125 °C for 4 h, mercerization at room temp for 48 h, and mercerization at 300 °C for 1 h. The absorption capacity (AC) varied with fiber type, absorption medium, and fiber treatment. Mercerization at 300 °C increased the water absorption of soybean residue up to 8 g/g. Mercerization at room temperature and the hot-water treatment at 125 °C increased the crude oil absorption capacity. After certain treatments, the crude oil absorption capacity of CBS and corn fibers increased over 5 g/g, and the motor oil absorption capacity of cattail, corn, and soybean also increased to 4 to 5 g/g.

  • Researchpp 6464-6476Dzurenda, L., and Pňakovič, L. (2016). "Influence of the burning temperature of the non-volatile combustible content of wood and bark of plantation-grown, fast-growing tree species upon ash production, and its properties in terms of fusibility," BioRes. 11(3), 6464-6476.AbstractPDF

    The influence of the burning temperature was evaluated for the non-volatile combustible content of wood and bark of plantation-grown trees, at temperature intervals ranging from 500 °C to 1000 °C relative to ash production and the concentration of Ca, Mg, K, Mn, Zn, and Fe in ash, thermal properties, and ash fusibility. Production of ash from combustion of juvenile wood at t = 500 °C was Ad = 0.74% and juvenile bark Ad = 6.88%. Ash production decreased with increasing burning temperature. This was attributed to the chemical diversity of minerals contained in the wood and bark and their slow decomposition. Analyses of the presence of inorganic substances in ash from wood and bark revealed the highest presence of Ca. The concentration of calcium in ash from wood was Ca = 189 ± 46 and in bark Ca = 278 ± The ratio of processed calcium, potassium, magnesium, zinc, manganese, and iron in ash from wood at a burning temperature of t = 500 °C was Ca:K:Mg:Zn:Mn:Fe = 1:0.58:0.13:0.04:0.03:0.02 and from bark Ca:K:Mg:Zn:Mn:Fe = 1:0.41:0.07:0.01:0.01:0.003, respectively. The influence of the burning temperature non-volatile combustible was reflected in the concentration of each elements in ash and was contradictory. While concentration of Ca, Mg, Mn, and Fe in ash from wood and bark increased, concentration K and Zn in ash decreased. The decrease in concentration K, had a positive influence upon the thermal characteristics of the ash and the creation of ash in the form of loose matter.

  • Researchpp 6477-6488Pan, C., Liu, Z., Bai, X., and Hui, L. (2016). "Structural changes of lignin from wheat straw by steam explosion and ethanol pretreatments," BioRes. 11(3), 6477-6488.AbstractPDF

    Effects of the pretreatment of wheat straw by steam explosion and ethanol were evaluated relative to the structural changes of lignin from the pretreated pulp. The lignin from steam explosion pulp (LS), lignin from steam blasting residual liquid (LL), lignin from ethanol pretreatment pulp (LE), lignin from black liquor (LB), and lignin from wheat straw (LW) were separated, and the structural characteristics of the lignin fractions were compared based on analyses of Fourier transform-infrared, ultraviolet, thermogravimetric, and 1H and 13C nuclear magnetic resonance spectra. The proportions of the three structural units in all lignin fractions clearly changed during the pretreatment process because of inter-conversion reactions. The conjugated structure of lignin was destroyed in the pretreatment process and was also affected by the alkali extraction process. The alcoholic hydroxyl links on the aliphatic side chain were partly transformed into carbonyl groups during ethanol pretreatment. Demethoxylation occurred in all lignin fractions during the ethanol pretreatment and steam explosion process. The thermal stability of the LB fraction was relatively high because of the condensation reaction.

  • Researchpp 6489-6504Jaya, H., Omar, M. F., Md Akil, H., Arifin Ahmad, Z., and Zulkepli, N. N. (2016). "Effect of particle size on mechanical properties of sawdust-high density polyethylene composites under various strain rates," BioRes. 11(3), 6489-6504.AbstractPDF

    There is a need to understand the effect of wood particle size, as it affects the characteristics of wood-based composites. This study considers the effect of wood particle size relative to the dynamic behavior of wood composites. The compression Split Hopkinson Pressure Bar (SHPB) was introduced to execute dynamic compression testing at the strain rate of 650 s-1, 900 s-1, and 1100 s-1, whereas a conventional universal testing machine (UTM) was used to perform static compression testing at the strain rate of 0.1 s-1, 0.01 s-1, and 0.001 s-1 for four different particle sizes (63 µm, 125 µm, 250 µm, and 500 µm). The results showed that mechanical properties of composites were positively affected by the particle sizes, where the smallest particle size gave the highest values compared to the others. Moreover, the particle size also affected the rate sensitivity and the thermal activation volume of sawdust/HDPE, where smaller particles resulted in lower rate sensitivity. For the post-damage analysis, the applied strain rates influenced deformation behavior differently for all particle sizes of the specimens. In a fractographic analysis under dynamic loading, the composites with large particles experienced severe catastrophic deformation and damages compared to the smaller particles.

  • Researchpp 6505-6517Cai, L., Chen, T., Wang, W., Huang, D., Wei, Q., Lin, M., and Xie, Y. (2016). "Optimization of aluminum/silicon compounds on fire resistance of old corrugated container fiber foam material," BioRes. 11(3), 6505-6517.AbstractPDF

    Old corrugated container fiber foam material (OCCM) was prepared using a liquid frothing approach. The effect of the content of Al/Si compounds, the molar ratio of Al3+/SiO2, and different addition form on the limited oxygen index (LOI) and residue percentage of OCCM was optimized using an orthogonal design. The fire resistance of OCCM was best when the content of Al/Si compounds was 900 mL, the molar ratio of Al3+/SiO2 was 1:1, and the aluminum sulfate solution was added first, followed by the separately added sodium silicate solution. Under these conditions, the LOI and residue percentage of OCCM reached 32.3 and 53.51%, respectively. Thermogravimetric analysis indicated that Al/Si compounds promoted char formation and reduced the heat release of the optimized OCCMs during depolymerisation. Compared with the control group, the residue percentage of optimized OCCM was increased from 12.49% to 37.98%. Fourier transform infrared spectroscopy identified the functional groups of Al/Si compounds in the optimized OCCMs, confirming that pyrolysis of the optimized OCCMs was affected by Al/Si compounds.

  • Researchpp 6518-6531Conesa, C., Seguí, L., Laguarda-Miró, N., and Fito, P. (2016). "Microwave-assisted alkali pretreatment for enhancing pineapple waste saccharification,"BioRes. 11(3), 6518-6531.AbstractPDF

    The effectiveness of microwave-assisted sodium hydroxide pretreatments to enhance the saccharification performance of pineapple waste was evaluated. Microwave alkali pretreatments for short exposure times (up to 60 s) significantly improved the yield of the enzymatic hydrolysis compared with non-pretreated waste. The greatest increase of fermentable (35.7%) and total sugars (33.5%) was obtained at 6.375 W/g for 5 s. However, longer exposure times resulted in sugar degradation and released fermentation inhibitors, such as phenols or hydroxymethylfurfural (HMF), as a consequence of thermal degradation. Nevertheless, the obtained phenols values were not sufficient to inhibit subsequent fermentation. Scanning electron microscope (SEM) images confirmed that applying microwaves for short exposure times promoted structural changes that improved enzymatic hydrolysis. By contrast, an increase in the severity of the treatment led to a compacted structure, which hindered access to enzymes and consequently reduced the release of sugars into the medium.

  • Researchpp 6532-6539Xu, A., Guo, X., Ma, J., Liu, C., Li, Q., and Wen, S. (2016). "Novel and efficient diethylene glycol/H2O solvent for lignin dissolution," BioRes. 11(3), 6532-6539.AbstractPDF

    Novel lignin solvents were developed by adding H2O to diethylene glycol (DEG). The solubility of lignin in the DEG/H2O solvents was determined at 25 °C, and the effect of mass ratio of H2O to DEG on lignin solubility was investigated. The DEG/H2O solvents exhibited highly efficient capacity for lignin dissolution, even at room temperature. The possible dissolution mechanism is proposed to be the interaction between the DEG and lignin. In addition, the DEG/H2O solvents hardly disrupt the structure of lignin.

  • Researchpp 6540-6551Zhang, Z. J., Qiu, L. X., Chen, Y. Z., Li, Z. H., Song, H. Y., and Chen, Q. W. (2016). "Effect of pulp concentration during cellulase pretreatment on microfibrillated cellulose and its film properties," BioRes. 11(3), 6540-6551.AbstractPDF

    Pulp concentration was increased, during preparation of microfibrillated cellulose (MFC), in an effort to improve the efficiency of cellulase pretreatment. It was hypothesized that increased pulp concentration could possibly increase the interactions between cellulase and cellulose, therefore improving the cellulase pretreatment efficiency and benefiting MFC and its film properties. Results showed that higher pulp concentration enhanced the cellulase adsorption ratio from 70% to 90% for pulp concentrations of 2% and 10%, during the pretreatment process. While pulp concentration was changed from 2% to 10% during cellulase pretreatment, the specific area rose from 30.1 m2/g to 35.5 m2/g. Compared with the original eucalyptus pulp, the crystallinity degree of different pulp concentration was increased, presumably due to the enzymatic breakdown of amorphous cellulose. In addition, the aspect ratio of MFC rose from 19.1 to 35.5. Concurrently, MFC film properties showed better performance, as the elongation at break increased from 0.75% to 1.95%, tensile strength increased from 15.3 MPa to 33.5 MPa, and oxygen permeability coefficient decreased from 111×10-14 cm3·cm/cm2·s·Pa to 89.7×10-14 cm3·cm/cm2·s·Pa, reflecting the oxygen barrier properties of MFC film.

  • Researchpp 6552-6565Li, P., Li, H., Yang, J., and Meng, Y. (2016). "Facile fabrication of superhydrophobic paper with excellent water repellency and moisture resistance by phase separation," BioRes. 11(3), 6552-6565.AbstractPDF

    A simple but effective method of fabricating superhydrophobic paper with excellent moisture resistance was developed by precipitating carnauba wax onto the surface of cellulose fibers using a phase separation method. Response surface methodology (RSM) was used to optimize the effects of the preparation variables on the water contact angle (WCA) of the paper surface. The four independent variables were carnauba wax concentration, immersion time, coagulation bath ratio (water/ethanol), and coagulation bath time. The optimal treatment conditions were as follows: wax concentration, 3.78% (wax/chloroform, w/v); immersion time, 1.46 h; coagulation bath ratio, 13/87 (water/ethanol, v/v); and coagulation bath time, 2.63 h. Under these conditions, the experimental WCA reached 152.7°, which agreed closely with the predicted value of 154.1°. The surface morphology of the superhydrophobic paper was characterized by scanning electron microscopy (SEM) and atomic force microscopy (AFM), and the images showed that cluster-like carnauba wax aggregation completely covered the fiber surface, resulting in increased roughness. Moreover, the moisture resistance of the obtained superhydrophobic paper was evaluated. The results demonstrated that under high relative humidity conditions, the moisture resistance of the superhydrophobic paper significantly improved, and its tensile strength remained high.

  • Researchpp 6566-6581Ventorino, V., Robertiello, A., Viscardi, S., Ambrosanio, A., Faraco, V., and Pepe, O. (2016). "Bio-based chemical production from Arundo donax feedstock fermentation using Cosenzaea myxofaciens BPM1," BioRes. 11(3), 6566-6581.AbstractPDF

    Bio-based organic acids are an eco-friendly alternative to petroleum-derived products. In this work, the production of organic chemicals was investigated for the first time in the Cosenzaea myxofaciens species using hydrolysed lignocellulosic biomass from Arundo donax. The strain C. myxofaciens BPM1, isolated from bovine rumen, was able to produce a high amount of lactic acid, followed by acetic and succinic acids in synthetic substrate in microaerophilic and anaerobic conditions. When hydrolysed lignocellulosic biomass from Arundo donax supplemented with several nitrogen sources was used as substrate in separate hydrolysis and fermentation in anaerobic conditions, a significant increase in organic acids was recovered, reaching values up to 12.13 ± 0.17, 1.68 ± 0.1, and 5.23 ± 0.04 g L-1 of lactate, succinate, and acetate, respectively. Moreover, the strain C. myxofaciens BPM1 was capable of synthesizing a small amount of ethanol, with a resulting concentration ranging from 0.67 ± 0.05 to 1.46 ± 0.03 g L-1. This work shows that the strain C. myxofaciens BPM1 is a potential source of interesting bio-based chemicals for a wide range of industrial applications. In addition, the inexpensive fermentation process using A. donax hydrolysate and corn steep liquor as carbon and nitrogen sources could be suitable for economical and efficient production of succinic acid in industrial processes.

  • Researchpp 6582-6589Lautenschläger, T., Kempe, A., Neinhuis, C., Wagenführ, A., Siwek, S. (2016). "Not only delicious: Papaya bast fibres in biocomposites," BioRes. 11(3), 6582-6589.AbstractPDF

    Previous studies have shown favourable properties for papaya bast fibres, with a Young’s modulus of up to 10 GPa and a tensile strength of up to 100 MPa. Because the fibres remain as residues on papaya plantations across the tropics in large quantities, their use in the making of green composites would seem to be worthy of consideration. This study aims to show that such composites can have very suitable mechanical properties, comparable to or even better than the common wood plastic composites (WPCs), and as such, represent a promising raw material for composites and a low-cost alternative to wood.

  • Researchpp 6590-6599Zhang, X., Han, G., Jiang, W., Zhang, Y., Li, X., and Li, M. (2016). "Effect of steam pressure on chemical and structural properties of kenaf fibers during steam explosion process," BioRes. 11(3), 6590-6599.AbstractPDF

    The chemical and structural properties of kenaf fibers that were treated at different steam pressures during the steam explosion process were investigated. With increased steam pressure, a higher percentage of cellulose and acid-insoluble lignin and a lower content of hemicellulose and pectin were obtained. This result was further confirmed by Fourier transform infrared (FTIR) spectroscopy. X-ray diffraction (XRD) studies revealed that the steam-exploded kenaf fibers were more crystalline than the raw kenaf fibers, and that excessive steam pressure above 3 MPa damaged the cellulose crystalline structure. Scanning electron microscopy (SEM) analysis showed a change in the surface morphology of the treated kenaf fibers. The lower content of gums and the effective defibrillation of steam-exploded kenaf fibers demonstrated the potential of steam explosion treatment in applications of kenaf fibers.

  • Researchpp 6600-6612Chen, Y., and Guo, W. (2016). "Mechanical properties evaluation of two wood species of ancient timber structure with nondestructive testing methods,"BioRes. 11(3), 6600-6612.AbstractPDF

    Mechanical properties of wood were evaluated using nondestructive test methods. The tests were conducted using the stress wave timing and resistance drilling machine, while static mechanical tests were conducted by an Instron universal testing machine. Both nondestructive and static mechanical tests were performed on wood specimens for Chinese fir (Cunninghamia lanceolata (Lamb.) Hook) and elm (Ulmus rubra). There were strong linear correlations between density (ρ) and resistance amplitude (F), static modulus of elasticity (MOE) and dynamic modulus of elasticity (ED), modulus of rupture (MOR) and ED, and ultimate compressive strength (UCS) and ED. Additionally, an algorithm of the reliability index was developed with the first-order second-moment method. The reliability analysis indicated that the reliability index increased with the decreased design value for both Chinese fir and elm, but it increased as the live-to-dead load ratio (ρ) increased. To achieve the reliability index requirements of the Chinese national code, the MOR design value should be set to 12.6 and 21.7 MPa, while the UCS design value should be set to 10.2 and 13.4 MPa for Chinese fir and elm, respectively.

  • Researchpp 6613-6624Euring, M., Kirsch, A., and Kharazipour, A. (2016). "Pre-pressing and pre-heating via hot-air/hot-steam process for the production of binderless medium-density fiberboards," BioRes. 11(3), 6613-6624.AbstractPDF

    The hot-air/hot-steam process was used for the first time as a combined pre-pressing and pre-heating system for the production of medium-density fiberboards (MDF) at the pilot scale. Pre-heating systems are designed to pre-heat fiber mats before pressing by hot-presses. Using such techniques, pressing times are reduced significantly and the board properties are influenced positively; both are essential for effective MDF production. In recent years, industry has searched for alternatives to petrochemical binders. Primarily, MDF are bonded by urea-formaldehyde (UF) resins in Europe. To replace UF resins, a laccase-mediator-system (LMS) was used to activate the wood fibers’ self-cohesion. It was found that the internal bond strength (IB) and thickness swelling (TS) were noticeably improved by applying the hot-air/hot-steam process before final hot-pressing for both LMS and 10% UF binding systems. Simultaneously, the total pressing time could be reduced by 25% when combining the hot-air/hot-steam process with hot-pressing.

  • Researchpp 6625-6638Liu, J., and Wang, X. (2016). "Effect of drying temperature and relative humidity on contraction stress in wood," BioRes. 11(3), 6625-6638.AbstractPDF

    As wood shrinks during the drying process, various stresses may develop and cause surface and internal checking. The aim of this study was to systematically investigate the effect of the drying temperature, relative humidity, and specimen thickness on the contraction stress in elm wood (Ulmus pumila L.) specimens during drying. The contraction stress was used as an indirect indicator of drying stresses. A measurement system was developed in-house and used to simultaneously and continuously obtain the required measurements during drying, which were then used to determine the moisture content, amount of shrinkage, and contraction stress of the wood specimens. In the process of drying, the contraction stress was initially negative with a decrease in the moisture content and an increase in the shrinkage. Then the contraction stress increased gradually and eventually stabilized upon reaching the maximum. The results also showed that as the temperature increased, the moisture content decreased, the shrinkage decreased, the maximum contraction stress decreased, and the contraction stress reached a maximum in a shorter amount of time.

  • Researchpp 6639-6648Dato’ Hasnan, M. A., Husseinsyah, S., Ying, L. B., and Abd Rahman, M. F. (2016). "Chemical modification of palm kernel shell filled polylactic acid biocomposite films," BioRes. 11(3), 6639-6648.AbstractPDF

    Palm kernel shell (PKS) was incorporated with polylactic acid (PLA) using a solution casting method to produce PLA/PKS biocomposite films. The effects of filler content and butyl methacrylate on the mechanical properties, morphological properties, and thermal properties of PLA/PKS biocomposite films were studied. The addition of PKS into the PLA matrix decreased the tensile strength and elongation at break of PLA/PKS biocomposite films with increasing filler content. In contrast, the modulus of elasticity of the biocomposite films increased. The use of butyl methacrylate as a chemical modification for PKS enhanced the interfacial adhesion and wettability of PKS inside the PLA matrix. This effect was confirmed by the increase in tensile strength, modulus of elasticity, and thermal stability of the biocomposite films. Moreover, scanning electron microscopy showed that there was better interfacial interaction between the filler and the PLA matrix.

  • Researchpp 6649-6662Tipu Sultan, M., Rahman, M. R., Hamdan, S., Chang Hui Lai, J., and Talib, Z. A. (2016). "Clay dispersed styrene-co-glycidyl methacrylate impregnated kumpang wood polymer nanocomposites: Impact on mechanical and morphological properties," BioRes. 11(3), 6649-6662.AbstractPDF

    Physical, mechanical, and morphological properties of a clay dispersed styrene-co-glycidal methacrylate (ST-co-GMA) impregnated wood polymer nanocomposite (WPNC) were evaluated. The WPNC was characterized by Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), 3-point bending, free-vibration testing, and X-ray diffraction (XRD) measurements. The FT-IR results showed that the absorbance at 1730 cm−1 was increased for ST-co-GMA-clay-WPNC compared with other nanocomposites and the raw material. The XRD results revealed that crystallinity index and d-spacing were increased compared to raw wood. The SEM results showed that ST-co-GMA-clay-WPNC had a smoother surface than other nanocomposites and raw wood. The modulus of elasticity (MOE), modulus of rupture (MOR), and dynamic Young’s moduli (Ed) of WPNCs were considerably increased compared to wood polymer composites (WPCs) and raw wood. The raw wood exhibited a higher water uptake (WU) than WPNCs and WPCs.

  • Researchpp 6663-6676Kılıç, M. (2016). "Effect on shear strength of machining methods in Pinus nigra Arnold bonded with polyurethane and polyvinyl acetate adhesives," BioRes.11(3), 6663-6676.AbstractPDF

    Specimens taken from Pinus nigra Arnold were subject to surfacing techniques by being cut with a circular saw, planed with a thickness machine, and sanded with a calibrating sanding machine (with P80 grit sandpaper). First, their surface roughness values were measured; then, the specimens were processed in the machines in a radial and tangential process. Afterwards, the change in shear strength (adhesiveness resistance) was analyzed as a result of bonding with various adhesive types (PVAc, PU) and pressure applications (0.45 N/mm² or 0.9 N/mm²). Approximately 600 specimens were prepared with the purpose of identifying the effect of variables on the bonding performance, and they were subjected to shear testing. The greatest shear strength achieved for both the tangential and radial surfaces in terms of cutting was observed in specimens processed in the thickness machine, on which polyvinyl acetate adhesive and 0.9 N/mm². pressure were applied. Specimens bonded with polyvinyl acetate adhesive displayed higher shear strength in general in comparison to those bonded with polyurethane for both tangential and radial surfaces.

  • Researchpp 6677-6691Han, J., Lv, J., Zhan, X., Huang, R., and Xu, X. (2016). "Interfacial adhesion and damping characteristics of laminated veneer lumber intercalated with rubber sheets," BioRes. 11(3), 6677-6691.AbstractPDF

    Laminated wood veneer lumber intercalated with rubber sheets (LLVR) was fabricated using a layered adhesive system composed of polyaryl polymethylene isocyanate (PAPI) for wood-rubber inter-bonding and phenol formaldehyde (PF) resin to glue the wood veneers. The optimized manufacturing process (chloroprene rubber: CR; PAPI: 80 g/m2; PF: 200 g/m2; and silane: 9.0 wt.%) was determined. The process as developed was then utilized to fabricate nine-ply LLVRs of five balanced constructions with two or three CR laminates used as various layers. The physico-mechanical properties of the LLVRs were evaluated, and the results showed that LLVRs had strong shear strength, sound dimensional stability, decent bending strength, and favorable toughening and buffering performances. The newly developed product is an interesting potential alternative to traditional laminated veneer lumber or plywood.

  • Researchpp 6692-6707Yao, L., Chen, C., Zheng, X., Peng, Z., Yang, H., and Xie, Y. (2016). "Determination of lignin-carbohydrate complexes structure of wheat straw using carbon-13 isotope as a tracer," BioRes. 11(3), 6692-6707.AbstractPDF

    To maximize the use of wheat straw as a feedstock for biofuels and other biorefinery products, the structure of lignin-carbohydrate complexes (LCCs) was characterized by injection of 13C isotope-labeled xylose into living wheat straw. Afterwards, lignin-carbohydrate complexes were extracted from the harvested straw by the Björkman method. The extracted LCCs were chemically characterized by Fourier transform-infrared spectroscopy (FT-IR), sugar composition, molecular weight analysis, 13C-NMR, and HSQC. The results showed that LCCs in wheat straw were particularly enriched with xylan and exhibited narrow polydispersity (Mw/Mn < 1.5). NMR analysis showed that the lignin was linked with the carbohydrates through γ-ester, phenyl glycoside, and benzyl ether bonds. In addition to S, G, and H lignin units, p-coumarate and ferulate were also in the LCCs. The substructures in lignin were β-O-4′, β-β’, and β-5′. Quantitative data analysis of 13C-NMR combined with HSQC showed that the lignin in the LCCs of wheat straw contained guaiacyl (G), syringyl (S), and p-hydroxyphenyl (H) units in the proportion of 5:4:1 (S:G:H). The main lignin substructure, β-O-4′, comprised 71.64% of the isolated lignin. The total LCC linkages (the sum of phenyl glycoside, γ-ester and benzyl ether bonds) were 210.86 /100C9 in 13C-LCC, which was dominated by phenyl glycoside linkages, followed by γ-ester bonds and minor amounts of benzyl ether bonds. Lignin and xylan in the LCCs of wheat straw were mainly linked by benzyl ether bonds and phenyl glycoside linkages.

  • Researchpp 6708-6726Oke, M. A., Ishola, M. M., Taherzadeh, M. J., Mohamad Annuar, M. S., and Simarani, K. (2016). "Effects of pretreatment of single and mixed lignocellulosic substrates on production of endoglucanase by Bacillus aerius S5.2," BioRes. 11(3), 6708-6726.AbstractPDF

    A mixed substrate (MS) comprising oil palm empty fruit bunch (EFB), oil palm frond (OPF), and rice husk (RH) was evaluated for endoglucanase production by Bacillus aerius S5.2. Effects of sulphuric acid, sodium hydroxide, N-methylmorpholine-N-oxide (NMMO), and hydrothermal pretreatments on endoglucanase production were investigated. Endoglucanase production by B. aerius on the untreated (0.677 U/mL) and pretreated MS (0.305 – 0.630 U/mL) was generally similar, except that the acid (0.305 U/mL) and hydrothermal (0.549 U/mL) pretreatments that were more severe consequently produced significantly lower titres. Alkali pretreatment supported the highest enzyme production (0.630 U/mL) among all pretreatments that were studied. When endoglucanase production on the alkali-pretreated MS and single substrates (SS) was compared, alkali-pretreated EFB produced a titre (0.655 U/mL) similar to the MS, and this was significantly higher than titres recorded on OPF (0.504 U/mL) and RH (0.525 U/mL). Lower enzyme production was found to be consistent with higher pretreatment severity and greater removal of amorphous regions in all the pretreatments. Furthermore, combining the SS showed no adverse effects on endoglucanase production.

  • Researchpp 6727-6741Ghorbani, M., Liebner, F., van Herwijnen, H. W. G., Pfungen, L., Krahofer, M., Budjav, E., and Konnerth, J. (2016). "Lignin phenol formaldehyde resoles: The impact of lignin type on adhesive properties," BioRes. 11(3), 6727-6741.AbstractPDF

    Lignin-phenol-formaldehyde (LPF) resoles were prepared using different types of lignin at various levels of phenol replacement by lignin (0 to 40 wt.%). Adhesive properties including thermal behavior as determined by differential scanning calorimetry (DSC), time-dependent development of bond strength during hot pressing as determined by automated bonding evaluation system (ABES), tensile shear strength of solid beech wood lap-joints, and free formaldehyde content of the adhesives were investigated. Preparation of phenol-formaldehyde (PF) resole was accomplished using molar ratios of formaldehyde/phenol and NaOH/phenol of 2.5 and 0.3, respectively. Four different types of technical lignins were studied: Sarkanda grass soda lignin, wheat straw soda lignin, pine kraft lignin, and beech organosolv lignin. The synthesis of the resoles was optimized for 20 and 40 wt.% phenol replacement by lignin. Increasing substitution of phenol resulted in faster gain of LPF viscosity for all studied lignins. The best curing performances of the LPF resoles were observed for pine kraft lignin at both 20 and 40% phenol replacement. The amount of formaldehyde not consumed during cooking increased with increasing level of phenol replacement. However, no differences in free formaldehyde content were observed between the different lignin samples at comparable levels of phenol replacement.

  • Researchpp 6742-6755Saurabh, C. K., Dungani, R., Owolabi, A. F., Atiqah, N. S., Zaidon, A., Sri Aprilia, N. A., Md. Sarker, Z., and Abdul Khalil , H. P. S. "Effect of hydrolysis treatment on cellulose nanowhiskers from oil palm (Elaeis guineensis) fronds: Morphology, chemical crystallinity, and thermal characteristics," BioRes. 11(3), 6742-6755.AbstractPDF

    Oil palm fronds biomass was used as a source for isolation of cellulose nanowhiskers (CNW), and its subsequent characterization was done. Non-cellulosic components such as lignin, hemicellulose, and pectin were removed from the biomass by chemimechanical alkaline hydrogen peroxide method followed by sulphuric acid hydrolysis having different time duration of hydrolysis. Apart from the progressive reduction in peaks characteristic of hemicellulose and lignin dissolution, FTIR spectroscopy analysis showed that there were no significant variations in peak positions, signifying that the hydrolysis did not affect the chemical structure of CNW. FESEM showed that there was gradual reduction in the aggregated structure of fiber due to bleaching. Nanoscale structure of CNW was revealed by TEM. XRD analysis revealed that the natural structure of cellulose I polymorph was maintained irrespective of the hydrolysis time. High thermal stability and aspect ratio of the extracted CNW demonstrated its suitability as a reinforcement material in nanocomposites.

  • Researchpp 6756-6767Xu, Q., Wen, J., and Wang, Z. (2016). "Preparation and properties of cassava starch-based wood adhesives," BioRes. 11(3), 6756-6767.AbstractPDF

    A biodegradable, environmentally friendly starch-based wood adhesive with cassava starch as a raw material and butyl acrylate (BA) as a co-monomer was synthesized. Results revealed that this cassava starch-based wood adhesive (SWA) was more stable than corn starch-based wood adhesive, and its bonding performance was close to that of commercial PVAc emulsion, even after 90 days of storage. Further analysis found that the improved stability of the adhesive could be attributed to its low minimum film forming temperature (MFFT) and glass transition temperature (Tg) of cassava starch. Moreover, the amount of total volatile organic compounds (TVOCs) emitted by the cassava starch-based wood adhesive were much lower than the Chinese national standard control criteria. Therefore, cassava SWA might be a potential alternative to traditional petrochemical-based wood adhesives.

  • Researchpp 6768-6779Hosseinihashemi, S. K., Eshghi, A., Ayrilmis, N., and Khademieslam, H. (2016). "Thermal analysis and morphological characterization of thermoplastic composites filled with almond shell flour/montmorillonite," BioRes. 11(3), 6768-6779.AbstractPDF

    The main objective of this research was to study the potential uses of almond shell flour (ASF) in the production of thermoplastic composites containing montmorillonite (MMT). Thirty, 35, and 40 wt% ASF was used, and 2.0 wt% maleic anhydride-grafted polypropylene was used as the compatibilizer. Two levels of MMT nanoclay, 2.5 and 5.0 wt%, were mixed with polypropylene (PP). The effects of MMT on the thermal properties of the blended composites were evaluated using thermogravimetric analysis (TGA), morphological characterization, scanning electron microscopy (SEM), and X-ray diffraction (XRD). The XRD data showed that the relative intercalation of the composites with 2.5 wt% MMT was higher than that of the 5.0 wt% nanoclay composites. The TGA results indicated that by increasing the MMT percentage, the degradation temperature and the thermal stability were enhanced. The MMT exhibited better dispersion in the clay layers of the polymer-matrix composites when increased from 2.5 to 5.0 wt%, and at the 5.0 wt% MMT loading, the size of MMT became larger. The total weight loss of the ASF/PP/MMT composite decreased as the filler content increased, and the thermal stability increased as the MMT content increased.

  • Researchpp 6780-6800Rahman, M. L., Sarkar, S. M., Yusoff, M. M., Kulkarni, A. K. D., Chowdhury, Z. Z., and Ali, M. E. (2016). "Poly(amidoxime) from polymer-grafted Khaya cellulose: An excellent medium for the removal of transition metal cations from aqueous solution," BioRes. 11(3), 6780-6800.AbstractPDF

    A free radical chain initiation reaction was exploited to prepare poly(acrylonitrile)-grafted Khaya cellulose. The synthesis of the poly(amidoxime) ligand was also performed using oximation reactions. Transition metal cations formed some complexes with the polymeric ligand. The pH of the solution played an important role in the optical detection of Cu2+ ions. The highest absorbance (approximately 94%) of the [Cu-ligand]n+ complex was at pH 6. The sorption quantity increased with increasing Cu2+ ion concentration, which was reflected by a broad peak at 600 nm that was attributed to the charge transfer (- transition) process. The equilibrium sorption capacity of 282 mg/g, with faster adsorption rates (t1/2 = 8 min), suggested that copper possessed excellent adsorption capacity compared with the other cations (Fe3+, Co3+, Cr3+, Ni2+, and Zn2+). The sorption data for all of the cations followed the Freundlich isotherm model, with a high coefficient of determination, reflecting a heterogeneous sorption process by the cellulose-based, poly(amidoxime) adsorbent. The feasibility for recycling of adsorbent was evaluated by the sorption/ desorption study, and the results suggest that a new type adsorbent can be reused in seven cycles without any significant loss in its original sensing and removal performances.

  • Researchpp 6801-6807Liu, Y., Li, H., Yang, J., Li, B., Zhang, C., and Liu, M. (2016). "An improved method for determination of pentosans in pulps using dual-wavelength spectroscopy," BioRes. 11(3), 6801-6807.AbstractPDF

    The aim of this study was to determine the pentosan content in pulps by a dual-wavelength spectrophotometric method. The method was based on the boiling reaction between pentosan and 12% hydrochloric acid, in which pentosan was subsequently converted to furfural. The concentration of furfural in the distillate was determined by the absorbance at 280 nm and 290 nm. Several different simultaneous equations were solved to obtain the concentrations of furfural in the distillate. The results showed that the method had an excellent accuracy (RSD ≤ 0.61%) and reproducibility (RSD = 3.25%). The spectral interference of the 5-hydroxymethyl-2-furaldehyde in the distillate was eliminated by the dual-wavelength measurement technique. Compared with the TAPPI method (colorimetric method), this method is simple, user-friendly, and practical and has high detection sensitivity.

  • Researchpp 6808-6821Zhang, F., Wang, S., Chen, J., Wang, Y., Ru, B., and Zhu, L. (2016). "Effect of coal ash on the steam reforming of simulated bio-oil for hydrogen production over Ni/γ-Al2O3," BioRes. 11(3), 6808-6821.AbstractPDF

    An improved system for hydrogen production by the steam reforming of simulated bio-oil was developed. The coal ash was packed in front of nickel-based catalysts, acting as a guard catalyst. The model compounds passed through coal ash and were preliminarily reformed to smaller molecular intermediates containing more CO and CH4, which were then further reformed over the following nickel-reforming catalyst. The improved reaction system succeeded in effectively converting the complex simulated bio-oil into hydrogen and exhibited high activity. For 15 wt.% Ni/γ-Al2O3 catalyst with coal ash packing, the catalyst lifetime was extended to 8 h, with simulated bio-oil almost completely converted into hydrogen. In addition, coke deposition was suppressed.

  • Researchpp 6822-6835Park, J., Horvath, L., and Bush, R. J. (2016). "Process methods and levels of automation of wood pallet repair in the United States," BioRes. 11(3), 6822-6835.AbstractPDF

    This study documented the current status of wood pallet repair in the United States by identifying the types of processing and equipment usage in repair operations from an automation perspective. The wood pallet repair firms included in the study received an average of approximately 1.28 million cores (i.e., used pallets) for recovery in 2012. A majority of the cores received were stringer-style pallets. The most common pallet size received and repaired was 48 x 40 inch. The most commonly used stringer repair method was the application of companion stringers. It was found that most firms utilized high levels of manual labor, with limited machinery support. The board trimming and pallet sorting/stacking processes had the highest level of automation, while the inspection, nailing, and painting processes utilized manual labor.

  • Researchpp 6836-6853Kasal, A., Smardzewski, J., Kuşkun, T., and Erdil, Y. Z. (2016). "Numerical analyses of various sizes of mortise and tenon furniture joints," BioRes. 11(3), 6836-6853.AbstractPDF

    This study reports the moment resistance, stiffness, and numerical analysis of various sizes of round-end mortise and tenon joints. L-shaped and T-shaped specimens were constructed. Joints were manufactured using three tenon widths and three tenon lengths with 10 replications for each combination. Specimens were constructed of Turkish beech, and the joints were assembled with polyvinylacetate (PVAc) adhesive. Bending tests were carried out in compliance with accepted test methods. Numerical analyses were performed with finite element method (FEM) software. At the end of the study, the joints became stronger and stiffer as either tenon width or length increased. Tenon length had a more significant effect on moment resistance, while tenon width had a more significant effect on stiffness. Ultimate moment resistances were obtained with L-shaped joint construction of 50 × 50 mm tenons and T-shaped joint construction of 40 × 50 mm tenons. Strength of a chair could be increased by considering these results in engineering design process. Results showed that the numerical analyses gave reasonable estimates of mechanical behavior of joints. Analytical calculations and numerical simulations confirmed that the maximum stress in the glue line was concentrated at the edge and corners, and that the modeled joints had a shape-adhesive nature.

  • Researchpp 6854-6866Li, M., Han, G., Song, Y., Jiang, W., and Zhang, Y. (2016). "Structure, composition, and thermal properties of cellulose fibers from Pueraria lobata treated with a combination of steam explosion and laccase mediator system," BioRes. 11(3), 6854-6866.AbstractPDF

    Cellulosic fibers from the bast of Pueraria lobata (P. lobata) vine were separated using a “green” and efficient method that combined steam explosion (SE) and a laccase mediator system (LMS). The chemical components, structure, and thermal alterations in the fibers were evaluated. The SE performed at 180 °C for 10 min did not change the chemical composition of P. lobata; however, SE did alter the fiber structure and rendered its surface more accessible to the laccase enzyme. Treated and untreated samples were characterized by scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR), X-ray diffractometry (XRD), thermogravimetric analysis (TGA), and chemical methods. The cellulose content of the processed fibers was approximately 68.2%, and the lignin content was 11.8%, which was much lower than the 22.98% lignin content of the raw material. The cellulose fibers exhibited higher cellulose crystallinity and thermal stability compared with the untreated samples. This combined treatment approach may be useful for the isolation of cellulose fibers for composites, textiles, and other industrial applications.

  • Researchpp 6867-6879Ma, Z., Li, S., Qiao, W., and Ren, S. (2016). "Hydrothermal degradation of enzymatic hydrolysis lignin in water-isopropyl alcohol co-solvent," BioRes. 11(3), 6867-6879.AbstractPDF

    The effect of hydrothermal conditions on enzymatic hydrolysis lignin (EHL) degradation in water-isopropyl alcohol co-solvent and optimal conditions were investigated. The yields and reactivity toward formaldehyde of degraded enzymatic hydrolysis lignin (DEL) were determined. The optimal conditions of temperature, time, and ratio of solids to liquids were 250 °C, 60 min, and 1:10 (w/v), respectively. The EHL and DEL were characterized by gel permeation chromatography (GPC), Fourier transform infrared spectroscopy (FT-IR), 1H nuclear magnetic resonance (1H NMR), thermal gravity (TG), and differential scanning calorimetry (DSC) analyses. The results revealed that the molecular weight and polydispersity of DEL were lower than that of EHL. Although the fundamental structure of lignin before and after hydrothermal degradation was retained, the ether (β-O-4, α-O-4, etc.) content decreased, while that of hydroxyl (phenolic and aliphatic) increased. The DTGmax and Tg values shifted from 334 and 117 °C to 304 and 105 °C, respectively.

  • Researchpp 6880-6895Liew, F. K., Hamdan, S., Rahman, M. R., Mahmood, M. R., Rahman, M. M., Lai, J. C. H., and Sultan, M. T. (2016). "4-methylcatechol-treated jute-bamboo hybrid composites: Effects of pH on thermo-mechanical and morphological properties," BioRes. 11(3), 6880-6895.AbstractPDF

    Hybrid composites were fabricated with 4-methylcatechol-treated jute and bamboo fiber at different pH levels. The effects of different pH levels on the thermal, mechanical, and morphological properties of jute-bamboo hybrid composites were investigated. Fabricated hybrid composites were characterized by Fourier transform infrared spectroscopy (FTIR), thermogravimetric analysis (TGA), differential scanning calorimetry (DSC), dynamic mechanical thermal analysis (DMTA), and adhesion test analysis. Additionally, surface morphology and tensile testing were reported. Fourier transform infrared spectroscopy (FTIR) revealed that the peak intensities at 1634 and 1643 cm-1 disappeared in treated jute and bamboo fibers. This resulted from the removal of hydroxyl groups on the treated fibers. A higher pH (9 or 10) resulted in the effective modification of bamboo and jute fibers. The TGA results showed that the presence of hybrid fiber led to an earlier degradation of the hybrid composite. The DSC results showed that the crystallinity index declined by 7% to 8%, which improved the adhesion between the fiber and the polymer. According to these finding, the pH level contributed to an improvement in the mechanical properties of the composites. The pH 10-treated hybrid composites exhibited the highest tensile strength and modulus. The surface morphology revealed that at higher pH, the treated hybrid composites exhibited strong adhesion characteristics.

  • Researchpp 6896-6908Sakagami, H., Tokunaga, A., Fujimoto, N., Koga, S., Kobayashi, I., and Momohara, I. (2016). "Effects of drying temperature for Cryptomeria japonica on the permeability of wood preservative. II. The permeability of dried, split log pieces," BioRes. 11(3), 6896-6908.AbstractPDF

    Poor impregnation of sapwood from Cryptomeria japonica kiln-dried logs is a problem for preservative treatment in Japan. The permeability of copper azole (CuAz) into sapwood was reported to decrease with an increase in the drying temperature of logs, due in part to the presence of bordered pits. However, damaged and aspirated bordered pits appeared abundantly at 100 °C and 120 °C, although the difference in permeability was very little. To investigate this phenomenon, two types of smaller split log pieces, one containing both heartwood and sapwood, and the other containing sapwood without heartwood, were dried at 20 °C to 120 °C to test higher drying conditions. Results were similar to those of the dried logs. However, the impregnation and penetration at 80 °C were the lowest, and those at 100 °C and 120 °C were greater than the dried logs. Additionally, the number of damaged bordered pits on dried, split samples was generally higher than that of dried logs, as observed with scanning electron microscopy.

  • Researchpp 6909-6919Boruszewski, P., Borysiuk, P., Mamiński, M., and Czechowska, J. (2016). "Mat compression measurements during low-density particleboard manufacturing,"BioRes. 11(3), 6909-6919.AbstractPDF

    This study regards the effect of technological aspects on mat compression during the manufacturing of low-density particleboards made of two low density species – i.e. poplar and pine. Using these materials, three-layer low-density particleboards (500 kg/m3) were prepared. Three series were manufactured: (1) neat pine, (2) poplar-pine (face layer and core layer, respectively) and (3) neat poplar boards. Measurements of real-time variations in mat core temperature, pressure, and mat thickness allowed for the analysis of the mat compaction. Selected mechanical properties (modulus of rupture, modulus of elasticity, and internal bonding) of the manufactured particleboards were determined. Raw material of lower density used for particleboard manufacturing required either prolonged pressing time or more intense heat transfer into the mat core. The highest strength values were obtained for the poplar-pine particleboards.

  • Researchpp 6920-6931Guo, T., Wang, Y., and Huang, J. (2016). "Studies of electroless copper plating on poplar veneer," BioRes. 11(3), 6920-6931.AbstractPDF

    Copper coating was deposited on poplar veneer using different relative concentrations of plating solution. The coating structure, thickness, crystal structure, surface resistivity, contact angle, surface free energy, and electromagnetic shielding effectiveness were investigated. The surface morphology and thickness were observed using scanning electron microscopy, and the crystal structure was analyzed using X-ray diffraction. Increasing the relative concentration of plating solution resulted in a uniform and dense coating structure, and the thickness notably increased. In addition, the lateral direction resistivity was two times greater than the longitudinal direction resistivity, and the surface wettability changed from hydrophilic to hydrophobic, which led to a decline in surface free energy. Electromagnetic shielding effectiveness reached 62 dB in the frequency range of 10 kHz to 1.5 GHz. The electroless plating copper veneer was optimal when the solution contained 80 g/L of CuSO4·5H2O, 20 g/L of C4O6H4KNa, 40 g/L of EDTA-2Na, and 40 mL/L of HCHO 40 mL/L.

  • Researchpp 6932-6939Nonaka, H., Yamamoto, R., Katsuzaki, H., and Funaoka, M. (2016). "Suggested production of a guaiacyl benzofuran derivative from softwood via lignocresol,"BioRes. 11(3), 6932-6939.AbstractPDF

    Lignocresol was isolated from softwood with p-cresol using sulfuric acid and phase separation. An alkaline treatment of the lignocresol, followed by acidification, selectively yielded a guaiacyl coumaran, G1, in the acid-soluble fraction. With further alkaline treatment of G1 in 0.5 M of NaOH solution at 170 °C for 60 min, it was strongly suggested that a guaiacyl benzofuran derivative, G2, was obtained by the elimination of formaldehyde, based on analytical data of the reaction mixture. The process is very unique and well-designed based on the reactivity of Cα-ethers, or Cα-OH, Cβ-aryl-ethers, and Cγ-OH of lignin, although condensation reactions via formaldehyde occurred in parallel to give condensed products with a diarylmethane structure. Because these phenolic dimers, G1 and G2, were recovered from the guaiacyl unit linked with the neighboring guaiacyl units via two b-aryl-ether bonds, they are promising lignin-derived chemicals that are obtainable in a high yield.

  • Researchpp 6940-6947Wang, J., Wang, F., Gao, Z., Zheng, M., and Sun, J. (2016). "Flame retardant medium-density fiberboard with expanded vermiculite," BioRes. 11(3), 6940-6947.AbstractPDF

    This study investigated the effect of expanded vermiculite (EV) on the flammability properties of medium-density fiberboard (MDF), which was evaluated by limiting oxygen index (LOI) and simultaneous thermal analysis (TG-DSC). In addition, the modulus of rupture (MOR) and the modulus of elasticity (MOE) of the samples were studied. The results indicated that the addition of EV increased the LOI of MDF, while it decreased the MOR and MOE of MDF quite rapidly. The TG data showed that the fiber-charring rate of the fire retardant MDF increased sharply, more than 10 times that of untreated MDF. Moreover, with increasing of the ratio of the EV and fiber (V/F), it increased the fiber-charring rate of the MDF sharply, decreased the temperature of the maximum mass loss, and decreased the maximum mass loss rate of MDF. The DSC test results indicated that the total temperature range of the exothermic stage had extended and that the first peak in the exothermic stage decreased rapidly with increasing of V/F ratio.

  • Researchpp 6948-6967Chu, D., Xue, L., Zhang, Y., Kang, L., and Mu, J. (2016). "Surface characteristics of poplar wood with high-temperature heat treatment: Wettability and surface brittleness," BioRes. 11(3), 6948-6967.AbstractPDF

    The many uses of wood are greatly affected by its surface properties, which are significantly altered by heat treatment. Investigated here are the wettability and surface brittleness when treating poplar wood with heat at 160, 180, 200, and 220 °C for 2 h. Contact angles were measured by the sessile drop method, and surface free energy was calculated. Surface brittleness was expressed by hardness (HD value), roughness (Ra, Rq, Ry, and Rz values), and abrasive resistance (K value). Next, non-destructive Fourier transform near-infrared spectroscopic (FT-NIR) and X-ray photoelectron spectroscopic (XPS) measurements were employed to analyze the surface chemical changes. Scanning electron microscopy (SEM) revealed the post-heating microscopic structure. The results demonstrated that heat treatment reduces the surface wettability while increasing the surface brittleness, which becomes more apparent with increased temperature. Significant differences were determined (p < 0.05) between the surface parameters at four different temperatures. The degradation of cell wall components and the deterioration of microstructures was further expounded by FT-NIR, XPS, and SEM analyses. Furthermore, the abrasive resistance and hardness values decreased in line with the rate of weight loss (WL, %) and temperature. This indicates a strong correlation between the surface characteristics and the WL or temperature. The intensity of heat treatment appears to be predictable and easy to regulate.

  • Researchpp 6968-6983Abdolhosseini Sarsari, N., Pourmousa, S., and Tajdini, A. "Physical and mechanical properties of walnut shell flour-filled thermoplastic starch composites,"BioRes. 11(3), 6968-6983.AbstractPDF

    The goal of this work was to evaluate the technical feasibility of walnut shell flour (WSF) as substitute for wood in walnut shell flour/thermoplastic starch (WSF/TPS) composites. The effects of walnut shell flour (WSF), thermoplastic starch (TPS), and nanoclay on the physical and mechanical properties of WSF/TPS composites were investigated. The composite samples were formed in a Colin extruder with four-chamber heat with temperatures. Then, test samples were made using injection molding. The addition of up to 40% WSF greatly improved the tensile strength, flexural strength, and elasticity modulus of the composite. Also, the composites made with higher WSF contents had increased thickness swelling and water absorption. The incorporation of nanoclay (0% to 5%), greatly improved the tensile properties. Soil burial degradation experiments showed that biodegradation was accelerated by the increase of starch in the composite mixtures. The study showed that WSF can be successfully utilized for the manufacture of composites with useful physical and mechanical properties.

  • Researchpp 6984-7000Bankeeree, W., Prasongsuk, S., Imai, T., Lotrakul, P., and Punnapayak, H. (2016). "A novel xylan-polyvinyl alcohol hydrogel bead with lacasse entrapment for decolorization of reactive black 5," BioRes. 11(3), 6984-7000.AbstractPDF

    In an attempt to find a more efficient technique for biodegradation of the recalcitrant Reactive Black 5 (RB-5) dye, a composite xylan-polyvinyl alcohol (xylan-PVOH) hydrogel was used to immobilize laccase from the white-rot fungusTrametes versicolor. Xylan was prepared from the black liquor of pulp and paper effluent, and it was esterified with citric acid prior to cross-linking with polyvinyl alcohol (PVOH). The optimum composition for the immobilized laccase bead formation consisted of 4% (w/v) modified xylan, 10% (w/v) PVOH, and 15 U.mL-1 crude laccase. The maximum decolorization of RB-5 (98.45 ± 1.96 %) was obtained within the first cycle (6 h) at 40 °C. In the eighth cycle, the reused beads were able to decolorize 55.35 ± 2.46 % of the RB-5. Moreover, the xylan-PVOH beads extended the optimum pH range of laccase activity from 6 to 10 and tolerated a temperature up to 10 °C higher than that of the free enzyme. These results suggest that the xylan-PVOH bead has great potential as the polymer matrix for enzyme immobilization, which has applications in wastewater treatment.

  • Researchpp 7001-7015Matthews, S., Toghyani, A. E., Ovaska, S.-S., Eskelinen, H., Kärki, T., and Varis, J. (2016). "Post-extrusion processing of extruded wood plastic composites and selection of belt conveyor cover material," BioRes. 11(3), 7001-7015.AbstractPDF

    Wood plastic composites (WPCs) have recently gained increased market share as a result of their beneficial properties and use of sustainable material sources. Currently, however, WPC products are limited to extruded profiles. More complex product shapes and geometries will increase market potential, but they demand additional post-processing after extrusion. Post-processing machinery coupled online with an extruder necessitates material handling, which is commonly achieved using belt conveyors. This paper considers transport of WPC material through a post-extrusion process using a belt conveyor system. Special emphasis is placed on studying the friction and surface energy properties of the belt conveyor. Friction at the interface of the raw material and belt cover was tested using a standard incline-plane method, and adhesion and stickiness were evaluated by determining the surface free energies of the belt cover and WPC material at 23 and 100 °C. On the basis of these measurements, this paper investigates key aspects of belt cover material selection and proposes a conveyor belt configuration for a prototype post-extrusion process line that can be utilized in commercial mass production of WPC products.

  • Researchpp 7016-7025Tahri, I., Ziegler Devin, I., Ruelle, J., Segovia, C., and Brosse, N. (2016). "Extraction and characterization of fibers from palm tree," BioRes. 11(3), 7016-7025.AbstractPDF

    The characterization of fibers extracted from leaflet, the empty fruit bunches, leaf sheath, and spath of palm tree was performed. The fibers were extracted using three different procedures through chemical and /or enzymatic methods. The raw fibers studied have xylose contents between 13-22% and glucose content between 30% and 45%. The microfibrillar angle (MFA) values are in the order: bunch > spath > leaf sheath >> leaflet. Spath and leaf sheath, which naturally occur in a woven form present poor mechanical strength but could be readily used to produce cheap composites. Leaflet fibers extracted from date palm tree exhibiting a low MFA (16°), a high cellulose content, and cellulose crystallinity present the highest ultimate tensile strengths (≈ 1250

  • Researchpp 7026-7035Wu, W., Li, J., Liu, W., and Deng, Y. (2016). "Temperature-sensitive, fluorescent poly (N-Isopropyl-acrylamide)-grafted cellulose nanocrystals for drug release," BioRes. 11(3), 7026-7035.AbstractPDF

    Cellulose nanocrystals (CNCs) grafted with fluorescent and thermo-responsive poly (N-isopropylacryalamide) (PNIPAM) brushes were prepared for encapsulation and the release of 5-fluorouracil (5-FU). The successful grafting was evidenced by Fourier transform infrared (FTIR) spectroscopy and solid-state 13C nuclear magnetic resonance (13C NMR). Differential scanning calorimetry measurements suggested that the lower critical solution temperature of PNIPAM-grafted CNCs is close 32 °C. During polymerization, tuned fluorescence signatures were obtained by varying the dye dosages. At room temperature, the release amount of the loaded 5-FU was about 42% at a pH of 2.1, while this value approached 60% at a pH of 7.4. Both the cumulative release amount and the release rate were greatly increased when the temperature was raised to 37 °C. The novel PNIPAM-grafted CNCs with both fluorescence and stimuli-sensitive properties possess potential for application in intelligent drug delivery systems.

  • Researchpp 7036-7045Qian, S., Ren, H., Dai, H., and Omori, S. (2016). "Characterization of polypropylene fiber and lignocresol enhanced poly(3-hydroxybutyrate) composite films,"BioRes. 11(3), 7036-7045.AbstractPDF

    The depletion of fossil resources and the environmental impact of petroleum-based plastic materials have driven a strong global interest in renewable biobased polymers and composites derived from natural resources. Since biodegradable polymers have their own drawbacks, it is often combined as a composite with other fillers. Polypropylene (PP)/Poly(3-hydroxybutyrate) (PHB) composite films and lignocresol (LC)/PP/PHB composite films were cast by blending methods. This study investigated the effects of the amounts of added PP fiber and LC on the mechanical and thermal properties in the corresponding composite films. The overall properties of LC/PP/PHB composite films were best with 8 wt.% PP fiber content and 3 wt.% LC content. The tensile strength (13.00 MPa) was up to 1.25 times that of the original PHB film (10.44 MPa), and the thermal properties of the composite films were improved by adding 3 wt.% LC. Thermogravimetry (TG) analysis indicated that the onset temperature (382.0 °C) rose by 50.7 °C compared with PP/PHB film (331.3 °C), and the residual mass was close to 0%.

  • Researchpp 7046-7060Liu, Y. D., Xing, J. X., Liu, J. H., Chen, J. H., Wang, K., Jiang, J. X., and Sun, R. (2016). "Physicochemical characteristics of gradual fractionation ingredients of industrial galactomannan gums from Gleditsia microphylla and Cyamopsis tetragonoloba," BioRes. 11(3), 7046-7060.AbstractPDF

    Galactomannan in industrial Gleditsia microphylla and guar gum was successfully fractionated by gradual precipitation in an aqueous solution with increasing ethanol concentrations. The molecular properties of each fraction were characterized, and the galactomannans were added to photopolymerized hydrogels to test their effects on mechanical properties and swelling capacity. In the series fractions of guar gum, the sample precipitated from 20% EtOH solution had the highest yield, mannose to galactose ratio, and viscosity, and it had a slightly lower molecular weight than that precipitated by 30% EtOH. Correspondingly, the best tensile property of its photopolymerized hydrogel was finally detected. In terms of G. microphylla gum, the precipitation in 30% EtOH solution achieved the highest yield, M/G ratio, and molecular weight value, and it exhibited the best rheological property of all the samples. The hydrogel with the addition of this sample also had the best mechanical properties despite its lower hydroscopicity than the blank hydrogel. The unique properties of each fraction could probably lead to their use as biodegradable alternatives in different applications.

  • Researchpp 7061-7077Domínguez-Robles, J., Espinosa, E., Savy, D., Rosal, A., and Rodríguez, A. (2016). "Biorefinery process combining Specel® process and selective lignin precipitation using mineral acids," BioRes. 11(3), 7061-7077.AbstractPDF

    Soda black liquors from the Specel® process, which used wheat straw as the raw material, were subjected to an acid precipitation process to recover the lignin. Lignin was isolated by acid precipitation using three different inorganics acids (H3PO4, H2SO4, and HCl) at three concentration levels, and at pH values of 2 and 4. Even though the highest lignin yield was achieved using phosphoric acid, the most economical inorganic acid was sulphuric acid. Physico-chemical characterizations of the precipitated lignin samples were performed using differential scanning calorimetry (DSC), thermogravimetric analysis (TGA) (for thermal properties), Fourier transform infrared spectroscopy (FT-IR), and heteronuclear single quantum correlation spectroscopy (HSQC) (for chemical structures). No significant differences were found in the thermal properties and chemical structures of the isolated lignins, except for the lignin obtained with phosphoric acid to lower the black liquor from pH 10.72 to pH 2. Apart from the lignin fraction collected, the soda pulp obtained by the Specel® process using wheat straw could represent a good alternative for packaging industries.

  • Researchpp 7078-7090Qian, L., Yang, S., Hong, W., Chen, P., and Yao, X. (2016). "Synthesis of biomorphic charcoal/TiO2 composites from moso bamboo templates for absorbing microwave," BioRes. 11(3), 7078-7090.AbstractPDF

    Biomorphic charcoal/TiO2 composites (C/TiO2) from moso bamboo templates were produced for absorbing microwave. Subsequently, the characteristics of the C/TiO2 were investigated by scanning electron microscopy, thermogravimetric analysis, and vector network analysis. The results showed that the biomorphic microstructure of the moso bamboo charcoal was duplicated in the C/TiO2. Thus, the density of the C/TiO2 sintered at 1200 °C was lower and approximately 0.916 ± 0.003 g/cm3. Moreover, the ignition, the maximum combustion, and the burnout temperatures of the C/TiO2 sintered at 600 °C were ~320 °C, ~530 °C, and ~585 °C, respectively. Additionally, with the rising of the temperature sintering C/TiO2, the microwave absorbency of the C/TiO2 was improved over high frequency zones. Furthermore, the average imaginary-part values of the permittivity of the C/TiO2 sintered at 600 °C and 1200 °C notably increased by 11.16-fold. In addition, the peak of microwave reflection loss of the samples (2.0 mm thickness) from the C/TiO2 powder (wt. 20%) sintered at 1200 °C and the paraffin wax (wt. 80%) was observed as -18.0 dB at 17.4 GHz. Therefore, the C/TiO2 sintered at higher temperatures exhibited lower geometrical density, better thermostability, and favorable microwave absorptive properties.

  • Researchpp 7091-7101Kirsch, A., Ostendorf, K., Kharazipour, A., and Euring, M. (2016). "Phenolics as mediators to accelerate the enzymatically initialized oxidation of laccase-mediator-systems for the production of medium density fiberboards," BioRes. 11(3), 7091-7101.AbstractPDF

    Crude oil as a non-renewable resource is creating new challenges in many industrial sectors. Unsteady costs of crude oil at present and expected increases in the future are due to its limited availability as a finite resource, and these costs negatively impact the industry for wood-based panels, which use petrochemical resins in binding agents. Furthermore, wood panels that are conventionally bonded using urea formaldehyde diffuse formaldehyde into the surrounding air. To achieve independence from petrochemical products and harmful formaldehyde emissions, alternatives for their substitution are in demand. An alternative approach is the enzymatic activation of lignin located on the surface of thermomechanical pulp (TMP) fibers. The present study shows the results of internal bond strength (DIN EN 319 1993), modulus of rupture (DIN EN 310 1993), and thickness swelling (EN 317 2003) of medium-density fiberboards (MDF) bonded with laccase-mediator-system (LMS). Caffeic acid (CA), 4-hydoxy benzoic acid (HBA), and vanillic alcohol (VAl) were used as mediators. The physical and technological properties of MDF, such as internal bond strength, modulus of rupture, and thickness swelling, mostly fulfilled the European standards.

  • Researchpp 7102-7123Burli, P., Lal, P., Wolde, B., and Alavalapati, J. (2016). "Sustainability protocols and certification criteria switchgrass-based bioenergy," BioRes. 11(3), 7102-7123.AbstractPDF

    Production of bioenergy from cellulosic sources is likely to increase due to mandates, tax incentives, and subsidies. However, unchecked growth in the bioenergy industry has the potential to adversely influence land use, biodiversity, greenhouse gas (GHG) emissions, and water resources. It may have unintended environmental and socioeconomic consequences. Against this backdrop, it is important to develop standards and protocols that ensure sustainable bioenergy production, promote the benefits of biofuels, and avoid or minimize potential adverse outcomes. This paper highlights agronomic information on switchgrass, a high-potential bioenergy feedstock, and the role of specialized certification programs. The existing sustainability standards and protocols were reviewed in order to identify key gaps that justify a certification program specifically for switchgrass-based bioenergy. The criteria and indicators that should be considered for such a certification program are outlined.

  • Researchpp 7124-7132Moser, C., Henriksson, G., and Lindström, M. E. (2016). "Specific surface area increase during cellulose nanofiber manufacturing related to energy input,"BioRes. 11(3), 7124-7132.AbstractPDF

    Softwood fibers pretreated with a monocomponent endoglucanase were used to prepare a series of cellulose nanofiber qualities using a microfluidizer and 2 to 34 MWh ton-1 of energy input. The specific surface area was determined for the series using critical point drying and gas adsorption. Although the specific surface area reached a maximum of 430 m2 g-1 at 11 MWh ton-1, the nanofiber yield and transmittance continued to increase beyond this point, indicating that more energy is required to overcome possible friction caused by an interwoven nanofiber network unrelated to the specific surface area. A new method for estimating the surface area was investigated using xyloglucan adsorption in pure water. With this method it was possible to follow the disintegration past the point of maximum specific surface area. The technical significance of these findings is discussed.

  • Researchpp 7133-7144Yang, T., Jia, K., Kai, X., Sun, Y., Li, Y., and Li, R. (2016). "A study on the migration behavior of K, Na, and Cl during biomass gasification," BioRes. 11(3), 7133-7144.AbstractPDF

    The migration behavior of the alkali metals and chlorine were studied during rice straw and corn straw gasification in a fixed bed reactor at various temperatures using thermodynamic equilibrium calculations, X-ray diffraction (XRD), and scanning electron microscopy/energy dispersive spectrometry (SEM-EDS). The results showed that K and Na were released mostly in chloride form. The release of potassium, sodium, and chlorine increased upon the increase in temperature from 600 to 1000 °C. The maximum amounts of potassium, sodium, and chlorine that were released from rice straw were 38.9%, 18.7%, and 34.9%, respectively. The maximum amounts of potassium and chlorine that were released from corn straw were 24% and 43.6%, respectively, which occurred at 1000 °C. The maximum amount of sodium released from corn straw was 77.6%, at 700 °C, and the amount of sodium released was greater than that of potassium. Most of the potassium and sodium was converted into insoluble carbonate, sulfate, silicate, and aluminosilicate compounds in the gasification ash.

  • Researchpp 7145-7161Zhou, Y., Zhang, J., Luo, X., and Luo, Y. (2016). "Enhanced adsorption of mercury(II) and cadmium(II) from aqueous solution onto rice bran modified with chelating ligands," BioRes. 11(3), 7145-7161.AbstractPDF

    To enhance the removal of mercury (Hg(II)) and cadmium (Cd(II)) from aqueous solutions, rice bran (RB) was reacted with epichlorohydrin and then modified with ethylenediamine and sodium chloroacetate to bear iminodiacetate functional groups. The modified rice bran (MRB) was characterized by Fourier transform-infrared spectroscopy (FT-IR), thermogravimetric analysis (TG), energy dispersive spectroscopy (EDS), back titration, and X-ray photoelectron spectroscopy (XPS). The adsorption properties of MRB for Hg(II)/Cd(II) ions were also evaluated in batch experiments. The sorption kinetic experimental data were best described by the pseudo-second-order model. The maximum adsorption capacity (163.9 mg/g for Hg(II) at pH 5.0 and 106.4 mg/g for Cd(II) at pH 6.0) was observed at 298 K, and the isotherm adsorption equilibrium of MRB was followed by Langmuir isotherm equation. The major adsorption mechanisms should be predominantly controlled by the formation of complexes between the functional groups of MRB and Hg(II)/Cd(II) ions as well as ion-exchange. The regeneration experiments showed that the MRB could be successfully reused for six cycles when 0.1 M HCl eluent was used.

  • Researchpp 7162-7171Eckelman, C. A., Uysal, M., and Haviarova, E. (2016). "Statistical lower tolerance limits for rectangular mortise and tenon joints," BioRes. 11(3), 7162-7171.AbstractPDF

    Tests were conducted to determine the bending moment capacity of 215 red oak and 140 white oak T-shaped rectangular mortise and tenon joints. Rails measured 22.2 mm by 63.5 mm in cross section; tenons measured 32 mm in length by 38 mm in height by 9.5 mm in thickness. Specimens were assembled with a 40% solid content polyvinyl acetate adhesive. The average bending moment capacity of the red oak specimens was 353 Nm with a standard deviation of 48 Nm; in the white oak specimens, it was 358 Nm with a standard deviation of 62 Nm. The lower tolerance limits of the red oak specimens at the 75|75, 90|75, 75|90, 90|90, and 95|95 confidence|proportion levels were 318, 316, 289, 286, and 266 Nm, respectively, whereas in white oak specimens, the values were 314, 308, 273, 268, and 240 Nm, respectively.  Overall, the results indicated that the use of statistical lower tolerance limits procedures provide a systematic means of relating standard deviations to mean values in determining reasonable design values for the moment capacity of the joints. Conclusions were not reached concerning which confidence|proportion level might be best suited for determining reasonable design values for furniture joints, but the results did illustrate the consequences of a given choice.

  • Researchpp 7172-7190Abdul Rahman, M. B., Ishak, Z. I., Jumbri, K., Abdul Aziz, A., Basri, M., and Salleh, A. B. (2016). "Effect of ionic liquids on oil palm biomass fiber dissolution,"BioRes. 11(3), 7172-7190.AbstractPDF

    Ionic liquids (ILs) were used in the dissolution of oil palm biomass, primarily empty fruit bunches (EFB), oil palm fronds (OPF), and oil palm trunks (OPT). These ILs acted as alternative solvents that could dissolve biopolymer molecules up to 5 wt.%. The IL, [emim][OAc] was the best solvent, dissolving EFB, OPF, and OPT of 99%, 100%, and 97%, respectively, at 100 ⁰C and 16 h. The lignin content of the regenerated oil palm solids for all biomass was quantified and showed significant reduction up to 35%; fiber length was also reduced as the heating time increased after IL dissolution. Also, the effect of ILs on the different parts of oil palm biomass fibers was thoroughly studied. The lignin content was quantified.

  • Researchpp 7191-7204Yaşar, S., and İçel, B. (2016). "Alkali modification of cotton (Gossypium hirsutum L.) stalks and its effect on properties of produced particleboards," BioRes.11(3), 7191-7204.AbstractPDF

    This study evaluates the effect of 1% to 5% NaOH treatments of cotton stalk particles on the chemical composition and physical and mechanical properties of particleboards produced with this material. Gas chromatography and Fourier transform infrared (FTIR) spectroscopy indicated that the extractive, hemicellulose, and lignin content of the particles decreased during the alkali treatments, whereas the cellulose content increased. Thermogravimetric analysis (TGA) indicated that the untreated particles exhibited higher thermal stability than the particles treated with NaOH. The decrease in thermal stability of alkali-treated particles seems to be due to degradation of chemical components. Alkali treatments raised water absorption (WA) and thickness swelling (TS) of the produced particleboards. Except for 1% NaOH, the treatments reduced the modulus of elasticity (MOE), modulus of rupture (MOR), and internal bond (IB) strength in relation to the board made with untreated particles. The 1% NaOH treatment of cotton stalks was more effective and beneficial, leading to particleboards with satisfying MOE, MOR, and IB values that met the requirements for general-purpose particleboards used in dry conditions, as indicated by the TS-EN 312 (2012) standard.

  • Researchpp 7205-7213Liang, H., Cao, J., Tu, W., Lin, X., and Zhang, Y. (2016). "Nondestructive determination of the compressive strength of wood using near-infrared spectroscopy," BioRes. 11(3), 7205-7213.AbstractPDF

    In this study, Xylosma racemosum was selected as the raw material and its compressive strength was predicted through nondestructive methods. The test data consisted of 160 near-infrared (NIR) absorption spectra of the wood samples obtained using an NIR spectrometer, with the wavelength range of 900 to 1900 nm. The original absorption spectra were pre-processed with multiplicative scatter correction (MSC) and Savitzky-Golay (SG) smoothing and divided into several intervals using the backward interval partial least squares (BiPLS) method. The optimal combination of intervals with the smallest root mean square error of cross validation (RMSECV) value was selected, and a genetic algorithm (GA) was used to select featured wavelengths. Finally, a partial least squares (PLS) regression model was established with the featured wavelengths. The BiPLS-GA-PLS model outperformed the other models, resulting in a high prediction correlation coefficient of 0.927 and a root mean square error rate of 4.06. Based on the results, it is feasible to accurately measure the compressive strength of wood processed by different methods using near-infrared spectroscopy.

  • Researchpp 7214-7223Lara-Serrano, J. S., Rutiaga-Quiñones, O. M., López-Miranda, J., Fileto-Pérez, H. A., Pedraza-Bucio, F. E., Rico-Cerda, J. L., and Rutiaga-Quiñones, J. G. (2016). "Physicochemical characterization of water hyacinth (Eichhornia crassipes (Mart.) Solms)," BioRes. 11(3), 7214-7223.AbstractPDF

    Water hyacinth (Eichhornia crassipes) is an aquatic flowering plant that belongs to the Pontederiaceae family. The plant is a freshwater hydrophyte that grows in subtropical and tropical regions of the world. The objective of this study was to determine the physicochemical characterization of roots, stems, and leaves of E. crassipes. The pH, ash, 1% alkali solubility, extractives, lignin, holocellulose, tannins, and calorific value were determined. Our results showed that the mineral content is relatively high, whereas that for lignin and tannins is low. The pH is moderately acid, and the soluble substances easily dissolved in alkali or organic solvents. Potassium, calcium, and silicon are the major constituents present in the ash of this plant. The determined calorific value was approximately 14.4 MJ/kg.

  • Researchpp 7224-7241Chen, Y. W., Lee, H. V., and Abd Hamid, S. B. (2016). "Preparation of nanostructured cellulose via Cr(III)- and Mn(II)-transition metal salt catalyzed acid hydrolysis approach," BioRes. 11(3), 7224-7241.AbstractPDF

    Nanostructured cellulose was successfully prepared from native cellulose using a homogeneous catalytic H2SO4 hydrolysis pathway in the presence of Cr(III)- and Mn(II)-transition metal salts as the co-catalyst. The effect of transition metal salts with different valence states (Cr3+ and Mn2+) on the physicochemical properties (chemical characteristics, crystallinity index, nano-structure, thermal stability, and morphology) of prepared nanocellulose was investigated. Interestingly, TEM micrographs showed that the Cr(III)-treated and Mn(II)-treated nanocellulose exhibited a web-like nanostructured-surface with average diameters of 44.7 ± 13.2 nm and 58.4 ± 15.3 nm, respectively. XRD study revealed that the crystallinity of nanocellulose was increased because the catalytic degradation of the less crystalline regions of cellulose occurred at a faster rate than its crystalline phases. Cr(III)-treated nanocellulose was capable of rendering a higher crystallinity index (75.6 ± 0.1%) compared with Mn(II)-treated nanocellulose (72.3 ± 0.4%). Furthermore, a dynamic light scattering (DLS) study revealed that Cr(III)-treated nanocellulose showed a smaller distribution range (92% at 14 to 135 nm) compared with Mn(II)-treated nanocellulose (92% at 607 nm). A higher valence state for the Cr(III)-cation, with a trivalent state (+3), rendered a more effective hydrolysis reaction compared with the Mn(II)-cation, with a divalent state (+2), for preparing the nanocellulose.

  • Researchpp 7242-7257Hu, B., Zhu, S., Fang, S., Huo, M., Li, Y., Yu, Y., and Zhu, M. (2016). "Optimization and scale-up of enzymatic hydrolysis of wood pulp for cellulosic sugar production," BioRes. 11(3), 7242-7257.AbstractPDF

    With the decreased demand for pulp and paper worldwide, the reorganization of pulp and paper mills for cellulosic sugar production is possible. To maximize cellulosic sugar production from the wood pulp with minimum resources, the effects of pH, buffer system, temperature, enzyme loadings, pulp concentrations, and mixing modes on enzymatic hydrolysis were investigated, one factor at a time. Temperature played an important role in enzymatic hydrolysis. When the temperature was lower than 45 °C, the sugar production declined dramatically to almost half of the maximum value. Increasing enzyme dosage, increasing pulp concentration, and adding xylanase increased sugar production. The intermittent manual mixing mode generated higher concentrations of sugars and could be used for large-scale production. At pilot-scale, the diverted pulp for the pulping process was directly hydrolyzed without any treatment, and the residue after hydrolysis was hydrolyzed by adding fresh enzymes. This study provides insight on economically feasible enzymatic hydrolysis of wood pulp at large-scale cellulosic sugar production.

  • Researchpp 7258-7270Ren, J., Liu, L., Xu, Q., Li, X., Yong, Q., and Jia, O. (2016). "Comparative evaluation of magnesium bisulfite pretreatment under different pH values for enzymatic hydrolysis of corn stover," BioRes. 11(3), 7258-7270.AbstractPDF

    During pretreatment, the pretreatment pH often plays an important role in removing hemicelluloses and lignin for improving the conversion of biomass to sugars. In this study, corn stover was subjected to magnesium bisulfite pretreatment (MBSP) under various pH conditions. The obtained data showed that the hemicelluloses and lignin were solubilized by MBSP, which led to changes in the structural and chemical properties of the pretreated material. The pretreatment pH could alter the existing forms of SO2, and magnesium bisulfite was the most effective reagent for removing lignin. A relatively neutral MBSP (pH 5.13) not only considerably improved the enzymatic hydrolysis yield (80.18%), but also produced a large amount of high-value xylo-oligosaccharides in the spent liquor. Furthermore, only the hemicellulose removal showed a linear relationship with the enzymatic hydrolysis yield. These results suggest that removal of all the lignin might not be necessary to improve the hydrolysis efficiency.

  • Researchpp 7271-7281Cheng, X., He, X., Xie, J., Quan, P., Xu, K., Li, X., and Cai, Z. (2016). "Effect of the particle geometry and adhesive mass percentage on the physical and mechanical properties of particleboard made from peanut hull," BioRes. 11(3), 7271-7281.AbstractPDF

    Peanut hull residues were considered for the manufacturing of particleboards. Various concentrations of two types of adhesive—polymeric diphenylmethane diisocyanate (MDI) and urea-formaldehyde (UF)—were separately combined with four types of peanut hull particles (fine, mixed, coarse particles, and peanut hull powder) to manufacture particleboards with a certain target density. The confidence level of the effect of the selected production parameters on the physical and mechanical properties of the panels was evaluated. The results showed that increasing the adhesive mass percentage significantly improved the dimensional stability of the boards. A better mechanical performance was achieved for the MDI-bonded boards compared with the UF-bonded boards. Superior bonding between the MDI adhesive and the peanut hulls with different particle geometries was also observed; the peanut hull powder and coarse particles were unsuitable for the manufacturing of panels, due to the risk of an internal blowout. The water resistance of the panels was poor, whereas the mechanical strength of the peanut hull particleboard met the class M-1 requirement of the ANSI A208.1 (2009) standard for wood particleboard.

  • Researchpp 7282-7295Salman, S. D., Leman, Z., Sultan, M. T. H., Ishak, M. R., and Cardona, F. (2016). "Ballistic impact resistance of plain woven kenaf/aramid reinforced polyvinyl butyral laminated hybrid composite," BioRes. 11(3), 7282-7295.AbstractPDF

    Traditionally, the helmet shell has been used to provide protection against head injuries and fatalities caused by ballistic threats. In this study, because of the high cost of aramid fibres and the necessity for environmentally friendly alternatives, a portion of aramid was replaced with plain woven kenaf fibre, with different arrangements and thicknesses, without jeopardising the requirements demanded by U.S. Army helmet specifications. Furthermore, novel helmets were produced and tested to reduce the dependency on the ballistic resistance components. Their use could lead to helmets that are less costly and more easily available than conventional helmet armour. The hybrid materials subjected to ballistic tests were composed of 19 layers and were fabricated by the hot press technique using different numbers and configurations of plain woven kenaf and aramid layers. In the case of ballistic performance tests, a positive effect was found for the hybridisation of kenaf and aramid laminated composites.

  • Researchpp 7296-7304Huang, W., Wu, Y., Zhao, Z., Yi, S., and He, Z. (2016). "Influence of thermal treatment conditions on the release of volatile organic compounds from bamboo," BioRes. 11(3), 7296-7304.AbstractPDF

    Large quantities of volatile organic compounds (VOCs) are released from heat-treated bamboo during the manufacturing process of recombinant bamboo, which affects the environment and human health. In this study, bamboo was treated at 150 °C, 180 °C, and 210 °C for 3 h, and VOCs were collected every hour using a Tenax tube. The VOCs were analyzed with gas chromatography-mass spectrometry (GC-MS) to explore the effect of temperature and time on weight loss ratio, main components, and their relative proportions. The results showed that temperature considerably influenced weight loss ratio, and weight loss ratio increased rapidly at high temperature. Massive quantities of VOC were emitted during the first hour of treatment, and emissions decreased as the time and temperature increased. Terpenes were the primary component of the VOC emissions. Temperature and time exhibited minimal effects on the type of primary components, and the relative proportion of some components exhibited negligible changes over a range of temperatures and times.

  • Researchpp 7305-7321Zhang, H., Yang, S., Sun, X. Y., and Yuan, T. Q. (2016). "Biological treatment of poplar wood with white-rot fungus Trametes hirsuta C7784: Structural elucidation of the whole lignin in treated wood," BioRes. 11(3), 7305-7321.AbstractPDF

    Poplar wood was subjected to biological treatment with a white-rot fungus Trametes hirsuta C7784. The structural features of the lignin in the untreated and treated poplar wood samples were comparatively elucidated. Milled wood lignin (MWL) and residual enzymatic lignin (REL) fractions of each sample were sequentially isolated. The total pure yields of the isolated lignin fractions after white-rot fungus treatment exceeded 96% (based on the Klason lignin content), and thus, represented the whole lignin in the fungus-treated poplar wood. The structural features of the lignin fractions were quantitatively analyzed. βO-4′ structures were the most prominent linkage in the biologically treated wood, and there were more present than in the untreated wood. To this effect, the lignin in the fungus-treated poplar wood was easily degraded and removed under mild conditions, which is essential for subsequent conversion processes.

  • Researchpp 7322-7333Lehto, J. T., and Alén, R. (2016). "Organic material dissolved during oxygen-alkali pulping of hot-water-extracted spruce sawdust," BioRes. 11(3), 7322-7333.AbstractPDF

    Untreated and hot-water-extracted (HWE) Norway spruce (Picea abies) sawdust was cooked using the sulfur-free oxygen-alkali (OA) method under the following conditions: temperature, 170 °C; liquor-to-wood ratio, 5:1 L/kg; and NaOH charge, 19% on the oven-dry sawdust. In comparison with earlier studies conducted with birch sawdust, the spruce cooking yield data, together with the amount of the pulp rejects (78% to 86% for reference pulps from the initial feedstock and 73% to 83% for pulps from the HWE feedstock), revealed that the pretreatment stage prior to spruce OA pulping caused different effects on pulping performance. The analyses of the three main compound groups (i.e., lignin, volatile acids, and hydroxy acids) in black liquor indicated that slightly higher contents (25.5 to 45.9 g/L) of dissolved lignin were detected in black liquors originating from the HWE sawdust than in the black liquors from the reference material (27.2 to 39.6 g/L). In contrast, considerably lower (~20% decrease) volatile acid contents and similar or slightly decreased hydroxy acids contents were detected in the black liquors from the HWE sawdust.

  • Researchpp 7334-7344Gong, Y., Zhang, C., Zhao, R., Xing, X., and Ren, H. (2016). "Experimental study on tensile and compressive strength of bamboo scrimber," BioRes. 11(3), 7334-7344.AbstractPDF

    The objective of this study was to provide fundamental parameters for the utilization of bamboo scrimber in the building structure field as a green building material. Both static tensile and compressive tests were conducted on bamboo scrimber, with 180 specimens for compressive tests and 173 specimens for tensile tests. The normal and lognormal distributions were selected to fit the experimental data. The design values were calculated according to the Chinese allowable stress design method and ASTM D2915 (2003). The results showed that both tensile strength (UTS) and compressive strength (CS) parallel to the fiber of bamboo scrimber were significantly higher than those of wood and other bamboo-based composite materials. Kolmogorov-Smirnov and chi-squared test results indicated that a lognormal distribution was a good fit for the UTS and CS except for the fitting result of UTS by the chi-squared test. The calculated design values of UTS and CS using ASTM D2915 (2003) were higher compared with those found using the Chinese allowable stress design method.

  • Researchpp 7345-7354Yang, X., He, C., Liu, J., and Diao, H. (2016). "Influence on the physical properties of wheat straw hydrothermal and chemical treatments," BioRes. 11(3), 7345-7354.AbstractPDF

    The physical properties of wheat straw treated with hydrothermal and chemical treatments were investigated using an electronic universal testing machine, Fourier transform infrared spectroscopy (FT-IR), and scanning electron microscopy (SEM). The thermal stability of the wheat straw was also investigated using thermogravimetric analysis (TGA). The experimental results showed that the chemical treatment was a main factor governing the enzymatic saccharification of wheat straw. Different treatments of wheat straw had the same mass loss trend. The maximum mass loss occurred in the range between 250 and 400 °C for all straw samples. In this range, the wheat straw treated with NaOH showed an exothermic peak, while samples treated with the other treatments showed an endothermic peak. Chemical treatments disrupted the silicified waxy surface and destroyed the C-O bond. The internal structure of wheat straw treated with NaOH became porous and loose and exposed more accessible surface area of the cellulose to cellulase.

  • Researchpp 7355-7364Wysocka, K., Szymona, K., McDonald, A. G., and Mamiński, M. (2016). "Characterization of thermal and mechanical properties of lignosulfonate- and hydrolyzed lignosulfonate-based polyurethane foams," BioRes. 11(3), 7355-7364.AbstractPDF

    Lignosulfonate and lignosulfonate hydrolyzed under alkaline conditions were used as the polyol components in polyurethane foam formulations. Although the treatment increased hydroxyl group abundance, it did not improve the applicability of hydrolyzed lignosulfonate in polyurethane foam. Thus, the use of original lignosulfonate yielded foams of thermal stability and mechanical properties comparable to other types of bio-based foams (Young’s moduli 0.95 to 4.42 MPa, 50% weight loss, and temperature ca. 500 °C). Lignosulfonates can be a renewable polyol component for the formulation of rigid, semi-rigid, and flexible foams.

  • Researchpp 7365-7376Zhang, S., Fei, B., and Wang, C. (2016). "Effects of chemical extraction treatments on nano-scale mechanical properties of the wood cell wall," BioRes.11(3), 7365-7376.AbstractPDF

    Chinese fir (Cunninghamia lanceolata (Lamb.) Hook) was subjected to chemical extraction treatments with sodium chlorite (NaClO2) for delignification, as well as sodium hydroxide (NaOH) at various concentrations for extracting hemicelluloses gradually. Nanoindentation tests, X-Ray diffraction (XRD, and Fourier transform Raman (FT-Raman) spectroscopy studies revealed the changes in the mechanical properties and the nanostructure of the cell wall. The X-ray analysis indicated that delignification had only a moderate effect on the structure of the cell wall, while further alkali treatment led to major changes in the nanostructure. The nanoindentation tests showed that the indentation modulus and the hardness decreased after delignification and further alkali treatment, respectively. The indentation modulus of the cell wall with delignification decreased by 6.4% compared with the native cell wall, and the hardness decreased by 16.3%. After further alkali treatment, the indentation modulus and the hardness of the cell walls were 14.8% and 18.4% lower than that of the native cell walls, respectively. Additionally, the indentation modulus and the hardness of Chinese fir treated by NaOH decreased by 8.4%, and 2.1% in comparison with delignification, respectively. The results indicated that removal of hemicelluloses resulted in more damage to the mechanical properties of the cell wall compared with lignin.

  • Researchpp 7377-7393Zhang, C., Yuan, Z., Ji, X., Leng, J., Wang, Y., and Qin, M. (2016). "Facile preparation and functionalization of cellulose microgels and their properties and application in stabilizing O/W emulsions," BioRes. 11(3), 7377-7393.AbstractPDF

    The preparation and functionalization of cellulose microgels (CMGs) has been presented. Only a trace concentration of CMGs (< 0.2 wt.%) stabilized oil-in-water (O/W) emulsions and produced high internal phase emulsions (HIPE). The size and morphology of the CMGs were characterized with dynamic light scattering (DLS) and atomic force microscopy (AFM), and the structural properties were discussed. Based on the experimental results,the correlation between the amphiphilicity, and adsorption of the CMGs, and their capability to stabilize the emulsions, which are closely related to the cross-linking density of the CMGs, were elaborated. Having a porous percolating structure and being rich in free hydroxyl groups, the CMGs were functionalized by Fe3O4. The unique dispersibility of the Fe3O4-CMGs and their ability to stabilize the emulsions were investigated in detail. The results pave the way to a deeper understanding of Pickering emulsions stabilized by soft solvent-swollen materials and are expected to further expand the application of cellulose.

  • Researchpp 7394-7405Cheng, F., Lu, P., Ren, P., Chen, J., Ou, Y., Lin, M., and Liu, D. (2016). "Preparation and properties of foamed cellulose-polymer microsphere hybrid materials for sound absorption," BioRes. 11(3), 7394-7405.AbstractPDF

    Sustainability and eco-efficiency are presently directing the development of the next generation of acoustic materials. In this work, foamed cellulose-polymer microsphere (PM) hybrid materials, having sound-absorbing capability, were prepared by incorporating the PMs into cellulose fibers by dehydration and foaming processes. The evolution in morphology of PMs during foaming process was investigated for different heating temperatures. The beating process disintegrated the microscopic cellulose fiber into the smaller fibers, which connected the PMs by a unique fibrous network. The influences of foaming temperature, PM content, and total areal density on the sound absorbing property of composites were studied. The results showed that incorporating the acoustic unit of elastic PMs into the porous cellulose fiber-based network significantly improved the sound absorbing ability of the composites. The sound-absorbing hybrid materials appear to be a promising alternative to non-degradable organic or inorganic acoustic composites, being economical, simple, and eco-friendly.

  • Researchpp 7406-7415Zhang, M., Li, Q., Song, S., Hao, N., and Liu, G. (2016). "Increase of paper strength and bulk by co-flocculation of fines and fly ash-based calcium silicate,"BioRes. 11(3), 7406-7415.AbstractPDF

    Fly ash-based calcium silicate (FACS), which has a large surface area (121 m2/g) and porous structure, has the potential to be used as a filler for the production of high-bulk paper. In theory, paper with a higher bulk has a lower strength. This work explores the possibility of improving paper strength without compromising its bulk through co-flocculation of cellulosic fines and FACS. To investigate the effect of co-flocculation on paper properties, composites made with various ratios of fines to FACS were studied. Results showed that paper bulk and tensile strength increased with increasing ratio of fines to FACS, up to 0.3 at 17% filler content. To further confirm these findings, the structures of composites were studied with a light microscope and scanning electronic microscope (SEM). Images showed that the composite formed at the ratio of 0.3 exhibited a larger size and looser structure than other composites, which can be attributed to the improvement of the paper’s strength and bulk. Schemes for the composite formation process and its interactions with fibers were also proposed.

  • Researchpp 7416-7430Su, J., Zhu, H., Wang, L., Liu, X., Nie, S., and Xiong, J. (2016). "Optimization of microwave-hydrogen peroxide pretreatment of cellulose," BioRes. 11(3), 7416-7430.AbstractPDF

    A hydrogen peroxide (H2O2) solution was adapted for microwave pretreatment of microcrystalline cellulose, which can be further used for heavy metal adsorption. The H2O2 concentration, temperature, and retention time were the key factors affecting the microwave/hydrogen peroxide pretreatment process. A Box-Benhken design (BBD) with response surface methodology (RSM) was employed to design and optimize the microwave-hydrogen peroxide pretreatment process (H2O2 pretreatment) of cellulose. After the H2O2 pretreatment, the crystallinity of cellulose decreased by 20% and the degree of polymerization (DP) decreased by up to 30%. The optimal conditions obtained by BBD were a H2O2 concentration of 8.37%, a temperature of 90 °C, and a retention time 5.33 min. Under these conditions, a minimum DP of 91.74 was achieved. The results indicated that all three of the factors notably affected the reduction of cellulose polymerization degree and pronounced interactions existed among the response variables. The predictive model developed was able to optimize the pretreatment process for the reduction of cellulose polymerization degree, which could improve the cellulose modification reactivity.

  • Researchpp 7431-7450Dietzel, A., Raßbach, H., and Krichenbauer, R. (2016). "Material testing of decorative veneers and different approaches for structural-mechanical modelling: Walnut burl wood and multilaminar wood veneer," BioRes. 11(3), 7431-7450.AbstractPDF

    A methodology is presented for the determination of elastic material properties on laminated and non-laminated decorative veneers of a variety of wood types. For the uniaxial tensile tests performed, at various temperatures and wood moisture values, the metrological challenges as well as the test results are described and discussed. Subsequently, the characteristic values are transferred into corresponding material models. Also, as the inverse, model-based determination of characteristic values that cannot be determined experimentally is carried out.

  • Researchpp 7451-7461Zheng, T., Xing, Y., Zhou, Z., Cristhian, C., and Jiang, J. (2016). "Enhancement of bioethanol production using a blend of furfural production residue and tea-seed cake," BioRes. 11(3), 7451-7461.AbstractPDF

    The price of raw material, energy demand in the pretreatment step, and enzyme usage rate are the major cost factors in the process of converting biomass to bioethanol. Unwashed furfural residues (FRs) possess great potential for application in bioethanol production. Surfactant addition is an effective method to enhance the fermentation rate. In this study, unwashed FRs were used directly as raw materials to produce bioethanol. Tea-seed cake (TSC), tea seed residues that contained protein and saponin, was added in the simultaneous saccharification and fermentation (SSF) process. The effect of TSC dosage on SSF was compared. TSC was added at the dosage of 10 g/L, which resulted in a final ethanol yield of 87.2%. However, a high concentration of TSC could induce cytotoxicity in yeast. The surface tension (approximately 33.92 mM/m) at SSF using TSC-medium was much lower than that of other fermentation systems (about 64.67 mN/m). Further contact angle testing showed that TSC-medium (21.7°) had better wetting capacity than FRs (45.6°). This study provided a proposed process strategy that SSF with the addition of TSC could be a minimum consumption of chemicals and enzymes for future cellulosic ethanol production process.

  • Researchpp 7462-7475Song, X., Pei, Y., Su, J., Qin, C., Wang, S., and Nie, S. (2016). "Kinetics of adsorbable organic halides (AOX) reduction in laccase-aided chlorine dioxide bleaching of bagasse pulp," BioRes. 11(3), 7462-7475.AbstractPDF

    This paper presents a kinetic model of the laccase-aided chlorine dioxide bleaching of bagasse pulp. The kinetic model was based on the rate of reduction of adsorbed organic halogen (AOX). The effects of the laccase enzyme dosage, the mediator 1-hydroxybenzotriazole (HBT) dosage, and the reaction temperature on the AOX content of the bleaching effluent are discussed. Good fits were obtained for the experimental data obtained from the different laccase enzyme dosages, HBT dosages, and reaction temperatures, indicating the feasibility of the kinetic model as a means of predicting the optimal operation conditions for the laccase-aided chlorine dioxide bleaching of bagasse pulp in the future.

  • Researchpp 7476-7489Tufan, M., and Ayrilmis, N. (2016). "Potential use of hazelnut husk in recycled high-density polyethylene composites," BioRes. 11(3), 7476-7489.AbstractPDF

    Hazelnut husk was considered as a potential filler for thermoplastic composites. Different amounts of hazelnut husk flour and the recycled high-density polyethylene (R-HDPE) were used as the filler and polymer matrix, respectively. The composite compounds were produced using single-screw extrusion compounding, and then composite panels were prepared by hot-press compression molding. The morphological, physical, mechanical, and thermal properties, as well as the biological durability of the composites, were evaluated. The flexural and tensile modulus of the composites improved with increasing hazelnut husk filler content, whereas the physical properties, biological durability, and the flexural and tensile strengths were reduced. With the addition of a maleic anhydrite-grafted polyethylene (MAPE), the hazelnut husk filler was more finely dispersed within the polymer matrix and the degree of crystallinity was lower than that of the R-HDPE. This research revealed that hazelnut husk flour has potential for use as a filler in R-HDPE composites.

  • Researchpp 7490-7499Yang, H. S., Duncan, S. M., Hafez, I., Schilling, J. S., and Tze, T. Y. (2016). "Hydroxyl availability in aspen wood after dilute acid pretreatment and enzymatic saccharification," BioRes. 11(3), 7490-7499.AbstractPDF

    The production of cellulosic biofuels often leaves behind solid residues, which can be converted to useful co-products via chemical modification and processing. The objective of this study was to examine the changes in hydroxyl accessibility of a hardwood after the extraction of fermentable sugars (saccharification). Saccharification was performed on milled and dilute-acid pretreated aspen wood and resulted in a glucan-to-glucose conversion of 91%. The unhydrolyzed (solid) fraction was then analyzed for hydroxyl availability using an acetylation method, and the data were related to information of accessible pore volume evaluated using nitrogen adsorption. Different pore volumes were also created by oven-, air-, or freeze-drying of the samples. The results showed that more hydroxyls are available if the physical accessibility (pore volume) of a given substrate is better preserved. Upon saccharification, the accessible hydroxyls were reduced by at least half of that in untreated wood, while the specific pore volume increased 10 times. This finding suggests that future strategies for utilizing saccharification residues for co-products should tap the increased porosity and lower polarity of the substrate.

  • Researchpp 7500-7511Hickman, A. N., Nokes, S. E., Sympson, W. S., Ruwaya, M. J., Montross, M., and Knutson, B. L. (2016). "The confounding effects of particle size and substrate bulk density on Phanerochaete chrysosporium pretreatment of Panicum virgatum," BioRes. 11(3), 7500-7511.AbstractPDF

    Phanerochaete chrysosporium treatment is less effective as a biological pretreatment on feedstock with larger particle sizes. We hypothesized that the improved effectiveness of the pretreatment when smaller particle sizes are used may be due to the inherently higher bulk density with smaller particle sizes. The effects of substrate bulk density and particle size on the efficacy of P. chrysosporium pretreatment of switchgrass (Panicum virgatum) was tested experimentally. Phanerochaete chrysosporium was grown on senesced switchgrass (2 different particle sizes) with various bulk densities. In all treatments, the fungal-pretreated samples released more glucose during enzymatic saccharification than the control sample. Substrate bulk density was a statistically significant factor in explaining the variation in the amount of glucose released per gram of substrate used. However, the particle size was not found to be a significant factor. On-farm switchgrass pretreatment may not require particle size reduction if the switchgrass is supplied in high-density bales.

  • Researchpp 7512-7521Essien, C., Cheng, Q., Via, B. K., Loewenstein, E. F., and Wang, X. (2016). "An acoustics operations study for loblolly pine (Pinus taeda) standing saw timber with different thinning history," BioRes. 11(3), 7512-7521.AbstractPDF

    There is currently a request from landowners in southeastern USA to provide a nondestructive tool that can differentiate the quality between stands of 25 and 30 years of age subjected to different thinning treatments. A typical site with various thinning regimes was used to vary the wood quality and to determine whether acoustics had the ability to separate for stiffness differences at a given age and local geography. A stand at age 29 with three different spacing (prior thinning) levels was chosen. Three hundred trees (100 per treatment) were randomly selected and acoustically tested for sound velocity using the Time-of-Flight (ToF) method for unthinned, thinned, and twice-thinned stands, respectively. The key finding of the study was that the estimated stiffness of the previously thinned treatments was actually greater than that of the unthinned group, despite having diameters as much as 28% larger. During a forest cruise, knowing that a higher-diameter stand is similar or higher in stiffness could raise the dollar value and harvest priority.

  • Researchpp 7522-7536Zhang, C., Pei, H., Wang, S., Cui, Z., and Liu, P. (2016). "Enhanced enzymatic hydrolysis of poplar after combined dilute NaOH and Fenton pretreatment,"BioRes. 11(3), 7522-7536.AbstractPDF

    Five types of pretreatment processes were investigated to confirm the enhancement of the enzymatic hydrolysis of poplar. These processes included a hot water pretreatment, a calcium oxide pretreatment, NaOH extraction at low temperature, a Fenton reaction, and a combined dilute NaOH and Fenton pretreatment. The combined dilute NaOH and Fenton pretreatment was found to be the most effective pretreatment process. After enzymatic hydrolysis for 72 h, 74% of the cellulose recovery yield was obtained when the poplar substrates were pretreated with 2% NaOH at 75 °C for 3 h, followed by 20 mmol/g of H2O2 (30%) and 0.2 mmol/g of FeSO4·7H2O for a Fenton reaction period of 12 h. The cellulose recovery yield was approximately five-fold greater than that of the untreated sample directly processed by enzymatic hydrolysis. Furthermore, microscopic observations of changes in the surface structure of the pretreated residue were correlated with the enhancement of the enzymatic hydrolysis of cellulose. In conclusion, the combined dilute NaOH and Fenton pretreatment shows high potential for future application.

  • Researchpp 7537-7550Seo, H. J., Park, J. E., and Son, D. W. (2016). "Combustion and thermal characteristics of Korean wood species," BioRes. 11(3), 7537-7550.AbstractPDF

    This study examined the combustion and thermal characteristics of domestic wood species in Korea. Wood was tested using a cone calorimeter according to the KS F ISO 5660-1 (2003) standard. The combustion properties of the wood were measured in terms of the heat release rate (HRR), total heat released (THR), mass lose rate (MLR), and ignition time (time to ignition; TTI). An optical microscope was used to determine the anatomical characteristics of wood. Also, the thermal properties were measured using thermogravimetric analysis (TGA) to determine the thermal stability of wood. The results of this experiment could be useful for fundamentals of guiding the combustion properties and thermal stability when using wood for various applications.

  • Researchpp 7551-7565Zhou, T., Zhang, L., Zhao, H., Xu, F., and Yang, G. (2016). "Enhanced bioethanol production from industrial xylose residue using efficient delignification,"BioRes. 11(3), 7551-7565.AbstractPDF

    Xylose residue (XR), the abundant industrial residue from commercial xylose production, was delignified using alkali as a substrate for ethanol production via simultaneous saccharification and fermentation (SSF). It was found that pretreatment with 1.5% (w/v) NaOH at 140 °C for 1.5 h was optimal for delignification efficiency (72.2%) and low cellulose loss (7.1%). The physical changes in samples after alkaline pretreatment were characterized for crystallinity and imaged using scanning electron microscopy (SEM), which demonstrated that the surface of samples became coarser with lignin removal. There were rather significant changes in cellulose crystallinity. The widespread accessibility of cellulose in XR favored enzymatic hydrolysis and achieved considerable bioconversion (98.8% with 15 PFU/g substrate). The maximum for ethanol concentration using SSF bioconversion reached 16.3 g/L, which was about four times more than that of the untreated sample. XR treated using the processes of alkaline pretreatment and SSF was an excellent substrate for bioconversion.

  • Researchpp 7566-7579Liu, B., Li, Y., Gai, X., Yang, R., Mao, J., and Shan, S. (2016). "Exceptional adsorption of phenol and p-nitrolphenol from water on carbon materials preparedvia hydrothermal carbonization of corncob residues," BioRes. 11(3), 7566-7579.AbstractPDF

    Phenol and p-nitrophenol (PNP) are priority pollutants widely present in wastewater. Developing superior or low-cost sorbents for their removal would be of great benefit. Here, corncob residues (CCR) were converted to hydrochars via hydrothermal carbonization (HTC) and further upgraded to carbon materials by thermal activation in an N2 atmosphere. The influence of HTC conditions including the temperature, residence time, and CCR/water weight ratio on the material properties and their performance for removing phenol and PNP from water were investigated and compared with those that were obtained from pyrochar (directly pyrolyzed CCR). Hydrochars showed lower adsorption capacities for phenols than pyrochar. The initial hydrothermal treatment at 220 °C and 2 h resulted in an improved porosity and 4- to 5-fold higher adsorption capacities for phenol and PNP compared with the pyrochar. However, hydrochars prepared at 250 °C or with a prolonged residence time (4 and 6 h) could not be upgraded to high performance carbon materials by thermal activation. The adsorption isotherms of both phenols on the best performance material were well correlated by the Sips model.

  • Researchpp 7580-7594Salca, E. A., Krystofiak, T., Lis, B., Mazela, B., and Proszyk, S. (2016). "Some coating properties of black alder wood as a function of varnish type and application method," BioRes. 11(3), 7580-7594.AbstractPDF

    The objective of this study was to evaluate the adhesion strength and glossiness of black alder wood (Alnus glutinosa Gaertn. L.) coated with water-borne and UV varnishes by two application systems. Prior to coating, the samples were prepared by sanding with four combinations of grit size sandpapers, 180 being the final grit. The surface quality of the specimens was measured with a white light profilometer. Any increase in grit size gradually reduced surface roughness, which further influenced the overall coating performance of the samples. UV varnish applied by roller presented higher adhesion strength and gloss as compared to spraying. The specimens varnished with a water-borne finish by spraying exhibited a better adherence to the substrate than those of UV varnished samples by the same method and provided glossiness at 60° geometry in the same range. These results are valuable for the furniture manufacturing industry for generating a better use and efficiency of secondary wood resources in order to achieve value-added products.

  • Researchpp 7595-7607Senwitz, C., Kempe, A., Neinhuis, C., Mandombe, J. L., Branquima, M. F., and Lautenschläger, T. (2016). "Almost forgotten resources - biomechanical properties of traditionally used bast fibers from Northern Angola," BioRes. 11(3), 7595-7607.AbstractPDF

    The wide use of natural fibers has a long-standing history in Africa. In northern Angola, three native fiber plant species, namely Urena lobata, Triumfetta cordifolia, and Dombeya burgessiae, were investigated with regard to their potential usage in modern applications, such as green composites. Bast fibers of the three species were analyzed morphologically, chemically, and mechanically to determine properties such as fiber density, cellulose content, Young’s modulus, tensile strength, and breaking strain. In comparison to other natural fibers, all three species were characterized by high Young’s moduli up to 60 GPa and tensile strengths up to 950 MPa, yet retting is crucial to unfold the maximum strength of the fibers. Extending the retting time revealed higher values but probably negatively influences economic efficiency. The results demonstrated that the analyzed plants deliver strong and resistant fibers; based on their biomechanical performance, they are alternatives to commercially used natural fibers, such as jute (Corchorus spp.). However, as with other natural fibers, there was high variation in the mechanical properties in the studied species.

  • Researchpp 7608-7623Meekum, U., and Wangkheeree, W. (2016). "Manufacturing of lightweight sandwich structure engineered wood reinforced with fiber glass: Selection of core materials using hybridized natural/engineered fibers," BioRes. 11(3), 7608-7623.AbstractPDF

    Lightweight sandwich engineered wood reinforced with fiber glass using a natural fiber wood foam core was investigated. A prepreg epoxy formulation was used as both wood adhesive and matrix for the prepreg fiber glass. Combining 3 phr of oxybis(benzenesulfonylhydrazide) (OBSH) with 10 phr of ethyl acetate, as foaming agent enhanced the properties of the eucalyptus fiber (EF) wood foam. Incorporation of rice-husk fiber (RF) or bagasse (BG) into the EF reduced the mechanical properties due to the low aspect ratio and high non-compacted bulk density of RF and BG. The high hydrophilicity of BG increased the water uptake and decreased the dimensional stability of the wood core. The mechanical performance of the natural fiber cores was improved by using randomized unidirectional engineered glass (GF), carbon (CF), and Kevlar (KF) fibers. However, the hybridized cores with long fibers and high elastic modulus, with respect to the sample thickness, had a negative impact on the woods due to internal residual stress, leading to a spring-back effect. A fiber glass reinforcement lightweight sandwich structure with engineered wood derived from the EF/BG and its 30% hybrid lightweight cores yielded superior mechanical and durability properties.

  • Researchpp 7624-7636Qin, Y., Zhao, Z., Wiltowski, T., Aloqaili, M., and Liang, Y. (2016). "Investigation of co-gasification reactivity of torrefied Jatropha seed cake with Illinois #6 coal char," BioRes. 11(3), 7624-7636.AbstractPDF

    Coal and torrefied biomass co-gasification is one of the potential solutions to the reduction of greenhouse gas emissions. For this study, Jatropha seed cake was torrefied at a temperature range of 200 to 300 °C under a nitrogen atmosphere. The torrefied material was then co-pyrolyzed and isothermally co-gasified at 900 °C with two Illinois (IL) #6 coal chars in a fixed-bed reactor connected to an on-line gas chromatography analyzer. Carbon dioxide and carbon monoxide were the primary gas products from the torrefaction process. Kinetic models, such as the shrinking core model, the homogenous model, and the catalysis-controlled model, were used to analyze the gasification mechanism. The results showed that the shrinking core and homogenous models provided the best fits for the gasification reaction data. Jatropha seed cake torrefied at 260 and 280 °C exhibited the best reaction activity with the IL #6 coal chars. The reactivities of coal char with torrefied biomass obtained at 200 and 300 °C were lower in comparison with the others.

  • Researchpp 7637-7653Zarrinbakhsh, N., Wang, T., Rodriguez-Uribe, A., Misra, M., and Mohanty, A. K. (2016). "Characterization of wastes and coproducts from the coffee industry for composite material production," BioRes. 11(3), 7637-7653.AbstractPDF

    This study characterizes and compares coffee chaff (CC) and spent coffee grounds (SCG), the two most useful coffee waste products, and evaluates their performance as fillers and/or reinforcing agents in polymer composites. The morphologies of the CC and the SCG were studied using a scanning electron microscope (SEM). Detailed compositional and elemental analyses of the samples were carried out using several techniques. The thermal stabilities of the two types of biomass were evaluated using thermogravimetric analysis (TGA). Infrared spectroscopy was performed to investigate the functional groups available on the surface of the biomass. It was found that the CC had higher thermal stability, lower fat content, and a denser fibrous structure than the SCG, making it potentially a more suitable material than the SCG for use as a reinforcing filler in polymer composites. To verify this potential, CC and SCG filled polypropylene composites were produced and evaluated.

  • Researchpp 7654-7671Ge, S. B., Li, D. L., Wang, L. S., Jiang, T., Peng, W. X. (2016). "Understanding the bioconversion of Quercus baronii wood during the artificial cultivation ofLentinus edodes," BioRes. 11(3), 7654-7671.AbstractPDF

    To reuse waste wood bioresources and determine the factors required for the growth of Lentinus edodes, Quercus baronii wood bioconversion during the artificial cultivation of L. edodes was characterized by X-ray diffraction (XRD), TG, FT-IR, and TD-GC-MS. Mycelia were observed to grow in wood if cellulose was sufficiently degraded and wood extractives were adequately retained. L. edodes grew inwood if the extractives, cellulose, hemicellulose, and lignin maintained a stable quality ratio. Mycelium and L. edodes grew in samples with high cellulose crystallinity. FT-IR spectra showed that L. edodes grew as the intensity of absorbance associated with unconjugated C=O stretching decreased. TG curves suggested that the samples with lower weight loss were suitable for mycelium, but those with higher weight loss were suitable for L. edodes. TD-GC-MS indicated that the samples containing more phenol derivatives and less acetic acid were suitable for mycelium; the opposite trends were observed for L. edodes.

  • Researchpp 7672-7685Hu, X. M., Li, S., Ma, H. H., Zhang, B. X., and Gao, Y. F. (2016). "Pyrrolidinium ionic liquids as effective solvents for lignin extraction and enzymatic hydrolysis of lignocelluloses," BioRes. 11(3), 7672-7685.AbstractPDF

    Lignocellulosic biomass as a renewable and valuable resource has been a very active research area during recent years. Ionic liquids (ILs) are an attractive approach for the pretreatment of lignocelluloses. In this work, a series of pyrrolidinium-based ionic liquids were prepared simply and were investigated for the pretreatment of corn stalk at 90 °C for 30 min. The characteristics of regenerated lignin and cellulose-rich materials were determined by Fourier transform infrared spectroscopy (FTIR) analysis. Both ILs and ILs/H2O were studied. Notably, 10.17% lignin based on the original corn stalk was recovered with [Hmp]Cl-pretreatment; 21.34% and 15.83% reducing sugar based on the original corn stalk were observed during pretreatment with [Hmp]HSO4/H2O and [Hmp]Cl/H2O pretreatment, respectively; 80.54% of reducing sugar was obtained based on the cellulose-rich materials with [Hmp]Cl/H2O-pretreatment. Also, the glucose and cellobiose yields were 73.82% and 8.64%, respectively.

  • Researchpp 7686-7696Uzun, O., Percin, O., Altınok, M., and Kureli, I. (2016). "Bonding strength of some adhesives in heat-treated hornbeam (Carpinus betulus L.) wood used of interior and exterior decoration," BioRes. 11(3), 7686-7696.AbstractPDF

    Heat-treated wood has an ever-expanding market for exterior and interior applications. The objective of this study was to determine the effect of a heat treatment on the bonding strength of hornbeam (Carpinus betulus L.) wood that was bonded with melamine formaldehyde (MF), polyurethane (PUR), and polyvinyl acetate (PVAc-D4) adhesives. Hornbeam lamellas were heat treated at 150 °C, 175 °C, 200 °C, and 225 °C for 3 h and then bonded. The bonding strength of the specimens was determined. In addition, the density, weight loss, and pH value of the heat-treated wood were investigated. The results showed that the bonding strengths of the heat-treated wood specimens decreased with the temperature of the heat treatment. The bonding strength of the PUR adhesive was higher than the MF and the PVAc-D4.

  • Researchpp 7697-7709Seki, M., Kiryu, T., Miki, T., Tanaka, S., Shigematsu, I., and Kanayama, K. (2016). "Extrusion of solid wood impregnated with phenol formaldehyde (PF) resin: Effect of resin content and moisture content on extrudability and mechanical properties of extrudate," BioRes. 11(3), 7697-7709.AbstractPDF

    A new deformation technique of wood flow forming is promising for industrial uses of solid wood. Flow deformability, size stability, and good mechanical properties were obtained by using wood impregnated with low molecular weight phenol formaldehyde (PF) resin. In this study, to clarify the effect of the PF resin and moisture contents in wood on the flow deformability (extrudability) and the mechanical properties of the product (extrudate), a lateral extrusion was conducted by using wood impregnated with various contents of PF resin and three levels of moisture content. The results indicated that the extrudability of wood impregnated with PF resin improved with an increase in both PF resin and moisture content. The mechanical properties of the extrudate worsened with increases in the moisture content of the wood impregnated with PF resin. Because most of the water in the wood remained in the mold during the extrusion process, chemical changes of the wood substance and PF resin occurred due to steam forming under the high temperature and pressure of the extrusion. The steam worsened the mechanical properties of the extrudate.

  • Researchpp 7710-7720Kasmani, J. E. (2016). "Effects of ozone and nanocellulose treatments on the strength and optical properties of paper made from chemical mechanical pulp," BioRes. 11(3), 7710-7720.AbstractPDF

    This effects of ozone and nanocellulose treatments were studied relative to the optical and strength features of chemical mechanical pulp (CMP) papers. An ozone treatment was performed at room temperature, and then nanocellulose was added. Sixty-gram handmade papers were made, and their physical, mechanical, and morphological properties were studied using X-ray diffraction (XRD) and scanning electron microscopy (SEM). With the ozone treatment, changes in the optical features were not significant at the 95% level; however, the addition of nanocellulose led to significant changes: the tensile strength, burst strength, air resistance, opacity, and brightness increased by 14.1%, 15.9%, 34.8%, 2.8%, and 3.2%, respectively, in comparison with the control sample. The enhancement with nanocellulose reduced the tear strength, coarseness, and yellowness by 15.7%, 12.9%, and 7.6%, respectively, compared with the control sample. The crystallinity of neat nanocellulose was 65.59%, while the crystallinities with the use of 5% to 10% nanocellulose were 72.41% and 62.26%, respectively. The SEM results indicated that using a 10% nanocellulose treatment led to the reduction of the CMP paper’s porous character.

  • Researchpp 7721-7736Saba, N., Tahir, P. M., Abdan, K., and Ibrahim, N. A. (2016). "Fabrication of epoxy nanocomposites from oil palm nano filler: Mechanical and morphological properties," BioRes. 11(3), 7721-7736.AbstractPDF

    The aim of this research was to fabricate epoxy nanocomposites by utilizing the developed nano filler from oil palm mills agricultural wastes oil palm empty fruit bunch (OPEFB) fibers for advanced applications. Epoxy-based polymer nanocomposites were prepared by dispersing 1, 3, and 5 wt. % nano OPEFB filler by using a high speed mechanical stirrer through hand lay-up technique. The mechanical (tensile and impact) properties and morphological properties of nano OPEFB/epoxy nanocomposites were examined and compared. Morphological properties were analyzed by transmission electron microscopy (TEM) and scanning electron microscopy (SEM) to look at the dispersion of the nano OPEFB filler in the epoxy matrix. The tensile and impact properties of nanocomposites increased until 3% nano filler loading, but beyond 3% they decreased. Overall mechanical properties reached maximum values for 3% loading, due to better stress transfer owing to homogenous dispersion of nano OPEFB filler within epoxy matrix. The observed results were also confirmed by SEM and TEM micrographs.

  • Researchpp 7737-7753Malik, J., Santoso, M., Mulyana, Y., and Ozarska, B. (2016). "Characterization of Merbau extractives as a potential wood-impregnating material," BioRes. 11(3), 7737-7753.AbstractPDF

    This study aimed to investigate the major content of merbau extractives (ME) and their potential use as an impregnating material for low-quality timber. Extraction was done by maceration with ethanol, ethyl-acetate, and hot-water. Physico-chemical, phyto-chemical, UV-visible, and infrared spectroscopy, as well as py-GCMS analysis were then performed on dried extract. The results showed that organic solvent extractions resulted in much higher yields, by 12.50% than that of hot water (1.10%). The merbau extractives liquid obtained had a low acidity, with a pH ranging from 5 to 6, which is typical of phenolic compounds. Flavonoids and phenolics were found as the major compounds.  UV-vis spectra showed that ME (λ=279 nm) consists of conjugated or aromatic systems, similar to standard resorcinol, which was used as the reference (λ=274 nm). The FTIR spectra showed the absorption bands at 3369 cm-1 that represent the functional group of hydroxyl (OH) bonds, and 1619 and 1510 cm-1, representing the aromatic ring (C=C), which could be associated with resorcinol. The Py-GCMS showed that ME is predominated by resorcinol (C6H6O2) with a 79% concentration. The ME could be potentially used for producing phenolic/resorcinolic resin through polymerization, which could be applied for wood impregnation.

  • Researchpp 7754-7768Rangel, G., Chapuis, H., Basso, M. C., Pizzi, A., Delgado-Sanchez, C., Fierro, V., Celzard, A., and Gerardin-Charbonnier, C. (2016). "Improving water repellence and friability of tannin-furanic foams by oil-grafted flavonoid tannins," BioRes. 11(3), 7754-7768.AbstractPDF

    Tannin-furanic biobased foams, based on the co-reaction of bark-derived condensed tannins and thermoset furanic polymers, have low thermal conductivity, are self-extinguishing, and have high fire resistance, which allows their development for several industrial uses. One of their main drawbacks, however, is the absorption of water within the foam itself. Another problem is the rather friable surface, which is a definite drawback for some potential applications. In this work, these two problems are minimized or eliminated by introducing a component of oil-grafted tannin in the foam formulation. The incorporation of fatty chains markedly decreased foam friability and increased water repellency in the body of the foams. These properties and the compounds formed by fatty acids grafting onto the tannin flavonoids were extensively tested.

  • Researchpp 7769-7780Zhang, J., Lei, Y., Shi, M., and Song, X. (2016). "Influence of fiber bundle morphology on the mechanical and bonding properties of cotton stalk and mulberry branch reconstituted square lumber," BioRes. 11(3), 7769-7780.AbstractPDF

    The mechanical properties of natural fiber composites can be strengthened in the longitudinal direction if the fiber is formed in a parallel manner. Reconstituted cotton stalk lumber and mulberry branch lumber were fabricated using hot-press technology, and the effects of fiber morphology on their mechanical and bonding properties were investigated. The fiber bundle size had a great influence on the mechanical and bonding properties of the final products. The maximum specific modulus of rupture (MOR) and specific modulus of elasticity (MOE) of the reconstituted lumber were obtained for medium-size fiber bundles, and the maximum MOR and MOE of reconstituted cotton stalk lumber was 130.3 MPa·g-1·cm-3 and 12.9 GPa·g-1·cm-3, respectively. The maximum MOR and MOE of the mulberry branch lumber was 147.2 MPa·g-1·cm-3 and 14.7 GPa·g-1·cm-3, respectively. Mechanical interlocking structures in the lumber were observed via fluorescence microscopy, showing that phenol-formaldehyde adhesive had penetrated into several cell layers of the fiber bundle under heating and pressure. The adhesive penetration capacity was stronger when the fiber bundles were smaller in size and density. The reconstituted lumber fabricated from both materials exhibited excellent mechanical performance in the parallel direction. Therefore, reconstituted cotton stalk and mulberry branch lumber are attractive potential materials for the construction industry.

  • Researchpp 7781-7789Ordaz-Díaz, L. A., Rojas-Contreras, J. A., Flores-Vichi, F., Flores-Villegas, M. Y., Álvarez-Álvarez, C., Velasco-Vázquez, P., and Bailón-Salas, A. M. (2016). "Quantification of endoglucanase activity based on carboxymethyl cellulose in four fungi isolated from an aerated lagoon in a pulp and paper mill," BioRes. 11(3), 7781-7789.AbstractPDF

    The aim of this study was to identify cellulolytic fungal strains capable of degrading cellulose from an aerated lagoon in a pulp and paper mill. Four fungal strains that were found to be highly active were isolated on carboxymethyl cellulose (CMC) and suggested to be CMCase/endoglucanase. The identified strains were Aspergillus niger,Penicillium sp., Aspergillus fumigatus,and Mucor sp. All the strains were studied in terms of cultural morphological characteristics and microscopic examinations. The endoglucanase with the highest isolate production was Penicilliumsp., which also showed the highest qualitative endoglucanase activity (1.3 cm), in addition to the main activity of endoglucanase with 297 mmol/mg.min after 116 h. The results indicated that CMC is able to induce endoglucanase enzyme production and that the fungal isolates showed significant cellulose degradation properties.

  • Researchpp 7790-7802Li, Y., Li, X., Liu, D., Cheng, X., He, X., Wu, Y., Li, X., and Huang, Q. (2016). "Fabrication and properties of polyethylene glycol-modified wood composite for energy storage and conversion,"BioRes. 11(3), 7790-7802.AbstractPDF

    Green fir wood (Pseudotsuga menziesii) was modified with polyethylene glycol (PEG) to produce wood composites for energy storage and conversion. The PEG-modified wood composites were evaluated based on their dimensional stability, durability, and thermal properties by various analytical methods. The differential scanning calorimetry (DSC) results showed the melting temperature and the latent heat of the phase change material (PCM) composite were 26.74 °C and 73.59 J/g, respectively. Thermal cycling tests and thermogravimetric analysis confirmed the composite exhibited good thermal stability, reliability, and chemical stability. All treated specimens were free from noticeable defects, and the addition of a surface varnish coating prevented PEG from leaching. The PEG-modified composites exhibited improved dimensional and thermal performance, which makes this material a potential candidate for economical and green, lightweight building materials.

  • Researchpp 7803-7810Ayrilmis, N., and Kuzman, M. K. (2016). "Properties of honeycomb paperboards faced with heat-treated thin medium-density fiberboards," BioRes. 11(3), 7803-7810.AbstractPDF

    In this study, 4-mm-thick medium-density fiberboard (MDF) panels were heat-treated at 140 °C for 30 or 60 min and at 180 °C for 30 or 60 min. Then, 10-mm-thick lightweight honeycomb paperboards made from kraft paper (130 g/m2, cell diameter of honeycomb, 14 mm; compression strength, 0.21 N/mm2) were faced with the untreated and heat-treated MDF panels (thickness: 4 mm) using a two-component polyurethane adhesive. The density, thickness swelling, water absorption, and flexural properties of the paperboards faced with the untreated and heat-treated MDF panels were investigated. The lowest flexural strength (3.76 N/mm2) and flexural modulus (392 N/mm2) values were found in the specimens faced with the MDFs treated at 180 °C for 60 min, while the highest flexural strength (4.20 N/mm2) and flexural modulus (457 N/mm2) values were found in the specimens faced with the untreated MDFs. The loss in strength was primarily attributable to the degradation of hemicelluloses, which are less stable to heat than cellulose and lignin. The thickness swelling and water absorption of the honeycomb paperboards faced with the heat-treated MDF panels significantly (p < 0.01) decreased with the increase in heat-treatment temperature and duration.

  • Researchpp 7811-7821Qiu, S., Wang, Z., He, Z., and Yi, S. (2016). "The effect of ultrasound pretreatment on poplar wood dimensional stability," BioRes. 11(3), 7811-7821.AbstractPDF

    Dimensional stability is a key property of wood that significantly affects its applications. The effect of an ultrasound pretreatment on poplar wood (Populous tomentosa) dimensional stability was examined. During the pretreatments, wood samples were immersed in distilled water and treated ultrasonically under three different powers and frequencies. The samples were then analyzed by Fourier transform infrared spectroscopy (FTIR) and X-ray diffraction (XRD). The chemical transformation of the cell-wall material was studied and then associated with the change of water absorption and the swelling coefficient. The results showed that the water absorption decreased after the ultrasonic pretreatment. The axial and radial swelling coefficients of the pretreated samples decreased, while the tangential swelling coefficients increased. The volumetric swelling coefficient of pretreated specimens fluctuated near 4.48% (the volumetric swelling coefficient of untreated wood). Ultrasonic pretreatment increased the number of hydrophilic groups, such as the hydroxyl, acetyl, and uronic ester groups. Meanwhile, the pretreatment also increased the degree of crystallinity and reduced the available polar groups. These two factors together caused the change of the moisture absorption and the swelling coefficient of the pretreated wood. These conclusions suggest that the ultrasonic pretreatment is a promising method for further chemical modification of wood.

  • Researchpp 7822-7838Budakçı, M., Pelit, H., Sönmez, A., and Korkmaz, M. (2016). "The effects of densification and heat post-treatment on hardness and morphological properties of wood materials," BioRes. 11(3), 7822-7838.AbstractPDF

    This study investigated the effects of densification and heat post-treatment on the Janka hardness and microscopic structure of relatively low-density Uludağ fir, linden, and black poplar woods. Wood samples were densified with compression ratios of 25% and 50% at 100 °C and 140 °C, respectively. Heat post-treatment was then applied to the samples at     185 °C and 212 °C for 2 h. The hardness in the radial and tangential directions was determined, and morphological changes in the cell structures were analyzed using scanning electron microscopy (SEM). The hardness values in the radial and tangential directions of the densified samples increased depending on the compression rate and treatment temperature. The hardness values in both directions were higher in the 50% compressed samples. For samples compressed at 140 °C, the hardness values were higher in the tangential direction, whereas the samples compressed at 100 °C were higher in the radial direction. After the heat post-treatment process, the hardness values of all samples decreased. As the treatment temperature increased, more adverse effects on the hardness was noted. According to the SEM analyses, the densification and heat post-treatment deteriorated the cell structure of the samples. The more cell deformation was observed in the samples densified at 100 °C with compression ratio 50% and high heat post-treatment temperature.

  • Researchpp 7839-7848Chen, T., Xie, Y., Wei, Q., Wang, X., Hagman, O., Karlsson, O., and Liu, J. (2016). "Effect of refining on physical properties and paper strength of Pinus massoniana and China fir cellulose fibers," BioRes. 11(3), 7839-7848.AbstractPDF

    To obtain a suitable refining process for Pinus massoniana cellulose fibers (PMCF) and China fir cellulose fibers (CFCF), the effects of the beating gap and the pulp consistency on the physical properties and the morphology of the two cellulose fibers were investigated. The results showed that the physical properties of the PMCF and the CFCF were well affected by the beating gap and the pulp consistency. The CFCF showed a smaller weight-average length and width than that of the PMCF. The CFCF exhibited smaller weight-average length, width, and kink index than the PMCF. It is easy to get the high beating degree, indicating it is more easily to be refined. Additionally, the tensile index and burst index of PMCFP and CFCFP increased with increasing beating degree, while the tear index decreased. Compared to the CFCF, the paper made from PMCF had superior strength properties. Consequently, the PMCF was suitable for refining with a high pulp consistency and a medium beating gap, whereas the CFCF had a medium pulp consistency and a big beating gap.

  • Researchpp 7849-7858Weeraphan, T., Tolieng, V., Kitpreechavanich, V., Tanasupawat, S., and Akaracharanya, A. (2016). "Sodium hydroxide-steam explosion treated oil palm empty fruit bunch: Ethanol production and co-fermentation with cane molasses," BioRes. 11(3), 7849-7858.AbstractPDF

    Oil palm empty fruit bunch (OPEFB) was pretreated by NaOH-steam explosion and then fermented to ethanol by separate hydrolysis and fermentation (SHF) and simultaneous saccharification and fermentation (SSF) processes usingKluyveromyces marxianus G2-16-1 at 40 ºC. The maximum ethanol production by the SHF and SSF processes was 8.09 g/L (22.21 g/L reducing sugar, 0.08 g/g OPEFB) and 13.658 g/L (0.136 g/g OPEFB), respectively, at 48 h. The OPEFB hydrolysate mixed with molasses to 22% (w/v, total sugar) gave an ethanol yield of 61.60 g/L (0.38 g/g total sugar) at 72 h, while molasses alone gave 53.89 g/L (0.34 g/g total sugar). The OPEFB slurry (OPEFBS; OPEFB hydrolysate containing the solid residue of pretreated OPEFB) gave a maximum ethanol yield of 68.77 g/L (0.44 g/g total sugar) when it was mixed with molasses. Scanning electron micrographs of the solid OPEFB residue in the OPEFBS showed yeast cells adsorbed to the OPEFB fibers. The results indicated that ethanol production from molasses mixed with OPEFB hydrolysate was equal to the cumulative sum of ethanol production from each raw material, and the solid OPEFB residue in the OPEFBS increased the ethanol production in the co-fermentation of molasses and OPEFB hydrolysate.

  • Reviewpp 7859-7888Pásztory, Z., Mohácsiné, I. R., Gorbacheva, G., and Börcsök, Z. (2016). "The utilization of tree bark," BioRes. 11(3), 7859-7888.AbstractPDF

    The utilization of natural raw materials has been practiced for centuries. Of raw materials, wood and its bark have outstanding significance because of their special chemical components and unusual structure. Annual bark production is estimated to be between 300 and 400 million m3. The bark of different tree species has been used extensively in or in conjunction with modern technologies. This article presents a comprehensive summary of these methods of utilization and their results. The diversity of bark utilization derives from the variety of the bark of different species and from the possibilities encoded in the material. Following the anatomic summary, the protective role of the bark is discussed, highlighting its physical-chemical properties and the different methods of medical, energetic, and industrial utilization.

  • Reviewpp 7889-7901De Araujo, V. A., Cortez-Barbosa, J., Gava, M., Garcia, J. N., Souza, A. J., Savi, A. F., Morales, E. A. M., Molina, J. C., Vasconcelos, J. S., Christoforo, A. L., and Lahr , F. A. R. (2016)."Classification of wooden housing building systems," BioRes. 11(3), 7889-7901.AbstractPDF

    Wooden housing is one of the most sustainable building alternatives. In many European and North American countries, wooden houses provide the most common, economical, and practical solution for construction. The timber buildings present adequate levels of durability, acoustics, and thermal comforts. Despite their popularity, wood houses do not have a standardized classification to define and organize their main aspects. In literature dealing with timber construction, most authors emphasize structural systems for large spans (bridges, hangars, roofs, etc.). The presence of some classifications of timber construction results in unclear issues, and few studies have covered and regarded wooden buildings as residential construction typologies. Accordingly, this paper proposes a classification that connects the aspects and details of wooden housing materials in relation to the industrialization level and chronological origin. We expect this classification to assist in a better understanding of distinct wooden housing techniques commercially produced worldwide, diffusing their concepts and possibilities as forestry-timber products.

  • Reviewpp 7902-7916Liu, Y., Shi, L., Cheng, D., and He, Z. (2016). "Dissolving pulp market and technologies: Chinese prospective - A mini-review," BioRes. 11(3), 7902-7916.AbstractPDF

    Cellulose is the most abundant natural polymer on earth. As the market and the public demands more and more natural products, cellulose and its derivatives are becoming increasingly more attractive. The production of dissolving pulp, which is the main feedstock for cellulose-related products, has been growing over the past decade, while the technologies for manufacturing these pulps have also been advanced. In this literature review, the production and consumption of dissolving pulp are analyzed with a focus on the Chinese market. The manufacturing processes, including raw materials, pulping methods, pulp bleaching, and post-treatments are discussed.

  • Reviewpp 7917-7927Wu, C. (2016). "The potential of pre-hydrolysis liquor from the dissolving pulp process as recovery source of xylooligosaccharide - A mini-review," BioRes. 11(3), 7917-7927.AbstractPDF

    Currently, xylooligosaccharides (XOs), which are a kind of nutraceutical that can be produced from lignocellulosic biomass, have an important place in the global market. In this critical review the raw materials and manufacturing methods of XOs are briefly considered. The results in some publications indicate that the pre-hydrolysis liquor (PHL) from dissolving pulp process is a potential source of XOs. However, it is very difficult to separate and further remove the lignin in PHL, which is detrimental to the separation and further purification of XOs. Based on these problems, a number of important aspects with respect to PHL, including industrial treatment technologies, composition, and lignin removal technologies, are described in this review. In addition, some XOs purification technologies in PHL are also introduced.

  • Reviewpp 7928-7952Singh, D., Cubbage, F., Gonzalez, R., and Abt, R. (2016). "Locational determinants for wood pellet plants: A review and case study of North and South America," BioRes. 11(3), 7928-7952.AbstractPDF

    The European Union’s Renewable Energy Directive has led many electricity producers in Europe to use wood pellets in place of fossil fuels. North America has become one of the primary suppliers of wood pellets to Europe. This paper critically examines literature, economic models and data, as well as the supply chain and country risk factors, related to wood pellet production to anticipate where North and South American pellet mills should be built to meet Europe’s demand. Canada, the United States, and Brazil maintain the largest natural forest area, planted forest area, and industrial roundwood production; however, South American countries achieve faster plantation growth rates. The World Bank’s Logistic Procurement Index and IHS’s Country Risk Index were used to score and rank countries’ investment climates, based on their supply chain and risk factors. In this regard, the United States, Canada, and Chile performed best, in contrast to Venezuela, Bolivia, and Ecuador. When considering both wood supply and investment climates, the United States, Canada, and Chile were the most attractive countries to build a pellet mill, while countries, such as Argentina, Brazil, Colombia, Paraguay, and Peru present significant trade-offs between having significant wood resources and riskier investment climates.

  • Reviewpp 7953-8091Hubbe, M. A., Metts, J. R., Hermosilla, D., Blanco, M. A., Yerushalmi, L., Haghighat, F., Lindholm-Lehto, P., Khodaparast, Z., Kamali, M., and Elliott, A. (2016). "Wastewater treatment and reclamation: A review of pulp and paper industry practices and opportunities," BioRes. 11(3), 7953-8091.AbstractPDF

    The pulp and paper (P&P) industry worldwide has achieved substantial progress in treating both process water and wastewater, thus limiting the discharge of pollutants to receiving waters. This review covers a variety of wastewater treatment methods, which provide P&P companies with cost-effective ways to limit the release of biological or chemical oxygen demand, toxicity, solids, color, and other indicators of pollutant load. Conventional wastewater treatment systems, often comprising primary clarification followed by activated sludge processes, have been widely implemented in the P&P industry. Higher levels of pollutant removal can be achieved by supplementary treatments, which can include anaerobic biological stages, advanced oxidation processes, bioreactors, and membrane filtration technologies. Improvements in the performance of wastewater treatment operations often can be achieved by effective measurement technologies and by strategic addition of agents including coagulants, flocculants, filter aids, and optimized fungal or bacterial cultures. In addition, P&P mills can implement upstream process changes, including dissolved-air-flotation (DAF) systems, filtration save-alls, and kidney-like operations to purify process waters, thus reducing the load of pollutants and the volume of effluent being discharged to end-of-pipe wastewater treatment plants.

  • Reviewpp 8092-8115Pan, M., Zhu, L., Chen, L., Qiu, Y., and Wang, J. (2016). "Detection techniques for extracellular polymeric substances in biofilms: A review" BioRes. 11(3), 8092-8115.AbstractPDF

    Extracellular polymeric substances (EPS) are one of the main components of biofilm, prompting biofilm to form a cohesive three-dimensional framework. Numerous methods are available to help characterize the properties and the structural, chemical and physical organizations of EPS during the biofilm formation process. This review highlights key techniques from different disciplines that have been successfully applied in-situ and non-destructively to describe the complex composition and distribution of EPS in biofilm, especially microscopic, spectroscopic, and the combination of multi-disciplinary methods that can provide new insights into the complex structure/function correlations in biofilms. Among them, confocal laser scanning microscopy (CLSM) is emphasized, and its principles, applications, advantages, and limitations are summarized. Multidisciplinary techniques have been developed and recommended to study EPS during the biofilm formation process, providing more in-depth insights into the composition and spatial distributions of EPS, so as to improve our understanding of the role EPS plays in biofilms ultimately.