NC State
  • Editorialpp 1-3Yao, Y. (2017). "Models for sustainability" BioRes. 12(1), 1-3.  AbstractArticlePDF
    As one of the major methodologies used in the modeling of sustainability, Life Cycle Assessment (LCA) is widely used to evaluate the environmental impacts of emerging technologies and to enhance decision making towards sustainable development. However, most of the current LCA models are static and deterministic. More insights could be generated when LCA models are coupled with higher-resolution techniques in a prospective fashion. Instead of trying to accurately predict the future, the purpose and value of integrated prospective models are to explore the boundaries of possibility and to shed light on directions that can lead to sustainable pathways. The biggest challenge is to determine the appropriate model resolution so that both big-picture insights and critical details are included. This challenge is hard to address, especially for interdisciplinary models that try to incorporate more than one dimension related to sustainability. However, improvements can be made continually through efforts from a growing population of interdisciplinary researchers.
  • Editorialpp 4-7Derikvand, M., Nolan, G., Jiao, H., and Kotlarewski, N. (2017). "What to do with structurally low-grade wood from Australia's plantation eucalyptus; Building application?," BioRes. 12(1), 4-7.AbstractArticlePDF

    About one million hectares of plantation hardwoods, mostly eucalyptus trees of different sub-species (E. nitens and E. globulus), are annually being managed in Australia, which provides a promising resource of raw materials for fibre industries. However, the timber boards required by the Australian hardwood sector are still being either imported from other countries or harvested from the native forests. There is a need to find a practical way to use the plantation eucalyptus in the Australian timber industry. However, the fibre-managed plantation eucalyptus produces structurally low-grade timber which could not be used as individual boards for structural applications—such as building construction. Unsuitable for appearance applications, the structurally low-grade boards may be suitable for producing innovative high-mass engineered timber products. This editorial will briefly discuss drivers, opportunities, and challenges associated with conducting such a research project.

  • Researchpp 8-18Chen, T., Wu, Z., Wei, W., Xie, Y., Wei, Q., Wang, X., Hagman, O., and Karlsson, O. (2017). "Optimizing refining conditions of Pinus massoniana cellulose fibers for improving the mechanical properties of ultra-low density plant fiber composite (ULD_PFC)," BioRes. 12(1), 8-18.AbstractArticlePDF
    Response surface methodology was used to optimize the refining conditions of Pinus massoniana cellulose fiber and to improve the mechanical properties of ultra-low density plant fiber composite (ULD_PFC). The effects and interactions of the pulp consistency (X1), the number of passes (X2), and the beating gap (X3) on the internal bond strength of ULD_PFC were investigated. The results showed that the optimum internal bond strength (91.72 ± 2.28 kPa) was obtained under the conditions of 8.0% pulp consistency, two passes through the refiner, and a 30.0 μm beating gap. Analysis of the physical properties of the fibers and handsheets showed that the fibrillation of fibers with optimum refining conditions was improved. Also, the tear index of the optimal specimen was 13.9% and 24.5% higher than specimen-1 with a lowest beating degree of 24 oSR and specimen-6 with a highest beating degree of 73 oSR, respectively. Consequently, the optimal refining conditions of the fibers are valid for preparing ULD_PFCs.
  • Researchpp 19-28Cao, J., Liang, H., Lin, X., Tu, W., and Zhang, Y. (2017). "Potential of near-infrared spectroscopy to detect defects on the surface of solid wood boards," BioRes. 12(1), 19-28.AbstractArticlePDF

    Defects on the surface of solid wood boards directly affect their mechanical properties and product grades. This study investigated the use of near-infrared spectroscopy (NIRS) to detect and classify defects on the surface of solid wood boards. Pinus koraiensis was selected as the raw material. The experiments focused on the ability to use the model to sort defects on the surface of wood into four types, namely live knots, dead knots, cracks, and defect-free. The test data consisted of 360 NIR absorption spectra of the defect samples using a portable NIR spectrometer, with the wavelength range of 900 to 1900 nm. Three pre-processing methods were used to compare the effects of noise elimination in the original absorption spectra. The NIR discrimination models were developed based on partial least squares and discriminant analysis (PLS-DA), least squares support vector machine (LS-SVM), and back-propagation neural network (BPNN) from 900 to approximately 1900 nm. The results demonstrated that the BPNN model exhibited the highest classification accuracy of 97.92% for the model calibration and 97.50% for the prediction set. These results suggest that there is potential for the NIR method to detect defects and differentiate between types of defects on the surface of solid wood boards.

  • Researchpp 29-42Abdul Khalil, H. P. S., Tye, Y. Y., Chow, S. T., Saurabh, C. K., Paridah, M. T., Dungani, R., and Syakir, M. I. (2017). "Cellulosic pulp fiber as reinforcement materials in seaweed-based film," BioRes. 12(1), 29-42.AbstractArticlePDF
    Composite materials made from renewable resources can minimize the environmental pollution. In this work, biocomposite films were produced using seaweed as matrix and empty fruit bunch (EFB) pulp fibers as reinforcement. Based on the results, the EFB pulp-seaweed composite films exhibited better mechanical properties than the seaweed film. It was also observed that 50% EFB pulp loading gave the highest tensile strength (81.4 MPa) and elongation at break (5.4%). This phenomenon was supported by SEM analysis, in which more fiber breakage than fiber pull-out was observed on the tensile fracture surface of composite film. Additionally, no agglomeration of the pulp fibers was observed. Instead, the pulp fibers were homogenously distributed throughout the film. In contrast, the contact angle of the seaweed-based films started to decrease once the pulp fibers were added. The decrease in the contact angle was attributed to the hydrophilic nature of the pulp fibers. Nevertheless, the contact angle values of all composite films were still comparatively high and thus, this would not affect their application as a packaging film.
  • Researchpp 43-55Guo, X., Lin, Y., Na, B., Liang, X., Ekevad, M., Ji, F., and Huang, L. (2017). "Evaluation of physical and mechanical properties of fiber-reinforced poplar scrimber," BioRes. 12(1), 43-55.AbstractArticlePDF

    The mechanical properties of poplar scrimber reinforced with glass fiber mesh were investigated. The influence of the different structures and densities were studied with respect to the modulus of rupture (MOR), modulus of elasticity (MOE), and impact toughness (IT). The glass fiber improved the mechanical properties of poplar scrimber. The MOR, MOE, and IT of the scrimber had an obvious dependence on the number of glass fiber layers. When the layers of glass fiber meshes were increased, the MOR, MOE, and IT were increased compared to the control group (scrimber without glass fiber reinforcement). The MOR, MOE, and IT of single-layer glass fiber reinforced scrimber increased a lot compared to the control group. The MOR, MOE, and IT of double-layer glass fiber reinforced scrimber (DGRS) were increased, but the amplitude of the increase was smaller than that of SGRS. Compared to the MOR, MOE, and IT of DGRS, the MOR, MOE, and IT of triple-layer glass fiber reinforced scrimber (TGRS) decreased slightly. When the density was increased, the increasing rate of the MOR, MOE, and IT of the glass fiber reinforced scrimber showed a downward trend, and the glass fiber had better strengthen effects on the scrimber at low density (0.6 g/cm3 and 0.7 g/cm3).

  • Researchpp 56-67Zhang, S. Y., Li, Y. Y., Wang, C. G., and Wang, X. (2017). "Thermal insulation boards from bamboo paper sludge," BioRes. 12(1), 56-67.AbstractArticlePDF
    This study was conducted to evaluate the properties of insulation boards made from bamboo paper sludge and fly ash floating beads. An orthogonal test design was applied to study the effects of certain factors on the properties of the insulation boards. The results indicated that the sequence of significant effect of factors on the properties of the composite boards was particle size of bamboo paper sludge, thickness of boards, and weight ratio of sludge to fly ash floating beads. The verified optimal conditions were confirmed to be 20 to 40 mesh, 80:20, and 14 mm, representing the particle size of bamboo paper sludge, weight ratio of sludge:fly ash floating beads, and thickness of boards, respectively. The thermal conductivity of the bamboo paper sludge and fly ash floating beads insulation boards was measured and suggested that both insulation boards had thermal conductivity values ranging from 0.12 to 0.165 W/mK, which is close to the conventional insulation material lightweight concrete.
  • Researchpp 68-81Ahamad Nordin, N. I. A., Ariffin, H., Hassan, M. A., Shirai, Y., Ando, Y., Ibrahim, N. A., and Wan Yunus, W. M. Z. (2017). "Superheated steam treatment of oil palm mesocarp fiber improved the properties of fiber-polypropylene biocomposite," BioRes. 12(1), 68-81.AbstractArticlePDF

    The effect of fiber surface modification by superheated steam (SHS) treatment and fiber content (30 to 50 wt.%) was evaluated relative to the mechanical, morphology, thermal, and water absorption properties of oil palm mesocarp fiber (OPMF)/polypropylene (PP) biocomposites. SHS treatment of OPMF was conducted between 190 and 230 C for 1 h, then the SHS-treated fiber was subjected to melt-blending with PP for biocomposite production. The biocomposite prepared from SHS-OPMF treated at 210 C with 30 wt.% fiber loading resulted in SHS-OPMF/PP biocomposites with a tensile strength of 20.5 MPa, 25% higher than untreated-OPMF/PP biocomposites. A significant reduction of water absorption by 31% and an improved thermal stability by 8% at T5%degradation were also recorded. Scanning electron microscopy images of fractured SHS-OPMF/PP biocomposites exhibited less fiber pull-out, indicating that SHS treatment improved interfacial adhesion between fiber and PP. The results demonstrated SHS treatment is an effective surface modification method for biocomposite production.

  • Researchpp 82-94Gáborík, J., Gaff, M., Ruman, D., Gašparík, M., Svoboda, T., Vokaty, V., and Síkora, A. (2017). "Quality of the surface of aspen wood after pressing," BioRes. 12(1), 82-94.AbstractArticlePDF

    This paper explores changes in the quality of the surface of aspen wood after pressing. Pressing, a type of processing, facilitates changes in surface quality and smoothness, thereby producing wood suitable for the furniture industry. The results obtained for the pressed wood surface were compared with those obtained for wood surfaces that were not subjected to pressing. Attention was paid to the impact of moisture, the degree of compression, and plasticizing by steam. The change in smoothness/ roughness was monitored in both the longitudinal and transverse directions (relative to the grain). The contact method was used to measure the roughness both before and after pressing. The independent variables of moisture content and degree of compression had the greatest impact on the smoothness/roughness. Plasticizing by steam had no greater impact. Therefore, the non-plasticized aspen wood was determined to be more suitable for the given purpose.

  • Researchpp 95-106Yang, X., Wang, X., Liu, H., Zhao, Y., Jiang, S., and Liu, L. (2017). "Impact of dimethyl sulfoxide treatment on morphology and characteristics of nanofibrillated cellulose isolated from corn husks," BioRes. 12(1), 95-106AbstractArticlePDF

    This work investigated the impact of dimethyl sulfoxide (DMSO) treatment in the isolation of nanofibrillated cellulose (NFC) from corn husk by the 2,2,6,6,-tetramethylpilperidine-1-oxyl (TEMPO) oxidation method. NFC-A and NFC-B were prepared without and with DMSO treatment before TEMPO oxidation. The extracted NFC were characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), Fourier transform infrared spectroscopy (FTIR), zeta potential analyzer, X-ray diffraction (XRD), and thermogravimetric analysis (TGA). The results showed that the dimension of both NFC-A and NFC-B were in nanoscale. The crystalline type of NFC was cellulose I, and the crystallinity of NFC was obviously increased. The thermal stability of NFC was reduced slightly. Compared with NFC-A, NFC-B had a narrower distribution range, higher crystallinity, and better thermal stability. This result demonstrated that DMSO treatment did not change the chemical structure of NFC, but it affected their dimension and distribution and improved their dispersion stability, crystallinity, and thermal stability.

  • Researchpp 107-116Mishra, P. K., Gregor, T., and Wimmer, R. (2017). "Utilising brewer's spent grain as a source of cellulose nanofibres following separation of protein-based biomass," BioRes. 12(1), 107-116.AbstractArticlePDF

    A multistage process was employed to obtain value-added products from brewer’s spent grain (BSG). This paper is focused on the production and characterisation of cellulose nano-fibres (CNF) as one of the products obtained during the complete process. In the first stage, protein-rich liquor was separated via the alkaline (NaOH) treatment of dried BSG and stored for further utilisation. In the second stage, bleaching treatments were conducted to separate cellulose, which was later converted to CNF by high-pressure homogenisation. The lignocellulosic product from each step was analysed for its chemical composition by means of alkaline hydrolysis combined with the HPEAC method. The thermal properties were measured using thermogravimetric analysis (TGA). The morphology was studied using scanning electron microscopy (SEM) and atomic force microscopy (AFM). X-ray diffraction (XRD) was done to observe changes in crystallinity. The nano-cellulose produced can be regarded as a value-added material from the bio-refinery of BSG along with numerous already-reported products.

  • Researchpp 117-142Žlahtič, M., and Humar, M. (2017). "Influence of artificial and natural weathering on the moisture dynamic of wood," BioRes. 12(1), 117-142.AbstractArticlePDF

    Wood that is used in outdoor applications is frequently exposed to weathering and is thus prone to fungal degradation. Ways to prevent fungal degradation include keeping the wood dry. The majority of hydrophobic and wood modification systems have been tested only on freshly treated wood. Little information is available on how various wood-based materials perform after a certain period of weathering. To elucidate this question, 17 wood samples were tested from the following species: oak (Quercus), sweet chestnut (Castanea sativa), European larch (Larix decidua), Scots pine heartwood and sapwood (Pinus sylvestris), Norway spruce (Picea abies), and beech (Fagus sylvatica). Moisture performance of the wood samples was improved with thermal modification, wax, oil, and biocide treatment. Specimens were exposed to various degradation-aging factors (blue stain fungi, decay fungi, artificial weathering, and natural weathering). Various moisture performance tests were applied before and after aging: short-term water uptake (tensiometer), long-term water uptake, water vapor tests, drying tests, etc. The water exclusion efficacy of wood was decreased after aging. Aging factors were found to act synergistically and to have a more prominent influence on less durable wood compared to durable or preservative-treated wood. Wax-treated wood performed best, regardless of which moisture performance test was applied.

  • Researchpp 143-156Nejad, M., Shafaghi, R., Pershin, L., Mostaghimi, J., and Cooper, P. (2017). "Thermal spray coating: A new way of protecting wood," BioRes. 12(1), 143-156.AbstractArticlePDF

    Thermal spray technology was used to apply a thin layer of copper (Cu metal as an antimicrobial coating) on the surfaces of a number of different solid woods and medium-density fiberboard (MDF) wood composites. The adhesion of a Cu coating to Swietenia macrophylla (mahogany), Quercus (oak), Acer saccharinum (silver maple), Picea (spruce), Pinus strobus (white pine), and MDF was evaluated by a pull-off adhesion test. The resistance of Cu-coated samples to mildew, decay fungi, and water uptake was assessed in the lab. Also, the weathering performance of Cu-coated untreated and heat-treated spruce was evaluated. After proper surface preparation, the adhesion of Cu coatings to hardwood and softwood samples was considered very good, and the adhesion of the Cu coating to MDF was much stronger than the internal bond strength of MDF itself. The Cu coating effectively protected the wood from decay fungi and mildew, while it had no effect on the rate of water absorption and desorption from the wood. After one year of natural weathering in Toronto, Canada, the Cu-coated heat-treated spruce samples had significantly fewer checks than coated, untreated wood. Thermal spray copper coating proved to have the potential to protect wood from biological degradation while also serving as an antimicrobial coating.

  • Researchpp 157-167Kunthiphun, S., Phumikhet, P., Tolieng, V., Tanasupawat, S., and Akaracharanya, A. (2017). "Waste cassava tuber fibers as an immobilization carrier of Saccharomyces cerevisiae for ethanol production," BioRes. 12(1), 157-167.AbstractArticlePDF

    Waste cassava tuber fibers (wCTF), derived from the ethanolic fermentation of cassava tubers, have potential use as anatural adsorption immobilization carrier. Ethanol fermentation was conducted using 15% (w/v) glucose-containing mediumat 40 °C for 48 h by Saccharomyces cerevisiae G6-2-2 (1.3 x 1010cells). Ethanol concentration produced by free, wCTF (1.2 g dry weight) adsorbed, wCTFadsorbed-calcium alginate entrapped,and calcium alginate entrapped cellswere 42.10 ± 0.61, 67.35 ± 0.53, 52.10 ± 0.40, and 46.45 ± 0.18 g/L (0.34, 0.45, 0.35, and 0.31 g ethanol/g reducing sugar), respectively. The wCTF adsorbed cells produced a maximum ethanol yield of 82.15 ± 0.48 g/L (0.43 g ethanol/g total sugar) from molasses (20% w/v initial total sugar) after 48 h, compared to 74 g/L to 76 g/L and 48 h to 100 h for the free suspension cells. The increase in ethanol produced by the wCTF adsorbed cells compared to free cells reflected that the cells were protected from environmental stresses and received amino nitrogen from the wCTF that supported growth and ethanol tolerance.

  • Researchpp 168-182Watchman, M., Potvin, A., and Demers, C. M. H. (2017). "Wood and comfort: A comparative case study of two multifunctional rooms," BioRes. 12(1), 168-182.AbstractArticlePDF

    Many environmental advantages of wood in buildings have been thoroughly documented; however, this material’s effects on occupants are not well known or fully comprehended. This research aims to study comfort parameters in a multifunctional room characterised by extensive wood surfaces in comparison with a similar room with more conventional surfaces at Laval University, Quebec, Canada. The objectives of this research focus on determining the thermal, visual, and acoustical similarities and differences between two rooms using on-site surveys. Analysis of instrumental measurements and images of each room’s indoor environment under overcast skies determined the colour and texture of the surfaces. Quantitative and qualitative analyses revealed that both rooms share similar thermal and acoustic comfort parameters, but have contrasting visual characteristics. The colour, knots, and grain of the wood contributed to producing visually warm experiences resulting in a yellowish room, whereas a mix and match of artificial finishes generates a colder, bluish ambiance in the other room. The conclusion suggests that architects and designers should consider the indoor use of wood for its unique visual ambiances that enhance comfort levels.

  • Researchpp 183-194H’ng, Y. Y., Nakagawa-Izumi, A., Leh, C. P., Das, A. K., and Ohi, H. (2017). "Characterization of residual lignin obtained by the enzymatic hydrolysis of oil palm empty fruit bunch pulps," BioRes. 12(1), 183-194.AbstractArticlePDF

    Residual lignin present in alkali pulps prepared from oil palm (Elaeis guineensis) empty fruit bunch was isolated using an enzymatic method and characterized successfully by pyrolysis-gas chromatography-mass spectrometry (Py-GC/MS). These pulps were prepared by soda-anthraquinone (AQ) and prehydrolysis (PH) soda-AQ cooking methods (pulp yields were 45.3 and 33.9%, respectively). Py-GC/MS of the residual lignin showed that two pyrolysis products which were indole and methylindole originating from the enzyme (contents 12 to 44%), in addition to eight pyrolysis products originating from syringyl (S) and guaiacyl (G) structure of lignin. Furthermore, palmitic acid was also detected in the residual lignin (contents 0.11 to 0.28%). The residual lignin was subjected to further purification by a cellobiose treatment method, and the quantity of enzyme present in the residual lignin was found to decrease after the treatment. Residual lignin in PH-soda-AQ pulp exhibited a higher S/G ratio (0.86 to 0.98) than that in soda-AQ pulp (0.76 to 0.97). This study showed that the contents of lignin (19 to 44%) and enzyme in enzymatically isolated lignin can be estimated by the Py-GC/MS method.

  • Researchpp 195-210Guo, H., Du, L., Liang, J., Yang, Z., Cui, G., and Zhang, K. (2017). "Influence of alkaline-thermal pretreatment on high-solids anaerobic digestion of dewatered activated sludge," BioRes. 12(1), 195-210.AbstractArticlePDF
    The influence of alkaline (23.77 mg NaOH/g total solid), thermal (134.95 °C), and combined alkaline-thermal pretreatment on parameters of dewatered activated sludge (DAS) during high-solids anaerobic digestion was investigated. Soluble chemical oxygen demand (SCOD), soluble proteins, and VFAs (volatile fatty acids) concentrations were significantly higher (by two-fold) in pretreated DAS samples than in the control. During subsequent anaerobic digestion, the concentrations first increased and then decreased. Total chemical oxygen demand (TCOD) decreased by 28.40% to 40.92%, and ammonia nitrogen accumulated during anaerobic digestion. For the alkaline, thermal, and alkaline-thermal pretreatments, daily methane yield significantly increased in mid-anaerobic digestion and cumulative methane yield (CMY) increased by 9.92, 35.25, and 52.95%, respectively, relative to the control. There were clear synergistic effects of alkaline-thermal pretreatment, resulting in a 17.20% increase in CMY compared with the sum of the separate alkaline and thermal pretreatments. Therefore, alkaline-thermal pretreatment was helpful for high-solids anaerobic digestion of DAS and was an effective pretreatment method. Gompertz model fitting to the CMY curve produced determination coefficients (R2) greater than 0.9931 for all pretreatments, which was better than for a first-order kinetic model fitting curve.
  • Researchpp 211-227Karthikeyan, R., Tjong, J., Nayak, S. K., and Sain, M. M. (2017). "Mechanical properties and cross-linking density of short sisal fiber reinforced silicone composites," BioRes. 12(1), 211-227.AbstractArticlePDF

    In the low cost application of vacuum casting in rapid prototyping, a mould cavity with high modulus is necessary for producing plastics parts in small quantity. In this work, a silicone matrix was reinforced with natural fibers to improve the modulus of composites to mould and to reduce the cost of silicone materials. Sisal fiber with different compositions was reinforced with silicone in a compression moulding process. Mechanical properties were studied. An increase in tensile strength, tear strength, and better hardness was observed in sisal fiber composites . The silane-treated fiber improved the adhesion between fiber and matrix and enhanced the mechanical properties of the composites. The swelling method was adopted to determine the cross-linking density of composites through the Flory-Rehner equation. The flexibility of silicone composites decreased for higher fiber loading and there was an increase in cross-linking of the fiber network to improve modulus of the composites. A morphological study was conducted using X-ray tomography and scanning electron microscopy (SEM) to predict the defects, orientation, debonding, fractography, and interfacial adhesion of fiber/matrix composites.

  • Researchpp 228-254Song, W., Wei, W., Li, X., and Zhang, S. (2017). "Utilization of polypropylene film as an adhesive to prepare formaldehyde-free, weather-resistant plywood-like composites: Process optimization, performance evaluation, and interface modification," BioRes. 12(1), 228-254.AbstractArticlePDF
    To develop formaldehyde-free wood-based composites, plywood-like composites (WV/PPF) were prepared using wood veneer (WV) with polypropylene film (PPF) as a novel formaldehyde-free, water-resistant adhesive. To prepare WV/PPF, the effects of hot-pressing conditions (temperature, 165 to 195 °C; pressure, 0.9 to 1.3 MPa; duration, 40 to 70 s/mm; and adhesive dosage between adjacent WVs, 100 to 200 g/m2) were investigated. Results showed that conditions at 180 °C, 0.9 MPa, 70 s/mm, and 150 g/m2 gave WV/PPF desirable physical-mechanical properties. Then, WV/PPF was compared with plywood-like composites using, respectively, polyethylene film (PEF), urea-formaldehyde resin (UFR), and phenol-formaldehyde resin (PFR) as adhesives. Results showed that the physical-mechanical properties of WV/PPF were favored over WV/PEF and WV/UFR, and were comparable to those of WV/PFR. Maleic anhydride grafted polypropylene (MAPP) or γ-aminopropyltriethoxysilane (APTES) surface modification of WV was performed to enhance the interface compatibility of WV/PPF. Results showed that the physical-mechanical properties of modified WV/PPF were favored over those of WV/PFR; MAPP modification was better for shear properties, while APTES modification was better for dimensional stability and flexural properties. Overall, the environmental and technological benefits demonstrated the potential of WV/PPF as a novel construction and building material.
  • Researchpp 255-269Müller, M., Valášek, P., and Ruggiero, A. (2017). "Strength characteristics of untreated short-fibre composites from the plant Ensete ventricosum," BioRes. 12(1), 255-269.AbstractArticlePDF

    The plant Ensete ventricosum is used in agriculture in Africa. It is a source of fibres, which can be used in the interaction with polymers. This study deals with a material utilization of these fibres with a length of 1 to 2 mm, 2 to 3 mm, and 3 to 5 mm, together with reactoplastics resin ChS Epoxy 1200/324, following requirements of developing countries. Some areas of the African continent suffer from a lack of wood, and material based on epoxy and fibres can substitute for many wood products. The aim of this experiment was to describe basic mechanical properties (tensile strength σm, strain at the break εb, modulus of the elasticity Et, and impact strength an) of the composite material reinforced with fibres of the false banana plant, Ensete ventricosum. The plant, which originated in Ethiopia, is exploitable in developing countries. Geometrical aspects and morphology of the used fibres was characterized by scanning electron microscopy (SEM). The addition of fibres increased the modulus of elasticity and the impact strength, whereas the tensile strength and the strain at break were decreased.

  • Researchpp 270-282Hodoušek, M., Dias, A. M. P. G., Martins, C., Marques, A. F. S., and Böhm, M. (2017). "Comparison of non-destructive methods based on natural frequency for determining the modulus of elasticity of Cupressus lusitanica and Populus x canadensis," BioRes. 12(1), 270-282.AbstractArticlePDF

    A non-destructive method for measurement of the modulus of elasticity (MOE) was compared with the static method on beams of Cupressus lusitanica and Populus x canadensis. The dynamic method is based on the principle of the resonance frequency, using longitudinal vibrations (Timber Grader MTG, accelerometer) and the static method for measurement of the flexural modulus of elasticity is according to EN 408 (2012). The differences between the ascertained dynamic and static MOE values were 1.1% to 2.4% for the Populus x canadensis sample and 12.7% to 15.5% for the Cupressus lusitanica sample. Furthermore, the correlation dependence of the applied methods was determined and the regression equations are shown. Experimental measurement showed the effect of the knot clusters, which appeared primarily in Cupressus lusitanica samples and considerably impacted the resultant values.

  • Researchpp 283-295Elustondo, D., Myronycheva, O., Sundqvist, B., and Karlsson, O. (2017). "Localized wood surface modification, Part I: Method characterization," BioRes. 12(1), 283-295.AbstractArticlePDF
    This study assesses the potential of an open process for treatment of European Scots pine (Pinus sylvestris) with chemicals that could potentially make the surfaces stronger, more dimensionally stable, or more durable, depending on the treatment solution. The method provides an intermediate solution between full volume impregnation by pressure treatment and superficial surface treatment by dipping. Figuratively speaking, the process creates the equivalent of a layer of coating applied below the wood surfaces rather than above. Two different techniques were compared, namely, heating-and-cooling (H&C) and compression-and-expansion (C&E). Taking into account that commercial suppliers recommend 0.15 to 0.25 L/m2 of coating in sawn wood and 0.1 to 0.15 L/m2 in planed wood surfaces, then this study demonstrates that the H&C method can impregnate an equivalent amount of solution under the surfaces in less than 15 min using treatment temperatures below 150 °C.
  • Researchpp 296-315Lv, E., Xia, W., Tang, M., and Pu, Y. (2017). "Preparation of an efficient oil-spill adsorbent based on wheat straw," BioRes. 12(1), 296-315.AbstractArticlePDF

    Acetylation of cellulose fiber extracted by methylbenzene/ethanol (2/1), sodium chlorite solution, and sodium hydroxide from raw wheat straw (RWS) was studied to examine its potential as an oil-spill adsorbent. Wheat straw cellulosic sorbent was produced by using acetic anhydride as an acetylating reagent and N-bromosuccinimide (NBS) as a catalyst. Effects of the volume ratio of acetic anhydride (from 6.25% to 57.5%), catalyst concentration (from 10 to 60 mM NBS), reaction temperature (from 50 to 120 °C), and reaction time (from 0.5 to 3 h) on oil-sorption properties were evaluated. The best oil absorbencies for diesel fuel, diesel oil slick, corn oil, and corn oil slick treatments were 24.21 ± 0.76, 22.39 ± 0.77, 25.61 ± 2.13, and 24.73 ± 1.19 g/g, respectively. Chemical composition and morphologic structure of RWS before and after acetylation were investigated and compared. Oil-absorption capacity, oil-retention ability, recyclability, and selectivity of RWS, pretreated wheat straw, and acetylated wheat straw were also discussed. The acetylated wheat straw demonstrated good potential for the utilization of agricultural residues as natural sorbents in oil cleanup.

  • Researchpp 316-325Liu, W., Qi, W., Zhou, W., Liu, S., Zhang, X., Zhou, J., Yuan, Z., and Zhuang, X. (2017). "Analysis of hydrolyzates produced from cellulose catalyzed by carbonaceous solid acid in an ionic liquid," BioRes. 12(1), 316-325.AbstractArticlePDF

    The hydrolysis of cellulose using carbonaceous solid acid (CSA) in an ionic liquid was studied. The types and concentrations of products generated during the hydrolysis of the cellulose under different conditions, including temperature, reaction time, water addition, and recycle time, were investigated. The CSA prepared in the study contained 1.45 mmol/g of acidic groups, which was higher than the theoretical amount of sulfonic groups. The highest yields of total reducing sugars (TRS) and glucose were obtained at 5% water content, 6 h of reaction time, and 140 °C. The cellulose was hydrolyzed effectively via catalysis of CSA in [AMIM][Cl] with a low water content. Analysis of the products under different conditions in this work provides a strong basis for the full use of hydrolyzed cellulose.

  • Researchpp 326-343Du, J., Qian, Y., Qu, H., Xi, Y., Huang, H., Jin, H., Xu, Y., Lü, X., and Chang, Z. (2017). "Comparative analysis of single-stage and two-stage fermentation systems under various process conditions," BioRes. 12(1), 326-343.AbstractArticlePDF

    A comparative study of single-stage fermentation (wet or dry) and two-stage (wet-dry and dry-wet) fermentation systems was carried out under medium temperature conditions. The effect of the length of the first wet or dry fermentation stage (5-, 10-, 15-, 20-, and 25-d) in the two-stage anaerobic fermentation was investigated. The results showed that the gas production of wet fermentation and two-stage wet-dry fermentation was better than that of the dry fermentation and two-stage dry-wet fermentation. The cumulative gas production increased gradually with increased stage conversion times for the two-stage wet-dry fermentation. The gas production for the 20-d experimental group of the two-stage wet-dry fermentation system was the best. The cumulative biogas production in the anaerobic fermentation of straw correlated significantly with the changes in the degradation rates of volatile solids, cellulose, and hemicellulose (P < 0.01). The kinetic fitting analysis showed that the Reaction Curve (RC) model was more suitable for data modeling of the single-stage wet fermentation and two-stage wet-dry fermentation with straw than the Modified Gompertz (GM) and Modified Logistic (LM) models. The results of this study provided a theoretical basis for choosing a fermentation process for large-scale biogas production with straw.

  • Researchpp 344-361Yang, H., Li, J., Xu, J., and Mo, L. (2017). "The critical analysis of catalytic steam explosion pretreatment of corn stalk, lignin degradation, recovery, and characteristic variations," BioRes. 12(1), 344-361.AbstractArticlePDF
    The lignin degradation and its structural change as a result of catalytic steam explosion pretreatment can be considered of great importance for both the subsequent fermentation and the further utilization of the lignin fraction. This work investigated the degradation mechanism and change in the characteristics of lignin during dilute sulphuric-acid catalytic steam explosion (SE) pretreatment and ammonia catalytic steam explosion (AE) pretreatment of corn stalk. For this purpose, two types of lignin samples obtained from the two pretreatments of aqueous products and solid residues were fractionated, and they were then characterized by a series of comprehensive analyses that consisted of gas chromatography-mass spectroscopy (GC-MS), ion chromatography (IC), Fourier transform infrared (FT-IR), Carbon-13 nuclear magnetic resonance (13C NMR), Carbon-Hydrogen two-dimensional heteronuclear single quantum coherence (13C-1H 2D HSQC), pyrolysis-GC-MS (Py-GC-MS), and field emission scanning electron microscopy (FE-SEM). Overall, the characteristic diversity of the lignin provides useful reference for high-value applications of lignin.
  • Researchpp 362-392Daystar, J. S., Barnes, E., Hake, K., and Kurtz, R. (2017). "Sustainability trends and natural resource use in U.S. cotton production," BioRes. 12(1), 362-392.AbstractArticlePDF

    Cotton is a natural fiber that takes up carbon dioxide from the environment when grown; however, it requires various resources to be cultivated in a financially viable way. Resources such as fertilizer, pesticides, herbicides, and irrigation water can create environmental impacts as well as present significant costs to the grower. Understanding the efficacy of technologies and grower practices is an important aspect of developing best practices and guiding future research. To better understand the grower needs, practices, and resource use efficiency, a survey was conducted in 2015 with 925 U.S. cotton grower respondents. This survey gathered data on field performance, pest pressures, growing practices, and other parameters that were used to examine the resources used per pound of cotton lint as well as estimate the greenhouse gas emissions and energy use from cotton cultivation. In general, growers who used various precision agricultural technologies reported higher performing fields with higher resource use efficiencies than non-precision technology adopters.

  • Researchpp 393-406Zheng, J., Liu, Y., Sun, X., Wang, Q., Zou, H., Wang, J., Gao, M. (2017). "Open fermentative production of L-Lactic acid from Distillers' grains by Lactobacillus casei CICC 6056," BioRes. 12(1), 393-406.AbstractArticlePDF
    Distillers’ grains (DG) are potential fermentable sugar substrates for the production of value-added products. This study focused on the development of an open fermentation process for the production of L-lactic acid from DG using Lactobacillus casei CICC 6056. The open fermentation process was feasible, resulting in an L-lactic acid yield similar to that obtained with sterilized fermentation. However, a decrease in pH below 5.0 after 24 h resulted in a poor L-lactic acid concentration of 9.18 g/L and an inferior reducing sugar conversion rate of 53.6%. Therefore, an optimal pH adjustment method was sought. A pH adjustment to 6.5 every 24 h effectively improved the L-lactic acid concentration to 21.3 g/L with a 97.8% reducing sugar conversion rate. Furthermore, the application of a simultaneous saccharification and fermentation process at 50 °C in open condition increased the L-lactic acid concentration to 25.0 g/L. This yield was superior to L-lactic acid fermentation from DG using a separate hydrolysis and fermentation method (21.3 g/L) and from a commercial sugar in batch culture (23.6 g/L). These results demonstrated that L. casei CICC 6056 has great industrial potential as a superior candidate strain for the production of L-lactic acid from DG due to its broad applicability in a wide temperature range (from 37 to 50 °C).
  • Researchpp 407-418Kubš, J., Gašparík, M., Gaff, M., Kaplan, L., Čekovská, H., Ježek, J., and Štícha, V. (2017). "Influence of thermal treatment on power consumption during plain milling of lodgepole pine (Pinus contorta subsp. murrayana)," BioRes. 12(1), 407-418.AbstractArticlePDF
    This paper investigated the energy consumption differences during plain milling of thermally treated and untreated lodgepole pine wood (Pinus contorta subsp. murrayana). Thermal treatment was completed at four temperatures, which were 160 °C, 180 °C, 210 °C, and 240 °C. Power consumption measuring equipment was used for analysis in order to determine the cutting power of the milling process parameters during circumferential plain milling of lodgepole pine wood. The results indicated that the increase of cutting speed as well as feed speed caused a growth in cutting power. On the other hand, the increase of rake angle and thermal treatment temperature led to strong lowering of cutting power. The highest decrease (26.9%) in cutting power was caused by thermal treatment temperature 240 °C.
  • Researchpp 419-43Qian, S., Zhang, H., and Sheng, K. (2017). "Cellulose nanowhiskers from moso bamboo residues: Extraction and characterization," BioRes. 12(1), 419-433.AbstractArticlePDF
    To take full advantage of moso bamboo processing waste, bamboo cellulose nanowhiskers were isolated from bamboo residues using sulfuric acid hydrolysis. Changes in bamboo cellulose at different stages of processing, as well as the roles of acid concentrations (55 wt% and 65 wt%) and hydrolysis times (1 h to 5 h) on the characteristics of nanowhiskers were investigated by scanning electron microscopy (SEM), transmission electron microscopy (TEM), thermogravimetry-Fourier transform infrared spectroscopy analysis (TGA-FTIR), synchrotron radiation wide angle X-ray scattering (WAXS), composition analysis, and Brunauer-Emmett Teller (BET) analysis. Both rod-like and network-like nanowhiskers were observed. Alkaline pretreatment removed impurities and part of the hemicellulose. Cellulose content increased to nearly 85%, and specific surface area improved as well after bleaching. Nanowhiskers had an average length of 455 nm, diameter of 12 nm, and an aspect ratio of about 37. Cellulose I was the dominant composition in bamboo cellulose; the transformation of cellulose Iα to cellulose Iβ was observed. Nanowhiskers presented greater crystallinity and crystallite size than those of cellulose without hydrolysis, but lower thermal stability. These bionanowhiskers might be used as reinforcements in nanocomposites.
  • Researchpp 434-447Wu, H., Xue, Y., Li, H., Gan, L., Liu, J., and Long, M. (2017). "Heterologous expression of a new acetyl xylan esterase from Aspergillus niger BE-2 and its synergistic action with xylan-degrading enzymes in the hydrolysis of bamboo biomass," BioRes. 12(1), 434-447.AbstractArticlePDF
    Efficient utilization of plant biomass by enzymatic hydrolysis is currently studied worldwide but still faces enormous challenges because of the inability to break down lignocellulosic materials with high sugar yields and low enzyme dosage. Therefore, the synergistic action between various enzymes plays an important role in reaching this goal. The synergistic cooperation between a novel acetyl xylan esterase (heterologous expressed at high levels in this study) and four other xylan-degrading enzymes (reported previously) were performed in this study. The acetyl xylan esterase (AnAxe) gene was cloned from Aspergillus niger BE-2 and expressed in Pichia pastoris GS115. The deduced amino acid (aa) sequence consisted of 304-aa and included a 23-aa signal peptide and 281-aa mature protein. The AnAxe was extracellularly expressed with a molecular weight of ca. 31 kDa. The purified AnAxe exhibited maximal specific activity of 480.2 IU/mg at pH 7.0 and 40 °C and was still thermostable below 50 °C. The metal ions used in this study and EDTA showed a slight effect on the AnAxe. A significant synergistic effect was determined between AnAxe and the other four xylan-degrading enzymes, including endo-Beta-1,4-xylanases, Beta-xylosidases, alpha-L-arabinofurano-sidases, and alpha-glucuronidases, on the degradation of bamboo biomass. The highest degree of synergism was obtained between AnAxe and endo-Beta-1,4-xylanases/Beta-xylosidases.
  • Researchpp 448-456Gáborík, J., Gaff, M., Ruman, D., Šomšák, M., Gaffová, Z., Svoboda, T., Vokaty, V., and Síkora, A. (2017). "The influence of thermomechanical smoothing on beech wood surface roughness," BioRes. 12(1), 448-456.AbstractArticlePDF

    This paper deals with the change of roughness of compressed beech wood. Effects of temperature, pressure, and time on the results of pressing were examined. The surface roughness of beech wood in longitudinal and transversal directions was evaluated. Roughness was described by Ra. A contact method was applied. The results show that by increasing pressure, time, or temperature, the surface roughness of beech wood decreases. The highest roughness reduction occurred at the temperature of 150 °C, pressure 4 MPa, and time 20 min.

  • Researchpp 457-468Yang, Z., Zhang, J., Zhang, M., Wang, M., and Cao, J. (2017). "Characteristics of pollution from waste liquor of poplar pre-conditioning refiner chemical alkaline peroxide mechanical pulping," BioRes. 12(1), 457-468.AbstractArticlePDF
    The molecular weight distribution and composition of organic pollutants from chemi-mechanical pulping waste liquor was studied using ultra-filtration, Fourier transform infrared spectra, and gas chromatography-mass spectrometry. The concentration of dissolved chemical organic compounds was approximately 1.81 × 104 mg·L-1. In addition, the wastewater had poor biodegradability. The chemical oxygen demand (COD) was primarily composed of small molecular organic pollutants, and the larger pollutants in the waste liquor were its primary source of color. The data indicated that there were chromophoric and auxochrome groups in the waste liquor. The waste liquor contained 38 types of organic pollutants, which were aromatic compounds, including phenols, ketones, alcohols, and fatty acids.
  • Researchpp 469-477Yan, L. Y., Li, S. Y., and Song, X. L. (2017). "Preparation of paper strengthening agent by esterification of cellulosic fines," BioRes. 12(1), 469-477.AbstractArticlePDF
    Paper strengthening agents play an important role in the papermaking industry with the increase of secondary fiber applications. The objective of this study was to create a dry-strength agent by esterification. The fines from the pulp were collected and modified with trimesic acid and citric acid, respectively, to obtain the dry-strength agent. The influences of acid type and dosage on the enhancing effect were investigated. Compared with the control sample, the physical properties of paper sheet were improved after adding modified fines. The properties of recycled paper were also improved by the modified fines. When the dosage of citric acid agent was 7%, the effect on paper properties saw the greatest improvement. The tensile index, burst index, and folding endurance were increased by 60.3%, 18.3%, and 146.2%, respectively, compared with the control. The improvement of paper properties was due to the increase of carboxyl content in the modified fines. Based on the findings, it can be concluded that the esterification is an effective approach for producing paper dry-strengthening agent.
  • Researchpp 478-494Ouyang, H., Hou, K., Wang, L., and Peng, W. (2017). "Optimization protocol for the microwave-assisted extraction of antioxidant components from Pinus elliottii needles using response surface methodology," BioRes. 12(1), 478-494.AbstractArticlePDF
    Response surface methodology (RSM) based on a Box–Behnken rotatable design was used to determine the optimum conditions for the microwave-assisted extraction of antioxidant compounds from Pinus elliottii needles. Four process variables were evaluated at three levels (29 experimental conditions): ethanol (50, 70, and 90%), solvent:solute ratio (25:1, 20:1, and 15:1), extraction temperature (60, 70, and 80 °C), and ultrasonic power (100, 150, and 200 W). Using RSM, a quadratic polynomial equation was obtained by multiple regression analysis to predict the optimized extraction protocol. The radical scavenging capacity was determined by O2−, ·OH, and DPPH methods. For the microwave-assisted extraction of antioxidant compounds from Pinus elliottii needles, the optimum process used ethanol at 72%, a solvent:solute ratio of 21:1 mL/g, an extraction temperature of 67 °C, and an ultrasonic power of 200 W. The results indicated good correlation between total polyphenols content and O2−, ·OH, and DPPH radical scavenging activities.
  • Researchpp 495-513Gašparík, M., Gaff, M., Ruman, D., Záborský, V., Kašičková, V., Sikora, A., and Štícha, V. (2017). "Shear bond strength of two-layered hardwood strips bonded with polyvinyl acetate and polyurethane adhesives," BioRes. 12(1), 495-513.AbstractArticlePDF

    This article deals with the effects of various parameters on the shear bond strength (SBS) of glued wood. A four-factor analysis showed that the combination of only non-densified wood pieces achieves higher shear bond strength values than densified ones. In this case, only the piece combination was a significant factor. The other factors (glue type, wood species, and number of loading cycles) had no significant effect. Although the differences were not large, a higher SBS was achieved in beech wood glued with polyvinyl acetate (PVAc) glue. Glued wood consisting of the combination of densified and non-densified pieces had slightly lower SBS values. In this case, all the factors were statistically significant. Beech wood had a more significant impact on the SBS than aspen wood. The effect of the type of glue showed an opposite trend than that in the previous variant, i.e., a higher SBS was achieved with polyurethane (PUR) glue. Wood subjected to cyclic loading had slightly higher SBS values than non-cyclically loaded wood. The degree of densification had no significant effect. Glued wood composed entirely of densified pieces showed greater SBS variation between versions.

  • Researchpp 514-532Wang, B., Li, D. L., Chen, T. Y., Qin, Z. Y., Peng, W. X., and Wen, J. L. (2017). "Understanding the mechanism of self-bonding of bamboo binderless boards: Investigating the structural changes of lignin macromolecule during the molding pressing process," BioRes. 12(1), 514-532.AbstractArticlePDF

    Binderless boards were produced from bamboo particles through a molding pressing process. The boards were investigated for the chemical and structural changes of lignin and their mechanical strengths to evaluate the mechanism of self-bonding. The structural transformations of milled wood lignin (MWL) obtained from raw bamboo and molding pressed bamboo boards were investigated by Fourier transform infrared (FT-IR), gel permeation chromatography (GPC), quantitative 13C-NMR spectra, two-dimensional heteronuclear single quantum coherence (2D-HSQC) spectra, 31P-NMR, thermogravimetric analysis (TGA), and differential scanning calorimetry (DSC) techniques. Both molding press temperature and time affected the distribution and abundance of typical lignin linkages (β-O-4′, β-β′, and β-5′), as well as the S/G ratios of the lignin, demethoxylation, and the contents of attached molecules (PCE). In addition, a decrease in aliphatic OH and an increase in phenolic hydroxyl groups occurred in lignin as molding pressing proceeded. The optimal internal bonding strength (0.98 MPa) of the bamboo binderless board was obtained under the condition of 180 ºC for 20 min. Although the lignin obtained under this condition was structurally similar to the raw MWL, the decreased molecular weight, increased phenolic hydroxyl groups, and observable glass-transition temperature (thermal softening of lignin) provide some evidence to explain the acceptable internal bonding strength.

  • Researchpp 533-545Liang, S., Zhang, L., Chen, Z., and Fu, F. (2017). "Flame retardant efficiency of melamine pyrophosphate with added Mg-Al-layered double hydroxide in medium density fiberboards," BioRes. 12(1), 533-545.AbstractArticlePDF
    The main objective of this study was to investigate the flame retardant (FR) efficiency of melamine pyrophosphate (MP) with added layered double hydroxide (LDH) in medium density fiberboards (MDFs) to be used as building decorative materials. The thermal degradation, FR efficiency, and combustion properties of MDF were analyzed by Fourier transform infrared spectra (FTIR), thermogravimetric analysis (TGA), limiting oxygen index (LOI) test, and cone calorimetric test. The TGA results showed that the combination of MP and LDH led to a lower decomposition temperature than the pure MP and pure LDH. The LOI results showed that the LOI values increased with the addition of the FRs. The cone calorimetric results showed that the addition of four proportions (1:1, 2:1, 1:2, and 1:3) of the compounds into MDF can clearly decrease the peak heat release rate (PHRR) and mean heat release rate (MHRR). The results indicated that the MP and LDH compounds have a synergistic effect to improve the flame retardancy and smoke suppression in the MDFs. The combination of MP and LDH in a 1:1 ratio under 10 wt% FR addition has the best flame retardant efficiency in the MDFs.
  • Researchpp 546-570Gosselin, A., Blanchet, P., Lehoux, N., and Cimon, Y. (2017). "Main motivations and barriers for using wood in multi-story and non-residential construction projects," BioRes. 12(1), 546-570. AbstractArticlePDF

    Steel and concrete are traditionally used as structural materials for non-residential and multi-housing buildings. However, wood can meet the same structural property requirements, and a variety of multi-story buildings have recently been built all over the world using this key material. In this study, the main motivations and barriers to wood adoption for structural uses in non-residential buildings are highlighted, based on an analysis of grey literature concerning some well-known buildings and on scientific literature. The motivations found were linked to sustainability, lack of expertise, costs, rapidity of erection, and aesthetic of wooden structures. In contrast, the barriers preventing its use encompass building code implementation, technology transfer, costs, material durability and other technical aspects, culture of the industry, and material availability. Furthermore, an analysis of non-residential timber building meeting minutes for nine projects is also presented to support the identification of problems and concerns related to site assembly issues, the conception of the building, the scheduling, and stakeholders’ relationships. With a better understanding of the expectations and challenges concerning wood usage in non-residential construction projects, companies will be able to adapt their business models and use the resource even more in the future to develop innovative structures.

  • Researchpp 571-585Chang, L., Guo, W., and Tang, Q. (2017). "Assessing the tensile shear strength and interfacial bonding mechanism of poplar plywood with high-density polyethylene films as adhesive," BioRes. 12(1), 571-585.AbstractArticlePDF
    A series of high-density polyethylene (HDPE) films were tested as adhesives for plywood and were fabricated using hot pressing followed by cold pressing. The effects of the moisture content, HDPE dosage, and the hot-press temperature and pressure on the mechanical properties were evaluated by analyzing the tensile shear strength. The results indicated that the HDPE films that were used as adhesives in plywood had good bonding strength, meeting the requirements for type II-grade plywood according to the GB/T 9846.3 standard (2004, Beijing, China). The bonding mechanism was also investigated using the width of the bond line, the average penetration (AP), and the effective penetration (EP) through the use of optical microscopy and scanning electron microscopy (SEM). The results showed that the HDPE is able to penetrate into the vessels, xylem, and so on. On the whole, both the AP and EP increased with an increase in the HDPE dosage and hot-press temperature and pressure, but not with an increase in the moisture content. In addition, the effects of the factors mentioned above on the width of the bond line, AP, and EP were also investigated by an ANOVA analysis.
  • Researchpp 586-596Altun, S., and Tokdemir, V. (2017). "Modification with melamine formaldehyde and melamine-urea formaldehyde resin to improve the physical and mechanical properties of wood," BioRes. 12(1), 586-596.AbstractArticlePDF
    Scots pine and white poplar were modified with melamine formaldehyde (MF) and melamine-urea formaldehyde (MUF) resins to improve their physical and mechanical properties. Impregnation was conducted at 4 bar pressure for 30 or 60 min, and the samples were cured at a temperature of 150 °C for 40 min in an oven. The density, equilibrium moisture content, weight percent gain, bulking effect, water uptake, volumetric swelling, anti-swelling efficiency, modulus of rupture, modulus of elasticity, compression strength parallel to the grain, and Brinell hardness of the modified wood were determined. The anti-swelling efficiencies were 57% and 74% in Scots pine and white poplar, respectively, using the melamine formaldehyde resin. Modification of white poplar with melamine-urea formaldehyde increased the modulus of elasticity, compression strength, and Brinell hardness considerably. Both resins were successful at improving the physical and mechanical properties of Scots pine and white poplar woods.
  • Researchpp 597-607Jankowska, A., Drożdżek, M., Sarnowski, P., and Horodeński, J. (2017). "Effect of extractives on the equilibrium moisture content and shrinkage of selected tropical wood species," BioRes. 12(1), 597-607.AbstractArticlePDF
    The main objective of this research was to investigate tropical wood sorptive properties. For selected tropical wood species (courbaril, ipe, light red meranti, merbau, tatajuba, and teak), the equilibrium moisture content was determined at 20 °C and 9, 30, 55, 70, and 97% relative humidity. The experimentally determined values were analysed using the Hailwood-Horrobin sorption model to compute the fibre saturation point and mono- and multi-layer sorption. There were significant differences in the sorption behaviour of different wood species. Generally, the fibre saturation point of tropical wood species is lower than in wood species from moderate climate zones. The lowest values of fibre saturation point were found for ipe (18.7%), courbaril (20.4%), and tatajuba (20.5%). Furthermore, chloroform-ethanol extractives content was correlated with multilayer sorption and the fibre saturation point, such that a higher content of chloroform-ethanol extractives was associated with a lower equilibrium moisture content. Therefore, chemisorption was not influenced by chloroform-ethanol extractives. Ethanol extracts showed an influence on monomolecular-bound water.
  • Researchpp 608-621Chen, Q., Liu, G., Chen, G., Mi, T., and Tai, J. (2017). "Green synthesis of silver nanoparticles with glucose for conductivity enhancement of conductive ink," BioRes. 12(1), 608-621.AbstractArticlePDF
    This work reported a green method of synthesizing silver nanoparticles (AgNPs) with glucose acting as reducing agents to improve the conductivity of conductive ink. Silver nitrate, glucose, and polyvinylpyrrolidone (PVP), were used as silver precursor, reducing agent, and capping agent, respectively. The optimal condition of synthesizing AgNPs was obtained by varying the reactant ratio and temperature. The AgNPs were characterized by X-ray diffraction (XRD), UV-visible spectroscopy (UV-Vis), and scanning electron microscope (SEM). The obtained AgNPs with diameters of 80 to 100 nm were almost spherical and they were redispersed well in polyurethane acrylate (PUA). Compared with traditional hydrazine hydrate, the prepared AgNPs were better with respect to uniform size, dispersion, stability, and the absence residual solvent. After UV sintering, the conductivity (2.3×105 S/m) and mechanical properties of prepared conductive ink were good. Therefore, using glucose as a reducing agent to prepare AgNPs conductive ink is feasible and noteworthy because it is an extremely common material.
  • Researchpp 622-642He, T., Meng, J., Chen, W., Liu, Z., Cao, T., Cheng, X., Huang, Y., and Yang, X. (2017). "Effects of biochar on cadmium accumulation in rice and cadmium fractions of soil: A three-year pot experiment," BioRes. 12(1), 622-642.AbstractArticlePDF
    A three-year rice pot experiment was conducted to investigate the effects of biochar on cadmium (Cd) accumulation in rice and Cd fractions of soil. The biochar was derived from farmland waste and applied to contaminated paddy soil at various application rates (0, 1, 2, and 4%). The dry matter accumulations in rice, Cd contents of various rice organs, and fraction distributions of Cd in soil were measured. In a 3-year experiment, the results indicated that biochar treatments reduced the exchangeable Cd concentrations by 28.5 to 59.4% in soil, the total Cd accumulations in rice by 2.7 to 23.8%, and promoted rice growth by 0.7 to 3.9%. The application rates of 2% to 4% were considered to be reasonable for both rice growth and remediation of Cd-contaminated soil. Meanwhile, the Cd-contaminated biochar and straw were studied in the above manner for two years. Contaminated biochar reduced the Cd content of individual rice plants and ensured the normal growth of rice, but it had little effect on the Cd contents in specific organs of rice and Cd fractions of soil. However, this indicated that contaminated biomass materials have the possibility to be reused after pyrolysis for remediation of contaminated paddy soil.
  • Researchpp 643-654Wang, Q., Yu, M., Chen, G., Chen, Q., and Tai, J. (2017). "Facile fabrication of superhydrophobic/superoleophilic cotton for highly efficient oil/water separation," BioRes. 12(1), 643-654.AbstractArticlePDF
    This paper presents a facile and versatile strategy to fabricate robust and superhydrophobic/superoleophilic cotton for the removal of oils and organic solvents from polluted water. The superwettability cotton was prepared via in-situ hydrolysis of tetraethoxysilane (TEOS) on the cotton fiber surface using polyvinylpyrrolidone (PVP) as a coupling agent and subsequent hexadecyltrimethoxysilane modification. By simply adjusting the molecular weight of PVP and the concentration of NH3•H2O, the surface roughness of SiO2-modified cotton fibers could be well controlled to generate cotton fibers with excellent superhydrophobicity. The prepared cotton fibers were used as superabsorbents for oil/water separation. It absorbed up to 35 times and 50 times its own weight of n-hexane and chloroform, respectively, while repelling water completely. After collecting the absorbed oils via a simple squeezing method, the cotton could be reused for at least 5 cycles. Moreover, the whole procedure was carried out in a mild environment, with no intricate instruments or toxic reagents.
  • Researchpp 655-661Fan, H., Liu, P., Wang, X., Gao, D., and Liu, J. (2017). "Effect of the crystal shape of precipitated calcium carbonate on the whiteness of modified fly ash," BioRes. 12(1), 655-661.AbstractArticlePDF

    Fly ash was modified using calcium oxide and carbon dioxide. The effects of reaction temperature, the rate of carbon dioxide, and the concentration of calcium hydroxide on the crystal shape of precipitated calcium carbonate coated on the surface of fly ash were studied. The effects of the crystal shape of precipitated calcium carbonate on the whiteness of modified fly ash were analyzed. The research showed that the crystal shape of precipitated calcium carbonate was lamellar when the reaction temperature, the rate of carbon dioxide, and the concentration of calcium hydroxide were 20 °C, 0.2 L/min, 20%, respectively, which was conducive to the higher whiteness of modified fly ash.

  • Researchpp 662-672Panaitescu, D. M., Frone, A. N., Chiulan, I., Gabor, R. A., Spataru, I. C., and Căşărică, A. (2017). "Biocomposites from polylactic acid and bacterial cellulose nanofibers obtained by mechanical treatment," BioRes. 12(1), 662-672.AbstractArticlePDF
    Bacterial cellulose nanofibers (BCNF), obtained by the mechanical disintegration of BC pellicles, were used without any surface treatment for the fabrication of poly(lactic acid) (PLA) nanocomposites by a melt compounding process. The addition of BCNF in different amounts improved both the Young’s modulus and tensile strength of PLA. A 22% increase in these properties was observed in the nanocomposite with 2 wt.% nanofibers, due to the BCNF network formed at this concentration and characterized by atomic force microscopy. BCNF addition also increased the crystallinity and thermal stability of PLA, which were evaluated by thermal analysis. Due to the high purity of BCNF and the environmental friendliness of melt processing, it was concluded that PLA/BCNF nanocomposites can be designed for biomedical field and food packaging.
  • Researchpp 673-683Chen, Y., Wan, J., Wu, Q., and Ma, Y. (2017). "Chemical modification of laccase from Aspergillus oryzae and its application in OCC pulp," BioRes. 12(1), 673-683.AbstractArticlePDF

    Laccase activity and stability were improved and modified through the interaction between laccase amino acid residues (e.g., amino groups (-NH2) and carboxyl groups (-COOH)) and the chemical reagents thiourea dioxide (TDO) and L-phenylalanine methyl ester hydrochloride (L-PME). Compared with the control sample, the activity of the laccase modified with these chemical reagents was increased by 209% and 50%, respectively. The stability of the laccase modified with L-PME increased by 56.9%. However, the laccase modified with TDO only improved slightly. It was clear that reagent L-PME was more efficacious than TDO. The paper formed with addition of L-PME-modified laccase exhibited better performance in terms of tensile strength, bursting strength, and tear strength, which increased by 13%, 10%, 9%, respectively, compared with the paper formed with unmodified laccase.

  • Researchpp 684-695Shen, X., Xie, Y., and Wang, Q. (2017). "Improved acetylation efficacy of wood fibers by ionic liquid pretreatment," BioRes. 12(1), 684-695.AbstractArticlePDF

    Poplar wood fibers (WFs) were pretreated with ionic liquid (IL) 1-butyl-3-methylimidazolium chloride ([C4mim]Cl) at 125 °C for 1 h, and the influence of the wood loadings (5%, 15%, 30%, and 50%) on the pretreatment efficiency and downstream acetylation was studied. The crystallinity and lignin content of the WFs decreased after IL pretreatment at low wood loadings, especially at 5%. Wood fiber acetylation was performed under a molar ratio (acetic anhydride/–OH in the WFs) of 2:1, with toluene as the reaction medium and pyridine as the acid capturer. Ionic liquid pretreatment at 5% and 15% loading greatly contributed to the increase of weight percent gain (WPG) after acetylation, leading to much higher reaction efficiency, or lower energy consumption. The acetylated products that underwent pretreatment (mainly at 5% loading) had slightly higher thermal stability than those that did not undergo pretreatment. The crystallinity and moisture sorption ability of the products were determined primarily by the WPG value.

  • Researchpp 696-703Vanbeveren, S. P. P., Magagnotti, N., and Spinelli, R. (2017). "Increasing the value recovery from short-rotation coppice harvesting," BioRes. 12(1), 696-703.AbstractArticlePDF

    Farmers are reluctant to establish short-rotation coppice because too many uncertainties remain about its economic feasibility. Up to now, most progress has been accomplished by increasing plantation yields through genetic improvement and by reducing management costs through mechanization. In contrast, the potential increase of value recovery has received much less attention. We therefore compared whole-tree chipping with integrated harvesting to test whether more profit could be made by producing pulpwood logs and wood chips, rather than wood chips only. The two systems were compared side-by-side with identical machinery on the same field. Chip production cost was higher for integrated harvesting (15 € Mg-1), because the system was less productive (9 Mg h-1), as compared with whole-tree chipping (9 € Mg-1 and 25 Mg h-1). Pulpwood log production only occurred with the integrated harvesting system, at a cost of 8 € Mg-1. Integrated harvesting incurred higher production costs, but also accrued better value recovery. Under current market conditions, the two systems offered similar profits, in the vicinity of 5000 € ha-1. However, integrated harvesting offered higher flexibility, with a potentially better resilience to market fluctuations.

  • Researchpp 704-714Oleszek, M., and Krzemińska, I. (2017). "Enhancement of biogas production by co-digestion of maize silage with common goldenrod rich in biologically active compounds," BioRes. 12(1), 704-714.AbstractArticlePDF
    This paper analyses the suitability of common goldenrod plants as mono- and co-substrates for biogas production. Furthermore, the role of bioactive compounds included in the biomass of this plant species was investigated. The results showed that the common goldenrod species produced lower biogas and methane yields than maize silage. However, the methane fermentation of their mixture resulted in approximately 9.5% higher biogas yield and 16.6% higher methane yield compared to the theoretical yields estimated based on two mono-digestions. A statistically significant increase in biogas production efficiency resulted from more favorable C/N ratio and the influence of bioactive compounds contained in common goldenrod. The addition of goldenrod crude extract caused an approximately 30% increase in the biogas yield of maize silage. This effect may be associated with a positive impact of biologically active substances on microorganisms or with a decrease in redox potential of the fermenting mass.
  • Researchpp 715-734Yasim-Anuar, T. A. T., Ariffin, H., Norrrahim, M. N. F., and Hassan, M. A. (2017). "Factors affecting spinnability of oil palm mesocarp fiber cellulose solution for the production of microfiber," BioRes. 12(1), 715-734.AbstractArticlePDF

    Cellulose microfiber (MF) formation by electrospinning is affected by several factors. In this paper, fabrication of MF from oil palm mesocarp fiber (OPMF), a biomass residue abundantly available at the palm oil mill, was conducted by electrospinning. The effect of OPMF-cellulose solution properties on the spinnability of the solution was determined. Extracted cellulose from OPMF was dissolved in four different formulations of ionic liquids: (i) ([EMIM]Cl), (ii) ([EMIM][Cl):DMF, (iii) ([EMIM]Cl):([C10MIM][Cl]), and (iv) ([EMIM]Cl):([C10MIM][Cl]):DMF at cellulose concentrations of 1% to 9% (w/v). Scanning electron microscopy (SEM) analysis showed that MF formed had diameter sizes ranging from 200 to 500 nm. MF was formed only at 6% (w/v) cellulose concentration, when DMF was mixed in the solution. The results showed that cellulose concentration and viscosity played major roles in the spinnability of cellulose solution, in which too high viscosity of the cellulose solution caused failure of the electrospinning process and eventually affected the formation of MF. The characteristics of MF obtained herein suggest the potential of OPMF cellulose as a starting material for the production of MF.

  • Researchpp 735-747Ciolacu, F., Nicu, R., Balan, T., and Bobu, E. (2017). "Chitosan derivatives as bio-based materials for paper heritage conservation," BioRes. 12(1), 735-747.  AbstractArticlePDF
    Three water-soluble chitosan derivatives (ChDs)- carboxymethyl- chitosan (CCh), alkyl-chitosan (ACh), and quaternary-chitosan (QCh)- were evaluated as new materials for paper conservation. Several series of samples were prepared by coating different paper types with ChDs or methylcellulose (MC). The ChDs’ effectiveness were analyzed by their effects on the strength (tensile energy absorption (TEA), double folds) and water barriers (Cobb60, contact angle (CA)). The coatings on laboratory paper showed strength improvements for the CCh/QCh coatings that were consistent with an increase in the coating weight (CW). The ACh had little effect on the strength, but developed an effective barrier to water. The coatings on printing paper were performed at a constant CW by applying two layers of the same ChD or MC, and by combining CCh or QCh in the first layer with ACh in the second layer. Homogenous coatings based on the CCh or QCh resulted in high strength improvements, comparable to MC, but only ACh coatings developed an effective barrier to water. Combinations of the CCh or QCh with ACh provided the best relationship between the strength and barrier properties and proved their effectiveness as strengthening/protective materials in the treatment of natural aged paper.
  • Researchpp 748-759Zhao, J., and Cai, Y. (2017). "Measuring moisture content of wood using a transient hot-wire technique," BioRes. 12(1), 748-759.AbstractArticlePDF

    Wood easily acquires a large amount of moisture when it is exposed to high-humidity conditions. The high moisture content influences the service life of wood. Thus, there is a need for an accurate, rapid, nondestructive, and simple measurement technique for wood’s moisture content. This investigation proposes a method to measure the moisture content of wood by the wood volumetric heat capacity using a transient hot wire (THW) technique. The moisture content was inferred from the change of the volumetric heat capacity before and after the wood acquired moisture; the volumetric heat capacity is the ratio of the thermal conductivity to the thermal diffusivity. The results were validated by the gravimetric method, displaying good agreement, with discrepancies within 4%.

  • Researchpp 760-773Sonmez, S. (2017). "Development of printability of bio-composite materials using Luffa cylindrica fiber," BioRes. 12(1), 760-773.AbstractArticlePDF

    This study examined the surface adhesion of ink on bio-composite materials that were produced using Luffa cylindrica fiber and epoxy. To increase the ink adhesion on the surface, two different production methods were developed. The surface roughness and the surface contact angle of the bio-composite surfaces manufactured by each method were determined. The printing was applied on the surface of the bio-composite materials using a screen-printing procedure. While keeping the printing conditions constant, two different ink types, environmentally friendly water-based ink and solvent-based ink, were utilized. As a result of this study, the two types of ink were adhered on the polymer-coated surface, and there was no adhesion on the uncoated surfaces. In addition, the printability of the solvent-based ink was better than the water-based one, and the image of the transfer had higher quality. When the water or solvent-based inks were applied on the surface, the groups capable of forming hydrogen bonds, which were present in both kinds of ink, constituted hydrogen bonds with the C=O and N-H groups. This resulted in better adhesion on the surface, which was due to the presence of the separator.

  • Researchpp 774-784Denes, L., Lang, E. M., and McNeel, J. F. (2017). "Development of veneer-based corrugated composites, Part 1: Manufacture and basic material properties," BioRes. 12(1), 774-784.AbstractArticlePDF
    Typically, wood-based composite materials have been developed through empirical studies. In these products, the constituent wood elements have broad spectrums regarding species, size, and anatomical orientation relative to their own dimensions. To define special strength and stiffness properties during a long-term study, two types of corrugated wood composite panels were developed for possible structural utilization. The constitutional elements of the newly developed products included Appalachian hardwood veneer residues (side clippings) and/or rejected low quality, sliced veneer sheets. The proposed primary usage of these veneer-based panels is in applications where the edgewise loading may cause buckling (e.g., web elements of I-joists, shear-wall and composite beam core materials). This paper describes the development of flat and corrugated panels, including furnish preparations and laboratory-scale manufacturing processes as well as the determination of key mechanical properties. According to the results in parallel to grain direction bending, tension and compression strengths exceeded other structural panels’ similar characteristics, while the rigidities were comparable. Based on the research findings, sliced veneer clipping waste can be transformed into structural panels or used as reinforcement elements in beams and sandwich-type products.
  • Researchpp 785-798Sun, E., Huang, H., Sun, F., Wu, G., and Chang, Z. (2017). "Degradable nursery containers made of rice husk and cornstarch composites," BioRes. 12(1), 785-798.AbstractArticlePDF

    The degradation behavior was investigated for eco-composite nursery containers (NCs) prepared with rice husk and cornstarch adhesive modified with urea formaldehyde (UF) as a wet strength agent. The wet shear strength, water absorption capacities, and biological degradation of NCs within soil were also investigated. Quantitative analysis of the thermal degradation behavior of different NC versions was performed by thermo-gravimetric analysis (TGA). The results demonstrated that the introduction of the UF agent accelerated the soil degradation of the NCs matrix to a certain extent. The maximum cumulative mass loss was 51.1% when the UF content of NCs was 8 wt.%. Moreover, the dry strength of the mixed urea formaldehyde-cornstarch adhesive (UCA) was increased by 108.9% compared with cornstarch adhesive (CA). The results of this work indicate the improved biodegradability of the NC eco-composites, which could make them potential sustainable alternatives for conventional plastic pots.

  • Researchpp 799-818Nnaji, C. C., Ebeagwu, C. J., and Ugwu, E. I. (2017). "Physicochemical conditions for adsorption of lead from water by rice husk ash," BioRes. 12(1), 799-818.AbstractArticlePDF

    The effects of physico-chemical parameters such as pH, temperature, and lead concentration on the efficiency of lead adsorption by rice husk ash were determined. Rice husk was incinerated at 800 °C for 6 h and then activated with 0.5 M HCl. Rice husk and rice husk ash (RHA) were characterized using scanning electron microscopy and X-ray fluorescence. Batch adsorption tests were conducted at different pH, temperature, and initial lead concentration. Kinetic studies were conducted at optimum pH of 3.0. The optimum lead removal of 80% was recorded at pH 3.0. Efficiency of lead removal by RHA decreased to 45% as pH increased to 9.0. Freundlich, Langmuir, Temkin, and Dubinin Radushkevich (D-R) isotherms performed acceptably well, with R2 values of 0.954≤R2≤0.991, 0.965≤R2≤0.996, 0.949≤R2≤0.979, and 0.970≤R2≤0.997, respectively. Lead removal efficiency decreased from 75% to 50% as temperature increased from 30 °C to 40 °C. The adsorption of lead by RHA was by ion exchange in the acidic pH range and by physisorption in the alkaline pH range. Thermodynamic studies revealed that the process was exothermic and spontaneous and further confirmed the feasibility of the process with -22.34≤∆G0≤-24.94. The intraparticle diffusion model and the pseudo first order kinetic model fit the experimental data very well, with average R2 values of 0.985 and 0.987, respectively.

  • Researchpp 819-838Holeček, T., Gašparík, M., Lagaňa, R., Borůvka, V., and Oberhofnerová, E. (2017). "Measuring the modulus of elasticity of thermally treated spruce wood using the ultrasound and resonance methods," BioRes. 12(1), 819-838.AbstractArticlePDF
    The effect of thermal treatment temperatures on the dynamic and static modulus of elasticity (MOE) of Norway spruce wood (Picea abies (L.) H. Karst.) was evaluated. The dynamic MOE was measured using ultrasound and resonance methods in the longitudinal and transverse directions. The static MOE was determined by the three-point bending test. The dynamic MOE values determined by the ultrasound method were higher than the static MOE values in each case. As the temperature of the thermal treatment increased, the difference between the dynamic and static MOE values decreased. The MOE increased with increasing temperature, and it was more pronounced on a tangential surface. Increasing the sensor distance had a positive effect on the correlation between the static and dynamic MOE, and the effect from the increased temperature decreased. Measurement by the resonance method showed twice as high MOE values in the transverse direction than in the longitudinal direction. The thermal treatment caused a significant decrease in the MOE only in the transverse direction, and the differences were insignificant in the longitudinal direction. The dynamic MOE values measured by the resonance method were higher than the static MOE values but slightly lower than the values measured by the ultrasound method.
  • Researchpp 839-852Kucuktuvek, M., Kasal, A., Kuskun, T., and Erdil, Y. Z. (2017). "Utilizing poppy husk-based particleboards as an alternative material in case furniture construction," BioRes. 12(1), 839-852.AbstractArticlePDF
    Particleboard can be defined as a wood-based panel produced under pressure and heat with the inclusion of wood particles or other lignocellulosic materials and an adhesive. The need for alternative resources to replace wood raw material has emerged. Poppy husk biomass might have a value-added opportunity, and it is possible to produce particleboards from poppy husk and other softwood species. In this study, moment capacities of L-type corner joints fabricated from poppy husk-based particleboards, which are expected to be an alternative material for case furniture, were investigated. For this purpose, particleboards with five different ratios of poppy husk (P1, P2, P3, P4, P5) were produced, and then L-type corner joints were prepared. Corner joints were connected to each other with two different joint techniques (screwed, minifixed). Specimens were tested under static tension and compression loads, which are the loads commonly experienced by joints during service. According to the results, joints constructed from P5 and connected with screws had the highest moment capacity, whereas joints constructed from P1 and connected with minifix had the lowest moment capacity. In conclusion, from a technical point of view, poppy husk-based particleboards could be utilized in case furniture manufacturing for applications that are not overstressed.
  • Researchpp 853-870Wiedenbeck, J., Scholl, M., Blankenhorn, P., and Ray, C. (2017). "Lumber volume and value recovery from small-diameter black cherry, sugar maple, and red oak logs," BioRes. 12(1), 853-870.AbstractArticlePDF

    While only a very small percentage of hardwood logs sawn by conventional sawmills in the U.S. have small-end diameters less than 10 in, portable and scragg mills often saw smaller logs. With the closure of regionally important oriented strand board and pulpwood operations, small-diameter logs are considered to have no value in some markets. This study was conducted to assess the volume and value of lumber produced from small-diameter hardwood logs of three important commercial species: red oak, sugar maple, and black cherry. Value assessments included determining yields for both green and kiln-dried lumber subjected to different dry kiln schedules. Volume and grade recovery from these small-diameter logs were lower than prior studies suggested. The value of recovered lumber per ft3 of log volume was not found to be affected by log small-end diameter class for black cherry and red oak, but the value was significantly affected for sugar maple. The loss in lumber value that was attributed to kiln-dried based grade changes was greatest for red oak and least for sugar maple. For red oak, the modified dry kiln schedule did not affect the lumber value. For black cherry and sugar maple, there were kiln-schedule based differences in the value of the dry lumber recovered.

  • Researchpp 871-881Xing, L., Xu, M., and Pu, J. (2017). "The properties and application of an ultrasonic wheat straw pulp having enhanced tendency for ash formation," BioRes. 12(1), 871-881.AbstractArticlePDF

    Ultrasonic-assisted pulping technology integrates pulping and bleaching processes in one reactor with good yields performance of approximately 60% to 70%. The properties of ultrasonic-assisted wheat straw pulp were compared, i.e., composition, strength, and whiteness, with those of other conventionally pulps. The ash content of ultrasonic wheat straw pulp (the content is 27.81%) was much higher than that of traditional wheat straw pulp (the content was approximately 15%). Upon comparison with the ash content of the raw material, X-ray diffraction analysis, and thermogravimetry, the authors believe that some heat-resistant material was produced during the ultrasonic pulping process. The strength and whiteness performance of ultrasonic wheat straw pulp was better than that of traditional wheat straw pulp and was close to that of reed soda-anthraquinone (soda-AQ) pulp. Offset paper was successfully made using ultrasonic wheat straw pulp.

  • Researchpp 882-898Hajar, S., Islam, M. S., Rahman, M. L., Rashid, S. S., Chowdhury, Z. Z., Ali, M. E., Sarkar, S. M. (2017). "Highly active and reusable kenaf cellulose supported bio-poly(hydroxamic acid) functionalized copper catalysts for C-N bond formation reactions," BioRes. 12(1), 882-898.AbstractArticlePDF
    Distinctly active poly(hydroxamic acid) anchored copper (Cu) catalysts were synthesized from chemically modified kenaf cellulose. They were characterized by Fourier transform infrared spectroscopy (FT-IR), field emission scanning microscopy (FESEM), high resolution transmission electron microscopy (HRTEM), inductively coupled plasma atomic emission spectrometry (ICP-AES), UV-vis spectroscopy (UV), and X-ray photoelectron spectroscopy (XPS). The Cu-catalysts were successfully applied to the Michael addition reaction of amines with α,β-unsaturated carbonyl/cyano compounds and to the Click reactions of organoazides with alkynes under mild reaction conditions. The catalysts enabled excellent yields (88% to 95%) in both of the C–N bond formation reactions and showed easy recycling with outstanding reusability for seven cycles without any distinguished decrease in their catalytic activity.
  • Researchpp 899-911Yan, L., Ma, R., Bu, Q., Li, L., Zhou, X., Xu, Y., and Hu, C. (2017). "Characterization of value-added non-carbohydrate compounds solubilized during acidic hot water flowthrough pretreatment of poplar wood," BioRes. 12(1), 899-911.AbstractArticlePDF

    Acidic hot water flowthrough pretreatment (AHWF) is an attractive approach primarily because of its high efficiency for sugar recovery. However, a significant portion of carbon content in the solubilized fractions from lignin depolymerization and monosugar degradation has been studied to a lesser degree. Herein, we investigated the solubilized non-carbohydrate products from a series of flowthrough pretreatments of poplar wood by water-only or very dilute acid (0.05% to 0.1% w/w, H2SO4) at different temperatures (220 to 280 °C) and flow rates (10 to 62.5 mL/min). Results revealed that tailoring reaction parameters (temperature) and operational parameters of reactor (flow rate) without adding expensive catalysts can selectively produce specific non-carbohydrate compounds. Up to 50.9% selectivity of vanillin and 45.0% selectivity of syringaldehyde were obtained at 240 °C for water-only treatment with flow rates of 25 mL/min and 62.5 mL/min, respectively. Lower temperature (e.g., 220 °C) was favorable for the formation of coniferyl alcohol, with the highest selectivity of 36.2%. Higher temperature (e.g., 280 °C) or lower flow rate (e.g., 10 mL/min) led to the formation of varied other aromatic compounds and HMF. Adding very dilute acid (0.05% to 0.1% w/w, H2SO4) into the water-only system considerably enhanced the formation of HMF with up to 66.7% selectivity.

  • Researchpp 912-922Chai, Y., Liu, J., Wang, Z., and Zhao, Y. (2017). "Dimensional stability and mechanical properties of plantation poplar wood esterified using acetic anhydride," BioRes. 12(1), 912-922.AbstractArticlePDF
    Plantation poplar (Populus ussuriensis) wood was esterified using acetic anhydride without catalysts to improve its dimensional stability. The effects of acetylation temperature (100 °C, 120 °C, and 140 °C) on the dimensional stability, mechanical properties, microstructure, and functional groups of the resulting acetylated wood were systematically investigated. Results showed that the wood acetylated at 100 °C and 120 °C had an improved dimensional stability and comparable mechanical properties to those of the control wood. Wood acetylated at 140 °C had an improved dimensional stability and decreased mechanical properties as compared to those of the control wood. Scanning electron microscopic (SEM) analysis showed that the wood acetylated at 140 °C had obviously different microstructures than the control wood and the wood acetylated at 100 °C and 120 °C. The changes of functional groups in the acetylated wood were revealed by Fourier transform infrared spectroscopy (FTIR). The –OH groups of cellulose, hemicellulose, and lignin all were shown to participate in the acetylation reaction.
  • Researchpp 923-931Liu, L., Ju, M., Lai, R., Zhang, S., and Li, W. (2017). "Ammonium sorption onto polymeric adsorbing material from corn stalks oxidized and loaded with magnesium," BioRes. 12(1), 923-931.AbstractArticlePDF
    Corn stalks were modified by magnesium loading and an oxidation process and then characterized by a series of methods. The ammonium in wastewater showed high sorption efficiency onto the polymeric adsorbing material during the process, with a biochars dosage of 20 g/L for 8h. Mg2+ was the dominant cation exchanger on the modified corn stalk, and it played an important role in ammonium sorption. Large amounts of NH4+ were exchanged onto the corn stalk, and they formed strong complexes with oxygen-containing groups on the corn stalk surface through polar bonds, resulting in the removal of NH4+ from the solution. Na+ present in wastewater was the major influence on ammonium sorption onto the corn stalk.
  • Researchpp 932-946Záborský, V., Borůvka, V., Ruman, D., and Gaff, M. (2017). "Effects of geometric parameters of structural elements on joint stiffness," BioRes. 12(1), 932-946.AbstractArticlePDF

    Joints are one of the most important issues in the design of furniture structures. Joints in furniture structures made from wood and wood materials represent a critical area because furniture most often breaks at the joints of structural elements. This article discusses the analysis of the effect of selected factors: type of loading (compressive, tensile), wood species (Fagus sylvatica L., Picea abies L.), thickness of joint (one-third and half the thickness of the tenon), type of glue (polyvinyl acetate and polyurethane), and the annual ring deflection, on the elastic stiffness of joints. These results indicated significant effects for the wood species, thickness of joint, and type of glue used. The annual ring deflection was on the borderline of statistical significance, while its effect was more significant than the effect of the basic material characteristic, i.e., the wood density. The type of loading was not statistically significant.

  • Researchpp 947-959Čekovská, H., Gaff, M., Osvald, A., Kačík, F., Kubš, J., and Kaplan, L. (2017). "Fire resistance of thermally modified spruce wood," BioRes. 12(1), 947-959.AbstractArticlePDF

    The risk of possible ignition and burning is one of the greatest disadvantages of using wood as a construction material. An environmentally appropriate method of improving the fire-resistant properties of wood is available via thermal treatment. In this study, spruce wood (Picea abies L.) was thermally modified at 160 °C, 180 °C, and 210 °C. The effect of thermal modification on the fire performance of the wood, including weight loss and burn rate, was evaluated. A new testing method was designed to be sufficiently sensitive to monitor fire performance. The results showed that the thermally modified spruce wood had a lower weight loss than untreated wood. The burn rate of wood that was thermally modified at 160 °C was similar to that of untreated wood. Higher thermal treatment temperatures caused a higher burn rate. After the flame was removed, the burning process was rapidly stopped in thermally treated wood.

  • Researchpp 960-980Khaliukova, O., Paull, D., Lewis-Gonzales, S. L., André, N., Biles, L. E., Young, T. M., and Perdue, J. H. (2017). "Geospatial economics of the woody biomass supply in Kansas - A case study," BioRes. 12(1), 960-980.AbstractArticlePDF

    This research assessed the geospatial supply of cellulosic feedstocks for potential mill sites in Kansas (KS), with procurement zones extending to Arkansas (AR), Iowa (IA), Missouri (MO), Oklahoma (OK), and Nebraska (NE). A web-based modeling system, the Kansas Biomass Supply Assessment Tool, was developed to identify least-cost sourcing areas for logging residues and upland hardwood roundwood biomass feedstocks. Geospatial boundaries were used according to the 5-digit zip code tabulation area (ZCTA). This higher level of resolution advanced the understanding of the geospatial economics of modeling the supply chain for cellulosic feedstocks. The analyses were conducted for six sub-regions (Chanute, Effingham, El Dorado, Manhattan, Ottawa, and Pratt) within Kansas that were identified by the US Forest Service as suitable for forest habitat. Atchison County of Effingham region had the least marginal costs for upland hardwood roundwood, ranging from $92.59 to $108.68 per dry metric ton, with an available annual supply of approximately 72 thousand dry metric tons. The least favorable was the El Dorado region, where the marginal costs ranged from $97.32 to $108.05 per dry metric ton, with an annual supply of approximately 4.4 thousand dry metric tons.

  • Researchpp 981-991Fang, Y., Li, Y., Yi, W., Liu, S., and Bai, X. (2017). "Fractionation of pyroligneous acid: The first step for the recovery of levoglucosan," BioRes. 12(1), 981-991.AbstractArticlePDF
    Levoglucosan (LG) obtained from lignocellulosic biomass exhibits great potential as a specific tracer for biomass burning aerosols and as a raw material for synthesizing stereoregular polysaccharides. One potentially viable source of LG is pyroligneous acid (PA). This study investigated the effects of heating temperature on the extraction capability and the chemical composition of distillate and residual fractions. The results demonstrated that vacuum distillation extracted the acids, alcohols, ketones, aldehydes, and other organic matter. When the heating temperature was above 80 °C, the moisture content of the residual fraction was unchanged. The chemical composition of residual fraction was analyzed by gas chromatography-mass spectrometry (GC-MS). The analysis showed that the relative content of the LG, as obtained from the 90 °C distillation temperature, was 75.6%. Thus, it can be used as raw material for subsequent purification.
  • Researchpp 992-1006Fu, Y., Li, G., Wang, R., Zhang, F., and Qin, M. (2017). "Effect of the molecular structure of acylating agents on the regioselectivity of cellulosic hydroxyl groups in ionic liquid," BioRes. 12(1), 992-1006.AbstractArticlePDF
    Homogeneous functionalization of cellulose with chloroacetyl chloride (CAC), 2-bromoisobutyryl bromide (BrBiB), and 2-chloro-2-phenylacetyl chloride (CPAC) was performed in ionic liquid to evaluate the effect of the molecular structure of the reagents on the reactivity of the cellulosic hydroxyl groups. The results showed that the reaction was very selective for the less hindered C6-OH group, but the substitution of the secondary OH group still occurred, which indicated that the acylation of cellulose was only partly regioselective. The reaction extent and regioselectivity of the cellulosic hydroxyl groups partly depended on the molecular structure of the acylating agents. The reaction rate of the CAC was much faster than the relatively bulky BrBiB and CPAC, but the bulky acylating agents showed a higher C6-OH selectivity. Moreover, the BrBiB was less reactive than the CPAC, although they showed the same regioselectivity for the three hydroxyl groups. The acylation decreased the thermal stability of the cellulose, which decreased further as the bulk of the substituted groups increased.
  • Researchpp 1007-1014Belleville, B., Amirou, S., Pizzi, A., and Ozarska, B. (2017). "Optimization of wood welding parameters for Australian hardwood species," BioRes. 12(1), 1007-1014.AbstractArticlePDF

    Optimal linear wood welding parameters along the end-grain-to-end-grain faces were determined for Eucalyptus saligna, Eucalyptus pilularis, and Corymbia maculata. Joints made using Eucalyptus saligna showed a significant interaction between welding time (WT), amplitude (WA), and pressure (WP). A preheating phase of 3 s at 0.4 MPa WP and 0.75 mm WA coupled with a WT of 2 s at 2.0 MPa WP and 1.5 mm WA provided the best shear strength results of 5.1 MPa. Joints made using Eucalyptus pilularis and Corymbia maculata snapped once the holding pressure was removed, suggesting that end-grain-to-end-grain welded fibers cannot withstand the thermal stresses generated when the surface to be welded is too small (e.g., 13.5 cm2). However, grain orientation had a significant effect on the weld mechanical properties, as very strong edge-grain-to-edge-grain joints were produced with Eucalyptus pilularis and Corymbia maculata (9.5 and 6.2 MPa, respectively). The joints made of Eucalyptus saligna also showed significant improvement (7.3 MPa). Energy efficient combinations were usually those involving low WA and short WT, as WP had a marginal effect on energy consumption during the welding process.

  • Researchpp 1015-1030Liu, J., Zhang, Z., Chen, R., Xu, Y., Wang, C., and Chu, F. (2017). "Use of modified lignocellulosic butanol residue in phenol-resorcinol-formaldehyde polymers," BioRes. 12(1), 1015-1030.AbstractArticlePDF

    Lignocellulosic butanol residue (BR), obtained as the by-product of lignocellulosic butanol production, was used for the preparation of lignin-based phenol-resorcinol-formaldehyde resins (LPRFRs) by condensation polymerization. The lignin was first phenolated under sodium hydroxide catalysis at 90 to 92 °C at various phenolation times (1.0 to 4.0 h). The structural differences between BR and phenolated BR (PBR) were studied using Fourier transform infrared (FT-IR) spectroscopy, ultraviolet (UV) spectroscopy, thermogravimetric analysis (TGA), and gel permeation chromatography (GPC). The BR phenolated for 3.0 h had high phenol hydroxyl content, low molecular weight, and good thermal stability. The LPRFRs with 30 wt.% BR had the lowest free formaldehyde and phenol. With the substitution of BR for phenol, the hydrophilicity of LPRFRs increased. In addition, the mechanical, fragility, thermal properties, and morphology of lignin-phenol-resorcinol-formaldehyde foams (LPRFFs) were also investigated. The LPRFFs had excellent comprehensive properties when 30 wt.% PBR was substituted for phenol. These experimental findings could provide a new avenue for further study and application of bio-phenol-resorcinol foams.

  • Researchpp 1031-1040Wang, S., Chen, J., Yang, G., Chen, K., Yang, R., and Zeng, J. (2017). "Microstructure properties and cellulase hydrolysis efficiency of hybrid Pennisetum with [Amim]Cl pretreatment," BioRes. 12(1), 1031-1040.AbstractArticlePDF
    The complex microstructure of lignocellulosic biomass restricts its conversion into bio-ethanol. In this study, the effects of an ionic liquid (IL) 1-allyl-3-methylimidazolium chloride ([Amim]Cl) pretreatment on the microstructure properties and cellulase hydrolysis efficiency of hybrid Pennisetum (P. americanum × P. purpureum, lignocellulosic biomass) were investigated. After the [Amim]Cl pretreatment, the bonds of lignin-carbohydrate complex (LCC) and C=O in xylan were destroyed and the content of inter-molecular H-bonds O(6)H…O(3’) decreased by 47.2%, while the content of intra-molecular H-bonds of O(2)H…O(6) and O(3)H…O(5) increased by 9.5% and 47.0%, respectively. The crystallinity and the crystallite size decreased by 20.8% and 42.22%, respectively, and the cellulose crystalline structure changed from cellulose crystalline I to cellulose crystalline II. The specific surface area increased from 0.15 to 10.11 m2/g after the [Amim]Cl pretreatment. The glucose recovery increased by 10.3 times after being pretreated with [Amim]Cl, compared with the unpretreated sample.
  • Researchpp 1041-1051Zhang, C., Song, Z., Shi, H,. Fu, J., Qiao, Y., and He, C. (2017). "The effects of pre-treatments and low-temperature pyrolysis on surface properties of biochar from sunflower straw as adsorption material," BioRes. 12(1), 1041-1051.AbstractArticlePDF
    Carbon adsorbent materials that were prepared from sunflower straw by a combination of pre-treatment and low-temperature pyrolysis showed better adsorption compared with untreated carbon. Four different pre-treatment agents (steam, alkali (KOH), phosphoric (H3PO4), and salt (ZnCl2)) were analyzed with respect to their effects on the maximum surface area and the micropore area. Samples were measured by thermogravimetric analysis (TGA), X-ray powder diffraction (XRD), scanning electron microscopy (SEM), surface area analysis, and pore size analysis. The surface area, pore volume, and N2-adsorption capacity of the samples were closely correlated with the pre-treating agent. A biochar with a maximum surface area of 877.6 m2/g and a micropore area of 792.8 m2/g was prepared with phosphoric acid (H3PO4) as the pre-treatment agent at a temperature of 400 °C. The main result of the one-stage pre-treatment procedure was the number of micropores. The two-stage, low-temperature pyrolysis procedure focused on the volume of the pores. Carbonized sunflower straw, with pretreated and low-temperature pyrolysis procedures, was judged to be a highly effective and economic method to prepare carbon adsorbents.
  • Researchpp 1052-1063Farías-Sánchez, J., Velázquez-Valadez, U., Pineda-Pimentel, M. G., López-Miranda, J., Castro-Montoya, A. J., Carrillo-Parra, A., Vargas-Santillán, A., and Rutiaga-Quiñones, J. G. (2017). "Simultaneous saccharification and fermentation of pine sawdust (Pinus pseudostrobus L.) pretreated with nitric acid and sodium hydroxide for bioethanol production," BioRes. 12(1), 1052-1063.AbstractArticlePDF

    With the purpose of taking advantage of pine sawdust residue coming from a sawmill located in Michoacán, México, a pretreatment with nitric acid and sodium hydroxide was performed. Also, the production of bioethanol by enzymatic hydrolysis was investigated. Using a response surface method, the intermediate points for the optimal HNO3 concentration were determined. Results showed that using HNO3 as a pretreatment leads to higher ethanol yields at an optimal concentration of 10.90% HNO3. After a 30-min pretreatment with 10.90% HNO3 at 114.32 °C, followed by 1% NaOH and enzymatic hydrolysis performed in shaker at a pH of 4.8 and 150 rpm for 72 h, with an enzyme loading of 25 FPU/g of total carbohydrates, the reducing sugars concentration was 99.2% (conversion of polysaccharides to monomers). On the other hand, the ethanol yield obtained from the simultaneous saccharification and fermentation treatment was 15.0 g/L, and the separate hydrolysis and fermentation was 17.1 g/L at a pH of 4.8 and 150 rpm with 1X107 Cel/mL of Saccharomyces cerevisiae and an enzymatic loading of 25 FPU/g of total carbohydrates. When comparing the results obtained with literature data, it is concluded that this procedure is suitable to exploit the lignocellulosic wastes from the Indigenous Community of San Juan Nuevo Parangaricutiro, Michoacán, Mexico.

  • Researchpp 1064-1076Jin, K., Cui, H., Liu, X., and Ma, J. (2017). "Topochemical correlation between carbohydrates and lignin in Eucommia ulmoides cell wall from tissue to cell level," BioRes. 12(1), 1064-1076.AbstractArticlePDF

    The efficient conversion of biomass into biofuels is closely associated with the topochemistry of the cell wall. In this study, the topochemical correlation between carbohydrates and lignin in the Eucommia ulmoides cell wall was investigated in situ by confocal Raman microscopy. The carbohydrates and lignin were mainly collocated in the secondary wall of the fiber, ray parenchyma, and vessel in E. ulmoides. High carbohydrates were associated with low lignin or vice versa, indicating that a high concentration of carbohydrates leads to a drop in the degree of lignification. Furthermore, the band intensity ratio of S- and G-lignin to carbohydrates (I1333/I2889 and I1274/I2889) in morphologically distinct regions of fiber was calculated. In accordance with the wet chemical analysis, a higher ratio of lignin to carbohydrates was observed within the middle layer of the 3-year-old E. ulmoides fiber secondary wall. The results potentially extend the current understanding of the carbohydrate and lignin topochemistry in woody biomass and may facilitate an efficient wood bioconversion process in future biorefineries.

  • Researchpp 1077-1089Tu, Y., Peng, Z., Xu, P., Lin, H., Wu, X., Yang, L., and Huang, J. (2017). "Characterization and application of magnetic biochars from corn stalk by pyrolysis and hydrothermal treatment," BioRes. 12(1), 1077-1089.AbstractArticlePDF

    Two novel magnetic biochar composites (FeC-H and FeC-P) were synthesized using corn stalks and ferrous sulfate through hydrothermal method and traditional pyrolysis, respectively. The samples were characterized by Fourier transform infrared spectroscopy (FTIR), X-ray powder diffraction (XRD), vibrating sample magnetometer, and particle size analyzer. Batch experiments were conducted to investigate the ability of those samples to absorb aqueous phosphate. FeC-H had lower surface area than FeC-P, but more hydrophilic functional groups were detected on the rough surface of FeC-H. The impregnated iron was present as Fe3O4 in the prepared magnetic biochar composites. The introduced Fe3O4 resulted in high performance of magnetic separation and also played the role as adsorption sites for phosphate. FeC-H and FeC-P demonstrated higher sorption capacity than bare Fe3O4 due to the highly dispersed and smaller crystalline sizes of Fe3O4 particles loaded in corn stalk derived-biochar support. FeC-H had the best performance, with Langmuir adsorption capacity as high as 5.04 mg/g for phosphate. These results indicate that the magnetic biochar composites prepared from corn stalks by hydrothermal method (FeC-H) have potential as a high-efficiency and cost-effective adsorbent for phosphorus removal from wastewater.

  • Researchpp 1090-1101Nikmatin, S., Syafiuddin, A., and Irwanto, D. A. Y. (2017). "Properties of oil palm empty fruit bunch-filled recycled acrylonitrile butadiene styrene composites: Effect of shapes and filler loadings with random orientation," BioRes. 12(1), 1090-1101.AbstractArticlePDF

    Exploration of natural resources as composite fillers is still under intensive investigation. Previous works mention that nano-size natural fillers provide an alternative solution to improve certain composite properties compared with macro- and micro-size nanofibers. This work prepared biocomposites formulated from recycled acrylonitrile butadiene styrene (ABS) reinforced by nano powders or long fibers of oil palm empty fruit bunch (OPEFB). Composite properties in terms of density, Fourier transform infrared spectroscopy, surface morphology, melt flow rate, tensile strength, impact strength, and hardness were studied. The density of all composites generally increased with increasing filler loading. Composites with nano powder fillers had lesser voids than those composites with the long fiber. Melt flow rate of all composites fluctuated with filler loadings. Increasing filler loadings for composites with long fiber increased brittleness. By contrast, composites with nano powder fillers were more elastic at the higher filler loading. It was confirmed that impact and hardness properties of the composites with nano powder fillers increased with increasing filler loading. Moreover, composites with long fiber fillers decreased their impact and hardness properties with filler loadings increase.

  • Researchpp 1102-1111Sujová, A., Michal, J., Kupčák, V., and Dudík, R. (2017). "The impact of international trade of raw wood to the economic growth of forest-based sectors in the Czech and Slovak republics," BioRes. 12(1), 1102-1111.AbstractArticlePDF
    International trade metrics can indicate the competitive advantage of the industry in international markets. However, the export of the raw materials utilized by the industry can influence company and industry performance negatively. This article assessed the effectiveness of the international trade with raw wood and its impact on the economic results of the industry. A system of indicators was formed to measure the international trade impact on the industry performance, and the following hypothesis was established: increasing the international trade with raw wood influences the economic growth of the industry negatively. The results confirmed the hypothesis, showing that the growth of export volume and also import of raw wood decreased industry performance during the monitored period. In the forestry sector, the more significant influence appeared in revenues, which influenced the profit most in the timber industry. Other findings demonstrated that the international wood trade in the Czech Republic and the Slovak Republic does not create a comparative advantage, but decreases competitiveness of the forestry sector.
  • Researchpp 1112-1127Colson, J., Kovalcik, A., Kucharczyk, P., and Gindl-Altmutter , W. (2017). "Reinforcement of poly(lactic acid) with spray-dried lignocellulosic material," BioRes. 12(1), 1112-1127.AbstractArticlePDF

    Effects of the addition of spray-dried lignocellulosic material in polylactic acid (PLA) were evaluated in this work. The lignocellulosic material was produced by spray-drying unbleached fibrous material provided by a paper mill. Beforehand, this material was made hydrophobic in the sizing step of the papermaking process. We propose that size present on the lignocellulose powder may act as a potential alternative to commonly-used coupling agents in the compounding of cellulosic filler with PLA. The lignocellulose powder was compounded with PLA in various amounts by extrusion and injection-moulding. Homogeneous dispersion of the lignocellulose powder in PLA was achieved. However, comprehensive mechanical and microscopic characterisation revealed only minor positive effects of the filler on PLA in a limited number of cases. Further investigation by gel permeation chromatography (GPC) showed a reduction of the average molar mass of the PLA matrix with increasing filler content, partly due to the residual inorganic matter in the spray-dried powder. This effect overshadowed the homogeneous dispersion and resulted in composites with weaker mechanical properties in most cases.

  • Researchpp 1128-1135Liang, T., and Wang, L. (2017). "Thermal treatment of poplar hemicelluloses at 180 to 220 °C under nitrogen atmosphere," BioRes. 12(1), 1128-1135.AbstractArticlePDF

    Hemicelluloses were separated from poplar wood and exposed to thermal treatment. Changes in chemical content were investigated from 180 °C to 220 °C in a nitrogen atmosphere. Fourier transform infrared spectroscopy, X-ray diffraction, and differential thermal gravimetric analysis were used to characterize the hemicellulose before and after the thermal treatment. The effects of temperature on hygroscopicity and color were measured. The results showed that hemicelluloses were sensitive to temperature. β-glucosidic bonds and side chains in hemicelluloses were cleaved around 180 °C, and the increased temperature promoted the breaking process. Esterification reactions happened during the treatment. When the treatment temperature reached 220 °C, all side chains broke down, and partial carbonization occurred. Therefore, the color became darker, and the hydrophobicity increased. This study could help to explain the changes in wood that occur during thermal treatment.

  • Researchpp 1136-1149Yang, H., Li, J., Mo, L., and Xu, J. (2017). "Gas-trap capturing of enzyme inhibitors in explosion gas from the pretreatment of corn stalk with dilute-sulfuric acid steam," BioRes. 12(1), 1136-1149.AbstractArticlePDF

    In order to reduce production costs, heated explosion gases generated from dilute-sulfuric acid catalytic steam explosion (SE) pretreatment in the pilot production were recovered to provide energy for subsequent steps and to supply heated water (gas condensate water) for the washing steps. However, organic compounds in the explosion gases accumulated in the circulating water during continuous production, which affected subsequent enzymatic hydrolysis steps. The aim of this work was to investigate the major organic components in SE pretreatment gaseous products, their formation mechanism, and their inhibitory effects on the subsequent enzymatic hydrolysis of pretreated corn stalk.

  • Researchpp 1150-1164Chen, W., Zhou, X., Shi, S., Nguyen, T., and Chen, M. (2017). "Thermal behavior and kinetic analysis of enzymatic hydrolysis lignin and high-density polyethylene during co-pyrolysis," BioRes. 12(1), 1150-1164.AbstractArticlePDF
    The thermal behaviors of enzymatic hydrolysis lignin (EHL), high-density polyethylene (HDPE), and their blend (50:50 wt.%) were revealed using thermogravimetric analysis coupled with Fourier transform infrared spectroscopy (TG-FTIR). A first-order reaction model (Coats-Redfern) and non-isothermal model-free method (Ozawa-Flynn-Wall) were applied to the TG experimental data to determine the pyrolysis kinetic parameters. The results showed that H2O and CO2 were first released from the EHL due to the degradation of the weakly linked side chains. The degradation of lateral chains, the breakage of aromatic series in the EHL structure, and the β scission of HDPE led to the formation of H2O, CO2, C=O, aromatics, alkanes, and alkenes. Low intensities of H2O, CO2, alkanes, and alkenes were also observed in the final pyrolysis stage due to the degradation of lignin groups. Interactions during co-pyrolysis were observed in the pyrolysis stages of 390 to 542 °C and 563 to 790 °C. The activation energy values of EHL, HDPE, and their blend obtained by the Coats-Redfern method were 48.0 to 94.4 kJ/mol, 230.2 kJ/mol, and 42.7 to 260.1 kJ/mol, respectively. When the Ozawa-Flynn-Wall method was applied, activation energy ranges of 121.4 to 243.7 kJ/mol, 143.5 to 335.9 kJ/mol, and 74.8 to 260.9 kJ/mol for EHL, HDPE, and their blend, respectively, were observed.
  • Researchpp 1165-1178Todhanakasem, T., and Jittjang, S. (2017). "Evaluation of cellulase production by Zymomonas mobilis," BioRes. 12(1), 1165-1178.AbstractArticlePDF

    Z. mobilis has been widely studied as a potential microbe for consolidated bioprocessing to convert lignocellulosic biomass to fermentable sugars while at the same time producing ethanol. To achieve this goal, Z. mobilis must be evaluated for the production of cellulolytic enzyme. This work reports on the potential of intracellular and extracellular crude extracts from Z. mobilis ZM4 and TISTR 551 to hydrolyze various cellulosic materials including carboxymethylcellulose (CMC), delignified rice bran, microcrystalline cellulose, and filter paper. Crude intracellular extracts from ZM4 and TISTR 551 showed high endoglucanase activity with CMC substrates at an optimal pH of 6 to 7 and temperature range of 30 to 40 °C. The endoglucanase activity from the crude extracts was significantly higher than the exoglucanase activity. Of the high crystalline celluloses substrates tested, the best results were obtained for the hydrolysis of delignified rice bran by crude intracellular enzyme extracts of Z. mobilis TISTR 551.

  • Researchpp 1179-1189Jiménez-Leyva, M., Beltrán-Arredondo, L. I., Cervantes-Gámez, R., Cervantes-Chávez, J., López-Meyer, M., Castro-Ochoa, D., Calderón-Vázquez, C. L., and Castro-Martínez, C. (2017). "Effect of CMC and MCC as sole carbon sources on cellulase activity and egIS gene expression in three Bacillus subtilis strains isolated from corn stover," BioRes. 12(1), 1179-1189.AbstractArticlePDF
    Cellulolytic activities in Bacillus subtilis have been demonstrated and it is known that the eglS gene encodes an endoglucanase that could play a key role. Three Bacillus subtilis strains (RZ164, RS351, and RS273) isolated from corn stover with contrasting cellulase activity were examined in this work. The aim was to analyze the influence of eglS gene on the ability of bacteria to grow on a liquid medium supplied with carboxymethyl cellulose (CMC) or microcrystalline cellulose (MCC) as sole carbon sources. All strains displayed similar growth in CMC medium and comparable exoglucanase and endoglucanase activity. However, the expression of eglS did not correlate among strains. On the other hand, when MCC was the carbon source tested, the growth of RS351 was higher than that obtained by RZ164 and RS273 strains. This behavior could be related to the level of cellulase activities displayed by this strain. Besides, eglS expression was higher in RS351 strain, suggesting a direct participation of this enzyme when the carbon source is MCC. Taken together, eglS could be involved in different roles exerted by these strains on either exo- or endoglucanase activity and under either substrate. The enzymes described here could be considered good alternatives for biomass conversion.
  • Researchpp 1190-1200Cheng, Z., Yang, R., and Liu, X. (2017). "Production of bacterial cellulose by Acetobacter xylinum through utilizing acetic acid hydrolysate of bagasse as low-cost carbon source," BioRes. 12(1), 1190-1200.AbstractArticlePDF
    Bacterial cellulose (BC) is a promising and renewable nanomaterial due to its unique structural features and appealing properties. Intensive study on BC preparation has been mainly focused on biosynthesis by certain bacteria, while the high economic costs of fermentation, especially the carbon sources, remain challenges to its application. In this study, bacterial cellulose was synthesized by Acetobacter xylinum with the acetic acid hydrolysate of bagasse used as carbon source. After the bagasse was pretreated by acetic acid, the components in hydrolysate and the removal rate was investigated, and the pretreatment conditions were optimized as follows: temperature of 160 °C, heating time of 60 min, addition of acetic acid of 2.0% (m/m), and solid-to-liquid ratio of 1/5. Prior to Acetobacter xylinum cultivation, the hydrolysate was detoxified by activated carbon. The detoxification process was very efficient for BC production, with a yield up to 2.13 g/L when the dosage of activated carbon was 5% (m/V). Furthermore, the obtained BC was characterized by scanning electron microscopy (SEM), which showed that the ribbons width of BC was between 30 and 80 nm. X-ray patterns showed the crystallinity value was 74.6 % and the crystallinity index (CI%) was 66.5 %, which also evidenced the presence of peaks characteristic of Cellulose I polymorph. In conclusion, it is feasible to produce BC from bagasse hydrolysate. This model of waste recycling could aid in the development of sustainable strategies.
  • Researchpp 1201-1215Cai, C., Liu, Q., Tan, J., Wang, T., Zhang, Q., and Ma, L. (2017). "Conversion of cellulose to 5-hydroxymethylfurfural using inorganic acidic catalysts in the presence of pressurized water steam," BioRes. 12(1), 1201-1215.AbstractArticlePDF

    Traditionally, 5-hydroxymethylfurfural (HMF) is produced by using a water-organic solvent medium, which inevitably increases production costs and adds subsequent separation processes. To minimize cost and/or toxic organic solvent usage, this study presents an effective pathway for producing HMF from cellulose. The process uses a fixed bed reactor with a steam stripping process in which the cellulose is converted into HMF and other products in the presence of acidic inorganic salts. In the process, the cellulose was hydrolyzed to glucose, which was followed by isomerization to fructose and fructose dehydration into HMF. The produced HMF was easily vaporized into the gas phase, which avoided its conversion into undesired byproducts. An acceptable HMF yield of 28.2 mol% was obtained using KH2PO4 as the catalyst at 270 °C. This technology could be used to obtain both HMF and furfural (FF) from different lignocellulosic biomasses. This stripping technology has advantages such as the lack of organic solvents, showing an alternative and green HMF and/or FF production from lignocellulosic biomass.

  • Researchpp 1216-1227Kılıç, M. (2017). "Determination of the surface roughness values of Turkish red pine (Pinus brutia (Ten.)) woods," BioRes. 12(1), 1216-1227.AbstractArticlePDF
    The aim of this study was to determine the surface roughness values of Turkish red pine samples obtained from the seven natural growth areas in Turkey. The samples were cut with a circular saw, planed with a thickness machine, and sanded with a sanding machine (with No. 80 sandpaper). After the samples were processed as radial and tangential surfaces in the machines, their surface roughness values (Ra, Ry, and Rz) were measured in accordance with ISO 4288 (1996). According to the statistical results, the lowest surface roughness values were in the samples obtained from the Muğla and Samsun areas on the tangential surfaces that were processed with the thickness machine.
  • Researchpp 1228-1245Huabcharoen, P., Wimolmala, E., Markpin, T., and Sombatsompop, N. (2017). "Purification and characterization of silica from sugarcane bagasse ash as a reinforcing filler in natural rubber composites," BioRes. 12(1), 1228-1245.AbstractArticlePDF
    This work studied the chemical composition, cure characteristics, and morphological and mechanical properties of natural rubber (NR) compounds filled with silica, which was derived from bagasse ash (BA). The BA filler underwent various preparation processes (untreated, hydrochloric acid (HCl)-treated, and HCl/ammonium fluoride (HCl/NH4F) extracted). The results revealed that the main functional group of the BA was silica. After purification by HCl and HCl/NH4F, the silica content increased from 77.2% to 90.6% and 97.0%, respectively. Longer cure times and lower crosslinking were obtained after purifying the silica. Treatment of silica with HCl/NH4F improved the tensile strength and compression set when added at 15 parts per hundred rubber (phr) loading. Purification with HCl and HCl/NH4F acted as an obstacle to rubber-rubber crosslinking, but helped to moderate the filler–filler interaction. The elongation range for the NR containing the BA silica in this work was 900% to 1,100%. The use of HCl/NH4F-extracted silica in NR vulcanizates had no effect on the lightness, while the untreated and HCl-treated silica displayed decreased lightness. The silica from BA is recommended for use as reinforcing filler in NR compounds if treated with HCl followed by NH4F extraction before use. The optimal loading of the treated silica was 15 phr.
  • Researchpp 1246-1262Zhao, W., Luo, L., Wang, H., and Fan, M. (2017). "Synthesis of bamboo-based activated carbons with super-high specific surface area for hydrogen storage," BioRes. 12(1), 1246-1262.AbstractArticlePDF

    Activated carbons (ACs) were developed from the agricultural by-products of moso bamboo by pyrolysis carbonization and the KOH activation process. N2 adsorption-desorption at 77 K, thermogravimetric analysis (TG), X-ray photoelectron spectrometry (XPS), element analysis (EA), X-ray diffraction (XRD), scanning electron microscopy (SEM), high- resolution transmission electron microscopy (HRTEM), and Fourier transform infrared spectroscopy (FTIR) were used to investigate the synthesis process, the impact of the weight ratio of KOH/bamboo charcoal (BC), and the characteristics of the bamboo charcoal and ACs produced. The results showed that the developed bamboo ACs achieved surface areas (SBET) as high as 3208 m2/g and micropores volumes (VDR) as high as 1.01 cm3/g. The carbonation and activation of the bamboo resulted in the enhancement of the microstructure of the bamboo ACs, and hence improvements in the sorption behavior and storage capacity. The highest hydrogen storage capacities achieved were 6.6 wt.% at 4 MPa and 2.74 wt.% at 1 bar, both at 77 K, which were much higher than those of a well-known commercial activated carbon.

  • Researchpp 1263-1272Li, Q., Wang, A., Ding, W., and Zhang, Y. (2017). "Influencing factors for alkaline degradation of cellulose," BioRes. 12(1), 1263-1272.AbstractArticlePDF

    Different factors that influence the alkaline degradation of cellulose in the pulping process were considered in this study. The factors were the reaction temperature, reaction time, dosage of NaOH, and metal ions. Microcrystal cellulose (MCC) was applied as the model compound. To measure the influence of different metal ions on the alkaline degradation of cellulose, K+ and Mg2+ were added into the reaction system. The Fourier transform infrared (FTIR) spectra of the MCC in the solution with and without K+ and Mg2+ were analyzed to clarify the reaction mechanism of the alkaline degradation of cellulose and MCC. Alkaline degradation increased with increasing reaction temperature, reaction time, and alkali concentration. When the reaction temperature was above 80 °C, the reaction time was above 2 h, or the alkali content was below 5 g/L, the degradation ratio of MCC decreased. The amount of degraded MCC and the concentration of glucose in the reaction solution exhibited a nearly linear relationship when the alkali quantity increased from 0 g/L to 5 g/L. K+ and Mg2+ had an opposite impact on the alkaline degradation. While the K+ promoted the alkaline degradation of cellulose, the Mg2+ inhibited it, along with an increase of the dosage of the two metal ions.

  • Researchpp 1273-1287Daud, S., Ismail, H., and Abu Bakar, A. (2017). "A study on the curing characteristics, tensile, fatigue, and morphological properties of alkali-treated palm kernel shell-filled natural rubber composites," BioRes. 12(1), 1273-1287.AbstractArticlePDF

    Effects of alkali treatment of palm kernel shells (PKS) were investigated relative to curing characteristics, tensile properties, and fatigue of PKS-filled natural rubber (NR) composites. The PKS powder was subjected to alkali treatment using 5% sodium hydroxide. The treated PKS was incorporated into the NR composites during compounding, with the concentrations of the composites ranging from 5 to 20 phr. The properties of treated PKS-filled NR composites were compared with those of untreated PKS-filled NR composites. The cure times, scorch times, and maximum torque values were all lower for alkali-treated PKS/NR composites compared with those of untreated PKS/NR composites. Tensile strength and elongation at break were higher for treated PKS composites, while the moduli (M100 and M300) were lower than those of untreated PKS/NR composites. The fatigue tests for treated PKS/NR composites also showed higher fatigue values than the untreated PKS/NR composites. Scanning electron microscopy revealed that the higher tensile strength, elongation at break, and fatigue values of treated PKS/NR composites were due to the removal of hemicellulose and lignin in PKS fillers. This removal increased in the surface roughness of the filler and led to improved rubber-filler adhesion.

  • Researchpp 1288-1299Wen, Y., Song, J., Chen, J., Sun, Y., and Yang, W. (2017). "Synergistic conductivity and electromagnetic interference shielding effectiveness of epoxy/carbon fiber and epoxy/carbon black composites via mixing with bamboo charcoal," BioRes. 12(1), 1288-1299.AbstractArticlePDF

    This study was aimed at preparing electromagnetic interference (EMI) shielding materials based on carbon black (CB), carbon fiber (CF), bamboo charcoal (BC), and epoxy resin. The effects of adding bamboo charcoal on the mechanical properties and electrical resistivity of epoxy composites were studied. Scanning electron microscopic (SEM) analysis, electrical resistivity, and electromagnetic interference (EMI) shielding effectiveness were also investigated. The composites were prepared at 120 °C by the curing-molding method through blending the fillers in epoxy resin. The results revealed that the BC/CB and BC/CF composites had perfect conductive network structure and resulted in better dynamic thermal mechanical properties. The electrical resistivity declined with the increase of bamboo charcoal contents; consequently, the EMI shielding effectiveness improved gradually. The lowest electrical resistivity, down to 0.071 Ω·m, corresponded to the best EMI shielding effectiveness of BC/CF composites, which could be above 60 dB over a frequency range of 30 MHz to 1500 MHz while the carbon fiber content was at 40 wt.%.

  • Researchpp 1300-1316Chen, Z., and Wang, D. (2017). "Power consumption for core scraping in the separation of rind-pith from corn stalk," BioRes. 12(1), 1300-1316.AbstractArticlePDF
    In order to study the energy consumption of separation of pith and rind of corn stalk, a self-designed corn stalk separating unit was adopted in this work to measure the energy consumption by an electric power method. Four parameters—the rotational speed of pith-stripping, clearance between teeth and panel, feeding speed of stalk, and helix angle—were selected as influencing factors. By choosing the three indicators, effective specific energy (ESE), total specific energy (TSE), and energy utilization ratio (EUR) as evaluation indexes, response surface analysis was employed to obtain the influence law model of various experimental factors on evaluation indexes based on orthogonal tests. After all evaluation indexes, working efficiencies, and stalk scraping effects were taken into a comprehensive consideration, the working parameters of the core scraping mechanism were selected as follows: 840 r/min for the rotational speed of pith-stripping, 413 r/min for the feeding speed, 1.56 mm for the tooth-panel clearance, and 25° for the helix angle of scrapper blade. In this case, ESE, TSE, and EUR were 2.21 Wh·kg-1, 10.73 Wh·kg-1, and 22.29%, respectively. The results could be applied to the design and optimization of separation of pith and rind of corn stalk.
  • Researchpp 1317-1334Xing, X., Li, Y., Xing, Y., Xu, B., Fan, F., Zhang, X., and Xing, J. (2017). "Co-combustion characteristics and kinetic analyses of biomass briquette and municipal solid waste in N2/O2 and CO2/O2 atmospheres," BioRes. 12(1), 1317-1334.AbstractArticlePDF

    The thermal behavior of cotton straw briquette (CSB), municipal solid waste (MSW), and their blends was investigated using a thermogravimetric analyzer under N2/O2 and CO2/O2 atmospheres at 20 °C/min from an ambient temperature to 1000 °C. The kinetics and synergistic interaction between MSW and CSB in the co-combustion process were evaluated. The results indicated that MSW blended with CSB improved the ignition and burnout characteristics of the blends, while decreasing the comprehensive combustion characteristics index. The suitable proportions of CSB were less than 60% and 40% separately under 80N2/20O2 and 80CO2/20O2 atmospheres, respectively. The inhibitory effect of CO2 induced burnout temperature and residual mass increased, and the high-temperature stage reaction varied. Kinetic analysis of the blends indicated that blending with CSB could promote MSW combustion in the first reaction stage, while the second and third decomposition stages were complicated because of the synergistic interaction between MSW and CSB in the co-combustion process. The nth order reaction model fit the mass loss of theca-combustion process for the blends very well.

  • Researchpp 1335-1343Liu, X., Wu, Z., and Zhang, J. (2017). "The effects of heating treatment on the tensile properties of palm petioles fiber," BioRes. 12(1), 1335-1343.AbstractArticlePDF

    Palm petioles fibers (PPF) are used widely in China to make mattresses. The changes of the properties of PPF after heat treatment is an important factor that should be considered. This study focuses on the fiber tensile test after heat treatment under different temperatures and at different times. As the temperature of treatment was increased, the Young’s modulus of PPF increased, while the breaking strength and elongation declined. The turning point of the tensile properties was 160 °C. The heating time also had a significant influence on the tensile properties. As the heating time increased, the Young’s modulus grew, while the breaking strength and elongation declined.

  • Researchpp 1344-1357Zhou, Z. R., Zhao, M. C., Gong, M., and Wang, Z. (2017). "Variation of density and dynamic modulus of elasticity of poplar veneer and its impact on grade yield," BioRes. 12(1), 1344-1357.AbstractArticlePDF

    To maximize the value of poplar wood in manufacturing of laminated veneer lumber (LVL), its radial (from pith to bark) and longitudinal (from bottom to top) variations were examined in terms of the density and dynamic modulus of elasticity (ED) of veneer. The veneer sheets were rotary-peeled from seven representative poplar butt bolts (the bottom part of a stem) and seven representative poplar second bolts (the middle part of a stem). A grading strategy for selecting veneer was proposed based on the requirements of LVL products. In this study, the ED value of each poplar veneer sheet was non-destructively measured by the ultrasonic method. The results showed that there was a weak correlation between veneer density and ultrasonic wave velocity. The bolt class (butt or second bolt) did not significantly influence the variation of veneer density and ED. However, the among-bolt variation played a significant role in the variability. A large difference in diameter between two ends of a bolt (i.e. the within-bolt variation) resulted in a low veneer ED. According to the sorting criteria of Chinese Standard “Laminated Veneer Lumber”, the estimated grade yields of the poplar veneer studied were 45.2% for G1, 39.3% for G2, 13.1% for G3, and 2.4% for G4.

  • Researchpp 1358-1368Kang, C. W., Wen, M. Y., Park, H. J., Kang, H. Y., Kang, S. G., and Matsumura, J. (2017). "Changes in some mechanical and physical properties and anatomical structure of spruce and larch wood after fire-retardant treatment," BioRes. 12(1), 1358-1368.AbstractArticlePDF
    Changes in the physical and mechanical properties and anatomical structures of spruce (Picea) and larch (Larix) specimens before and after fire-retardant impregnation were studied. Results indicated that the static modulus of elasticity (MOE), dynamic modulus of elasticity (DMOE), and the Brinell hardness of the specimens decreased for both wood species upon post-treatment. This could be accounted for by the degradation of hemicelluloses by the phosphorus-based compound, the minute cracks in the latewood cell wall, and the enlarged width of the cell lumen of the specimen resulting from the vacuum-pressure treatment. However, the decreased ratio of the MOR and DMOE to density contributed to lower sound transmission, which is expected to be important in a housing environment.
  • Researchpp 1369-1381Hosseinzadeh, A. (2017). "The effect of using the flour of kiwi (Actinidia sp.) twigs and refined fibers in the production of polypropylene/wood plastic composites," BioRes. 12(1), 1369-1381.AbstractArticlePDF
    This study uses a combination of wood flour, obtained from kiwi twigs, together with refined fibers and polypropylene material to make a hybrid composite of polypropylene/wood/fiber. The materials were mixed in a twin-screw extruder, and the samples were made via an injection molding method. The tensile, flexural, and impact strengths, as well as the physical characteristics were measured based on ASTM standards. The results indicated that when the flour dimensions were reduced from 20 mesh to 40 mesh, the tensile and flexural strength, tensile and flexural modulus, and elongation at break were reduced. The notched impact strength, water absorption, and thickness swelling during 2 h and 24 h of immersion in water, and the water absorption and thickness swelling during 2 h immersion in boiling water, increased. In addition, by increasing the amount of refined fiber instead of kiwi wood flour, the tensile and flexural strength, tensile and flexural modulus, elongation at break, and the notched impact strength wereincreased. The water absorption and thickness swelling during 24 h of immersion in water and the water absorption and thickness swelling during 2 h immersion in boiling water were decreased.
  • Researchpp 1382-1394Ghaje Beigloo, J., Eslam, H. K., Hemmasi, A. H., Bazyar, B., and Ghasemi, I. (2017). "Effect of nanographene on physical, mechanical, and thermal properties and morphology of nanocomposite made of recycled high density polyethylene and wood flour," BioRes. 12(1), 1382-1394.AbstractArticlePDF
    The effects of the amount of nanographene on physical, mechanical, and thermal properties and morphology of the wood-plastic composites were investigated. This wood-plastic was made using recycled high density polyethylene (HDPE), nanographene, and wood flour. Four weight levels, 0, 0.5, 1.5, or 2.5 wt.% of nanographene, were combined with 70% polymeric matrix and 30% lignocellulosic material with an internal mixer. The results showed that by increasing the amount of nanographene up to 0.5% by weight, the flexural strength, flexural modulus, and notched impact strength of the composite increased. After adding 2.5 wt.% nanographene, these properties were reduced. By increasing the amount of nanographene, both the amount of residual ash and the thermal stability increased. Study of the images from scanning electron microscope (SEM) showed that the samples containing 0.5% of nanographene had less pores and were smoother than other samples.
  • Researchpp 1395-1402Olsson, C., and Westman, G. (2017). "Co-solvent facilitated in situ esterification of cellulose in 1-ethyl-3-methylimidazolium acetate," BioRes. 12(1), 1395-1402.AbstractArticlePDF
    The homogeneous conversion of cellulose to cellulose propionate with propionic acid anhydride in the ionic liquid 1-ethyl-3-methylimidazolium acetate and two different co-solvents, dimethyl sulfoxide and 1-methylimidazole, was studied. The software MODDE was used to generate an experimental design and evaluate the significance of the studied parameters. The methods 1H and 13C nuclear magnetic resonance (NMR) spectrometry and ion chromatography were used to analyze the obtained materials both qualitatively and quantitatively. The NMR spectrometry of dissolved cellulose esters confirmed there was covalent bonding with an even distribution pattern. From both ion chromatography and NMR spectroscopic data, it was concluded that by adding large amounts of co-solvent and using a high reagent-to-anhydroglucose unit ratio, it was possible to reduce the amount of acetylation caused by acetate anions in the ionic liquid. At the same time, it was shown that the reaction time and temperature was not at all significant in this respect. There was no notable difference detected in the degree of substitution between the reactions performed using dimethyl sulfoxide or 1-methylimidazole as a co-solvent.
  • Researchpp 1403-1416Xu, Y., Chen, M., and Zhou, X. (2017). "Improvement of the bondability of wheat straw treated by water vapor plasma for bio-composites manufacture," BioRes. 12(1), 1403-1416.AbstractArticlePDF
    Wheat straw (WS) was first modified with water vapor plasma to enhance its interfacial bonding performance. The treatment effects during the entire exposing process were investigated in terms of surface wettability, physicochemical characteristics, and mechanical properties of glued test-pieces (three different forms) using contact angle analysis, free energy analysis, scanning electron microscopy (SEM), atomic force microscopy (AFM), X-ray photoelectron spectroscopy (XPS), and shear strength analysis. The results showed that 180 s of plasma treatment time resulted in a low instantaneous and equilibrium contact angle of urea-formaldehyde (UF) – 40.8% and 46.5% lower, respectively, in comparison with that of the untreated WS exterior surface. Obvious etching morphology was observed on the WS surfaces and positive activation was detected, demonstrating a remarkable increase in the surface free energy and O/C ratio. With the water vapor plasma treatment, the use of electrochemical reaction to introduce polar groups and etching to produce glue nails, were effective methods for improving the bonding performance of the WS.
  • Researchpp 1417-1429Söğütlü, C. (2017). "Determination of the effect of surface roughness on the bonding strength of wooden materials," BioRes. 12(1), 1417-1429.AbstractArticlePDF
    The purpose of this study was to determine the effect of surface roughness on bonding strength in Oriental beech, cherry, Scots pine, and Taurus cedar woods. In conformance with this objective, after planing the wooden materials under different conditions, their surface roughness values were determined in accordance with various standards using scanning equipment. The bonding strength test specimens were prepared using polyvinyl acetate (PVAc) and polyurethane (PUR) adhesives after the wooden materials were separated into three groups of varying surface roughness values, after which bonding strength experiments were carried out. The data obtained from the experiments were evaluated statistically at a 95% level of confidence. According to the test results, the highest bonding strength was obtained in the Oriental beech (9.27 N/mm2), whereas the lowest bonding strength was obtained in the Scots pine (3.65 N/mm2). There was not a statistically significant difference between the bonding strength of the cherry and Oriental beech woods. The PVAc adhesive (7.61 N/mm2) produced more successful results than the PUR adhesive (5.63 N/mm2). Furthermore, it was found that in the specimens with low surface roughness values for each wood type and used adhesives had high bonding strengths.
  • Researchpp 1430-1446Ratnasingam, J., Ark, C. K., Mohamed, S., Liat, L. C., Ramasamy, G., and Senin, A. L. (2017). "An analysis of labor and capital productivity in the Malaysian timber sector," BioRes. 12(1), 1430-1446.AbstractArticlePDF

    The remarkable transformation of the Malaysian timber sector from a net-importer to a multi-billion-dollar export-oriented sector has become a success model for many other resource-rich countries throughout the world. In view of the increasing socioeconomic importance of the timber sector in this country, the productivity performance of the six major timber sub-sectors was investigated in this study. Productivity is defined as the ratio of output to input and was analyzed from the year 2010 through 2014. The productivity performance was evaluated based on certain input factors, namely labor and capital. Generally, the productivity of the timber sector can be regarded as stagnating. Furthermore, the value-added was affected due to high reliance on labor for production. Among the factors that account for this lack of productivity growth are the increased competition in the international market, small domestic market, improper industrial development policies, poor adoption of technology, and the high dependency on human capital.

  • Researchpp 1447-1462Rashid, B., Leman, Z., Jawaid, M., Ghazali, M. J., and Ishak, M. R. (2017). "Influence of treatments on the mechanical and thermal properties of sugar palm fibre reinforced phenolic composites," BioRes. 12(1), 1447-1462.AbstractArticlePDF

    Sugar palm fibre (SPF) was used to prepare composites with phenolic resin. The SPF underwent treatment with either sea water for 30 d or a 0.5% alkaline solution for 4 h. The composites contained 30% (vol.) SPF in a powdered form, and the composite samples were fabricated by a hot press machine. The effects of the fibre treatments on the mechanical (flexural, impact, and compressive), thermal, and morphological properties of the composites were analyzed. The SPF treatments considerably improved the mechanical properties of the composites compared with the untreated composite. The alkaline treatment resulted in the most improved flexural and impact strength of the composites. In contrast, the sea water treatment had the best results for improving the compressive strength. Morphological analyses indicated that the surface treatments improved the fibre-matrix bonding. The thermal degradation analysis showed that both the sea water and alkaline treatments of the SPF slightly affected the thermal stability of the composites. Consequently, SPF can be effectively used as an alternative natural fibre for reinforcing bio-composites.

  • Researchpp 1463-1478Mateus, M. M., Ventura, P., Rego, A., Mota, C., Castanheira, I., Bordado, j. M., and dos Santos, R. G. (2017). "Acid liquefaction of potato (Solanum tuberosum) and sweet potato (Ipomoea batatas) cultivars peels - pre-screening of antioxidant activity/ total phenolic and sugar contents," BioRes. 12(1), 1463-1478.AbstractArticlePDF
    In the present study, the liquefaction of both regular and sweet potato peels was conducted to investigate the bio-oil produced, the sugar and total phenolic content, and antioxidant activity. Initially, the bio-oil obtained after liquefaction was partitioned into two different fractions, a hydrophilic fraction and the other consisted of the portion that contained the apolar compounds. Afterward, the samples of the whole bio-oil, aqueous extract, and organic phase of both cultivars were analyzed by attenuated total reflection- Fourier Transform infrared (ATR-FTIR) spectroscopy, hydroxyl number, and acid value. This was done in combination with assessment of the sugar and total phenolic contents and antioxidant activity. The samples demonstrated a considerable content of phenolic moieties in their composition. The antioxidant activity, which was assessed by the 2,2-diphenyl-1-picrylhydrazyl radical method, revealed that the antioxidants of the liquefied products and its extracts were generally better than that of butylated hydroxytoluene. Glucose, sucrose, and maltose were identified and quantified within all of the samples.
  • Researchpp 1479-1490Kubš, J., and Kminiak, R. (2017). "The effect of selected factors on the milled surface quality of thermally modified solid beech," BioRes. 12(1), 1479-1490.AbstractArticlePDF

    The milling of thermally modified wood is a very broad topic that deserves attention. The acquired knowledge concerning the geometry of the tool and milling process may assist manufacturers in designing new tools and thus improving the efficiency and quality of the process. This article focuses on finding the differences in the roughness of wood surfaces after surface milling of native beech wood (Fagus sylvatica L.) and thermally modified beech wood at 190 °C and differing technological conditions, cutting speeds (20, 30, and 40 m/s), feed speeds (4, 8, and 11 m/min), and rake angles of the tool (15°, 20°, and 25°). In comparison with natural wood, thermal treatment had a positive effect on the quality of the wood surface after milling. The results also demonstrated an increased quality of surface finish with a decrease in feed speed and increase in cutting speed.

  • Researchpp 1491-1505Li, C., Li, J. B., Lei, C. Y., and Liu, P. H. (2017). "Preparation and in vitro release mechanisms of modified pectin matrix tablets for colon-targeted drug delivery," BioRes. 12(1), 1491-1505.AbstractArticlePDF
    To deliver bioactive components to the colon, an oral, colon-targeted, microparticle delivery system was developed based on pectin. Pectin was modified by mechanical activation, resulting in controllable release properties, as well as dramatic decreases in solubility. Mechanically activated pectins (MAP) were characterized by Fourier transformed infrared (FTIR) spectroscopy, nuclear magnetic resonance (1H-NMR) spectroscopy, differential scanning calorimetry (DSC), and scanning electron microscopy (SEM). The FTIR and 1H-NMR analyses revealed that after mechanical activation, the hydrogen bonds between pectin molecules were broken, and intermolecular crosslinking was decreased. The DSC analysis indicated that the thermal stability of pectin was decreased by mechanical activation. The SEM revealed that MAP particles were smaller, more uniform, and had smoother surfaces than unmodified pectin. An in vitro release assay and the study of drug release kinetics demonstrated that bovine serum albumin (BSA) release from MAP-containing matrix tablets was controllable. The results demonstrated that at a suitable pectin content and hydrophobicity level, matrix tablets prepared with MAP can exhibit good colon-targeted drug release.
  • Researchpp 1506-1531Lacoa, U., Velarde, G., Kay, M., Blanco, E., and Saloni, D. (2017). "Design and development of logistics models for residential and commercial biomass pellets for heat and power generation in the U.S.," BioRes. 12(1), 1506-1531.AbstractArticlePDF
    The U.S. is an important wood pellets producer for Europe, but in recent years there is special attention in the domestic market. This project developed mathematical logistics models in MatLab® that estimate distribution channels, transportation, and volumes for the domestic wood pellet demand. The models consider only demand in the northeastern U.S. based on current production in the Southeast. Two cases were studied: distribution to power plants and distribution to retail stores. Once the market needs were identified, logistics engineering principles and models were run to predict the distribution to different markets. Tools used in facility location and freight transportation analysis were run to provide an estimated logistic cost. One bulk pellet with 2 scenarios and 3 bagged pellet models (RISI 2016; 2017; 2018) with 2 scenarios were developed. After analyses for each model, it was concluded that wood pellet industry should direct its efforts to negotiate lower transport rates, which could represent a 70% cost reduction. While the wood pellet industry volume is smaller than the coal and chemical industries, the considerable cost difference indicates an opportunity to negotiate lower rates. The models developed can be used as tools to minimize the cost of distributing wood pellets to the northeast.
  • Researchpp 1532-1547Giacomozzi, D. E., and Joutsimo, O. (2017). "Drying temperature and hornification of industrial never-dried Pinus radiata pulps. 2. Voith Sulzer refining," BioRes. 12(1), 1532-1547.AbstractArticlePDF

    The results from Voith Sulzer refining, porosity, and morphology studies of bleached Pinus radiata fibers showed the main effects described for hornification in dried pulps compared with never-dried pulps. Dried pulps showed higher deformations, measured as an increase in kinks. However, these deformations were shown to be reversible, based on zero-span development after Voith Sulzer refining. It is hypothesized that the observed changes in refining energy, drainability, tensile, zero span, bulk, and optical properties upon drying can be explained based on a combination of mechanisms including delamination and microfibril disarrangement and aggregation in the cell wall. Results suggested that drying-induced deformations and changes in orientation of fiber wall segments were similar to those observed in processing. Solute exclusion and nuclear magnetic resonance results also confirmed expected decreases in pore volume and average pore size for dried pulps (pores under 220 nm in size) and increase in cellulose inner crystallinity upon drying.

  • Researchpp 1548-1565Sameni, J., Krigstin, S., and Sain, M. (2017). "Solubility of lignin and acetylated lignin in organic solvents," BioRes. 12(1), 1548-1565.AbstractArticlePDF

    The solubility of four lignin samples and their acetylated forms was determined in a series of organic solvents to investigate the relationship between solubility and the solubility parameter. The solubility parameter of lignin samples and acetylated lignin was calculated based on the number of atoms or groups on lignin units. Lignin samples were obtained by isolating lignin from lignocellulosic bioethanol residues (Lignin 1 [L1]), isolating lignin from kraft hardwood black liquor (Lignin 2 [L2]), commercial kraft softwood lignin (Lignin 3 [L3]), and commercial soda non-wood lignin (Lignin 4 [4]). The solubility of lignin in organic solvents was not predictable due to poor correlation between the solubility of lignin and its solubility parameter. However, the solubility of lignin in an organic solvent depended on the molecular weight and the aliphatic hydroxyl number of the lignin. L2, with a lower molecular weight than other lignin samples, had the highest solubility in organic solvents, and L3, with highest aliphatic hydroxyl number, had the lowest solubility in organic solvents. All acetylated lignins were soluble in most of the organic solvents. Furthermore, the molecular weights of the soluble parts of all four lignins in ethyl acetate were found to be lower than the original lignins.

  • Researchpp 1566-1578Fang, G., Chen, H. G., Chen, A. Q., Mao, K. W., and Wang, Q. (2017). "An efficient method of bio-chemical combined treatment for obtaining high-quality hemp fiber," BioRes. 12(1), 1566-1578.AbstractArticlePDF

    This bio-chemical study focuses on obtaining high-quality hemp fiber. The effects of the structures and properties of hemp fibers in different treatment periods were studied. Moreover, the changes of the surface morphology, chemical composition, and breaking tenacity of hemp fibers were researched by scanning-electron microscopy (SEM), Fourier transform infrared spectroscopy (FT-IR), fluorescence microscopy, and fiber tensile testing. The results showed that by virtue of the enzyme scouring process, alkali refining process, and bleaching process, the pectin, lignin, and hemicellulose and other impurities were removed. Through the single factor experiment, the optimal process conditions for the bio-chemical combination of the degumming process were obtained. These conditions included 10 g of dried hemp fibers, 15% (v/v) pectinase solution, a temperature of 50 °C, a duration of 120 min, pH 8.0 (phosphate buffer), a liquor ratio (w/v) of 1:10, and 0.0625 mol/L NaOH. In these conditions, the residual gum content and breaking tenacity were 4.8% and 49.8 cN/tex, respectively, indicating that the treated hemp fibers met the requirements of the spinning process.

  • Researchpp 1579-1592Lieskovský, M., Jankovský, M., Trenčiansky, M., Merganič, J., and Dvořák, J. (2017). "Ash content vs. the economics of using wood chips for energy: Model based on data from central Europe," BioRes. 12(1), 1579-1592.AbstractArticlePDF

    Biomass utilization is vital for developing sustainability in the bioenergy sector. In this work the effects of high ash content on the heating properties of wood chips were evaluated. In an analysis of 450 wood chips samples, the ash content, moisture content, and gross calorific value were determined, and a generalized linear model was created to identify the relationship between the gross calorific value and the ash content of the wood chips. The mean ash content of the analyzed wood chips samples was 2.64%, the mean moisture content was 38.8%, and the mean gross calorific value was 19.43 MJ kg-1. Statistical analyses showed that 49% of the gross calorific value variability was due to the ash content variability. A one percent increase in ash content resulted in a 0.11 MJ kg-1 decrease of gross calorific value. The estimated costs of ash disposal at various ash contents were calculated. Burning wood chips with 5% ash content would lead to depositing an extra 5.6 megatons in the US or 21.2 megatons in the EU, compared to burning wood chips with 2.5% ash content.

  • Researchpp 1593-1610Yao, X., Xu, K., Yan, F., and Liang, Y. (2017). "The influence of ashing temperature on ash fouling and slagging characteristics during combustion of biomass fuels," BioRes. 12(1), 1593-1610.AbstractArticlePDF

    Three typical biomass fuels—rice husk, rice straw, and corn cobs—were combusted to understand the effects of ashing temperature on ash fouling and slagging characteristics. The ashes generated from combustion at 600 °C and 815 °C were characterized thoroughly with regard to their chemical composition. The systematic slagging/fouling indices of biomass were used to study the effects of ashing temperature on ash fouling and slagging propensities. The results showed that ashing temperature had a remarkable influence on ash composition, particle size distribution, ash morphology, ash fusibility, and thermal properties. Increased ashing temperature resulted in the expansion of ash particles together with the volatilization of alkali metals in the form of inorganic salts. Morphology analysis indicated that high ashing temperatures promoted biomass ash slagging. Ash fusion points increased at elevated ashing temperatures, while the ash content decreased. As a result of the volatilization and decomposition of biomass ash, a four-step mechanism of weight loss was clearly identified by thermal analysis. All prepared biomass ashes resulted in slagging and fouling problems at different levels during the thermo-chemical conversion of biomass.

  • Researchpp 1611-1623Liu, Z., Wang, L., Jenkins, B. M., Li, Y., Yi, W., and Li, Z. (2017). "Influence of alkali and alkaline earth metallic species on the phenolic species of pyrolysis oil," BioRes. 12(1), 1611-1623.AbstractArticlePDF
    Bio-oil as an important renewable energy product has been successfully made from corn stalks and lignin via a fast pyrolysis process. This study investigated the effects of alkali and alkaline earth metallic species (AAEMs) on phenolic products in corn stalk and lignin pyrolysis oil. Corn stalks were demineralized with 0.5 M HCl, and lignin was doped with 0.2wt%, 2wt%, and 20wt% KCl and CaCl2, respectively. The pyrolysis experiments were conducted in a fixed bed tubular furnace ranging from 450 °C to 600 °C. It was found that AAEMs exert positive effects on the formation of char and gas and inhibit the production of bio-oil. The effect of KCl on the product distribution from lignin is somewhat stronger than CaCl2. Moreover, the content of P, HP, GP, and SP decreases after removal of AAEMs. KCl can promote the polymerization of light molecular aromatic hydrocarbons to increase the SP yield at 600 °C, whereas the effect on increase in P and HP content is relatively weaker than CaCl2. KCl and CaCl2 play notable roles in demethxylation and demethoxylation in increasing phenol content and removing the R group from the ring.
  • Researchpp 1624-1635Xu, K., Xu, G., Huang, Y., Liu, C., Kang, K., and Zheng, Z. (2017). "The influence of environmentally friendly plasticizer on the bio-durability of wood plastic composites," BioRes. 12(1), 1624-1635.AbstractArticlePDF
    The influence of epoxidized soybean oil (ESO) plasticizer on the mould and algal resistances of wood plastic composites (WPCs) was studied using artificial accelerated tests. The macro- and micro-morphology of the colonization of algae and mould on the surface and fracture morphology of the WPCs samples were observed by digital camera and scanning electron microscopy (SEM). The water absorption and thickness swelling rates of different WPCs specimens with various addition amounts of ESO were also tested. The results indicated that as more of the ESO was added, the mould or algal resistance became weaker, especially on the surfaces of the specimens, which became harshly colonized when the addition amount of ESO was beyond 15 phr. The colonization speed and intensity of the mould were higher than the algae at the same addition level of ESO and the same testing time. The hyphae and spores of mould, but not algae, were found on the inner fracture layers.
  • Researchpp 1636-1646Jutakanoke, R., Tolieng, V., Tanasupawat, S., and Akaracharanya, A. (2017). "Ethanol production from sugarcane leaves by Kluyveromyces marxianus S1.17, a genome-shuffling mediated transformant," BioRes. 12(1), 1636-1646.AbstractArticlePDF

    Kluyveromyces marxianus S1.17, obtained by electroporation-mediated genome shuffling between K. marxianus G2-16-1, a cellobiase-producing yeast, and Pichia stipitis JCM 10742T, gave a maximum ethanol production level (of 0.86 g/L) from the hydrolysate of dilute sulfuric acid treated sugarcane leaves when treated under aerobic conditions for 72 h, compared to the ethanol production level of 4.73 g/L from the acid-treated sugarcane leaves fermented by the simultaneous saccharification and fermentation process under oxygen-limited conditions. The total ethanol produced from sugarcane leaves by K. marxianus S1.17 was 5.59 g/L (0.10 g/g, dry weight).

  • Researchpp 1647-1661Adanur, H., Fidan, M. S., and Yaşar, S. S. (2017). "The technological properties of Oriental beech (Fagus orientalis Lipsky) impregnated with boron compounds and natural materials," BioRes. 12(1), 1647-1661.AbstractArticlePDF
    Impregnation, drying, and varnishing are performed to increase the usage life of wood material by making it resistant to chemical, physical, and biological agents. The most common wood protection procedures are chemical methods. Therefore, it is essential to develop new impregnation substances that do not harm the environment and human health but are still economically efficient. In this study, oriental beech (Fagus orientalis Lipsky) was impregnated with borax and boric acid in 1%, 3%, and 5% aqueous solutions. Quechua (Caesalpinia spinosa) was also used as a natural impregnation substance. The retention amount of the impregnated samples was examined for the oven-dried density, bending strength, elastic modulus, screw holding strength tests, compression strength parallel to the grain, and Bending strength parallel to the grain. The samples impregnated with borax had higher oven-dried density, bending strength, elasticity modulus in bending, and Bending strength parallel to the grain tests than samples treated with boric acid; however, the screw holding strength tests showed the opposite trend. The screw holding strength was higher in the impregnated samples than in controls. The bending strength, the elasticity modulus in bending, and the Bending strength parallel to the grain were lower in the control samples.
  • Researchpp 1662-1679Chen, D., Li, R., Bian, R., Li, L., Joseph, S., Crowley, D., and Pan, G. (2017). "Contribution of soluble minerals in biochar to Pb2+ adsorption in aqueous solutions," BioRes. 12(1), 1662-1679.AbstractArticlePDF

    Biochar is widely used as an adsorbent to remove heavy metals from aqueous solutions. To investigate the contribution of soluble minerals (mainly anions) to Pb2+ removal in solution, wheat straw biochar was washed with deionized water to remove soluble minerals. Batch adsorption was conducted using washed biochar (WBC) and unwashed biochar (BC) to absorb Pb2+. After washing, the pH and ash content of biochar were reduced, while the specific surface area and total pore volume were increased. Adsorption kinetics of Pb2+ onto BC and WBC were well fitted to the pseudo-second-order model (R2 > 0.99). Pb sorption on BC and WBC were better fit with the Langmuir model (R2 = 0.96 to 0.97) than the Freundlich model (R2 = 0.71 to 0.87). The Langmuir maximum adsorption capacity of Pb on BC was 99.7 mg g-1, which was 4.5-fold higher than that on WBC when the initial solution pH was 5.0. The concentration of SO42-, CO32-, SiO32-, and PO43- in the equilibrium solution was reduced by 69, 89, 97, and 41%, respectively, with the increase of initial Pb2+ concentration. The difference of Pb2+ adsorption capacity between BC and WBC proved that the soluble anions in biochar play an important role in Pb2+ sorption onto biochar.

  • Researchpp 1680-1696Zoia, L., Salanti, A., Tolppa, E. L., Ballabio, D., and Orlandi, M. (2017). "Valorization of side streams from a SSF biorefinery plant: Wheat straw lignin purification study," BioRes. 12(1), 1680-1696.AbstractArticlePDF

    The lignocellulosic materials produced after each step of a biorefinery plant using simultaneous saccharification and fermentation (SSF) technology on wheat straw (Triticum spp.) for bioethanol production were characterized by spectroscopic and chromatographic techniques in order to investigate the macromolecular interactions between the lignin and polysaccharides. In order to valorize the lignin cakes, a purification step was set up and the extraction conditions (acid pretreatment, temperature, time, and NaOH concentration) were optimized by a chemiometric approach in terms of yield and purity. Residual carbohydrate impurities, free and/or chemically bonded to lignin (lignin carbohydrates complexes), were individuate as the most critical factor for a satisfactory lignin extraction. Finally, the lignin samples collected according to the optimized extraction conditions were chemically characterized and low molecular weight, high phenols concentration, and low carboxylic acids content were recognized as interesting features for industrial applications.

  • Researchpp 1697-1705Zhang, Y., Xu, D., Ma, L., Wang, S., and Liu, X. (2017). "Influence of heat treatment on the water uptake behavior of wood," BioRes. 12(1), 1697-1705.AbstractArticlePDF

    Dimensional stability is an important property of wood that is strongly influenced by its water uptake behavior. Heat treatment is one method to improve wood dimensional stability. This study investigated the effects of heat treatment on the water uptake behavior of wood using a wicking test. The thickness of the tested wood sample was similar to that of the surface wood panel in a 3-layer composite floorboard. It was treated at different temperatures ranging from 200 °C to 400 °C under a nitrogen atmosphere for 10 min to provide the test data to investigate the basic theory relating to dimensional stability of heat-treated wood processed at higher temperatures for a short length of time. During the test, the water uptake of larch (Larix gmelinii) and red oak (Quercus rubra) were recorded continuously. The heat-treated wood had a much lower water uptake ability than untreated wood during the early stage of the wicking test; untreated wood exhibited higher total water uptake. Compared with the untreated sample, the red oak wood treated at 400 °C had an average water uptake rate that decreased from 0.28 mg/mm3 per hour to 0.038 mg/mm3 per hour.

  • Researchpp 1706-1722Satari, B., Palhed, J., Karimi, K., Lundin, M., Taherzadeh, M. J., and Zamani, A. (2017). "Process optimization for citrus waste biorefinery via simultaneous pectin extraction and pretreatment," BioRes. 12(1), 1706-1722.AbstractArticlePDF

    In a novel valorization approach for simultaneous pectin extraction and pretreatment (SPEP) of citrus waste (CW) by dilute nitric acid and ethanol, almost all of the CW was converted to bio-derived chemicals in a single-step process at a low/moderate temperature. The SPEP was performed at different temperatures (70 °C and 80 °C), pH (1.8, 3.0, and 4.3), and extraction times (2 h and 3 h) with a full factorial design. The maximum pectin yield of 45.5% was obtained at pH 1.8, 80 °C, and 2 h. The pectin yields at pH 1.8 were much higher than at pH 4.3 and 3. Also, the degree of methyl-esterification at pH 1.8 was higher than 50%, whereas at the higher pH, low methoxyl pectins were extracted. The treated CW obtained after the SPEP, free from limonene, was subjected to separate cellulolytic enzymatic hydrolysis and ethanolic fermentation. The glucose yields in the enzymatic hydrolysates were higher for the CW treated at pH 1.8. The fermentation of the enzymatic hydrolysates by Mucor indicus resulted in fungal biomass yields in the range of 355 to 687 mg per g of consumed sugars. The optimum conditions for obtaining the maximum SPEP yield (glucose + pectin (g) / raw material (g))*100) were pH 1.8, 80 °C, and 2 h, which resulted in a yield of 58.7% (g/g CW).

  • Researchpp 1723-1736Liu, J., Liu, B., Zhan, L., Wang, P., Ju, M., and Wu, W. (2017). "Solid-state fermentation of ammoniated corn straw to animal feed by Pleurotus ostreatus Pl-5," BioRes. 12(1), 1723-1736.AbstractArticlePDF

    The solid-state fermentation (SSF) of ammoniated corn straw (ACS) by Pleurotus ostreatus Pl-5 was investigated. The SSF experiments were carried out for 20 d using ACS and corn straw (CS) as the substrates of the experimental group (EP) and control group (CP), respectively. The effects of the ammoniation pretreatment on the CS lignocellulose structure, fungal growth, enzyme production, and components of CS during the SSF process were analyzed. The ammoniation pretreatment effectively degraded the lignin and hemicellulose contents in the CS, by 15.3% and 7.7%, respectively. Thus, the in vitro digestibility (IVD) of the EP was higher than for the CP, and even higher than the ligninase activities (laccase: 661 U/g; MnP: 56.8 U/g) found in the CP. The higher cellulase activities (CMCase: 152.3 U/g; FPA: 224.7 U/g) in the EP improved the cellulose degradation, which also promoted the P. ostreatus Pl-5 growth, and the high total N content significantly increased the EP fungal biomass and amino acid contents. A shorter processing time and a higher level of nutrients were achieved by the SSF of ACS, which showed its potential for use in animal feed production.

  • Researchpp 1737-1748Przybysz, P., Kucner, M., Dubowik, M., and Przybysz, K. (2017). "Laboratory refining of bleached softwood kraft pulp in water and a series of alcohols of different molecular weights and polarities: Effects on swelling and fiber length," BioRes. 12(1), 1737-1748.AbstractArticlePDF

    Typical bleached pinewood kraft pulp from a paper mill was immersed in either water or different alcohols, such as methanol, ethanol, n-propanol, and n-butanol, and then refined in a PFI mill. After refining, changes in the internal fibrillation of the fibres were evaluated by measurements of water retention values (WRV), while fibre shortening was determined by measurements of the average weighted fibre length. The objective of this study was to determine the influence of a liquid used for refining on the principal refining effects such as the internal fibrillation and fiber shortening. The highest increase in the internal fibrillation was observed for the pulp samples refined in water, which has the higher dipole moment than the alcohols. For these samples, WRV increased from 93% to 201%, while the average weighted fiber length was reduced by only 0.6 mm. When the pulp was beaten in n-butanol, which was the least polar liquid among the liquids investigated, liquid retention value increased by only 23.5%, while the average weighted fibre length was reduced by 1.37 mm. These results showed the importance of water in the beating of cellulose fibres and demonstrated that the outcomes of this process depended on the dipole moment of the fiber immersion liquid.

  • Researchpp 1749-1766Basu, P., Kulshreshtha, A., and Acharya, B. (2017). "An index for quantifying the degree of torrefaction," BioRes. 12(1), 1749-1766.AbstractArticlePDF
    Torrefaction, a thermochemical pre-treatment process, is used to enhance the properties of biomass to make it more compatible with solid fossil fuels. A quantitative index (TI) is proposed here to define the degree or quality of torrefaction especially for its use in the energy industries. Torrefaction index is defined as the ratio of energy density enhancement factor of the product at the specified condition to that at a reference condition, which is torrefaction at 300 °C for 60 min. The index, calculated for a wide range of data shows a linear dependence on torrefaction temperature. Numerical values of this index were in range of 0.93 to 0.95, 0.95 to 0.97, and 0.97 to 1.0 for light, medium, and severe torrefaction conditions, respectively. Based on a wide range of experimental data of woody biomass, two empirical correlations for mass and energy yields were developed. These correlations permitted prediction of TI without performing torrefaction of the biomass.
  • Researchpp 1767-1778Kim, B. Y., Han, S. Y., Park, C. W., Chae, H. M., and Lee, S. H. (2017). "Preparation and properties of cellulose nanofiber films with various chemical compositions impregnated by ultraviolet-curable resin," BioRes. 12(1), 1767-1778.AbstractArticlePDF

    Nanocomposite films were prepared by impregnating cellulose nanofiber (CNF) sheets of various chemical compositions, i.e., lignocellulose nanofiber (LCNF), holocellulose nanofiber (HCNF), and bleached kraft pulp-based nanofiber (BKP-NF), with UV-curable resin. The effects of the CNF sheet porosity on the amount of impregnated resin and the tensile properties of the corresponding nanocomposite films were investigated. The defibration efficiency, viscosity, and filtration time of HCNF and BKP-NF were higher than those of LCNF, and these properties increased with defibration time for BKP-NF. The density and porosity of the LCNF sheets were lower and higher, respectively, than those of the HCNF and BKP-NF sheets. The porosity of the CNF sheets was successfully regulated using organic solvents with different polarities. The impregnated resin amount increased as the CNF sheet porosity and the ratio of monomer to oligomer in the resin increased. The tensile strengths and elastic moduli of all of the nanocomposite films were higher than those of the neat resin films. The specific tensile strength of the nanocomposite decreased with increasing impregnated resin content.

  • Researchpp 1779-1797Martínez-Patiño, J. C., Romero, I., Ruiz, E., Cara, C., Romero-García, J. M., and Castro, E. (2017). "Design and optimization of sulfuric acid pretreatment of extracted olive tree biomass using response surface methodology," BioRes. 12(1), 1779-1797.AbstractArticlePDF

    Olive tree biomass (OTB) represents an interesting feedstock for bioethanol production. In this study, olive tree pruning was water extracted and pretreated by dilute sulfuric acid to achieve high sugar recoveries from cellulosic and hemicellulosic fractions. Temperature (160 to 200 °C), acid concentration (0 to 8 g acid/100 g extracted raw material), and solids loading (15% to 35% w/v) were selected as operation variables and modified according to a Box-Behnken experimental design. The optimal conditions for the acid pretreatment were 160 °C, 4.9 g sulfuric acid/100 g biomass, and 35% solids loading (w/v), according to multiple criteria that considered the maximization of both the hemicellulosic sugars concentration in prehydrolysate and the overall sugar yield. These optimized conditions yielded a sugar concentration of 79.8 g/L, corresponding to an overall yield of 39.8 g total sugars/100 g extracted OTB. The fermentability of hemicellulosic sugars prehydrolysates from the acid pretreatment was evaluated by Escherichia coli after a detoxification stage by overliming. The prehydrolysates with lower concentrations of toxic compounds were fermented and achieved ethanol yields higher than 80% of the theoretical ethanol yield.

  • Researchpp 1798-1812Wang, Q., Zhuang, X., Wang, W., Yu, Q., Tan, X., Zhou, G., Qi, W., and Yuan, Z. (2017). "Influence of acetone co-solvent on furfural production and cellulose retention from lignocellulosic biomass," BioRes. 12(1), 1798-1812.AbstractArticlePDF
    This research aimed to obtain furfural from sugarcane bagasse with most cellulose residue preserved by using the system of diluted phosphoric acid and co-solvent acetone. Based on concentrated phosphoric acid and acetone pretreatment, 78.2% of the hemicelluloses in the bagasse were depolymerized into water soluble xylo-oligosaccharides, covering the cellulose residue. Then, in the pure acetone medium, no furfural was produced when pretreated bagasse was catalyzed by phosphoric acid at low reaction temperature (80 °C). The degradation of pretreated bagasse was strongly accelerated by increasing reaction temperature (120 °C), while no furfural was obtained due to its condensation with acetone. Adding water (12 mL) effectively slowed this process, with 10.6% furfural yield and 54.4% furfural selectivity, but acetone showed an inhibiting influence on furfural production compared to pure water system, under atmospheric conditions. Surprisingly, furfural production in the acetone-water medium was improved significantly when the reaction was pressurized, using xylose or bagasse as the feedstock. In pressurized conditions, higher furfural yield, shorter reaction time, and lower cellulose degradation were observed in the acetone-water medium versus the totally aqueous medium. This provided the potential of producing furfural and hydrolysable cellulose residue in the acetone co-solvent media.
  • Researchpp 1813-1825Boruszewski, P., Jankowska, A., and Kurowska, A. (2017). "Comparison of the structure of juvenile and mature wood of Larix decidua Mill. from fast-growing plantations in Poland," BioRes. 12(1), 1813-1825.AbstractArticlePDF

    The main objective of this study was to reveal variations in the wood structure and to define the location of the boundary between juvenile and mature wood Larix decidua Mill. from fast growing tree plantations. To reach these findings, the samples of wood from four short-rotation plantations in Central Europe (Poland) were selected and compared. The procedure used to determine the demarcation point between juvenile and mature wood resulted in strong correlations between the width of growth rings and the initial cambial age. It was found that the structure of wood from fast-growing trees differs from commercially available timber. The wood derived from plantations revealed wider annual rings than wood from natural forests. The analysis of the variability of wood structure resulted in defining the location of the boundary between juvenile and mature wood. Based on the analysis of structure of annual rings, the boundary of juvenile wood in fast-growing larch is placed between the 12th and 15th annual ring. The investigated material contained high proportions of juvenile wood, which makes up more than 70% of trunk volume. On the microscopic level, no visible changes, indicating the presence of a mature wood zone, were found.

  • Researchpp 1826-1834Yang, F., Zhang, Y., and Feng, Y. (2017). "Adding aluminum hydroxide to plant fibers using in situ precipitation to improve heat resistance," BioRes. 12(1), 1826-1834.AbstractArticlePDF
    Plant fiber is an environmentally friendly, renewable natural resource. It has several excellent properties such as a low density and high softness. These properties make it an especially good raw material for applications such as paper and construction. However, plant fiber has poor resistance to heat, which limits its application in high temperature conditions. Adding aluminum sulfate solution to plant fiber first, and then adding sodium hydroxide solution enables aluminum hydroxide to be distributed uniformly on the surface and interior of a plant fiber. This modification improves the thermo-stability of the plant fiber. Furthermore, compared with the traditional way of filling, using the fiber added aluminum hydroxide by in situ precipitation to make paper, the strength properties of the paper decreased slightly. By combining in situ precipitation with filling, more aluminum hydroxide could be added to the paper while still maintaining good paper strength and better heat resistance.
  • Researchpp 1835-1849EL-Hefny, M., Ali, H. M., Ashmawy, N. A., and Mohamed Z. M. Salem (2017). "Chemical composition and bioactivity of Salvadora persica extracts against some potato bacterial pathogens," BioRes. 12(1), 1835-1849.AbstractArticlePDF

    Potent antibacterial activities of solvent extracts (methanol:n-hexane) from the branch, leaf, and root-wood of Salvadora persica were examined against potato phytopathogenic bacteria, namely Pectobacterium carotovorum subsp. carotovorum, Dickeya solani, Ralostonia solanacerum, Enterobacter cloacae, and Bacillus pumilus. The main chemical constituents analyzed by gas chromatography–mass spectrometry (GC/MS) in the branch extracts were N-benzylbenzamide (71.08%), decane (3.17%), stigmasterol (3.17%), 9-desoxo-9-x-acetoxy-3,8,12-tri-O-acetylingol (2.33%), and β-sitosterol (2.15%). The main components in the leaf extracts were 2,6-dimethyl-N-(2-methyl-α-phenylbenzyl)aniline (28.65%), spiculesporic acid (13.60%), homo-γ-linolenic acid (12.63%), and methyl hexadecanoate (11.01%). The root-wood extracts contained, as primary parts, benzeneacetonitrile (71.47%), 4-aminocarbonyl-5-fluoro-1-α-D-ribofuranosyl-imidazole (10.99%), and benzylisothiocyanate (5.05%). The extracts from the root-wood showed moderate antibacterial activity against the potato bacterial pathogens, which was followed by leaf and branch extracts. The results suggested that S. persica plant extracts could be used as bioagents against potato soft and brown rot bacterial pathogens.

  • Researchpp 1850-1860Ma, X., Kirker, G. T., Clausen, C. A., Jiang, M., and Zhou, H. (2017). "Modulus of elasticity loss as a rapid indicator of rot-fungal attack on untreated and preservative-treated wood in laboratory tests," BioRes. 12(1), 1850-1860.AbstractArticlePDF

    The modulus of elasticity (MOE) of wood is a sensitive indicator of rot-fungal attack. To develop an alternative method of rapid assessment of fungal decay in the laboratory, changes in static MOE of untreated and preservative-treated wood were measured during exposure to the brown-rot fungus, Gloeophyllum trabeum, and the white-rot fungus, Trametes versicolor, in a standard soil bottle assay. Static MOE loss was compared with mass loss. The results showed that the MOE of wood was a sensitive and reliable indicator of rot-fungal attack, regardless of fungus or wood species. The MOE analysis of untreated wood reduced the 12- to 16-week exposure time necessary for the standard mass loss measurement to four weeks. Also, the exposure time for preservative-treated wood was reduced to eight weeks. Untreated wood was determined to be susceptible to decay if the MOE loss was 40% or more after a four-week exposure, while treated wood was considered susceptible to decay if the MOE loss was 40% or more after an eight-week exposure.

  • Researchpp 1861-1870Barański, J., Klement, I., Vilkovská, T., and Konopka, A. (2017). "High temperature drying process of beech wood (Fagus sylvatica L.) with different zones of sapwood and red false heartwood," BioRes. 12(1), 1861-1870.AbstractArticlePDF

    This study examined the changes in the properties of beech wood (Fagus sylvatica L.) after intense drying. Beech wood with false red heartwood was selected as the test specimen. The test samples had dimensions of 50 mm thickness, 180 mm width, and 350 mm length. The specimens were divided into two groups, false red heartwood and sapwood. These specimens were selected with different angles of the growth rings (radial and tangential). The results showed that samples with red heartwood, in comparison to samples with sapwood content, had a remarkable effect in covering. Observation of specimens with false red heartwood and sapwood before and after drying process revealed significant differences in color changes and measured values during the covering-slicing test, but not between samples with different growth ring angles.

  • Researchpp 1871-1889Rahman, M. R., Lai, J. C. H., and Hamdan, S. (2017). "Evaluation of acrylonitrile/butyl methacrylate/halloysite nanoclay impregnated wood polymer nanocomposites," BioRes. 12(1), 1871-1889.AbstractArticlePDF
    Acrylonitrile/butyl methacrylate/halloysite nanoclay wood polymer nanocomposites (AN-co-BMA-HNC WPNCs) were prepared via the impregnation method, and the effect of different ratios of polymers was investigated. The WPNCs were characterized through weight percent gain, Fourier transform infrared spectroscopy (FT-IR), scanning electron microscopy (SEM), the three-point flexural test, dynamic mechanical thermal analysis (DMTA), thermogravimetric analysis (TGA), differential scanning calorimetry (DSC) analysis, and the moisture absorption test. The weight percent gain in the 50:50 AN-co-BMA-HNC WPNCs was the highest compared with the raw wood (RW) and other WPNCs. The FT-IR results confirmed that polymerization took place in the nanocomposites, especially in the 50:50 AN-co-BMA-HNC WPNCs, with a reduction of hydroxyl groups. The SEM results revealed that the 50:50 AN-co-BMA-HNC WPNCs showed the best surface morphology. The 50:50 AN-co-BMA-HNC WPNCs showed the highest flexural strength and modulus of elasticity. The results revealed that the storage modulus and loss modulus of the AN-co-BMA-HNC WPNCs were higher, while the tan δ of the AN-co-BMA-HNC WPNCs was lower, compared with the RW. The AN-co-BMA-HNC WPNCs also exhibited higher thermal stability and exhibited remarkably lower moisture absorption compared with the RW. Overall, this study demonstrated that the 50:50 AN-co-BMA ratio was the most suitable to be introduced into RW.
  • Researchpp 1890-1902Pu, G., Zan, H., Du, J., and Zhang, X. (2017). "Study on NO emission in the oxy-fuel combustion of co-firing coal and biomass in a bubbling fluidized bed combustor," BioRes. 12(1), 1890-1902.AbstractArticlePDF

    Combustion experiments were performed in a bubbling bed combustor to explore the effects of various oxygen concentrations (21% to 40%), temperatures (850 °C to 950 °C), and mixing ratios (0% to 30%) on the formation of NO gas. In order to correspond to different combustion stages, the generated NO were distinguished as volatile-NO and coke-NO, respectively, and the total amount and the conversion rate of NO were analyzed. The results indicated that NO comes mainly from fixed carbon combustion, and an increased oxygen concentration in the environment could produce more NO during the combustion process, regardless of the blending of biomass. The temperature increase promoted the conversion of nitrogen in the anthracite and accelerated the release of volatiles from the pine powder. During mixed combustion with increasing temperature, the volatiles formed had diluted the environmental oxygen concentration, which led to suppressed NO emissions. In addition, increasing the blending ratio also resulted in decreased NO emissions due to the large amount of intermediates released by the burning pine powder that induced a deoxidation effect on the NO emission.

  • Researchpp 1903-1915Cuccui, I., Negro, F., Zanuttini, R., Espinoza, M., and Allegretti, O. (2017). "Thermo-vacuum modification of teak wood from fast-growth plantation," BioRes. 12(1), 1903-1915.AbstractArticlePDF

    Sawnwood of teak (Tectona grandis L. f.) from a Costa Rica plantation was thermally treated at different process conditions using thermo-vacuum technology. The main objectives of the study were to find the optimal combination of the process parameters, i.e. temperature (T), and duration (t), in order to minimise the colorimetric difference between sapwood and heartwood, and to evaluate the influence of the treatment on the modification pattern of physical properties of the material. The resulting mass loss (ML), hygroscopicity (H), dimensional stability (ASE), and lightness (L) were measured and compared. As expected, the temperature (T) is the main parameter influencing the extent of modification. The measured ML values turned out to be moderate even at high T values if compared with other hardwoods. The temperature range between 180 °C and 190 °C minimizes the colorimetric difference between treated sapwood and not treated heartwood.

  • Researchpp 1916-1923Erabee, I. K., Ahsan, A., Nik Daud, N. N., Idrus, S., Shams, S., Md Din, M. F., and Rezania, S. (2017). "Manufacture of low-cost activated carbon using sago palm bark and date pits by physiochemical activation," BioRes. 12(1), 1916-1923.AbstractArticlePDF

    Two raw materials, sago palm bark (SPB) and date pits, were utilized as precursors to prepare high porosity activated carbon (AC). The porosity of these two raw materials was compared with that of commercial AC made from coconut shells. The physicochemical activation method was used for AC preparation, and it consisted of two steps, carbonization and activation. The activation process was performed using zinc chloride (ZnCl2) as an activation agent. N2 adsorption-desorption analysis was carried out to characterize the porosity of AC. Thermogravimetric analysis (TGA) was conducted for the two raw materials. The adsorbent made from SPB, which showed the maximum surface area of 1634 m2/g at the 700 °C activation temperature for one hour, while the surface area of prepared AC from date pits was 1367 m2/g. Both prepared ACs had a larger surface area than commercial AC made with coconut shell (1348 m2/g).

  • Researchpp 1924-1942Poirier, G., Demers, M. H., and Potvin, A. (2017). "Experiencing wooden ambiences with Nordic light: Scale model comparative studies under real skies," BioRes. 12(1), 1924-1942.AbstractArticlePDF

    This study explored the potential of natural light to enhance wooden interior environments. Under Nordic light, natural materials such as wood finishes present an opportunity to create warm, bright, and pleasant atmospheres, enhancing psychological well-being and comfort. The objectives of this project were twofold: first, to study the diversity of northern sky conditions in terms of cloud cover and thickness, and, second, to evaluate the impacts of the diversity of natural light on five wooden scale models. The methodology involved weather data collection that took place during the spring equinox in Quebec City. In order to create a cloudiness scale, sky condition data and photometric measurements were collected. A photographic survey occurred in five scale models made with interior wooden finishes of varying color combinations, documenting the impact of sky diversity on brightness, hue, and contrast. Simultaneous scale model studies under a real sky allowed direct comparison under the same lighting conditions. There was a remarkable diversity of visual ambiences for a southeast-oriented space depending on the position of the sun and sky conditions. Gray-dyed wooden finishes created dull and unchanging atmospheres, while yellow oaked surfaces allowed various dynamic ambiences.

  • Researchpp 1943-1959Obradovic, J., Petibon, F., and Fardim, P. (2017). "Preparation and characterisation of cellulose-shellac biocomposites," BioRes. 12(1), 1943-1959.AbstractArticlePDF
    Composite materials comprising a mixture of shellac resin as the matrix and cellulose as the reinforcement were developed. The influence of the reinforcement content and the concentration of additives on the mechanical performance and processing were investigated. A high content of cellulose and low concentrations of ethanol and polyethylene glycol produced biocomposites with high stress resistance and a high Young’s modulus, whereas a low content of cellulose and a high concentration of additives gave samples a low Young’s modulus and high elasticity. Two types of cellulose-based reinforcements with different polarity, namely, mechanically refined wood pulp and cellulose acetate butyrate particles, were compared. The efficiency of the composite over the two model reinforcements, i.e., hydrophilic and hydrophobic components, respectively, was also studied. Although particle reinforcement was easier to process and evenly dispersed into the matrix, its mechanical performance was lower compared with refined fibres. Scanning electron microscopy showed that the matrix better coated the fibres than the particles, resulting in better adhesion and mechanical performance. The morphology of reinforcement played a key role; long fibres oriented in the pulling direction ensured a better mechanical resistance than particle fillers.
  • Researchpp 1960-1967Athijayamani, A., Das, M. Chrispin, Sekar, S., and Ramanathan, K. (2017). "Mechanical properties of phenol formaldehyde hybrid composites reinforced with natural cellulose fibers," BioRes. 12(1), 1960-1967.AbstractArticlePDF

    This paper reports on the preparation and mechanical properties of hybrid polymer composites involving areca fine fibers (AFFs), sisal fibers (SFs), and roselle fibers (RFs) as reinforcing agents in a phenol formaldehyde (PF) resin-based polymer matrix. For comparative study, an AFF/glass fiber-reinforced PF hybrid composite and AFF/PF composite were also prepared. Hybrid composites were fabricated using a hand lay-up technique, where the weight fraction of fibers was kept at 40 wt% at a ratio of 1:1. Tensile and flexural properties of randomly oriented intimately mixed hybrid polymer composites were evaluated. The results revealed that the mechanical properties of the AFF/PF composite increased by a considerable amount when hybridized with the sisal fibers. Scanning electron microscopy (SEM) was used to analyze the fractured surface of the composite specimens after mechanical testing.

  • Researchpp 1968-1981Huang, X. Y., Li, F., Xie, J. L., De Hoop, C. F., Hse, C. Y., Qi, J. Q., and Xiao, H. (2017). "Microwave-assisted liquefaction of rape straw for the production of bio-oils," BioRes. 12(1), 1968-1981.AbstractArticlePDF

    The acid-catalyzed liquefaction of rape straw in methanol using microwave energy was examined. Conversion yield and energy consumption were evaluated to profile the microwave-assisted liquefaction process. Chemical components of the bio-oils from various liquefaction conditions were identified. A higher reaction temperature was found to be beneficial to obtain higher energy consumption efficiency as heated by microwaves. Fourier transform infrared spectroscopy of the bio-oils indicated that hydroxyl groups underwent oxidation with increasing liquefaction temperature and/or prolonged reaction time; methanol esterification of oxidation products was also observed during the liquefaction process. The GC-MS chromatograms indicated that the further decomposition of C5 and C6 sugars resulted in a remarkable reduction of hydroxyl group products and an apparent increase in levulinic ester; furan derivatives and succinic acid derivatives were increased as well. The chemical reactions in liquefaction for the production of bio-oils mainly included decomposition of hemicelluloses, cellulose, and lignin; the oxidation reactions of the hydroxyl groups and methanol esterification were also presented. Comprehensively, a high content of hydroxyl group products was obtained at a moderate liquefaction condition (140 °C/15 min), and a high yield of levulinic ester products was acquired in severe reaction conditions (180 °C/15 min), regardless of energy consumption efficiency.

  • Researchpp 1982-1990Hu, Z., Fu, S., and Tang, A. (2017). "Fabrication of light-triggered AuNP/CNC/SMP nanocomposites," BioRes. 12(1), 1982-1990.AbstractArticlePDF

    Cellulose, an abundant natural polysaccharide, can be applied to immobilize particles on the surface due to the presence of ample hydroxyl groups. A series of different sizes and contents of gold nanoparticles (AuNP) were prepared on cellulose nanocrystal (CNC). The obtained AuNP/CNC nanocomposites were then blended with shape-memory polyurethane (SMP) to prepare light-triggered AuNP/CNC/SMP nanocomposites through solvent conversion and a solution casting method. The nanocomposite films were endowed with higher mechanical properties and striking remote-control light-triggered shape-memory properties. Moreover, the CNC in the composites also enhanced the photothermal effect of AuNPs by preventing the aggregation of AuNPs. At the same time, the content of AuNPs with existing CNC had a stronger effect on the elevated temperature (∆T) and the shape-memory properties of films in comparison to the size of the AuNPs.

  • Researchpp 1991-2003Zhao, G., Ji, S., Sun, T., Ma, F., and Chen, Z. (2017). "Production of bioflocculants prepared from wastewater supernatant of anaerobic co-digestion of corn straw and molasses wastewater treatment," BioRes. 12(1), 1991-2003.AbstractArticlePDF
    Novel bioflocculants (BS-MBF) were prepared using the wastewater supernatant from anaerobic co-digestion of corn straw and molasses wastewater as a nutrient resource. Acetic acid and ethanol were the dominant fermentation products during the anaerobic digestion process and were estimated to be 50.5% and 30.0%, respectively, after 150 d of operation. Equal volumes of bioflocculant producing bacteria F2 (Rhizobium radiobacter) and F6 (Bacillus sphaericus) were mixed to form F+, which was inoculated to wastewater supernatant at different times. A maximum flocculation activity of 91.3% was achieved, and 2.32 g/L of purified bioflocculant was extracted when a compound medium from 110-d wastewater supernatant was used. The removal efficiencies of heavy metals from simulated electroplating wastewater were tested by using these prepared bioflocculants. The optimal conditions for heavy metal removal to BS-MBF were found to be at 374 mg/L at an initial pH of 6.0 and a contact time of 40 min. The adsorption capacities for Cu2+ and Zn2+ reached more than 90%, while for Cr6+ it reached approximately 30%. Overall, the study showed for the first time that wastewater supernatant from anaerobic co-digestion of corn straw and molasses wastewater can be used for producing bioflocculants, which can be effectively used to remove heavy metals from electroplating wastewater.
  • Researchpp 2004-2014Shu, Z., Liu, S., Zhou, L., Li, R., Qian, L., Wang, Y., Wang, J., and Huang, X. (2017). "Physical and mechanical properties of modified poplar veneers," BioRes. 12(1), 2004-2014.AbstractArticlePDF
    To improve the performance and expand applications of poplar plantation wood, modified poplar veneers based on 1-butyl-3-methylchloride ([Bmim]Cl) were studied. Two groups of poplar veneers were impregnated in ionic liquid [Bmim]Cl (group C) and pure water (group B), separately. Techniques such as hot pressing-coagulation and bath-annealing were applied to these two groups to prepare modified samples. The physical and mechanical properties of each group were tested and characterized, using untreated group (A) as the control. The ductility and thickness variation rate of samples in group C were higher than those in group B. The width variation rate of samples in group C was 64% greater than those in group A and 50.4% greater than those in group B. Scanning electron microscopic (SEM) results also showed the plasticity and the improvement in the transverse connection of samples in group C; these results were more obvious than that for samples in group B. The tensile strength and elastic modulus of samples in group C were higher than those of group B. Compared with the control group, the crystallinity index (CrI) of samples in groups B and C was increased and that of group C was the maximum, but the crystal form remained unchanged.
  • Researchpp 2015-2030Moodley, P., and Kana, G. (2017). "Optimization of operational parameters for biohydrogen production from waste sugarcane leaves and semi-pilot scale process assessment," BioRes. 12(1), 2015-2030.AbstractArticlePDF

    This study modeled and optimized the operational parameters for biohydrogen production from waste sugarcane leaves and assessed hydrogen production on a semi-pilot scale. A Box-Behnken design with input variables of substrate concentration (8 to 24 g/L), inoculum concentration (10% to 50% v/v), and hydraulic retention time (HRT, 24 to 96 h) was used. A coefficient of determination (R2) of 0.90 and the predicted optimum operational set-points of 14.2 g/L substrate concentration, 32.7% inoculum concentration, and 62.8 h HRT were obtained. Experimental validation produced a biohydrogen yield of 12.8 mL H2/g fermentable sugar (FS). A semi-pilot scale process in a 13-L Infors reactor under optimized conditions gave a cumulative hydrogen volume and yield of 3740 mL and 321 mL H2 g-1 FS, respectively, with a peak hydrogen fraction of 37%. Microbial analysis from the process effluent conducted by Polymerase Chain Reaction cloning indicated the presence of hydrogen-producing bacteria belonging to Clostridium sp., Klebsiella sp., and Enterobacter sp. These findings highlight the feasibility of biohydrogen production from sugarcane waste and provide preliminary knowledge on process scale up.

  • Researchpp 2031-2039Chen, T., Li, Y., Lei, L., Hong, M., Sun, Q., and Hou, Y. (2017). "Influence of residual black liquor in pulp on wastewater pollution after bleaching process," BioRes. 12(1), 2031-2039.AbstractArticlePDF

    The influence of residual black liquor in pulp on wastewater pollution after the bleaching process was studied. The results show that the CODCr in bleaching effluent has a remarkable linearity with bleaching loss of pulps without residual black liquor. For pulps with some residual black liquor, more than 34% of the overall CODCr is produced by the residual black liquor. It follows that more effective washing to reduce the residual black liquor is an appropriate way to control the pollutant discharges from pulp and paper mill industry.

  • Researchpp 2040-2057González, M. E., Romero-Hermoso, L., González, A., Hidalgo, P., Meier, S., Navia, R., and Cea, M. (2017). "Effects of pyrolysis conditions on physicochemical properties of oat hull derived biochar," BioRes. 12(1), 2040-2057.AbstractArticlePDF

    The effects of the pyrolysis conditions in terms of temperature (400 to 600 °C), residence time (0.5 to 3.5 h), nitrogen flux (0 to 1 L/min), and temperature increase rate (1.5 to 3 °C/min) on the physicochemical properties of biochar were studied. The physicochemical properties evaluated in the biochar were specific surface area, pore volume, average pore size, total carbon content, pH, total acidity, elemental composition, and polycyclic aromatic hydrocarbons (PAHs) content. A higher specific surface area of 108.28 m2/g and a mean pore size diameter of about 2.24 nm were found when the pyrolysis was conducted at 600 °C. In general, the pH and total acidity increased with the increased pyrolysis temperature. The total PAH concentration in all of the combinations studied varied from 0.16 to 8.73 μg/kg, and only phenanthrene, pyrene, and chrysene were detected. The increased temperature seemed to decrease the PAH concentration in the biochar. Nevertheless, there was no correlation found between the PAH content and the combined evaluated parameters.

  • Reviewpp 2058-2080Vallejos, M. E., Felissia, F. E., and Area, M. C. (2017). "Hydrothermal treatments applied to agro- and forest-industrial waste to produce high added-value compounds," BioRes. 12(1), 2058-2080.AbstractArticlePDF

    Agro- and forest-industrial wastes are abundant and low cost sources of carbohydrates and phenolic compounds, which can be converted into biofuels, biomaterials, and high added-value compounds by different pathways in small and large biorefineries. The development of technologies based on hydrothermal treatments could improve the utilization of lignocellulosic wastes through the separation of its components (cellulose, hemicellulose, lignin, and extractives) in sequential processes. The adopted technologies for the separation and conversion of these lignocellulosic wastes into synthesis intermediates or products of high added value represent an important part of the total production cost. Low liquid to solid ratios and mild temperatures in the pre-treatment are interesting ways of reducing energy costs, subsequently economizing both steam and electricity. This work focuses on the advantages of using low liquid to solid ratios in the hydrothermal treatment of different agro- and forest-industrial wastes, paying particular attention to the performance of separation, purification, and conversion of hemicelluloses.

  • Reviewpp 2081-2107Brännvall, E. (2017). "The limits of delignification in kraft cooking," BioRes. 12(1), 2081-2107.AbstractArticlePDF
    The perspective of the article is to explore kraft cooking at the limits of delignification, i.e. what degree of delignification is needed to obtain fibre liberation and what is the maximum degree of delignification possible in the kraft pulping stage. The reasons for the quite narrow boundaries for sufficient and maximum delignification are explained, and the differences between the behaviour of hardwood and softwood kraft pulping are clarified.
  • Reviewpp 2108-2124Rezania, S., Md Din, M. F., Eva Mohamad, S., Sohaili, J., Mat Taib, S., Mohd Yusof, M. B., Kamyab, H., Darajeh, N., and Ahsan, A. (2017). "Review on pretreatment methods and ethanol production from cellulosic water hyacinth," BioRes. 12(1), 2108-2124.AbstractArticlePDF
    Lignocellulosic biomass resources are renewable materials that can be converted to fermentable sugars and subsequently into ethanol. Water hyacinth (Eichhornia crassipes) is a cellulosic aquatic plant that has high carbohydrates, low lignin content, and notable reducing sugars content in its structure. Based on the literature review in the case of water hyacinth, the most frequently used pretreatment methods were acid and alkali, while ionic liquid and microwave-assisted methods were used rarely. The dominant sugars were glucose, xylose, galactose, arabinose, and mannose. Based on the findings, cellulase and S. cerevisiae were mostly used for enzymatic hydrolysis and fermentation of water hyacinth to ethanol, respectively. This review presents the recent studies in pretreatment, hydrolysis, and fermentation of water hyacinth biomass into ethanol.
  • Reviewpp 2125-2142Zhao, J., and Kerekes, R. (2017). "A historical perspective of scientific advances in paper forming hydrodynamics: 1950-2000," BioRes. 12(1), 2125-2142.AbstractArticlePDF
    This paper reviews key advances in understanding the hydrodynamics of the forming section of papermaking during the years 1950 to 2000. Over this period papermaking advanced from rather slow-speed Fourdrinier machines to modern high-speed twin-wire formers. The advances are described in the context of technical problems faced at the time to increase machine speeds and improve paper properties. The scientific work and advances in machine design contributed greatly to the marvel of modern papermaking, which now includes machines 10 m wide operating at speeds over 100 km/h.
  • Reviewpp 2143-2233Hubbe, M. A., Ferrer, A., Tyagi, P., Yin, Y., Salas, C., Pal, L., and Rojas, O. J. (2017). "Nanocellulose in thin films, coatings, and plies for packaging applications: A review," BioRes. 12(1), 2143-2233.AbstractArticlePDF

    This review article was prompted by a remarkable growth in the number of scientific publications dealing with the use of nanocellulose (especially nanofibrillated cellulose (NFC), cellulose nanocrystals (CNC), and bacterial cellulose (BC)) to enhance the barrier properties and other performance attributes of new generations of packaging products. Recent research has confirmed and extended what is known about oxygen barrier and water vapor transmission performance, strength properties, and the susceptibility of nanocellulose-based films and coatings to the presence of humidity or moisture. Recent research also points to various promising strategies to prepare ecologically-friendly packaging materials, taking advantage of nanocellulose-based layers, to compete in an arena that has long been dominated by synthetic plastics. Some promising approaches entail usage of multiple layers of different materials or additives such as waxes, high-aspect ratio nano-clays, and surface-active compounds in addition to the nanocellulose material. While various high-end applications may be achieved by chemical derivatization or grafting of the nanocellulose, the current trends in research suggest that high-volume implementation will likely incorporate water-based formulations, which may include water-based dispersions or emulsions, depending on the end-uses.

  • Reviewpp 2234-2248Hu, Z., Tang, C,. He, Z., Lin, J., and Ni, Y. (2017). "1-methylcyclopropene (MCP)-containing cellulose paper packaging for fresh fruit and vegetable preservation: A review," BioRes. 12(1), 2234-2248.AbstractArticlePDF

    The freshness and safety of fruits and vegetables is important in our daily life. Paper products are often used for shipping, wrapping, and decoration in the retail for fruits and vegetables. When these paper products are modified with active substances, they can offer additional functions other than just packaging. Thus, introducing 1-methylcyclopropene (1-MCP) into paper products can impart a preservation function for fruits and vegetables. 1-MCP is an excellent and eco-friendly inhibitor of ethylene that can effectively retard the ripening of fruits and vegetables. This article reviews the ripening process induced by ethylene, the inhibition mechanism of 1-MCP, and the existing technologies and products for 1-MCP utilization. Novel active paper packaging products via the use of encapsulated 1-MCP complexes may have a great potential for commercialization. Such packaging containing 1-MCP active paper could be effective in prolonging the shelf-life and improving the quality of the product during the storage, shipping process, and retail market, and can be attractive economically, socially, and environmentally.