NC State
  • Editorialpp 6902-6903Wu, D., Qian, X., and Shen, J. (2017). "Macromolecular reorganization as a basis for converting cellulosic hydrogels into sustainable plastics," BioRes. 12(4), 6902-6903.AbstractArticlePDF

    The development of lignocellulose-derived sustainable plastics is an important strategy for a greener future. Cellulosic hydrogels, which are readily generated from a cellulosic source (e.g., wood pulp), can be converted into high-strength plastics by hot-pressing. In this process, cellulose macromolecules are fluidized and reassembled, leading to significant change of bonding interactions and structural characteristics. This interesting concept would open the door for new possibilities of bioproduct design.

  • Editorialpp 6904-6906Hubbe, M. (2017). "To repair or not to repair cracked wood," BioRes. 12(4), 6904-6906.AbstractArticlePDF

    If only wood could be defect-free, then the minimum strength of solid-wood beams and other structures could be much higher. Structural failures could be avoided, and-or less material might be required in some applications. Cracks in wooden structures can be filled with adhesives or with thermoplastic composite material. But to approach the intended strength of defect-free wood, it is necessary to use other strategies such as glued rods and surface patches. The ultimate answer may lie in better species selection, tree breeding, forestry strategies, lumber cutting practices, and lumber drying practices to avoid cracks in the first place.

  • Researchpp 6907-6923Carvalho, D. M., and Colodette, J. L. (2017). "Comparative study of acid hydrolysis of lignin and polysaccharides in biomasses," BioRes. 12(4), 6907-6923.AbstractArticlePDF

    Effects of different acid hydrolysis conditions were studied relative to the chemical transformations of lignin in eucalyptus, sugarcane bagasse, and sugarcane straw, and on the transformations of multiple polysaccharides in eucalyptus. The acid hydrolysis using 12 mol/L sulfuric acid followed by acid hydrolysis using approximately 0.41 mol/L sulfuric acid was used as the reference for the lignin and sugar analysis. During acid hydrolysis, the relative amount of lignin increased with longer reaction times and/or greater acid concentrations for all biomasses. The overestimation of lignin in harsher acidic conditions resulted from the summation of lignocellulosic-derivatives (pseudo-lignin) together with lignin itself. Lignin reactions (dissolution/deposition) for bagasse and straw occurred in a greater extent than for eucalyptus, considering similar conditions of acid hydrolysis. The sugar transformation during acid hydrolysis was also investigated for eucalyptus. The sugar content quantified in eucalyptus decreased as the acid concentration and/or reaction time in the second hydrolysis increased. Glucose, galactose, and mannose were more resistant to harsher acidic conditions than xylose and arabinose. However, the most severe conditions (121 ºC, 90 min, and 6.15 mol/L H2SO4) caused complete sugar degradation.

  • Researchpp 6924-6955Bekiroğlu, S., Mertoğlu Elmas, G. M., and Yagshiyev, Y. (2017). "Contribution to sustainability and the national economy through recycling waste paper from Istanbul’s hotels in Turkey," BioRes. 12(4), 6924-6955.AbstractArticlePDF

    Obtaining cellulose from recyclable waste paper contributes to the sustainability of forest resources, water and energy savings, and the reduction of environmental pollution. However, waste paper collected under inappropriate conditions for recycling can be degraded in a short time, thus becoming economically useless. This study examined the factors affecting source-separated collection processes of waste paper in Istanbul hotels, as well as the correlation among these factors. The economic value of the assumed benefits of source-separated waste paper was also calculated. To achieve these objectives, various inputs and methods were used, including the percent tabulation technique and the chi-square independence test. As a result, it was determined that 70% of managers and employees of Istanbul hotels were sensitive to recycling waste paper, but they were not aware of the entire benefits of waste paper recycling. It was also determined that because of waste paper recycling, 18 thousand trees, 5 million kWh of electricity, 3 thousand tons of water, and 1.3 thousand tons of fuel oil were saved, and the generation of 27 thousand tons of CO2 was prevented annually. Hotels in Istanbul provide the economy with an annual average of 752 tons of waste paper, which corresponds to 78% of the foreign trade deficit of Turkey’s paper and paper products sector in the last five years.

  • Researchpp 6956-6970Wang, X., Liu, Z., Wang, S., Kong, F., Yang, G., Fatehi, P., and Lucia, L. A. (2017). "Enhancing the alkaline peroxide mechanical pulp strength by cationization with 3-chloro-2-hydroxypropyl trimethyl ammonium chloride," BioRes. 12(4), 6956-6970.AbstractArticlePDF

    Alkaline peroxide mechanical pulp (APMP) is a newly emerging high yield pulp (HYP) with numerous advantages. However, the drawback of the alkaline peroxide mechanical pulp from untreated plant biomass is its poor network strength. In this work, 3-chloro-2-hydroxypropyl trimethyl ammonium chloride (CHPTAC) modification was proposed to enhance pulp network strength by fiber surface modification that could enhance fiber bonding. Three factors were analyzed by response surface methodology (RSM) to optimize treatment conditions based on factorial designs. The results showed that the optimal conditions were CHPTAC dosage of 0.8% (oven-dry pulp), NaOH dosage of 0.1% (oven-dry pulp), and pulp concentration of 8%. The modified pulp fibers were characterized by elemental analysis, charge density analysis, Fourier transform infrared spectroscopy (FTIR), thermal gravity analysis (TGA), and internal bond strength analysis, as well as zero span tensile analysis. The physical strength of the modified APMP pulp was increased in terms of tensile index, tear index, and burst index. After modification, the tensile index, tear index, and burst index increased by 35.3%, 29.2%, and 16.7% respectively. The internal bonding strength increased by 144.4%; however, the increase of zero span tensile index of modified pulp fibers was insignificant.

  • Researchpp 6971-6983Altuntas, E., Narlioglu, N., and Alma, M. (2017). "Investigation of the fire, thermal, and mechanical properties of zinc borate and synergic fire retardants on composites produced with PP-MDF wastes," BioRes. 12(4), 6971-6983.AbstractArticlePDF

    Synergic effects of different fire retardant compounds and zinc borate on wood-plastic composites filled with polypropylene (PP) and medium-density fiberboard (MDF) waste fibers were investigated. For this purpose, zinc borate, synergic compounds (antimony trioxide, ammonium phosphate, and magnesium hydroxide), and a coupling agent, i.e., maleic anhydride-grafted polypropylene (MAPP), were used in the production of wood-plastic composites (WPCs). The composite samples were characterized in terms of the burning rate and limiting oxygen index (LOI) analyses, thermal gravimetric analysis (TGA), and differential scanning calorimetry (DSC) along with mechanical tests, i.e., flexural properties, tensile properties, elasticity modulus, and impact strength. It was found that the synergic influence of the combination of zinc borate, antimony trioxide, and magnesium oxide on WPCs increased the heat resistance according to the burning rate, LOI, TGA, and DSC tests. Also, the mechanical properties of the WPCs decreased slightly, but their elasticity modulus increased.

  • Researchpp 6984-7001Gopinathan, P., Subramanian, K., Paliyath, G., and Subramanian, J. (2017). "Genotypic variations in characteristics of nano-fibrillated cellulose derived from banana pseudostem," BioRes. 12(4), 6984-7001.AbstractArticlePDF

    A laboratory study was undertaken to extract nano-fibrillated cellulose (NFC) from the pseudostem (a waste from the fruit harvest) of two commercial banana cultivars (‘Grand Naine’ and ‘Poovan’) in Tamil Nadu using a novel approach: a one-step method with a bleaching agent and alkali-free acid hydrolysis coupled with ultrasonication. The acid hydrolysis was performed using nitric acid and acetic acid (1:10 ratio). The treatment was effective in the depolymerization and defibrillation of banana pseudostem fiber and in the formation of NFC, which was confirmed by several physico-chemical techniques. The average diameters of the nanofibrils were 6 to 8 nm and 4 to 6 nm for ‘Grand Naine’ and ‘Poovan’, respectively. The XRD analysis revealed an increased cellulose crystallinity of almost 20% in the NFC compared with the respective raw banana fibers. The Fourier transform infrared (FT-IR) spectroscopy and thermal gravimetric analysis (TGA) confirmed the absence of lignin, hemicelluloses, and pectin in the nano-fibrillated samples. The thermal analysis showed the increased thermal stability of the NFC.

  • Researchpp 7002-7015Huang, W., Wang, E., Chang, J., Wang, P., Yin, Q., Liu, C., Zhu, Q., and Lu, F. (2017). "Effect of physicochemical pretreatments and enzymatic hydrolysis on corn straw degradation and reducing sugar yield," BioRes. 12(4), 7002-7015.AbstractArticlePDF

    Straw lignocelluloses were converted to reducing sugar for possible use for bioenergy production via physicochemical pretreatments and enzymatic hydrolysis. The experiment was divided into 2 steps. The first step focused on breaking the crystal structure and removing lignin in corn straw. The lignin, hemicellulose, and cellulose degradation rates observed were 92.2%, 73.7%, and 4.6%, respectively, after corn straw was treated with sodium hydroxide (3% w/w) plus high-pressure steam (autoclave), 74.8%, 72.5%, and 4.3% after corn straw was treated with sodium hydroxide (8%, w/w) plus wet steam explosion, compared with native corn straw (P < 0.05). The second step was enzymatic hydrolysis for the pretreated straw. The enzymatic hydrolysis could yield 576 mg/g reducing sugar and significantly degrade cellulose and hemicellulose contents by 93.3% and 94.4% for the corn straw pretreated with sodium hydroxide plus high-pressure steam. For the corn straw pretreated with sodium hydroxide plus wet steam explosion, the enzymatic hydrolysis could yield 508 mg/g reducing sugar, and degrade cellulose and hemicellulose contents by 83.5% and 84.2%, respectively, compared with the untreated corn straw (P<0.05). Scanning electron microscopy showed that the physicochemical pretreatments plus enzymatic hydrolysis degraded corn straw to many small molecules. Thus, physicochemical pretreatments plus enzymatic hydrolysis converted lignocellulose to reducing sugar effectively.

  • Researchpp 7016-7031Záborský, V., Borůvka, V., Kašičková, V., and Ruman, D. (2017). "Effect of wood species, adhesive type, and annual ring directions on the stiffness of rail to leg mortise and tenon furniture joints," BioRes. 12(4), 7016-7031.AbstractArticlePDF

    The effects of selected factors, wood species (Fagus sylvatica L. and Picea abies L.), type of joint (haunched mortise and tenon, and haunched dovetail mortise and tenon), tenon thickness (one-third and half-joint thickness), type of adhesive (polyvinyl acetate and polyurethane adhesive), loading type (compressive and tensile), and direction of the annual rings were evaluated relative to the elastic stiffness. The testing samples were loaded by bending moment with tensile and compressive forces in the angular plane. The wood species, type of joint, tenon dimension, and type of adhesive all had a statistically significant effect on the elastic stiffness. However, the interaction of those factors was statistically insignificant. The loading type and direction of the annual rings did not have a significant effect on the elastic stiffness. For spruce, the use of mortise and tenon with a toothed feather (MTTF) was found to be disadvantageous, whereas the use of a toothed feather was favorable for beech. Half thickness of the joint was always an advantage, such that the stiffness increased. For spruce joints, the type of glue was not important, whereas for beech, the stiffness of joints glued with PVAc was significantly higher than with PUR adhesive.

  • Researchpp 7032-7040Nosek, R., Holubcik, M., Jandacka, J., and Radacovska, L. (2017). "Analysis of paper sludge pellets for energy utilization," BioRes. 12(4), 7032-7040.AbstractArticlePDF

    The pulp and paper industry in Europe produces over 11 million tons of waste per year. Given high landfill operational costs, thermal co-processing with biomass may be a viable management and valorisation option for such wastes. In this work, the analysis of biomass (wood sawdust), mixture of primary and secondary pulp mill sludge and their respective blends (50 wt.%, 60 wt.%, 70 wt.% of sludge) was assessed by thermogravimetric analysis. One of the possibilities to ensure valorisation of paper pulp mill sludge is its combustion in the form of pellets containing a different amount of sludge. Production of pellets samples was realised on laboratory experimental device. The measurements showed that increasing the content of paper sludge in the produced pellets reduced the calorific value and increased the ash content. This research deals also with the effect of paper sludge on the ash melting temperatures. The results indicated that a higher content of paper sludge in the pellets increased the ash melting temperatures. This advantage of paper sludge can be utilized in co-combustion of biomass with a low ash melting temperature.

  • Researchpp 7041-7055Wei, Y., Wang, M., Zhang, P., Chen, Y., Gao, J., and Fan, Y. (2017). "The role of phenolic extractives in color changes of locust wood (Robinia pseudoacacia) during heat treatment," BioRes. 12(4), 7041-7055.AbstractArticlePDF

    To investigate the effects of phenolic extractives on the discoloration of black locust wood (Robinia pseudoacacia) during heat treatment, phenolic compounds were extracted using an accelerated solvent extraction. The main components of the phenolic extractives were analyzed. The phenolic compounds were heat treated at 120 and 140 °C in nitrogen, oxygen, and saturated steam. The results showed that the a* values shifted toward red and the b* values shifted toward yellow after the heat treatment. The changes in the color parameters were more pronounced when the samples were treated at 140 °C in saturated steam compared with treatment at 120 °C in oxygen or nitrogen atmosphere. During heat treatment, hydroxyl groups in the phenolic components were oxidized to form carbonyl groups, or the adjacent hydroxyl groups formed quinoid structures. It was possible that the sample underwent condensation reactions to produce conjugated double-bond structures that led to the increase in color parameters.

  • Researchpp 7056-7068Altuntas, E., Yilmaz, E., Salan, T., and Alma, M. H. (2017). "Combined effect of zinc borate and coupling agent against brown and white rot fungi in wood-plastic composites," BioRes. 12(4), 7056-7068.AbstractArticlePDF

    Fungal resistance was investigated for wood-plastic composites (WPCs) containing zinc borate, maleic anhydride grafted polyethylene (MAPE) as a coupling agent, wood fiber (Pinus sylvestris), and high-density polyethylene (HDPE). Decay resistance, water absorption, and surface hardness (Shore D) of the WPCs were tested. The reinforced wood-plastic composites were exposed to brown-rot fungus (Coniophora puteana, Postia placenta) and white-rot fungus (Trametes versicolor) in agar tests. The results showed that zinc borate improved the decay resistance of the WPCs against brown and white rot fungus according to their weight losses. Moreover, the water absorption and surface hardness tests indicated that the physical properties of the composites were weakened after fungal decay tests. The usage of MAPE and zinc borate alone or together was effective against both rot fungus species in WPCs. The synergy of 1% zinc borate and 3% MAPE in WPCs could considerably increase the fungal attack resistance. Scanning electron microscopy (SEM) revealed that both brown and white rot fungus attacked the surface of WPCs samples without both MAPE and zinc borate.

  • Researchpp 7069-7083Brandão, T. S. O., Pinho, L. S., Hughes, A. F. S., Souza, J. L., Rosa, C. A., Teshima, E., Brandão, H. N., and David, J. M. (2017). "Characterization of the jambolan (Syzygium cumini L.) fruit wine processing," BioRes. 12(4), 7069-7083.AbstractArticlePDF

    Yeasts were isolated and the alcohol genic features were tested for their direct use in the wine processing of jambolan. In addition, changes in the total phenolic compounds during the maceration-fermentation process were investigated. Yeasts were selected from the spontaneous fermentation of the jambolan pulp, and the feasibility and fermentative production of its alcohol was tested. Out of the group of yeasts selected, the one that stood out was subjected to DNA extraction and sequencing. The yeast was identified as Saccharomyces cerevisiae, and the fermentation tests came back as 80.6% and the ethanol production yield was 8.35%. The chemical composition of raw materials was analyzed by spectrophotometrics and high performance liquid chromatography (HPLC) methods. The overall results also indicated that the evolution during the maceration-fermentation process of phenolic compound concentrations was influenced by the varietal factor. The concentration of phenolic compounds increased 30%, while the concentration of tannins increased 27.4% in the final product.

  • Researchpp 7084-7095Ji, X., Ma, H., Tian, Z., Lyu, G., Fang, G., Chen, J., and Saeed, H. A. M. (2017). "Production of xylose from diluted sulfuric acid hydrolysis of wheat straw," BioRes. 12(4), 7084-7095.AbstractArticlePDF

    The objectives of this study were to generate fermentable xylose by sulfuric acid hydrolysis of wheat straw and investigate the effect of hemicellulose removal on the physical and chemical properties of the unhydrolyzed solid residue (USR). Different reaction conditions, including concentration of sulfuric acid (COS), temperature, and time, were tested for their effects on the yield of xylose and the USR. The ideal hydrolysis conditions for xylose production were 0.5% of COS at 140 °C for 90 min, with the xylose yield of 0.185 g/g wheat straw. The Fourier transform infrared spectroscopy (FTIR) and X-ray diffraction (XRD) analyses showed that the acid hydrolysis only caused slight changes in the functional groups and the crystal form of wheat straw at mild conditions, while higher temperature or higher COS exacerbated these changes.

  • Researchpp 7096-7106Chen, Q., Mi, T., Chen, G., and Li, Y. (2017). "Green synthesis of nano-silver particles using plant active substance from lemongrass extract," BioRes. 12(4), 7096-7106.AbstractArticlePDF

    Biosynthesis of nanoparticles by plant extracts is currently under exploitation. Plant extracts are very cost effective and eco-friendly and thus can be an economic and efficient alternative. This study investigates the mechanism of preparation of nano-silver using a plant active substance from lemongrass extract. The lemongrass ethanol extract was prepared using an ultrasonic cell crusher. Spherical silver nanoparticles were prepared with lemongrass extract and silver nitrate. The reaction mechanism of the preparation of nano-silver by plant extracts was analyzed by infrared and X-ray photoelectron spectrometer (XPS) measurements. The uniform and stable spherical silver nanoparticles with an average particle size of 22.99 nm were synthesized. Amide compounds in plant extracts may act as reductants and protective agents. The biomass of plants produces their nanomaterials through a process called biomineralisation. Thus, plant active substances can be used widely, and biological methods are completely feasible and worth studying for the chemical procedures, which are environmentally friendly and convenient.

  • Researchpp 7107-7117Mirski, R., Dziurka, D., and Derkowski, A. (2017). "Dimensional stability of oriented strand boards with external layers made of non-strand chips: Changes in board length," BioRes. 12(4), 7107-7117.AbstractArticlePDF

    The dimensional stability of oriented strand boards (OSB) was evaluated in terms of the changes in their length, static bending strength, and modulus of elasticity. Outer layers of these boards were manufactured from particles other than strand chips. The boards were exposed to an air relative humidity of 30%, 65%, or 85%. Dimensional alterations were determined separately for absorption (from 65% to 85% RH) and desorption (from 65% to 30% RH) changes. Changes in the mechanical properties of the boards were evaluated after they underwent two cycles of the conditioning process and were compared with the baseline values. The study implied that relative changes in the mechanical properties and length increased when there was a reduction in the size of chips that formed the outer layers. A linear relationship was established between the relative changes in the board length determined for the axis that was more susceptible to deformation and the modulus of elasticity. These changes were inversely proportional to the value of the modulus of elasticity.

  • Researchpp 7118-7132Chee, S. S., Jawaid, M., and Sultan, M. T. H. (2017). "Thermal stability and dynamic mechanical properties of kenaf/bamboo fibre reinforced epoxy composites," BioRes. 12(4), 7118-7132.AbstractArticlePDF

    An increased awareness of environmental concerns has increased the need for innovation to produce high performance engineering materials with natural renewable resources. In this study, 3 types of natural fibre (mat form) reinforced epoxy composites were prepared by the hand lay-up method, namely, kenaf (K)/Epoxy, bamboo (B)/Epoxy, and bamboo charcoal (BC)/Epoxy. The thermal stability of the specimens was investigated by thermogravimetric analysis (TGA) and the dynamic mechanical properties. Viscous elastic behaviour of the specimens was investigated via a dynamic mechanical analyzer (DMA). The TGA results revealed that the BC/Epoxy composite showed the highest thermal stability compared to K/Epoxy and B/Epoxy with the highest initial and final decomposition temperature at 348 °C and 463 °C, respectively. It also showed the highest charcoal content at 11.5%. From the DMA results, the K/Epoxy composite showed better dynamic mechanical properties with the highest complex modulus (E*) strength and the lowest damping behaviour (peak height of Tan δ). The DMA analysis also revealed that the glass transition temperature of the composites fell between 60 °C to 90 °C. This preliminary study may give a new path to develop a novel hybrid composite that offers unique properties unachievable in a single material system.

  • Researchpp 7133-7144Chin, S. X., Chook, S. W., Chia, C. H., Lau, K. S., Zakaria, S., and Tasirin, S. M. (2017). "Graphene oxide as support and regenerative substrate for lead ions in catalytic conversion of lactic acid," BioRes. 12(4), 7133-7144.AbstractArticlePDF

    Graphene oxide (GO) was used as a catalyst support and for regeneration of a homogeneous catalyst in the catalytic conversion of glucose to lactic acid (LA). First, a solid base catalyst was prepared through the adsorption of Pb2+ ions by GO through ionic interaction with oxygenated groups of GO. The collected GO-Pb catalyst was characterized, demonstrating the successful loading of Pb2+ onto GO sheets using FTIR and XPS. The GO-Pb catalyst was subsequently used for the conversion of glucose into LA. A maximum LA yield of approximately 30% was achieved in 30 min. The catalyst demonstrated the ability to be used for at least five cycles. In contrast, the leached Pb2+ ions during the hydrothermal process were regenerated through adsorption with fresh GO. The regenerated catalyst demonstrated the possibility of the regenerated Pb2+ ions for further catalytic conversions of lactic acid. This study could be essential to produce valuable chemicals through the use of heterogeneous catalysts that are produced via a simple and environmental benign process.

  • Researchpp 7145-7160Edhirej, A., Sapuan, S. M., Jawaid, M., and Zahari, N. I. (2017). "Tensile, barrier, dynamic mechanical, and biodegradation properties of cassava/sugar palm fiber reinforced cassava starch hybrid composites," BioRes. 12(4), 7145-7160.AbstractArticlePDF

    The hybrid composite was prepared from cassava bagasse (CB) and sugar palm fiber (SPF) by casting technique using cassava starch (CS) as a matrix and fructose as a plasticizer. The chemical composition and physical properties of SPF and CB were studied in this work. SPF was added at different loadings of 2, 4, 6, and 8% dry starch to the CS/CB composite films with 6% CB. The addition of SPF influenced the hybrid properties. It was observed that the addition of 6% SPF to the composite film increased the tensile strength and modulus up to 20.7 and 1114.6 MPa, respectively. Also, dynamic-mechanical properties of the hybrid composites were investigated using a DMA test. The incorporation of SPF increased the storage modulus (E’) value from 0.457 GPa of CS to 1.490 GPa of CS-CB/SPF8 hybrid composite film. Moreover, the incorporation of SPF slightly decreased the water vapor permeability (WVP) compared to the CS/CB composites film. It can be concluded that the incorporation of SPF led to changes in cassava starch composite film properties, potentially improving the bio-degradability, WVP, and mechanical properties of the film. Based on its excellent properties, CB/SPF-CS hybrid composite films are suitable for various purposes such as packaging, automotive, and agro-industrial applications, at lower cost.

  • Researchpp 7161-7177Altuntas, E., Yilmaz, E., Salan, T., and Alma, M. H. (2017). "Biodegradation properties of wood-plastic composites containing high content of lignocellulosic filler and zinc borate exposed to two different brown-rot fungi," BioRes. 12(4), 7161-7177.AbstractArticlePDF

    The decay resistance of zinc borate-reinforced wood-plastic composites (WPCs) was studied against two types of brown-rot fungi (Rhodonia placenta and Coniophora puteana). The WPCs with 70% wood fibers (Pinus sylvestris L.) were reinforced with 1% and 2% zinc borate. The reinforced WPCs were exposed to a decay test according to the EN 113 (1996) standard. The composite samples were characterized by their weight losses and water absorption capacity (WAC) as well as by Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), thermogravimetric analysis (TGA), and differential thermal analysis (DTA). The weight losses and WAC results showed that zinc borate improved the decay resistance of the WPCs to a certain degree against brown rot fungi. The FTIR and SEM results showed that the brown rot fungi attacked the WPCs. It was concluded that the use of 1-2% zinc borate provided resistance to fungal attack on WPCs to a certain degree.

  • Researchpp 7178-7194Löwe, A., Hauptmann, M., and Majschak, J. P. (2017). "The effect of ultrasonic oscillation on the quality of 3D shapes during deep-drawing of paperboard," BioRes. 12(4), 7178-7194.AbstractArticlePDF

    In this publication, the ultrasonic-assisted deep-drawing of fiber-based materials, whose implementation was presented in Löwe et al. (2016), was studied in detail. Methods were developed for measuring the properties of deep-drawn cups, including cup stability, shape deviation, and surface quality. The relationship between these properties and the process parameters were determined with a design of experiment, which allows the user to adjust the cup properties in order to optimize them.

  • Researchpp 7195-7204Stajic, M., Ćilerdžić, J., Galić, M., Ivanović, Ž., and Vukojević, J. (2017). "Lignocellulose degradation by Daedaleopsis confragosa and D. tricolor," BioRes. 12(4), 7195-7204.AbstractArticlePDF

    The properties and capacities of the ligninolytic enzymes of Daedaleopsis spp. are still unknown. This is the first study on the effect of plant residues and period of cultivation on the properties of Mn-oxidizing peroxidases and laccases of D. confragosa and D. tricolor, as well as their ligninolytic potentials. Wheat straw was the optimal carbon source for synthesis of highly active Mn-dependent peroxidases (4126.9 U/L in D. confragosa and 2037.9 U/L in D. tricolor). However, laccases were the predominant enzymes, and the best inducer of their activity (up 16000.0 U/L) was cherry sawdust. Wheat straw was the most susceptible plant residue to the effect of the enzymes, and extent of lignin degradation was 43.3% after 14 days of fermentation with D. tricolor. However, D. confragosa was a more effective lignin degrader, as it converted even 21.3% wheat straw lignin on the 6th day of cultivation. The results of the study clearly showed that delignification extent depends on mushroom species and on the type of plant residue, which is extremely important for potential use in biotechnological processes.

  • Researchpp 7205-7217Xu, Y., Wang, B., Shen, Y., Wu, J., Feng, L., and Yu, H. (2017). "Effect of softening treatment on cutting force during slicing the veneers of common fast-growing wood," BioRes. 12(4), 7205-7217.AbstractArticlePDF

    To verify the effect of softening treatment on the cutting force during slicing of veneers, an experiment was performed using a veneer slicer with steam injection heating function. Several conditions were set to soften the experimental materials of poplar (Populus L.), eucalyptus (Eucalyptus robusta Smith), pine (Pinus massoniana Lamb.), and Chinese fir (Cunninghamia lanceolata (Lamb.) Hook.). The cutting force was detected by the YE7600 signal analysis system. The results showed that the cutting force increased with increased slicing thickness. The cutting force was observed to follow the order, from high to low for the conditions of being soaked in cold water, then steam heated, water-poached, and steam heated again. Compared to the case of non-steam heating, the effect of steam heating on reducing the cutting force was satisfactory, and the maximum decrease percentage reached 83.1%. The cutting force was positively related to the wood density and hardness, and the cutting stroke had a great influence on the cutting force. After being softened, the four kinds of fast-growing wood were sliced into veneers with ≤ 6 mm thickness, and the cutting force was generally no more than 6850 N.

  • Researchpp 7218-7227Björngrim, N., Fjellström, P. A., and Hagman, O. (2017). "Factory-mounted and retrofit passive resistance sensors adapted to monitor moisture content in timber bridges," BioRes. 12(4), 7218-7227.AbstractArticlePDF

    The biggest threats to the longevity of a timber bridge are rot and decay. Wood protection by design, inspections, and monitoring of the bridge for elevated moisture content will ensure that the full service life of the structure can be achieved. Today’s sensors for moisture content measurements are limited in their functionality and range. This paper presents a sensor that can be both factory installed and retrofitted, which can measure the moisture content through the cross-section of the member in a timber bridge. The sensor has been mounted on Sundbron bridge during manufacturing and retrofitted on Gislaved bridge. The ensuing measurements helped to adjust a design flaw on Gislaved bridge. Monitoring of Sundbron showed that the bridge deck dried up after the bridge had been exposed to sleet and snow during the on-site assembly of the stress laminated bridge deck.

  • Researchpp 7228-7240Manyuchi, M. M., Frank, R., Mbohwa, C., and Muzenda, E. (2017). "Potential to use sorghum brewers spent grains as a boiler fuel," BioRes. 12(4), 7228-7240.AbstractArticlePDF

    The potential of using sorghum brewers spent grain (BSG) was examined for the production of bioelectricity. A local brewery company, with a production capacity of 24 tons per day of sorghum brewers spent grain as biomass waste, was used as a source of boiler fuel. After a full proximate analysis, the sorghum brewers spent grain had an average calorific value of 12.6 MJ/kg whilst coal had 19.9 MJ/kg. In addition, the BSG had a fixed carbon content of 41.6%. This indicated that it was feasible to generate electricity using sorghum brewers spent grain as a source of fuel just like coal; however the moisture content of the BSG must be controlled at minimum levels to attain high calorific values. An assumed feed rate of 1100 kg/h BSG being fed, operation at 86% efficiency, maximum pressure of 9 bars, and a steam output of 1689 kg/h were designed to supply a one megawatt (MW) turbine generator. An economic analysis was done with a total investment cost of USD$ 3.4 million, a payback period of 3.7 years, and a return on investment of 27.4%. Sorghum BSG can be provided as an alternative source of bioelectricity for the brewery industry.

  • Researchpp 7241-7254Chu, J., Jiang, W., and Wu, S. (2017). "Depolymerization characteristics during the pyrolysis of two industrial lignins," BioRes. 12(4), 7241-7254.AbstractArticlePDF

    For the value-added utilization of industrial lignin both from pulping black liquor and acid hydrolysis residues, the eucalyptus alkali lignin (AL) and enzymatic mild acidolysis corncob-to-xylitol residue lignin (EMARL) were isolated. Their pyrolysis behaviors were investigated by thermogravimetric analysis (TGA), in situ Fourier transform infrared spectroscopy (FTIR), and pyrolysis-gas chromatography/mass spectrometry (Py-GC/MS). The chemical bonds of EMARL were easier to break than AL at relatively lower temperatures, which was confirmed by the relationship between temperature and the differential absorbance of functional groups (such as carbonyl and hydroxyl). Based on the analysis of pyrolysis products, the value-added monomers were the main products. At 400 °C, AL mainly contained guaiacyl-type and syringyl-type compounds and the yields were 28.95% and 62.54%, respectively, while EMARL contained more guaiacyl-type products (62.96%). When the temperature was increased to 600 °C, the contents of phenol-type increased, suggesting that the demethoxylation reaction occurred during lignin pyrolysis. Study of the characteristics of pyrolysis could be significant for understanding the thermochemical depolymerization of AL and EMARL for value-added products.

  • Researchpp 7255-7267Nosáľ, E., and Reinprecht, L. (2017). "Anti-bacterial and anti-mold efficiency of ZnO nanoparticles present in melamine-laminated surfaces of particleboards," BioRes. 12(4), 7255-7267.AbstractArticlePDF

    Lamination is one of the most widely used techniques for the surface treatment of wood-based composites such as particleboards, fiberboards, etc. It is usually carried out using décor papers impregnated with amino thermosetting resins, mostly melamine-formaldehyde, urea-formaldehyde, or their mixture. Conventional laminates with non-bioactive surfaces are not able to reduce or stop microbial growth when contaminated with organic substances. In this work, zinc oxide (ZnO) nanoparticles were applied into their surface structure to improve their anti-bacterial and anti-mold properties. Melamine-formaldehyde (MF) resin, for the white décor paper impregnation, was modified with ZnO in amounts of 0.1 wt.%, 0.3 wt.%, 0.6 wt.%, and 1 wt.% and pressed onto particleboards. The presence of ZnO in the melamine-laminated surfaces somewhat improved their resistance to the Gram-positive bacteria Staphylococcus aureus (by 20.7% or 9.5%). However, the improvement was considerable (~65% or 46.8%) against the Gram-negative bacteria Escherichia coli. The presence of ZnO in MF resins increased the anti-mold resistance of the intentionally contaminated laminated surfaces against the microscopic fungi Aspergillus niger and Penicillium brevicompactum at most by approximately 50%. ZnO nanoparticles had none or only a small negative effect on the resistance of the laminated surfaces towards aggressive chemicals and dry heat 180 °C, and their abrasion resistance decreased at most by approximately 17%.

  • Researchpp 7268-7282Ratnasingam, J., Ramasamy, G., Ioras, F., and Senin, A. (2017). "Environmental and economic impact of using logging residues as bioenergy: The case of Malaysia," BioRes. 12(4), 7268-7282.AbstractArticlePDF

    The potential use of residues from the logging process was evaluated for electrical energy generation by direct combustion. The findings were based on logging residues accrued from 1990 to 2015 and were enumerated using a 43% residue recovery rate. The available logging residues were insufficient to supply the primary electrical energy demand as well as reduce the emission of carbon dioxide. However, when coupled with other agricultural residues, the potential energy generation from biomass was significant and could not only lead to reduced fossil fuel demand, but also improve the carbon credit and provide additional employment opportunities in the bioenergy sector.

  • Researchpp 7283-7300Özkan, A., Günkaya, Z., Yapıcı, E., and Banar, M. (2017). "Adsorption of copper from waste printed circuit boards with modified orange peels," BioRes. 12(4), 7283-7300.AbstractArticlePDF

    Copper adsorption from waste printed circuit boards (PCBs) was studied using biosorbents derived from waste orange peels (OP). The orange peels were modified by different methods including saponification with NaOH (OP-S), crosslinking with sodium trimetaphosphate and sodium tripolyphosphate (OP-C), hydroxypropylation with propylene oxide (OP-H), and acidification with citric acid (OP-A) to increase the adsorption capacity of orange peels. Adsorption tests on the copper (Cu) model solutions were performed by using native and modified orange peels at three different temperatures (25 °C, 40 °C, and 60 °C) to determine the optimum adsorption conditions. The PCB was pyrolyzed in a fixed bed stainless steel reactor to obtain a solid product that contained only inorganic material. Metals were then leached from the solid product, and adsorption studies were realized on the leach solution under optimum adsorption conditions. According to the analyses results, the best adsorption efficiency for the Cu model solution was obtained with OP-S at 25 C for 30 min. Under these conditions, the Cu adsorption efficiency from pyrolysis solid product was approximately 86%.

  • Researchpp 7301-7310Majová, V., Horanová, S., Škulcová, A., Šima, J., and Jablonský, M. (2017). "Deep eutectic solvent delignification: Impact of initial lignin," BioRes. 12(4), 7301-7310.AbstractArticlePDF

    This study aimed to resolve the issue of the lack of detailed understanding of the effect of initial lignin content in hardwood kraft pulps on pulp delignification by deep eutectic solvents. The authors used Kappa number of the concerned pulp, intrinsic viscosity, and selectivity and efficiency of delignification as the parameters of the effect. The pulp (50 g oven dry pulp) was treated with four different DESs systems based on choline chloride with lactic acid (1:9), oxalic acid (1:1), malic acid (1:1), and system alanine:lactic acid (1:9); the results were compared to those reached by oxygen delignification. The results showed that the pulp with a higher initial lignin content had a greater fraction of easily removed lignin fragments.

  • Researchpp 7311-7324Gaff, M., Ruman, D., Svoboda, T., Sikora, A., Záborský, V., and Vallejo, C. R. (2017). "Impact bending strength as a function of selected factors: 2 – Layered materials from densified lamellas," BioRes. 12(4), 7311-7324.AbstractArticlePDF

    This article examines the effect of selected factors (wood species, lamella combination, type of adhesive, number of loading cycles) on the impact bending strength (IBS) of laminated wood. The IBS was tested on specimens made from beech (Fagus sylvatica L.) and aspen lamellas (Populus tremula L.). The laminated wood was densified by 10% and 20% of the original thickness. For bonding the wood, polyvinyl acetate (PVA) adhesive was used, and the product was compared with laminated wood bonded with polyurethane adhesive (PUR). The wood species and lamella combination had significant effects on IBS. The highest values of IBS were found for beech wood lamellas.

  • Researchpp 7325-7340Mehryar, E., Ding, W., Hemmat, A., Talha, Z., Hassan, M., Mamat, T., and Hei, K. (2017). "Anaerobic co-digestion of oil refinery wastewater with bagasse; evaluating and modeling by neural network algorithms and mathematical equations," BioRes. 12(4), 7325-7340.AbstractArticlePDF

    To survey the anaerobic co-digestion (AcoD) of oil refinery wastewater (ORWW) with sugarcane bagasse (SCB), six different AcoD compositions were evaluated. Results including cumulative biogas production (BGP), bio-methane contents (BMP), and soluble chemical oxygen demand (CODs) removal rate were experimentally obtained. The negligible BGP by ORWW mono-digestion revealed that it could not support any microbial activity. However, increasing the SCB ratio in the AcoD compositions led to increased BGP and BMP contents. By considering the statistical test (LSD0.05) results for the kinetic parameters, the 1:4 ratio treatment was the most favorable AcoD composition. Moreover, the CODs removal rate from 22.34 ± 1.63% for the SCB mono-digestion was improved to 49.67 ± 0.38% for the 2:3 AcoD composition and BMP content from 54.12 ± 0.45% for the SCB mono-digestion was enhanced to 62.69 ± 1.22% for the 1:4 AcoD composition with 20% lower SCB usage. The results computed by applying three mathematical models determined that the modified Gompertz model provided the best fit. Also, implementing artificial neural network algorithms to model the BGP data revealed that the Back Propagation algorithm was the best suited for the experimental BGP data, with 0.6444 and 0.9658 for MSE and R2, respectively.

  • Researchpp 7341-7348Huang, W. X., Zhang, Y. H., Ge, Y. Y., Qin, L., and Li, Z. L. (2017). "Soft nitrogen and sulfur incorporated into enzymatic hydrolysis lignin as an environmentally friendly antioxidant and mercury adsorbent," BioRes. 12(4), 7341-7348.AbstractArticlePDF

    Soft donors of nitrogen and sulfur were incorporated into enzymatic hydrolysis lignin (EHL-NS) to make it suitable for multiple applications. Characterizations of the environmentally friendly material by Fourier transform infrared spectroscopy, scanning electron microscopy, energy dispersive spectroscopy, and thermogravimetric analysis confirmed the layered porous structure with nitrogen and sulfur groups. It exhibited high antioxidant activity due to the strong electron-donating capability of the soft donors. Moreover, the soft donors also contributed to the chemical complexation of Hg(II) with EHL-NS, which distinctly enhanced the adsorption of Hg(II) in water (Qe=180 mg/g, 25 °C). Given that the free radicals were highly effective at scavenging and adsorption, the functionalized enzymatic hydrolysis lignin is expected to serve a useful role.

  • Researchpp 7349-7362Zhang, L., Sun, Z., Liang, D., Lin, J., and Xiao, W. (2017). "Preparation and performance evaluation of PLA/coir fibre biocomposites," BioRes. 12(4), 7349-7362.AbstractArticlePDF

    Alkali-treated coir fibers were modified by silane coupling agent in a microwave oven. The use of microwave-assisted chemical treatments efficiently promoted the esterification reaction to improve the interfacial adhesion between the coir fibers and PLA matrix. Effects of the treated coir fiber content (1 wt.% to 7 wt.%) on the surface morphology and tensile, impact, and thermal properties of PLA/coir fiber biocomposites (AKWCF/PLAs) were evaluated. At a coir fiber content of 1%, the AKWCF/PLAs showed a remarkable increase of 28% in the percentage impact strength, while the tensile strength and breaking strength decreased with increasing coir fibre content. The thermal stability of the AKWCF/PLAs worsened and the degree of crystallinity increased with increasing fiber content. The decreased cold crystallization temperatures of AKWCF/PLAs further confirmed the role of coir fibers treated with the new combined method as an effective nucleating agent.

  • Researchpp 7363-7375Yang, Q., Wang, H., Larson, R., and Runge, T. (2017). "Comparative study of chemical pretreatments of dairy manure for enhanced biomethane production," BioRes. 12(4), 7363-7375.AbstractArticlePDF

    Dairy manure containing partially digested plant cells is an inexpensive bioenergy feedstock. The carbohydrates and lignin that remain after digestion are typically processed in an anaerobic digester to produce biomethane, but due to the remaining material’s recalcitrance, the process has a low conversion efficiency. To improve the conversion of this lignocellulosic material, chemical, thermal, or biological pretreatments can be considered. This study compared several chemical pretreatments including dilute acid, sulfite, and alkali pretreatments for dairy manure as a bioenergy feedstock and analyzed their impact on biomethane production. The comparative study showed that a hot alkali pretreatment (180 °C, 30 min) can improve the methane production of dairy manure by 50%, which is more effective than dilute acid (6.8%), sulfite (26.3%), and cold or ambient alkali (19.8 to 32.8%) pretreatments. However, the ambient alkali pretreatment (23 °C, 12 h) was calculated to be more economically feasible because of the net energy production.

  • Researchpp 7376-7394Martínez-Conde, A., Huber, D., Pinkl, S., Mahrdt, E., Teischinger, A., and Müller, U. (2017). "Dynamic compression: A novel technique to reduce energy consumption during wood fiber production," BioRes. 12(4), 7376-7394.AbstractArticlePDF

    Thermo-mechanical refining is a common fiber production process known for its high energy demands. Throughout this process, wood chips are subjected to repetitive shearing and compression such that the fibers separate and subsequently fibrillate. There is a growing body of research in the development of mechanical pre-treatments that reduce energy demands during chemo- and thermo-mechanical pulping, with shear/compression combinations currently standing as the most efficient method of initiating defibration. Given the common grounds between the fiberboard and paper refining processes, it could be possible to use paper pre-treatments during fiberboard pulp refining. Furthermore, as pulping fibers for fiberboard are less worked and refined, mechanical pre-treatments are assumed to be more efficient. In this study, the effectiveness of dynamic compression was assessed as a pre-treatment step before the chips enter the refiner. Shaped wet chips with an annual ring orientation of 45° were struck by a free-falling weight with a fixed potential energy using a special prototype. After refining both the reference and pre-treated chips using a pressurized disc refiner, the energy consumption of those fibers was 48% lower than that for non pre-treated chips for a comparable fiber quality.

  • Researchpp 7395-7412Gurau, L., Petru, A., Varodi, A., and Timar, M. C. (2017). "The influence of CO2 laser beam power output and scanning speed on surface roughness and colour changes of beech (Fagus sylvatica)," BioRes. 12(4), 7395-7412.AbstractArticlePDF

    The literature provides very little information about engraving or decorating wood using a laser beam. No study was found that considers the surface roughness of wood after such treatments. This paper therefore aimed to find the influence of varying the laser power output and scanning speed of a CO2 laser beam on the surface roughness and colour of beech wood (Fagus sylvatica) for aesthetic applications such as decorative drawing. Laser power outputs from 5.6 to 6.8 W were tested in combination with scanning speeds from 100 to 500 mm/s. The surface roughness was assessed with a robust filter and by following measuring and evaluation recommendations from previous research to reduce the bias from the wood anatomy. The surface roughness measured by a series of roughness parameters (Ra, Rq, Rt, Rk, Rpk, Rvk) and total colour difference DE increased with laser power and decreased with scanning speed. A good correlation was found between surface roughness and wood colour change. Such correlations can be useful for selecting the laser power-scanning speed combinations capable of giving the chosen colour change at a minimum surface roughness.

  • Researchpp 7413-7426Sedlecký, M., and Gašparík, M. (2017). "Power consumption during edge milling of medium-density fiberboard and edge-glued panel," BioRes. 12(4), 7413-7426.AbstractArticlePDF

    This paper presents the energy consumption differences during the edge milling of various board materials (medium-density fiberboard (MDF), medium-density fiberboard with single-sided lamination (MDF-L), and spruce edge-glued panel (SEGP)). The edge milling was carried out with various parameters: feed rate (4, 8, and 11 m/min); cutting speed (20, 30, 40, and 60 m/s); and blade type (tungsten carbide HW1, HW2, and HW1 coated with CrTiN (HW1 + CrTiN)). The results indicated that the increase in the cutting speed and feed rate cause the increase in cutting power. The highest cutting power values were observed with the milling of MDF; slightly lower values were observed with MDF-L, and the lowest values were observed with SEGP. Very similar cutting power values during milling were noted with HW1 and HW2 blades, whereas milling with the HW1 + CrTiN resulted in slightly higher values (e.g., 1% higher).

  • Researchpp 7427-7438Yin, Y., Zhao, L., Jiang, X., Wang, H., and Gao, W. (2017). "Synthesis of triazine derivative and its application in the modification of cellulose nanocrystals," BioRes. 12(4), 7427-7438.AbstractArticlePDF

    Cellulose nanocrystals (CNCs) were modified with triazine derivative in an effort to decrease the hydrophilicity of CNCs and improve their thermal stability. In recent decades, much attention has been given to the modification of CNCs to broaden their use in various applications, such as in nanocomposites, as adsorbents for the disposal of wastewater, and so on. The CNCs with a rod-like shape were obtained from cotton through sulfuric acid hydrolysis. Hydrophobic triazine derivative was synthesized via the reaction between triazine and n-butylamine (BA) and then applied to modify CNCs to improve their thermal stability and diminish the hydrophilicity of the nanoparticles. Results of thermogravimetric analysis (TGA) indicated a 150 °C increase in the initial thermal decomposition temperature of modified nanocrystals compared to the original CNCs. The improved thermal stability of modified CNCs was attributed to a shielding effect of the hydrophobic aliphatic amine layer on the surface of the nanoparticles. The results of the dynamic contact angle measurement revealed a decrease of hydrophilicity of the modified CNCs.

  • Researchpp 7439-7451Li, R., Yang, G., Wang, Q., Chen, J., Dong, J., and Zhang, X. (2017). "Preparation of carbon-based solid acid from corncob residual and its performance for acid-catalyzed hydrolysis," BioRes. 12(4), 7439-7451.AbstractArticlePDF

    A carbon-based solid acid catalyst (CHACS) derived corncob residual was prepared by incomplete hydrothermal carbonization followed by activation with phosphoric acid impregnation and sulfuric acid sulfonation. The structure of the solid acid catalyst was characterized using Fourier transform infrared spectra (FTIR), thermogravimetric analyzer (TGA), X-ray diffraction (XRD), scanning electron microscope (SEM), specific surface area (SSA), and elemental analysis. The -SO3H, -COOH, and phenolic -OH functional groups were successfully introduced. Phosphoric acid activation facilitated formation of the porous structure in the solid acid catalyst. The specific surface area and acid density were 1569 m2/g and 1.030 mmol/g, respectively. The CHACS exhibited better catalytic activity for hydrolysis conversion of corn stalk in ionic liquid with water as solvent. A total reducing sugars (TRS) yield of 68.3% was obtained in water and a TRS yield of 52.5% was obtained in an ionic liquid of [BMIM][Cl] at 140 °C for 120 min. The CHACS expressed good catalytic activity in each of 4 separate instances of reuse.

  • Researchpp 7452-7465Hidayat, W., Qi, Y., Jang, J. H., Febrianto, F., and Kim, N. H. (2017). "Effect of mechanical restraint on drying defects reduction in heat-treated okan wood," BioRes. 12(4), 7452-7465.AbstractArticlePDF

    Mechanical restraint through the use of clamps was applied as an attempt to prevent drying defects during the heat treatment of high-density wood. Boards of okan (Cylicodiscus gabunensis (Taub.) Harms) with the initial moisture content of 8.99% and 9.68% for sapwood and heartwood, respectively, were prepared. The boards were heat-treated under an oxygen atmosphere at the peak temperatures of 160 °C, 180 °C, 200 °C, and 220 °C with a residence time of 2 h. The occurrence of drying defects as checks (i.e., surface and end checks) and warps (i.e., bow, cup, and twist) were evaluated. Heat treatment stimulated the occurrence of drying defects in okan wood. The results revealed that the surface checks, end checks, and twists increased linearly with increased temperature. The occurrence of warps, such as bow and cup, after heat treatment was relatively low. Heartwood showed a higher degree of drying defects compared to the sapwood. Application of mechanical restraint by clamping efficiently decreased the occurrence of drying defects of okan wood, particularly surface checks, end checks, and twists.

  • Researchpp 7466-7478Diler, H., Acar, M., Balıkçı, E., Demirci, S., and Erdil, Y. Z. (2017). "Withdrawal force capacity of T-type furniture joints constructed from various heat-treated wood species," BioRes. 12(4), 7466-7478.AbstractArticlePDF

    The withdrawal force capacities were compared for T-type furniture joints made from heat-treated Siberian pine (Pinus sibirica), iroko (Chlorophora excelsa), and common ash (Fraxinus excelsior), which are commonly used in the construction of outdoor furniture. A total of 120 specimens that consisted of 3 wood species, 2 treatment processes (untreated and heat-treated), 2 adhesive types (polyurethane and polyvinyl acetate), and 2 joinery techniques (mortise and tenon, and dowel) were tested, with 5 replications for each condition. Half of the specimens were constructed from heat-treated wood materials, while the remaining half were prepared from untreated wood materials (control specimens). The joints constructed from common ash and iroko exhibited the highest withdrawal force capacity values. Overall, heat treatment reduced the withdrawal force capacity of joints by 25% compared with the joints constructed of control specimens. Mortise and tenon joints yielded 4 times higher performance than dowel joints. The polyurethane adhesive gave better results than the polyvinyl acetate adhesive. The best withdrawal force capacity values of heat-treated wood materials were obtained from the Iroko-polyurethane-mortise and tenon joint combination.

  • Researchpp 7479-7486Škulcová, A., Majová, V., Šima, J., and Jablonský, M. (2017). "Mechanical properties of pulp delignified by deep eutectic solvents," BioRes. 12(4), 7479-7486.AbstractArticlePDF

    Mechanical properties were evaluated for pulp delignified by four deep eutectic solvents (DES). The DES systems were based on choline chloride and lactic acid (1:9), oxalic acid:dihydrate (1:1), malic acid (1:1), and the system alanine:lactic acid (1:9). The results indicated that the type of DES system used influenced the delignified pulp’s mechanical properties including tensile, burst and tear indexes, tensile length, and stiffness. The most suitable DES systems were choline chloride:malic acid (1:1) and alanine:lactic acid (1:9), which achieved the best aforementioned mechanical properties compared to the other DES systems. The weakest performance in the process of pulp delignification was the system with choline chloride and oxalic acid dihydrate (1:1).

  • Researchpp 7487-7497Zhang, T., Liang, F., Xiang, H., Yang, X., Hu, W., Mi, B., and Liu, Z. (2017). "Fire performance of poplar and bamboo curtain veneers treated with fire retardants," BioRes. 12(4), 7487-7497.AbstractArticlePDF

    Bamboo curtain and poplar veneers, which are used as decorative building materials, were impregnated using two types of fire retardants (A and B) at atmospheric pressure in order to investigate fire retardancy using a cone calorimeter. When the impregnation time was longer, the fire retardancy was enhanced in the decorative material samples. When poplar veneer was treated by fire retardant A with impregnation times of 8 h, 16 h, and 24 h, the peak of heat rate release (pk-HRR) decreased by 41%, 51%, and 50%; the total heat release (THR) values decreased by 61%, 69%, and 75%; the total suspended particulates (TSP) values decreased by 90%, 82%, and 72%; and mass residues increased by 39%, 41%, and 43%, respectively. Treated bamboo curtain veneer had a lower fire retardancy when compared to poplar veneer. When bamboo curtain impregnation times were 8 h, 16 h, and 24 h, their pk-HRR values decreased by 37%, 45%, and 51%; the THR values decreased by 32%, 39%, and 44%; the TSP values decreased by 69%, 57%, and 78%; and the mass residues increased by 26%, 28%, and 29%, respectively. The results from this research should help to develop bamboo curtain veneer as an indoor decorative material.

  • Researchpp 7498-7514Kusumah, S., Arinana, A., Hadi, Y., Guswenrivo, I., Yoshimura, T., Umemura, K., Tanaka, S., and Kanayama, K. (2017). "Utilization of sweet sorghum bagasse and citric acid in the manufacturing of particleboard. III: Influence of adding sucrose on the properties of particleboard," BioRes. 12(4), 7498-7514.AbstractArticlePDF

    Sweet sorghum bagasse (SSB) and citric acid (CA) were used as sustainable raw materials in the development of environmentally friendly particleboard. Sucrose was added to improve the mechanical and physical properties of the particleboard. The effects of the weight ratio between CA and sucrose on the physical properties of the particleboards were investigated. The mechanical properties of particleboards bonded with adhesives at 15/85 and 10/90 wt.% ratios of CA to sucrose were superior to particleboard with other ratios. The thickness swelling of the particleboard increased with an increasing sucrose ratio. Moreover, the physical properties of the particleboard were comparable to those of particleboard bonded using phenol formaldehyde (PF) resin and satisfied the requirements of the type 18 JIS A 5908 (2003) standard. Also, the brittleness of the particleboard was decreased by adding sucrose. Low formaldehyde emission and biological durability against termites and decay were obtained by particleboard under suitable ratios of CA to sucrose. According to the results from thermal analysis and infrared spectra measurement, reactions leading to ester linkages occurred among the CA, sucrose, and SSB components.

  • Researchpp 7515-7524Yu, L., Cai, J., Wang, Y., Tang, Z., and Zhu, J. (2017). "Improved dimensional stability of nano-SiO2/wax modified ACQ-treated southern pine," BioRes. 12(4), 7515-7524.AbstractArticlePDF

    Southern yellow pine (Pinus sp.) wood cubes were vacuum-pressure treated with nano-SiO2 solution and different concentrations of amine copper quaternary (ACQ)/wax (0.5%, 2.5%, and 5.0% wax)-modified solutions. The effects of wax concentration and nano-SiO2 addition on water absorption, air drying shrinkage, and moisture swelling stabilities were investigated. The results showed that during the whole process of water absorption and air drying shrinkage, better stability of nano-SiO2 modified ACQ-treated wood could only be obtained with the ratio of wax addition equal to 2.5%. However, the best moisture swelling resistance was found in the samples modified with the highest wax addition (5.0%). Both wax and nano-SiO2 could be useful for keeping the dimensional stability of the treated wood.

  • Researchpp 7525-7538Li, X., Shi, J., Wang, Z., Duan, X., Chen, G., Guan, Q., Li, X., and Lei, T. (2017). "Preparation of carbon-based magnetic solid acid catalyst from various carbon sources and characterization of its catalytic performance," BioRes. 12(4), 7525-7538.AbstractArticlePDF

    Four kinds of carbon-based magnetic solid acid catalysts (CBMSACs) were prepared from rice husk, wood chips, peanut shells, and corn straw. The structure was investigated via x-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), elemental Analysis (EA), scanning/transmission electron microscope (SEM/TEM), and BET analyses. The catalysts were used to hydrolyze cellulose, and the hydrolysis efficiencies were determined. The catalysts were all comprised of a disordered carbon structure with random polycyclic aromatic hydrocarbons similar to graphite layers. This structure had a large number of -SO3H groups and the alkyl side chain, which increased the electron cloud density of the carbon carrier, relative to the other catalysts; this was advantageous to the adhesion of the -SO3H group to increase the activity of catalysts. The product also contained a large number of magnetic particles, making it easy to separate the catalysts from the reaction residue. The properties of the catalyst derived from corn straw as the carbon source appeared to be the best. Although it could be further recycled many times, the catalyst activity decreased due to the loss of -SO3H groups. At the same time, the catalyst had a high specific surface area of 755 m2/g.

  • Researchpp 7539-7551Hidayat, W., Qi, Y., Jang, J., Febrianto, F., and Kim, N. H. (2017). "Effect of mechanical restraint on the properties of heat-treated Pinus koraiensis and Paulownia tomentosa woods," BioRes. 12(4), 7539-7551.AbstractArticlePDF

    The objective of this study was to improve the properties of Korean white pine (Pinus koraiensis Sieb. & Zucc.) and royal paulownia (Paulownia tomentosa (Thunb.) Siebold & Zucc. ex Steud.) via heat treatment. The woods were treated at 160 °C, 180 °C, 200 °C, and 220 °C for 2 h. The effect of mechanical restraint through clamping during heat treatment on the dimensional stability, physical, and mechanical properties was evaluated. The results showed that increased temperature increased the weight loss and volume shrinkage, while equilibrium moisture content and wettability decreased. Royal paulownia showed higher weight loss, but lower shrinkage and equilibrium moisture content, when compared to Korean white pine. The samples with clamps in both woods had lower weight loss and volume shrinkage after heat treatment. The modulus of elasticity and modulus of rupture decreased with increased temperature followed by a noticeable decrease obtained after heat treatment at 200 °C and 220 °C. Clamping minimized strength reduction in both woods. Consequently, it was suggested that mechanical restraint was a useful method to maintain the wood properties during heat treatment.

  • Researchpp 7552-7565Kim, J., Kim, N., and Rie, D. (2017). "Characteristics of downward deep-seated fire in radiata pine based on changes in volumetric mass density," BioRes. 12(4), 7552-7565.AbstractArticlePDF

    The demand for and the consequent production of porous materials, such as wood, increase with industrial development and income. If a smoldering fire occurs in a porous material such as wood flour, it is difficult to find the fire location because of the development of a downward deep-seated fire. In this study, a down-scaled downward deep-seated fire model was adopted for wood flour to experimentally and theoretically elucidate the propagation phenomena of the downward velocity of deep-seated fires and subsequently predict their location. The experiment was performed on radiata pine wood flour with the density range of 0.2038 to 0.2343 g/cm3. Different tendencies were observed quantitatively in the downward temperature profiles with the changes in the volumetric mass density of the wood flour. Based on these results, it can be concluded that the deep-seated fire propagation speed is in the range of 0.0014 to 0.0018 cm/s. The practical applications of this result would be in effective extinguishing of fires in wood flour factories and silos by predicting the fire site based on the determination of the speed of propagation of the downward deep-seated fire.

  • Researchpp 7566-7589Gaitán-Alvarez, J., Moya, R., Rodríguez-Zúñiga, A., and Puente-Urbina, A. (2017). "Characterization of torrefied biomass of five reforestation species (Cupressus lusitanica, Dipteryx panamensis, Gmelina arborea, Tectona grandis, and Vochysia ferruginea) in Costa Rica," BioRes. 12(4), 7566-7589.AbstractArticlePDF

    Torrefaction can increase the energy yield of biomass for better utilization in bioenergy, but chemical changes occur during the pretreatment process. Wood residues of Cupressus lusitanica, Dipteryx panamensis, Gmelina arborea, Tectona grandis, and Vochysia ferruginea were torrefied for three different time periods (8, 10, and 12 min) and three different temperatures (200, 225, and 250 °C). The mass loss, net calorific value, ash, volatiles, lignin, cellulose, extractives, and infrared spectra were evaluated. The results showed that the mass loss in torrefied biomass varied between 10% and 70%, ash content varied between 0.19 and 7.00%, and volatiles content varied between 63 and 85%. Net calorific value values varied between 17 and 23 MJ/kg, increasing with the increased torrefaction temperature. Cellulose varied between 49.85 and 67.57%. Lignin varied between 27.33 and 41.09%. The extractives varied between 3.70 and 16.86%. The change in the ratio of intensity (RI) for the bands identified using FTIR analyses showed that large changes occurred in hemicellulose components. The multivariate analysis showed that lignin, ash, extractives in hot water, volatiles, and mass loss were the variables that contributed most. The analysis of all these variables showed that torrefaction at 250 °C for 12 min presented the greatest biomass degradation. Torrefaction at 200 °C and 225 °C for 8, 10, and 12 min was optimal for thermal treatment of the biomass of these woody species.

  • Researchpp 7590-7600Wang, H., Liang, J., Zhang, J., Zhou, X., and Du, G. (2017). "Performance of urea-formaldehyde adhesive with oxidized cassava starch," BioRes. 12(4), 7590-7600.AbstractArticlePDF

    Urea-formaldehyde (UF) resins based on different formaldehyde/urea (F/U) mole ratio were synthesized with oxidized cassava starch added at the final stage of the resin synthesis process. The basic characteristics of resins including solid content, viscosity, and curing time were studied, and the dry and wet bond strengths were evaluated by producing a three layer plywood. Additionally, the curing characteristics of different resins were investigated via differential scanning calorimetry (DSC). Structural distributions between UF and oxidized cassava starch were examined via FT-IR and 13C NMR analysis. The results indicated that the addition of oxidized starch not only improved resin bond strength but also notably reduced the curing start temperature of modified resins. Furthermore, a negative relationship between F/U mole ratio and the extent of reduction was identified. The structural distribution of UF resins changed dramatically because of oxidation cassava starch addition, but the changes varied due to different F/U mole ratios.

  • Researchpp 7601-7614Vainio-Kaila, T., Zhang, X., Hänninen, T., Kyyhkynen, A., Johansson, L. S., Willför, S., Österberg, M., Siitonen, A., and Rautkari, L. (2017). "Antibacterial effects of wood structural components and extractives from Pinus sylvestris and Picea abies on methicillin-resistant Staphylococcus aureus and Escherichia coli O157:H7,"  BioRes. 12(4), 7601-7614.AbstractArticlePDF

    Antibacterial properties of wood structural components and extractives were investigated against methicillin-resistant Staphylococcus aureus (MRSA) and Escherichia coli O157:H7 by placing bacterial inoculum on the model surfaces and incubating them for 2, 4, and 24 h. After incubation, the amount of viable bacteria on the surfaces was studied. The film coverage and thickness were evaluated with atomic-force microscopy (AFM) and X-ray photoelectron spectroscopy (XPS). The extracts were analyzed with gas chromatography–mass spectrometry (GC-MS). The results showed that films fully covered the glass surfaces. The XPS results confirmed the analysis of GC-MS, which revealed more similarities between the extractives of pine heartwood and spruce heartwood than between pine heartwood and pine sapwood. Only the pine heartwood extract showed an antibacterial effect against E. coli O157:H7. In contrast, MRSA was susceptible to all of the extracts and milled wood lignin (MWL).

  • Researchpp 7615-7627Salem, M. Z. M., Mansour, M. M. A., Mohamed, W. S., Mohamed Ali, H. M., and Hatamleh, A. A. (2017). "Evaluation of the antifungal activity of treated Acacia saligna wood with paraloid B-72/TiO2 nanocomposites against the growth of Alternaria tenuissima, Trichoderma harzianum, and Fusarium culmorum," BioRes. 12(4), 7615-7627.AbstractArticlePDF

    Acacia saligna wood was impregnated with 5% and 10% concentrations of Paraloid B-72/TiO2 nanocomposites using a soaking technique and evaluated for their antifungal activity against the growth of three molds in vitro, namely, Alternaria tenuissima, Trichoderma harzianum, and Fusarium culmorum. The Titanium (Ti) element peak of 0.14% and 0.23%, was found in the A. saligna wood treated with Paraloid B-72/TiO2 nanocomposites at 5% and 10%, respectively. Consolidant polymer Paraloid B-72 mixed with TiO2 nanocomposites at 5% and 10% showed antifungal activity against the three studied molds, while the linear growth of the studied molds reached the maximum in the control and Paraloid B-72 treatments. The results concluded that using synthesized Paraloid B-72/TiO2 nanocomposite could be considered as a new agent in the wood preservation field by prevention of mold fungal growth over the wood surfaces.

  • Researchpp 7628-7641Suzuki, A., Sasaki, C., Asada, C., and Nakamura, Y. (2017). "Characterization of cellulose nanofiber from steam-exploded Japanese cedar," BioRes. 12(4), 7628-7641.AbstractArticlePDF

    Cellulose nanofiber (CNF) was produced from Japanese cedar using a new environmentally friendly pulping process, i.e. a steam explosion treatment followed by water and acetone extractions. The effect of the steam explosion treatment on the morphological, chemical, and mechanical properties of steam-exploded CNF were clarified. The increase of steam explosion severity markedly decreased the molecular weight of α-cellulose in the steam-exploded cedar pulp. The maximum tensile strength value of 88.9 MPa and Young’s modulus value of 12.9 GPa were obtained for the films made from steam-exploded CNF at a steam pressure of 35 atm for a steaming time of 5 min. The results obtained in this work were useful for developing a new production method of CNF from various steam-exploded woody biomass.

  • Researchpp 7642-7655Gao, X., Yu, X., Tao, R., and Peng, L. (2017). "Enhanced conversion of furfuryl alcohol to alkyl levulinates catalyzed by synergy of CrCl3 and H3PO4," BioRes. 12(4), 7642-7655.AbstractArticlePDF

    To enhance the yield of alkyl levulinates, a mixed-acid catalyst system consisting of CrCl3 and H3PO4 was investigated for the transformation of furfuryl alcohol (FA). The CrCl3−H3PO4 system exhibited a positive synergistic catalytic activity for the synthesis of alkyl levulinates, which was especially obvious for n-butyl levulinate (BL) synthesis. The strongest synergic effect of mixed-acid system for BL production was achieved at the CrCl3 molar ratio of 0.3 (based on total moles of CrCl3 and H3PO4). Furthermore, the mixed-acid systems consisting of Cr-salts combined with H3PO4 and its salts in catalyzing FA conversion to BL were evaluated, and the evolution process of FA to produce BL was explored in the presence of CrCl3−H3PO4, sole CrCl3, and sole H3PO4. A possible synergistic catalytic pathway of CrCl3 combined with H3PO4 was proposed. Finally, the key process variables were examined. Under optimal conditions, a high BL yield of 95% was achieved from 99% FA conversion catalyzed by the synergy of CrCl3 and H3PO4.

  • Researchpp 7656-7679Kumar, V., Ottesen, V., Syverud, K., Gregersen, Ø. W., and Toivakka, M. (2017). "Coatability of cellulose nanofibril suspensions: Role of rheology and water retention," BioRes. 12(4), 7656-7679.AbstractArticlePDF

    Cellulose nanofibril (CNF) suspensions are not easily coatable because of their excessively high viscosity and yield stress, even at low solids concentrations. In addition, CNF suspensions vary widely in their properties depending on the production process used, which can affect their processability. This work reports roll-to-roll coating of three different types of CNF suspensions with a slot-die, and the influence of rheology and water retention on coatability is addressed. The impact of CMC addition on the high and low shear rate rheology, water retention, coatability, and final coating quality of these suspensions is reported. All three CNF suspensions were coated successfully using the slot-die coating process. CMC addition further improved the coatability by positively influencing both the low and high shear rate viscosity and water retention of the CNF suspensions. All CNF coatings significantly improved the air, heptane vapor, grease and oil barrier, while reducing the water vapor transmission rate to some extent.

  • Researchpp 7680-7691Li, P., Zhao, G., Zhang, K., and Wang, H. (2017). "Improvement of red pigment production during biomembrane surface cultivation of Penicillium novae-zelandiae by supplementing with corn straw," BioRes. 12(4), 7680-7691.AbstractArticlePDF

    Corn straw was used to improve the productivity of a red pigment during the biomembrane surface liquid cultivation of Penicillium novae-zelandiae. Both the dosage and particle size of corn straw powder had a significant effect on the fermentation period and pigment yield. After the optimization, the maximum yield of synthesised red pigment reached 0.43 g/L per day on day 9, which was 2.3 times higher than the initial productivity obtained by biomembrane surface cultivation without corn straw. An analysis on the mechanism suggested that corn straw shortened the fermentation period by providing the support for the growth of P. novae-zelandiae spores and biomembrane formation. Amino acids, including phenylalanine and tyrosine, released by corn straw, were the key reason for the improvement in the pigment yield. In addition, the increase of reducing sugars in the fermentation broth, due to the hydrolysis of cellulose and hemicellulose by the hydrolytic enzymes secreted by P. novae-zelandiae, provided a carbon source for fungal growth that might also be beneficial to pigment production.

  • Researchpp 7692-7710Leng, W., Hunt, J. F., and Tajvidi, M. (2017). "Screw and nail withdrawal strength and water soak properties of wet-formed cellulose nanofibrils bonded particleboard," BioRes. 12(4), 7692-7710.AbstractArticlePDF

    Wet-formed particleboard panels were made using cellulose nanofibrils (CNF) as the bonding material. The effects of panel density, CNF addition ratio, particle size, and pressing method on the nail and face screw withdrawal strength, water absorption (WA), and thickness swelling (TS) were investigated. The nail and face screw withdrawal strength increased with an increased panel density and CNF addition ratio. Mixed-size particles were favorable for better face screw withdrawal strength. The WA decreased while TS increased with increased panel density. The WA decreased with increased CNF addition ratio. The effect of CNF addition ratio on the TS was influenced by an interaction effect of the particle size, density, and pressing method. Smaller wood particles and the constant thickness (CT) pressing method were better for both WA and TS performance. All of the high- and medium-density panels failed to satisfy the standard requirements for face screw withdrawal strength. For low-density panels, those manufactured with mixed-sized particles all satisfied the standard requirements; those manufactured with large particles required at least 15% CNF to meet the standard, and those manufactured with small particles required at least 20% CNF to achieve the standard requirements. None of the panels met the standard TS requirement (< 8%).

  • Researchpp 7711-7730Chen, H., Yang, R., Wang, J., Zhao, H., Wang, B., Wo, Q., and Zheng, B. (2017). "Isolation of bacteria from old corrugated container slime and characterization of their biofilm-forming properties," BioRes. 12(4), 7711-7730.AbstractArticlePDF

    With the continuously increasing demand for paper and cardboard products, there is growing concern about the bacteria of the papermaking process. Bacterial growth not only affects normal manufacturing, but it also results in paper products with a total number of bacteria that exceeds the acceptable range, and thus poses a risk to the health of consumers. In this study, 99 pure bacterial strains were isolated from old corrugated containers (OCC) slime. The morphological, physiological, and biochemical properties of the bacterial strains were examined. Furthermore, the isolated strains were tested for their ability to form biofilms. The strains that could form biofilms were identified using 16S rDNA sequencing. The results revealed that some bacteria could form both a biofilm that adhered to the smooth tube wall, as well as abundant flocs at the bottom of the test tube. Conversely, the other bacteria could not form a noticeable biofilm. The bacteria with the most powerful biofilm-forming ability were identified as Proteus penneri, Klebsiella variicola, Klebsiella sp., and Proteus mirabilis.

  • Researchpp 7731-7743Liu, X., Jiang, Y., Yang, S., Meng, X., Song, X., and Wu, M. (2017). "Effects of pectinase treatment on pulping properties and the morphology and structure of bagasse fiber," BioRes. 12(4), 7731-7743.AbstractArticlePDF

    Bagasse was pretreated by pectinase, and both the control and pretreated bagasse were subjected to soda-anthraquinone (AQ) pulping. There were significant improvements in pulp properties after pectinase treatment, such as relative increases of brightness (5.5%), breaking length (17.1%), burst factor (16.5%), and tear factor (7.0%). The samples were analyzed by a fiber analyzer, scanning electron microscope (SEM), X-ray diffraction (XRD), and Fourier transform infrared spectroscopy (FTIR). The pectinase treatment changed the material properties, which would improve the efficiency of subsequent pulping, such as increasing the fiber length (20.0%), lowering the fines length (10.6%), and increasing the percentage of flexible fiber. Pectinase treatment removed some non-cellulose components; in particular, the pectin and alcohol-benzene extractives were decreased by 19.4% and 37.3% after enzymatic treatment. The hemicellulose and lignin were decreased by 5.5% and 1.9%, respectively. A bulkier and more collapsed fiber surface was observed in the treated fibers, which suggested greater pore volume and more accessible surface area. Treatment caused a slight incline by 4.8% in the crystallinity index. Some chemical structures in pectin, hemicellulose, and lignin were partly broken, showing the effect of pectinase treatment on the degradation of non-cellulose components. Pectinase treatment prior to pulping is therefore recommended, given its efficiency and eco-friendly nature.

  • Researchpp 7744-7755Zhang, H., Xin, C., Hong, L., Zhu, M., and Wang, N. (2017). "Yields analysis and structural characterizations of lignin extracted from Eucalyptus globulus with catalyzed ethanol systems," BioRes. 12(4), 7744-7755.AbstractArticlePDF

    A mild and successive method was proposed and evaluated for fractionating lignin samples from Eucalyptus globulus. The extraction efficiency and structural features of the extracted lignin samples were comprehensively investigated by a yields analysis, 1H-nuclear magnetic resonance (NMR), 13C-NMR, and two-dimensional heteronuclear single quantum coherence (2D-HSQC) NMR. The catalyzed ethanol systems consisting of ethanol, 4-methyl-2-pentanone, dimethyl sulfoxide (DMSO), formic acid, and distilled water were effective for extracting lignin from Eucalyptus globulus, and the yield of lignin was 75.2% when the extraction process was held at 145 °C for 180 min. Compared with that of the milled wood lignin (MWL), the NMR spectra of the extracted lignin fractions supported the destruction of β-O-4 units for the disappearance of Hα signals. Moreover, the striking characteristics of the extracted lignin were the destruction of ether bonds of S3,5 and the condensation of syringyl (S) and guaiacyl (G) units. In short, lignin fractions with relatively complete structures were effectively extracted with the catalyzed ethanol systems.

  • Researchpp 7756-7773Zhang, H., Shi, R., Gao, X., Chen, K., and Peng, L. (2017). "Effect of microwave-involved ClO2 bleaching on the characteristics of lipophilic extractives of bleached Eucalyptus globulus pulps," BioRes. 12(4), 7756-7773.AbstractArticlePDF

    The preparation of bleached pulp from Eucalyptus globulus pulp was evaluated after utilizing chlorine dioxide (ClO2) with or without microwave irradiation. The three ClO2-bleaching processes examined were water-bath heating; microwave heating; and microwave pretreatment combined with water-bath heating. These processes were applied to eucalypt pulps that were oxygen-delignified. The effects of the treatments on the levels of lipophilic extractives and properties of the resulting pulps were compared with one another. The microwave-induced treatment had a remarkable effect, leading to an increase in pulp brightness and a decrease in lipophilic extractives when compared with the control (i.e., A). The sample under the condition of microwave pretreatment combined with water-bath heating achieved a higher brightness and reduced lipophilic extractives, which were increased by 45.8% and reduced by 37.4%, respectively. This study demonstrated an effective microwave-pretreated method in ClO2 bleaching process, which provides a promising route for alleviating pitch deposition problems occurring during pulp manufacture.

  • Researchpp 7774-7783Wang, Y., He, B., and Zhao, L. (2017). "Fabrication of hydrophobic coating on filter paper from self-emulsifying carnauba wax-alcohol emulsions with nano-TiO2 particles for water/diesel separation," BioRes. 12(4), 7774-7783.AbstractArticlePDF

    Carnauba wax is a natural material with high hydrophobicity. In this study, molten carnauba wax was stably self-emulsified in ethanol without using additional emulsifiers. Hydrophobic titanium dioxide (TiO2) nanoparticles were dispersed into carnauba wax-ethanol emulsion to form a composite coating on filter paper. The results showed that immersion in the composite coating that contained wax and hydrophobic TiO2 conveyed to filter paper good hydrophobicity (water contact angle over 140°) and stability against acid or alkali solution. The scanning electron microscopy (SEM) images indicated the presence of micro bead/flake structures on the surface of filter paper. These obtained filter papers could effectively expel water from a water/diesel mixture. The water content in the water/diesel mixture decreased from 10% to 0.01% through the separation from the filter paper.

  • Researchpp 7784-7792De Almeida, A. C., De Araujo, V. A., Morales, E. A. M., Gava, M., Munis, R. A., Garcia, J. N., and Barbosa, J. C. (2017). "Wood-bamboo particleboard: Mechanical properties," BioRes. 12(4), 7784-7792.AbstractArticlePDF

    Mechanical characteristics were evaluated of wood-bamboo-based particleboard having the proportions of 100% wood and 0% bamboo, 75% wood and 25% bamboo, and 50% wood and 50% bamboo. This particleboard used Eucalyptus urophylla × grandis wood, Dendrocalamus asper bamboo, and castor oil-based polyurethane resin. Through destructive testing, the values of perpendicular tensile, static bending, modulus of elasticity, and screw pullout strength in the top and face surfaces were analyzed. For 0%, 25%, and 50% bamboo the values were 1.68 MPa, 1.37 MPa, and 1.4 MPa, respectively, for perpendicular tensile; 15.2 MPa, 17.6 MPa, and 18.5 MPa, respectively, for static bending; 2466 MPa, 2694 MPa, and 2922 MPa, respectively, for modulus of elasticity; 1256 MPa, 1922 MPa, and 1362 MPa, respectively, for screw pullout strength in top; and 1392 MPa, 1342 MPa, and 1414 MPa, respectively, for screw pullout strength in face. These results were superior to those presented by ABNT NBR 14810 (2013) and ANSI 208.1 (1999). After performing a Tukey test at 5%, the values for each treatment did not show a significant difference among them.

  • Reviewpp to be addedRazali, N., Hameed Sultan, M. T., and Jawaid, M. (2017). "A Review on detecting and characterizing damage mechanisms of synthetic and natural fiber based composites," BioRes. 12(4), Page #s to be addedAbstractArticlePDF

    The damage to composite structures caused by impact events is one of the most critical behaviors that inhibit the widespread application of composite material. As the application of synthetic and natural based composite material increases over time, improved knowledge of composite damage in areas such as automotive and aerospace is exceedingly necessary. It is important to study and understand the damage mechanism of composite structures to produce effective designs. The failure caused by damage in structural design can result in unintended consequences. Extensive research has been conducted to detect impact damage in synthetic fiber. There are various methods to identify and characterize the damage. This article provides a comprehensive review of recent literature focusing on the broader scope of impact damage and incipient thermal damage of synthetic and natural fiber-based composites. In this report, the available research is reviewed by considering all aspects related to damage in composite materials, particularly the work done on detecting and characterizing damage mechanisms of synthetic and natural fiber-based composites.

  • Researchpp 7793-7806Wang, S., Lai, Y., Yu, Y., Di, M., and Shi, J. (2017). "Effect of enzymatically hydrolyzed lignin on the curing characteristics of epoxy resin/polyamine blends," BioRes. 12(4), 7793-7806.AbstractArticlePDF

    Corn stalk enzymatically hydrolyzed lignin (EHL) was used to modify bisphenol A-type epoxy resin. The curing reaction processes of the epoxy resin/polyamine blends and the lignin/epoxy resin/polyamine blends were studied via isothermal differential scanning calorimetry (DSC), and the effect of enzymatically hydrolyzed lignin on the curing reaction of epoxy resin was also analyzed. The results showed that the curing kinetics for two blends were not in full compliance with the autocatalytic curing kinetic model, especially the lignin/epoxy resin/polyamine blends. The apparent activation energy of the epoxy resin/polyamine blends increased with the increased presence of the lignin. The presence of enzymatically hydrolyzed lignin was beneficial to the curing process of epoxy resin/polyamine blends at high temperatures. The addition of the lignin increased the final curing reaction conversion rate, improved the glass transition temperature (Tg) and increased the bending strength for the epoxy resin/polyamine blends. However, the impact strength decreased in this process.

  • Researchpp 7807-7818Zhang, Y., Song, Y., Chen, C., Li, M., Zhang, Z., and Fan, Y. (2017). "One-vessel synthesis of 5-hydroxymethylfurfural in concentrated zinc chloride solution from lignocellulosic materials," BioRes. 12(4), 7807-7818.AbstractArticlePDF

    The synthesis of bio-based chemicals, such as 5-hydroxymethylfurfural (HMF) and its derivatives, from cellulosic biomass resources has been attempted for years. However, the harsh reaction condition, toxicity of the catalysts applied, and low efficiency of the conversion process have deterred its industrial implementation. Herein, the authors investigated the degradation and conversion of cellulose into HMF in a concentrated zinc chloride solution. The effects of reaction conditions and co-catalysts on the conversion were evaluated. A 69.5% HMF yield from cellulose was obtained in the condition of 1 h and 150 °C using 0.2 mol·L-1 of HCl without co-catalyst during the conversion. Moreover, the ZnCl2 aqueous solution displayed good reusability. Finally, a simplified kinetic model of the conversion of cellulose to HMF in a concentrated zinc chloride solution was developed, and the reaction kinetics were investigated.

  • Researchpp 7819-7833Senthilkumar, K., Siva, I., Hameed Sultan, M. T., Rajini, N., Siengchin, S., Jawaid, M., and Hamdan, A. (2017). "Static and dynamic properties of sisal fiber polyester composites – Effect of interlaminar fiber orientation," BioRes. 12(4), 7819-7833.AbstractArticlePDF

    The effect of fiber orientation was studied relative to the static and dynamic properties of sisal/polyester composites. Different composites were developed using the compression moulding technique with the aid of a specially designed mould. Composite laminates were formulated by stacking a number of fiber lamina with different orientations such as 90º/0º /90º, 0º /90º /0º, 90º /0º /0º /90º, 0º /45º /0º, 0º /90º /45º /45º /90º /0º, and 0º /45º /90º /90º /45º /0º. In general, the performance of static and dynamic characteristics was found to be significantly influenced by the effect of interlaminar fiber orientation. Experimental results exhibited a higher flexural strength of 68 MPa and an impact strength of 320 J/m in the case of 0º /90º /45º /45º /90º /0º oriented composites. Dynamic characteristics such as natural frequency and damping were found to be higher in the case of 0º /45º /0º and 0º /90º /0º, respectively. Morphological analysis was performed for understanding the interlaminar orientation and failure mechanisms between the fiber and the matrix.

  • Researchpp 7834-7840Yang, J. E., Kim, J. K., Lee, S. H., Yu, J., and Kim, K. H. (2017). "Evaluation of commercial cellulase preparations for the efficient hydrolysis of hydrothermally pretreated empty fruit bunches," BioRes. 12(4), 7834-7840.AbstractArticlePDF

    The performance of cellulase in the enzymatic saccharification of lignocellulose depends on the characteristics of lignocellulosic biomass feedstocks and the pretreatment method used. Efficient hydrolysis of specifically pretreated lignocellulose necessitates the knowledge of the characteristics of the optimal commercial cellulases. In this study, commercial cellulase preparations (Accellerase™ 1000, Accellerase® 1500, and Spezyme® CP from DuPont and Cellic® CTec2 from Novozymes) were evaluated for their hydrolysis efficiency of hydrothermally pretreated empty fruit bunches (EFBs). The highest glucose yields of 91.3% and 84.7% were achieved for 30 FPU of Cellic® CTec2/g glucan with and without Cellic® HTec2, respectively. Of the four cellulases tested, Cellic® CTec2, which showed the highest cellobiohydrolase, xylanase, and β-glucosidase activities, showed the highest glucose yield in the enzymatic hydrolysis of hydrothermally pretreated EFBs. The results of this study are valuable for those who plan to enzymatically hydrolyze hydrothermally pretreated EFBs.

  • Researchpp 7841-7858Semple, K., and Smith, G. (2017). "Recovery modeling for OSB strand production from hollow bamboo culms," BioRes. 12(4), 7841-7858.AbstractArticlePDF

    Current methods of reducing giant Moso bamboo (Phyllostachys pubescens Mazel) to elements for composite manufacture are often inefficient and waste valuable biomass. This study employed geometric modelling to analyze and optimize the recovery of strands for oriented strand board manufacture. Three geometric models for calculating the numbers of strands, their widths, and their distribution based on culm diameter, wall thickness, target strand thickness, and flitch size were developed to determine an optimum slicing configuration. Real strands were produced by a disk flaker at the model strand thickness of 0.65 mm. Optimum configuration for the maximum number of usable strands per culm was from splitting culms into quarters, tight stacking, and radial slicing through the culm wall, which produced 37% more ‘usable’ strands 10 mm to 30 mm in width, fewer fines, and fewer excessively wide strands. Proportions of real strands fell into three size classes: < 10 mm, 10 mm to 30 mm, and > 30 mm, and closely matched modelled predictions. A slightly bimodal strand width frequency distribution observed from stranding full rounds was reflected in the distribution of the model strands calculated from slicing a full round into 0.65 mm increments.

  • Researchpp 7859-7872Zou, H., Liu, Z., Shi, Y., Su, Z., and Liu, J. (2017). "Isolation of lignocellulose-derived sugars, co-fermentation of lactic acid bacteria strains, and evaluation of L-lactic acid productivity," BioRes. 12(4), 7859-7872.AbstractArticlePDF

    High-productivity lactic acid bacteria (LAB) strains were screened and their capability to ferment lignocellulose-derived sugars into lactic acid were evaluated. Fifteen LAB strains were successfully isolated from cow dung, haystack, and sheep manure, respectively. Four relatively good strains were selected based on Gram stain, colony morphology, and catalase activity tests. The four strains and commercial inoculants (Lactobacillus pentosus and Enterococcus faecalis) were used to ferment cellobiose/ glucose/xylose to produce high-purity L-lactic acid. One of the strains (N4) presented the highest production of L-lactic acid after fermentation for 12 h and showed a L-lactic acid production of 15.1 g/L, 18.5 g/L, and 2.8 g/L and a productivity of 1.01 g∙L−1∙h−1, 3.68 g∙L−1∙h−1, and 0.47 g∙L−1∙h−1 by metabolizing cellobiose, glucose, and xylose, respectively. Through a phylogenetic tree analysis, strain N4 was identified as Enterococcus faecium and named Enterococcus faecium N4. Enterococcus faecium N4 has a great potential to ferment lignocellulose-derived sugars into L-lactic acid.

  • Researchpp 7873-7883Liang, S., Gu, H., and Bergman, R. D. (2017). "Life cycle assessment of cellulosic ethanol and biomethane production from forest residues," BioRes. 12(4), 7873-7883.AbstractArticlePDF

    There is a strong need to manage low-value forest residues generated from the management practices associated with wildfire, pest, and disease control strategies to improve both the environmental and economic sustainability of forestlands. The conversion of this woody biomass into value-added products provides a great opportunity to benefit both the environment and economy. This study aimed to assess the environmental impacts of converting forest residues into two renewable fuels, cellulosic ethanol and biomethane, by different biochemical conversion pathways. The energy balances and environmental impacts, including acidification, eutrophication, global warming, and photochemical ozone formation, of the two biorefinery approaches were addressed. This work illustrated the advantages of converting forest residues into biomethane from energy and environmental perspectives. The tradeoff between the economic benefits and potential environmental issues need to be carefully considered.

  • Researchpp 7884-7897Hitka, M., Lorincová, S., Ližbetinová, L., Pajtinková Bartáková, G., and Merková, M. (2017). "Cluster analysis used as the strategic advantage of human resource management in small and medium-sized enterprises in the wood-processing industry," BioRes. 12(4), 7884-7897.AbstractArticlePDF

    This paper presents the possibility of creating motivational programs for employees working in small and medium-sized enterprises (SMEs). The applicability of the proposed option is verified and presented to a medium-sized enterprise operating in the wood-processing industry in Slovakia. Using cluster analysis, three motivational-oriented groups were defined in the category of managers and three similar motivational-oriented groups in the category of workers. Subsequently, the sampling units were tested by the Tukey’s honest significant difference (HSD) test. In this way, the significance of the differences in arithmetic mean and the standard deviation of the individual motivational factors of the monitored sets at the significance level α = 0.05 were defined. The result of the analysis is a plan to create a group motivational program. The content of this program is a common motivational factor for groups, supplemented by employee-specific factors. Currently, businesses apply unified motivational programs based on two, three, or four main motivators. However, improperly designed and applied motivational programs have a negative impact on employees and do not motivate them to maximize performance. By implementing this method in wood-processing SMEs, the company’s performance can be increased, as the needs of most employees would be met.

  • Researchpp 7898-7916Tisserat, B., Reifschneider, L., Gravett, A., and Peterson, S. C. (2017). "Wood-plastic composites utilizing wood flours derived from fast-growing trees common to the Midwest," BioRes. 12(4), 7898-7916.AbstractArticlePDF

    There are several non-utilized or under-utilized hardwood trees common to the Midwestern states. Wood flour (WF) derived from fast-growing Midwest trees (Osage orange, black locust, and red mulberry) were evaluated as a source of bio-based fiber reinforcement. Wood-plastic composites (WPCs) of high-density polyethylene (HDPE), 25 wt.% of WF, and either 0% or 5% by weight of maleated polyethylene (MAPE) were produced via twin screw compounding and injection molding. Specimen bars were evaluated for their mechanical and flexural properties. Composite blends that employed the coupling agent MAPE were superior to composites without MAPE or neat HDPE in terms of their mechanical and flexural properties. The Osage orange WPC composed of juvenile WF had mechanical and flexural properties that were the same as the WPC composed of mature WF. The WPC composed of WF from Midwestern trees were comparable with the WPC composed of pine WF in terms of their mechanical and flexural properties. Soaking the bars of the various WPC blends in distilled water for 28 days altered their weights, mechanical properties, and color. Thermal properties of neat HDPE and WPCs were evaluated using differential scanning colorimetry and thermogravimetric analysis.

  • Researchpp 7917-7930Musat, E. C., Salca, E. A., Ciobanu, V. D., and Dumitrascu, A. E. (2017). "The influence of log defects on the cutting yield of oak veneer," BioRes. 12(4), 7917-7930.AbstractArticlePDF

    The quality of logs entering the production line is important because it controls the quality and yield of veneer. In Romania, Quercus species represent 18% of the total forests, and of which 2% is exclusively the pedunculate oak. The wood of pedunculate oak is hard and elastic, and it has a good natural durability. Due to such features it also has multiple uses in the furniture industry, construction, joinery, and cooperage works. The present work highlights the influence of some characteristics of the raw material on the cutting yield of veneer in the case of pedunculate oak logs purchased from different regions. Defects in the raw material had a certain negative influence on the veneer quality. The defects were identified and prioritized using the Pareto diagram.

  • Researchpp 7931-7942Chen, T., Zhang, L., Luo, G., and Yuan, W. (2017). "Butyric acid production by Clostridium tyrobutyricum in sugar mixtures and corncob hydrolysate containing arabinose," BioRes. 12(4), 7931-7942.AbstractArticlePDF

    The objective of this study was to understand arabinose effects on butyric acid fermentation by Clostridium tyrobutyricum in sugar-supplemented media and biomass hydrolysate. Compared to glucose and xylose, the conversion of arabinose to butyric acid was less efficient with a longer lag phase (4 d) and fermentation period (6 d), and a lower butyric acid yield of 0.26 g/g and 0.15 g/g in 5 g/L and 10 g/L of arabinose media, respectively. However, the addition of 2 g/L or 5 g/L of arabinose to the baseline medium that contained glucose (15 g/L) and xylose (15 g/L) enhanced butyric acid synthesis, resulting in 16.1 g/L and 20.3 g/L of butyric acid, respectively. Further increase in arabinose to 10 g/L in the medium of 10 g/L of glucose and 10 g/L of xylose showed inhibitory effects on C. tyrobutyricum, which suggested that high concentrations of arabinose (> 10 g/L) were not desirable. Dilute-acid pretreated corncobs that contained xylose (19 g/L) and a small amount of arabinose (2 g/L) were a feasible substrate for butyric acid production by C. tyrobutyricum, and resulted in 10.6 g/L butyric acid, which was slightly lower than in the mimic medium (11.3 g/L).

  • Researchpp 7943-7954Keturakis, G., Bendikiene, R., and Baltrusaitis, A. (2017). "Tool wear evolution and surface formation in milling various wood species," BioRes. 12(4), 7943-7954.AbstractArticlePDF

    This study presents the results of tool wear and surface roughness of wood processed by plain milling. The tests were done on wood samples of pine and black alder grown in Lithuania in order to clarify time-related tool blunting and the aspects of surface formation. The samples were milled along the fiber in the experimental wood cutting stand at two different cutting and feed speeds. The roughness parameter (Rz) of the processed samples was measured in five sectors along and across the fiber using a contact profilometer. Registered values were analyzed by a Gaussian digital filter and evaluated according to relevant statistics seeking to minimize influence of wood anatomy. The obtained results helped to determine distinctions and variations of surface roughness, which strongly depend on the cutting path, rounding radius of the tool’s cutting edge, cutting, and feed speeds while milling pine and black alder.

  • Researchpp 7955-7963Granados-Arvizu, J. A., Amaro-Reyes, A., García-Almendárez, B. E., Gracida-Rodríguez, J. N., and Regalado, C. (2017). "Optimization of dilute acid pretreatment of corn pericarp by response surface methodology," BioRes. 12(4), 7955-7963.AbstractArticlePDF

    Corn pericarp (CP) is an inexpensive agroindustrial by-product that is available in large quantity in Mexico. This work aimed to optimize the use of a dilute sulfuric acid pretreatment for CP hydrolysis to maximize the reducing sugars yield. A 2-step experimental design was used, first a full factorial followed by a central composite design (CCD). The CCD involved sulfuric acid (1.5% to 5%, v/v), a treatment at 121 ºC (15 min to 40 min), and varying CP content (10% to 20%, w/v). The response variables were the reducing sugars, glucose, and solubilized solids. Maximal responses were achieved at 3.4% (v/v) sulfuric acid, 20% (w/v) CP, and 22.3 min. A significant (R2 = 0.99) second-order model predicted maximal operational conditions that were experimentally validated: 80.1 g/L reducing sugars, 12.8 g/L glucose, and 69.2% solubilization of CP solids. The dilute sulfuric acid pretreatment solubilized all hemicellulose in CP.

  • Researchpp 7964-7974Ayrilmis, N., Akbulut, T., and Yurttaş, E. (2017). "Effects of core layer fiber size and face-to-core layer ratio on the properties of three-layered fiberboard," BioRes. 12(4), 7964-7974.AbstractArticlePDF

    The objective of this study was to transfer benefits of three-layered particleboards to medium density fiberboard (MDF) manufacture by using coarse fibers and, thus use less energy and lower-cost fibers as core layer material. In the first phase of this study, the effect of wood fiber size in the core layer on the properties of MDF was investigated. In the second phase, the effect of surface to core layer ratio (30/70, 40/60, 50/50, 60/40, and 70/30) on the properties of the MDF was investigated. The surface layers of the panels consisted of fine fibers. The wood fibers were produced using a thermo-mechanical refining process. The length and thickness of the fibers considerably increased with increasing defibrator discs distance. The 24-h TS values of the MDF specimens decreased from 36.8 to 34.2% as the fiber length in the core layer was increased from 4.3 to 11.5 mm. However, further increases in the fiber length increased TS values. Similarly, the bending strength, bending modulus, and internal bond strength increased with increasing fiber length (up to 11.5 mm) and thickness (up to 0.73 mm). The bending properties of the MDF specimens improved with increasing surface layer ratio, while the internal bond strength decreased.

  • Researchpp 7975-7985Li, L., Chang, J., Cai, L., and Shi, S. (2017). "Activated carbon monolith derived from polymer and fast pyrolytic char: Effect of bio-oil phenol-formaldehyde resin," BioRes. 12(4), 7975-7985.AbstractArticlePDF

    Activated carbon monoliths (ACMs) were fabricated by H2O activation using powdered fast pyrolytic char (PFPC) as a raw material and bio-oil phenol-formaldehyde (BPF) resin as a binder. The effects of the ratio of BPF resin to PFPC on textural and chemical-surface properties of the ACMs were investigated using elemental analysis, X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), and field-emission scanning electron microscopy (FE-SEM). The adsorption capacity and mechanical properties under different conditions were examined by N2 adsorption analysis and compression strength, respectively. The results indicated that the optimal ratio was 20 wt.% BPF resin binder. The compression strength of ACMs with a carbon content of 79.7 wt.% reached 3.74 MPa, while the BET surface area and total pore volume were 731.3 m2/g and 0.589 cm3/g, respectively. ACMs appeared to be mainly mesoporous with low graphitization and contained multiple functional groups such as alkyl, esters, ether, phenol, olefin, etc.

  • Researchpp 7986-8000Xuan, L., Hui, D., Wang, D., Cheng, W., and Han, G. (2017). "Effects of preservative pretreatments on moisture adsorption and desorption properties of corn stalk fiber/high-density polyethylene composites," BioRes. 12(4), 7986-8000.AbstractArticlePDF

    The impact of alkaline copper quat (ACQ) and zinc borate (ZB) on the moisture adsorption and desorption properties and leaching resistance of corn stalk fiber (CSF) reinforced high-density polyethylene (HDPE) composites was investigated. The equilibrium moisture content (EMC) was fitted by the Nelson model, and the interaction between the CSF component and the preservatives was characterized by Fourier transform infrared spectroscopy (FTIR). The effective components of the preservative were successfully immobilized on the CSF, which was observed by FTIR analysis. The leaching resistant analysis showed that the leaching amount of copper and boron elements reached a plateau, and that the leaching resistant performance in the ACQ treatment was better than in ZB. The moisture adsorption of CSF/HDPE composites was significantly reduced with ACQ treatment at low CSF content, but clearly increased in ZB treatment at high CSF content. The moisture adsorption and desorption EMC increased with the increased preservative (ACQ or ZB) embedding at a given CSF/HDPE component ratio. The experimental values were fitted well with the Nelson model; thereby this model could be used to predict the moisture adsorption and desorption EMC of CSF/HDPE composites at various relative humidity.

  • Researchpp 8001-8013Hassan, N., Idris, A., El-Enshasy, H., and Abd. Malek, R. (2017). "Scaling-up of simultaneous saccharification and fermentation of lactic acid from microwave-alkali-treated empty fruit bunches," BioRes. 12(4), 8001-8013.AbstractArticlePDF

    The goal of this work was to scale up the simultaneous saccharification and fermentation (SSF) of lactic acid using microwave-alkali-pretreated empty fruit bunches (EFB) from a scale of 16 L to a scale of 150 L. To facilitate the scaling-up process of lactic acid production by Rhizopus oryzae NRRL 395, a scaling-up criterion of constant kLa value was applied. Operating conditions, such as aeration rate and superficial velocity, were varied and evaluated on both scales (16-L and 150-L). The highest lactic acid yield of 6.8 g/L was obtained under an operating condition of 1 vvm (0.061 s-1). Parallel aeration rates were determined for the 150-L fermenter system to obtain the same kLa value as the 16-L fermenter. An operational condition of 0.5 vvm dissolved oxygen supply in the 150-L fermenter was optimal to support an identical value of kLa and production rate of lactic acid for both scales.

  • Researchpp 8014-8029Xu, B., Li, W., Tu, D., Wu, Z., and Song, C. (2017). "Effects of nitrogen-phosphorus flame retardants in different forms on the performance of slim-type medium-density fiberboard," BioRes. 12(4), 8014-8029.AbstractArticlePDF

    An orthogonal design was used to optimize the process of making slim medium-density fiberboard modified by a nitrogen-phosphorous series of flame retardants. Mechanical performance was the evaluating criterion. Subsequently, the combustion performances of each type of flame retardant, including in states solid, liquid, and their combination with a ratio of 1:1, were investigated to clarify the corresponding fire-retardant mechanism. The results showed that only physical bonding was responsible for connecting the wood fiber with the retardants, according to the Fourier transform infrared spectrum. Catalytic charring, flame retardancy, and the thermal insulation of three types of retardant were solidified by the results of a cone calorimeter (CONE) analysis, thermogravimetric (TG) analysis, and differential scanning calorimetry (DSC), and the mixture of solid and liquid was demonstrated as the primary choice. It was also found that after the mixture of the solid and liquid retardant was added, the limiting oxygen index of the board reached 43.3%, and it met the requirements of the B1 Class in the Chinese National Standard GB/T8624-2012 (2012).

  • Researchpp 8030-8046Sangian, H. F., and Widjaja, A. (2017). "Effect of pretreatment method on structural changes of coconut coir dust," BioRes. 12(4), 8030-8046.AbstractArticlePDF

    The pretreatment of a high lignin substrate, coconut coir dust, was studied by chemical techniques (NaOH solution, ionic liquid, and NaOH followed by ionic liquid) and by a physical method (subcritical water, SCW). Following substrate pretreatment and a washing step, structural analyses were performed by scanning electron microscopy, X-ray diffraction (XRD), and Fourier transform infrared spectroscopy. It was found that all substrates pretreated by chemical methods had more amorphous structures than the untreated substrate. The XRD patterns of the chemically treated substrates shifted toward higher angles by 0.50° to 1.00°. However, the XRD peak symmetry of the SCW-treated substrate did not shift, but its crystallinity index decreased. The results revealed that lignocellulose treated with NaOH followed by ionic liquid at 120 °C for 30 min showed the greatest extent of structural transformation.

  • Researchpp 8047-8057Ferrández-García, C. C., Ferrández-García, C. E., Ferrández-Villena, M. T., Ferrandez-García, M., and García-Ortuño, T. (2017). "Acoustic and thermal evaluation of palm panels as building material," BioRes. 12(4), 8047-8057.AbstractArticlePDF

    Acoustic and thermal properties were determined for boards made from Washingtonia palm tree pruning waste. Three types of boards with different particle sizes (0.25 to 1.00 mm, 1.00 to 2.00 mm, and 2.00 to 4.00 mm) were obtained from the rachis of the palm fronds. To bind the particles, 8% urea formaldehyde resin was used via hot pressing at 120 ºC for 6 min at 1.6 MPa. Three types of panels were generated to evaluate the influence of particle size. Analysis of their physico-mechanical properties showed that their mechanical performance was superior to the existing insulating boards used in the building industry. The average thermal conductivity of the panels was 0.062 W/(K·m) and did not depend on the size of the particles. At frequencies of 125 and 250 Hz, the experimental boards were classified as class D acoustic panels. The manufactured panels had high values of sound transmission loss (TL), despite the thinness of the panels, which indicates that they have good acoustic insulation capacity. Acoustic properties could be improved by increasing the thickness of the boards. Due to their mechanical, thermal, and acoustic properties, these panels could be used as lining and as false ceilings.

  • Researchpp 8058-8067Zhu, L., Liu, H., Qian, S., Dai, H., and Ren, H. (2017). "Improvement of the physical properties of paper sheet-lignophenol composites prepared using a facile impregnation technique," BioRes. 12(4), 8058-8067.AbstractArticlePDF

    Lignophenol was separated from bamboo (Sinocalamus affinis) using a phase separation system. Different concentrations of a lignophenol-acetone solution were used to impregnate hardwood pulp fiber sheets (80 g/m2). The results showed that the tightness, tensile index, tear index, and burst index properties of sheets impregnated with a lignophenol acetone solution (80 g/L) increased 5.66%, 160.08%, 93.66%, and 140%, respectively, compared with sheets prepared without lignophenol. The lignophenol-hardwood pulp fiber composites were characterized by scanning electron microscopy, X-ray photoelectron spectroscopy, and total reflectance Fourier transform infrared spectroscopy. The results indicated that lignophenol uniformly adhered to the pulp fibers but no chemical bonding occurred. Additionally, both virgin and recycled softwood pulp fiber sheets (80 g/m2) were tested using the same method. Although the strength of all composites increased after impregnation, the most obvious improvement was observed in the hardwood pulp-based composite. This simple method improved the physical strength and hydrophobicity of the composite sheets.

  • Researchpp 8068-8077Widyorini, R., Umemura, K., Kusumaningtyas, A. P., and Prayitno, T. A. (2017). "Effect of starch addition on properties of citric acid-bonded particleboard made from bamboo," BioRes. 12(4), 8068-8077.AbstractArticlePDF

    Citric acid has been investigated as a good adhesive for particleboard. This research studied the effect of starch addition on the properties of citric acid-bonded particleboard. Starch provides hydroxyl groups that can react with the carboxyl group in citric acid. Three kinds of starches were used in this research, i.e. corn, ganyong (Canna edulis Ker-Gawl), and garut (Maranta arundinacea L.) starches. Petung (Dendrocalamus sp.) bamboo particles were used as raw material. The mixture ratios of citric acid/starch were set at 100/0, 87.5/12.5, and 75/25 (w/w), while the resin content was set at 30 wt.% based on air-dried particles. The boards were then manufactured under pressing conditions of 180 °C for 10 min. Based on the physical and mechanical properties of the particleboards, it was concluded that the addition of starch tended to enhance the mechanical properties, while decreasing the physical properties of the boards. An addition of 12.5 wt.% starch in citric acid was the optimum resin ratio for manufacturing bamboo particleboard. Maranta and canna starches provided higher mechanical properties compared to corn starch. A FTIR analysis clearly showed that the intensity of carbonyl groups increased with increasing of starch content, which indicated that crosslinking between starch and citric acid occurred.

  • Researchpp 8078-8092Varila, T., Bergna, D., Lahti, R., Romar, H., Hu, T., and Lassi, U. (2017). "Activated carbon production from peat using ZnCl2: Characterization and applications," BioRes. 12(4), 8078-8092.AbstractArticlePDF

    The process for producing activated carbon from peat was optimized. The peat was impregnated with different ratios of ZnCl2, and the impregnated biomass was activated at different temperatures. The specific surface area, pore size distribution, total carbon content, and yield of the activated carbon were investigated. The best results for the specific surface area and mesoporosity of the activated peat were obtained by using a high impregnation ratio (2) and high activation temperature (1073 K). Highly porous activated carbon was produced that had a specific surface area of approximately 1000 m2/g and total pore volume that was higher than 0.5 cm3/g for most samples. The activated carbon had a high degree of mesoporosity. The adsorptive properties of the activated carbon were determined with methylene blue and orange II dyes.

  • Researchpp 8093-8105Morales-Martínez, T. K.,  Díaz-Blanco, D. I., Rodríguez-de la Garza, J. A., Morlett-Chávez, J., Castro-Montoya, A. J., Quintero, J., Aroca, G., and Rios-González, L. J. (2017). "Assessment of different saccharification and fermentation configurations for ethanol production from Agave lechuguilla," BioRes. 12(4), 8093-8105.AbstractArticlePDF

    Different strategies were assessed for the production of ethanol from Agave lechuguilla that was pretreated by autohydrolysis. Separate hydrolysis and fermentation (SHF) was compared against simultaneous processes including simultaneous saccharification and fermentation (SSF) and prehydrolysis and simultaneous saccharification and fermentation (PSSF) using different solids (15%, 20%, and 25% w/w) and enzyme loadings (15 FPU/g, 20 FPU/g, and 25 FPU/g glucan). The results showed that the maximum ethanol concentration (53.7 g/L) and productivity (1.49 g/L h-1) was obtained at 36 h in the SHF configuration at the highest solids and enzyme loadings (25% w/v and 25 FPU/g glucan, respectively). The ethanol concentration and productivity obtained in the PSSF configuration at the same time were 45 g/L and 1.25 g/L h-1, respectively. The SSF configuration exhibited the lowest ethanol concentration and productivity (10.4 g/L and 0.29 g/L h-1, respectively) at 36 h. The enzyme used, Cellic CTec3, allowed for high glucose yields at the lower enzyme dosage assessed. The SHF configuration exhibited the best results. However, the PSSF configuration can be considered an attractive alternative because it eliminated the need for solid-liquid separation devices, which simplifies the industrial implementation of the process.

  • Researchpp 8106-8118Igaz, R., Krišťák, L., Ružiak, I., Gajtanska, M., and Kučerka, M. (2017). "Thermophysical properties of OSB boards versus equilibrium moisture content," BioRes. 12(4), 8106-8118.AbstractArticlePDF

    The basic thermophysical properties of oriented strand boards were determined experimentally for use in humid conditions (OSB3) depending on the moisture content. The dependency between the thermal conductivity, thermal diffusivity, specific heat capacity, and the moisture content in the range of 0% to 10%, was examined. The non-stationary extended dynamic plane source (EDPS) experimental method was used. EDPS method was modified for anisotropic materials, i.e. with special considerations of heat-loss effect occurring at the edge of measuring samples, finite geometry of the sample and orthotropic thermal conductivity, for use with anisotropic materials. The validity of the experimental method was verified on polymethylmethacrylate (PMMA) samples. The error rate of measurements conducted on PMMA samples was less than 3%, and for OSB3 boards it was less than 5.5%. Based on the experimental results, regression equations of the dependency between the monitored properties and the moisture content were determined. In the case of thermal conductivity and thermal capacity, the determined dependencies showed a high correlation rate.

  • Researchpp 8119-8133Sedlecký, M. (2017). "Surface roughness of medium-density fiberboard (MDF) and edge-glued panel (EGP) after edge milling," BioRes. 12(4), 8119-8133.AbstractArticlePDF

    The mean arithmetic deviation of the roughness profile (Ra) was investigated for the edge surface after edge milling of medium-density fiberboard, medium-density fiberboard with single-sided lamination, and spruce edge-glued panel. Tungsten carbide blades with three different compositions and treatment (HW1, HW2, and HW1 + CrTiN coating) were used. During edge milling, the feed rate (4, 8, and 11 m/min) and cutting speed (20, 30, 40, and 60 m/s) were changed. The lowest roughness values were found in spruce timber, and the highest values were found in untreated MDF. The highest edge surface roughness was measured after using the HW2 tool. Slightly lower values were found using HW1 CrTiN, and the lowest values were found using HW1. Increasing the cutting speed led to a very slight increase in roughness. Increasing the feed rate had the same effect, but its effect was more significant. The article provides an understanding of the interaction of the most frequently occurring factors relative to the quality of the work surface of the large-area materials.

  • Researchpp 8134-8159John, R., Trommler, K., Schreiter, K., Siegel, C., Simon, F., Wagenführ, A., and Spange, S. (2017). "Aqueous poly(N-Vinylformamide-co-Vinylamine) as a suitable adhesion promoter for wood veneer/biopolyethylene composite materials," BioRes. 12(4), 8134-8159.AbstractArticlePDF

    Wood veneer/biopolyethylene (bio-PE) biocomposite materials were produced by using poly(N-vinylformamide-co-vinylamine) (PVFA-co-PVAm) copolymers as a phase-mediating reagent. In a preliminary step, PVFA-co-PVAm was adsorbed onto the wood veneer component from aqueous solution. In its adsorbed form, it served as an adhesion promoter and improved the compatibility between both the highly polar wood veneer and weakly polar bio-PE surface. Structural parameters and their effect on the adsorption process, such as the degree of hydrolysis (DH) of poly(N-vinylformamide) (PVFA) (30, 50, and > 90%), the molecular weight of PVFA-co-PVAm (Mw 10,000, 45,000, or 340,000 g/mol), and the pH value (4, 7, and 11) influenced the resulting wetting behavior of the PVFA-co-PVAm-modified wood veneer surface. Thus, the hydrophobizing effect of the PVFA-co-PVAm was clearly detectable because the contact angle with water was considerably increased up to 116° by adsorption of PVFA-co-PVAm 9095 at pH 11. The adsorbed amount of PVFA-co-PVAm was determined by energy-dispersive X-ray (EDX) spectroscopy and X-ray photoelectron spectroscopy (XPS). The PVFA-co-PVAm-coated wood veneers were consolidated with bio-PE in a hot press process. The modified composite materials showed remarkably improved Young’s moduli (552 MPa) and tensile strengths (4.5 MPa) compared to former composite materials produced without PVFA-co-PVAm modification.

  • Researchpp 8160-8179Huang, X., Qi, J., De Hoop, C., Xie, J., and Chen, Y. (2017). "Biobased polyurethane foam insulation from microwave liquefaction of woody underbrush," BioRes. 12(4), 8160-8179.AbstractArticlePDF

    Yaupon holly is one of the most widespread woody underbrush species in the southeastern United States, and it can undermine forest health and safety due to its biofuel-like nature during catastrophic wildfires. Yaupon holly was subjected to microwave liquefaction to produce biobased polyurethane (PU) foam insulation. Liquefaction parameters were optimized and summarized as follows: 1) particle size was controlled in the range of 16- to 40- mesh; 2) both the ratios of glycerol to ethylene glycol and liquid to solid were set at 3:1; 3) the reaction process was conducted at 160 °C for 10 min and catalyzed by 1.5% sulfuric acid. The optimal liquefaction conversion yield was 94.9%. The Fourier transform infrared spectra (FTIR) indicated the successful liquefaction and dissolution of wood essential components, i.e. hemicellulose, cellulose, and lignin. The optimal liquefaction product with solid residue was used directly to produce biofoams. With an increased isocyanate index, the thermal insulation properties, mechanical properties, and thermal stability of biofoams increased. Therefore, a promising biobased PU foam was obtained at an isocyanate index of 150. The density, thermal conductivity, Young’s modulus, and compressive stress of the promising biofoam were 18.5 kg·m-3, 0.033 W·m-1·K-1, 176.7 kPa, and 15.4 kPa, respectively.

  • Researchpp 8180-8198Shen, X. J., Huang, P. L., Chen, J. H., Wu, Y. Y., Liu, Q. Y., and Sun, R. C. (2017). "Comparison of acid-hydrolyzed and TEMPO-oxidized nanocellulose for reinforcing alginate fibers," BioRes. 12(4), 8180-8198.AbstractArticlePDF

    Two samples of acid-hydrolyzed nanocellulose and two samples of TEMPO-oxidized nanocellulose were separately prepared from cotton liner pulp and microcrystalline cellulose, and dispersed in water. Sodium alginate that was extracted from brown seaweed was dissolved in the nanocellulose suspensions and wet spun in a calcium chloride bath to form four kinds of alginate/nanocellulose composite fibers. The structures and properties of the obtained nanocellulose and composite fibers were investigated and compared. The results showed that all of the nanocellulose samples exhibited a needle shape with slightly different sizes. The incorporation of nanocellulose increased the opacity of the spinning dopes but improved the mechanical properties of the alginate fibers. The optimum addition amount for all of the nanocelluloses was 5% (based on the weight of sodium alginate). The TEMPO-oxidized nanocellulose produced from cotton liner pulp had the greatest influence on the strength of the fibers. All the composite fibers had an irregular cross-section with dense and uniform structure, which indicated the good compatibility between nanocellulose and alginate. In addition, the introduction of nanocellulose slightly improved the thermal stability of the alginate fibers.

  • Researchpp 8199-8216Cornelius, C., Saquing, C., Venditti, R., McCord, M., and Bourham, M. (2017). "The effect of atmospheric pressure plasma on paper and pulps," BioRes. 12(4), 8199-8216.AbstractArticlePDF

    The increased functionality of cellulose fiber based paper products is of high interest, as researchers are investigating methods to replace petroleum-based products with modified paper products. In this study, fully bleached wood pulps were treated with atmospheric pressure plasma, made into paper handsheets, and then tested for surface and other physical properties. Paper handsheets after formation were also treated with plasma to induce surface modifications. The plasma was generated using helium with fractions of either O2, CF4, or C3F6 to determine the effect of the nature of the gas. Drying methods had a greater effect on strength properties and density than plasma treatment. Plasma treatments on previously made paper increased the surface roughness, but plasma treatments on pulps prior to papermaking did not cause any roughness changes in the resulting paper. X-ray photoemission spectroscopy (XPS) revealed small increases in the oxygen to carbon ratios of oxygen enhanced plasmas for both pulp and paper treated samples. The plasma treatment showed evidence of surface fluorine in paper treated with CF4 containing plasma, but not in pulps treated with CF4 containing plasma and then made into paper.

  • Researchpp 8217-8229Tong, R., Wu, C., Zhao, C., and Yu, D. (2017). "Separation and structural characteristics of lignin in the prehydrolysis liquor of Whangee dissolving pulp," BioRes. 12(4), 8217-8229.AbstractArticlePDF

    Separation and structural characterization of lignin are essential for value-added utilization of hemicelluloses and lignin in the prehydrolysis liquor (PHL) of a kraft-based Whangee (a genus of bamboo) dissolving pulp production. In this work, lignin in the PHL was separated by acidification treatment (AT) and rotary vacuum evaporation treatment (RVET), and the separated crude lignin was then compared and characterized. The crude lignin separated by RVET could be justified as p-hydroxyphenyl (H) -syringyl (S) -guaiacyl (G) lignin, and a conjugated carbonyl was also found in it. The crude lignin separated by AT was mainly composed of S lignin that had β-1, β-5, β-O-4, and β-β bonds. Thermogravimetric analysis (TGA) showed that the maximum thermal decomposition temperatures and the final carbon residues of crude lignin separated by RVET and AT were 520 °C, 5.26%, and 470 °C, 27.92%, respectively. Moreover, of the five kinds of sugar (arabinose, galactose, glucose, xylose and mannose) in the PHL, only galactose and glucose were decreased after AT, while all five kinds were decreased after RVET.

  • Reviewpp to be addedMcDonald, J. D., and Kerekes, R. (2017). "Pragmatic mathematical models of wet pressing in papermaking," BioResources, 12(4), Page numbers to be added.AbstractArticlePDF

    This paper compares mathematical models developed over the years to estimate the moisture content of paper after wet pressing on paper machines. Models that assume all loading pressure to act upon water are discussed in detail. In contrast, most conventional models assume that pressure splits between a hydraulic component causing water removal and a structural component supported by the fibres. This assumption is shown to be questionable in light of theoretical considerations and experimental evidence. Despite their simpler nature, models based on hydraulic forces alone are often better able to account for experimental observations. The Decreasing Permeability (DP) model is the most complete model of this form and includes all major variables affecting pressing on paper machines, thereby enabling evaluation of key factors such as the relative importance of dewatering under flow-controlled and pressure-controlled conditions together with rewetting.

  • Researchpp 8230-8239Huang, Y., and Fei, B. (2017). "Comparison of the mechanical characteristics of fibers and cell walls from moso bamboo and wood," BioRes. 12(4), 8230-8239.AbstractArticlePDF

    Bamboo and wood fibers are important raw materials for pulp and papermaking, as well as fiber-reinforced composites. The mechanical properties of single fibers and the cell walls of moso bamboo (Phyllostachys heterocycla), Masson pine (Pinus massoniana), and Chinese fir (Cunninghamia lanceolata) were tested via single fiber tensile test and nanoindentation; their fracture characteristics were also compared. The single fibers and cell walls of moso bamboo had superior mechanical properties compared with those of Masson pine and Chinese fir. The bamboo fibers exhibited high strength, high elasticity, and superior ductility. The results indicated that the differences between the mechanical properties of the fiber cells and cell walls of moso bamboo and those of wood were largely dependent upon cell shape and structure.

  • Researchpp 8240-8254Zhang, D., Wang, F., Yi, W., Li, Z., Shen, X., and Niu, W. (2017). "Comparison study on pyrolysis characteristics and kinetics of corn stover and its digestate by TG-FTIR," BioRes. 12(4), 8240-8254.AbstractArticlePDF

    The pyrolysis potential of corn stover digestate (CSD) was compared with corn stover (CS). The effects of anaerobic digestion (AD) on pyrolysis were investigated at different rates by a thermogravimetric analyzer coupled with Fourier transform infrared spectrometry (TG-FTIR). The distributed activation energy model (DAEM) was used to show the differences in the kinetics. The results indicated that the AD process improved the thermal stability with lower mean reactivity (RM), higher solid residue (S850), and decreased release of observed gaseous productions, except for CH4. The release of CH4 from CSD was higher than that of CS, especially in the temperature range of 430 °C to 520 °C. The activation energies (E) of CS and CSD were 184 kJ/mol to 293 kJ/mol (conversions were 0.1 to 0.8) and 99 kJ/mol to 331 kJ/mol (conversions were 0.1 to 0.9), respectively. The activation energies decreased after AD at the same conversion level. The calculated TG data of CS and CSD from the kinetic parameters were in good agreement with the experimental curves.

  • Researchpp 8255-8271Salehi, K., Kordsachia, O., and Saake, B. (2017). "The potential of wheat straw high yield MEA pulp for enhancing strength properties of recycled paper," BioRes. 12(4), 8255-8271.AbstractArticlePDF

    This study investigated the blending of unbleached wheat straw high yield MEA (monoethanolamine) pulp with recycled pulp to improve the strength properties of recycled pulp. First, the cooking temperature in MEA high yield pulping was stepwise reduced from 160 °C to 120 °C to enhance pulp yield as much as possible. The optimum temperature for the intended application was 130 °C. In the second series of cooking performed at this temperature, the MEA charge was gradually reduced. However, with the reduction of MEA charge, the Kappa number rapidly increased. The solvent recycling was considered in a third series by reusing black liquor two times. The Kappa number increase, due to partial reuse of black liquor, was low, and the pulp strength remained at a high level. A MEA straw pulp, prepared without black liquor reuse, was refined with low energy input to various beating degrees to evaluate the refining behavior and strength development. The MEA straw pulp samples with different beating degrees were blended with recycled pulp. The ratio of blending varied between 5% and 20%. The results revealed that MEA straw pulp was well-suited as a reinforcement pulp. All strength properties of the recycled pulp, except tear strength, were improved.

  • Researchpp 8272-8285Afrida, S., Watanabe, T., and Tamai, Y. (2017). "A pronounced improvement of the kappa number reduction and pulp properties associated with the use of extracellular enzymes secreted by selected fungal strains," BioRes. 12(4), 8272-8285.AbstractArticlePDF

    A combination of extracellular enzymes secreted by Irpex lacteus KB-1.1 and Lentinus tigrinus LP-7 showed promising results in the reduction of kappa number of Acacia oxygen-delignified kraft pulp (A-OKP) in previous studies. However, the observed Kappa number reduction was low, and the bleaching process required further optimization. In the current study, the A-OKP was treated with a combination of extracellular enzymes of I. lacteus and L. tigrinus, with a subsequent alkaline peroxide extraction, which significantly improved the Kappa number reduction. The maximum achieved Kappa number reduction was 26%. The effects of static incubation and sterilization of the extracellular enzymes on biobleaching process were evaluated. Compared with a static biobleaching, biobleaching with shaking shortened the required incubation time required from 3 to 1 d. The utility of extracellular enzymes was tested with and without sterilization; no significant differences in Kappa number reduction, brightness, and physical properties of the pulp were observed. The physical properties of all pulp samples were improved following the enzymatic treatment. Furthermore, a low-cost medium containing wood powder supplemented with rice bran and palm sugar (WRBP) was used for the production of enzymes for biobleaching of A-OKP.

  • Researchpp 8286-8305Zheng, Y., Tao, L., Yang, X., Huang, Y., Liu, C., Gu, J., and Zheng, Z. (2017). "Effect of acidity and manner of addition of HZSM-5 catalyst on the aromatic products during catalytic upgrading of biomass pyrolysis," BioRes. 12(4), 8286-8305.AbstractArticlePDF

    To investigate the effects of acidity on aromatic yield and selectivity during the catalytic pyrolysis of biomass, the silica to alumina ratio (SAR), as well as the amount and addition method of HZSM-5 catalyst were varied. The results showed that with an increase in the SAR, the pore volume was reduced, the average pore diameter of the HZSM-5 catalyst increased, and the total acidity and catalytic activity decreased. Meanwhile, the increase in acidity led to an increased non-condensable gases yield, which was associated with a decrease in the bio-oil yield. The calorific value and moisture content increased, and the ability of deoxygenation was enhanced. The single ring aromatic hydrocarbons (BTXE) content increased, and the polycyclic aromatic hydrocarbons (2-ring, 3-ring) content decreased noticeably. The selectivity of BTXE decreased substantially from 69 wt.% to 6.85 wt.%, while the selectivity of naphthalene and its derivatives increased remarkably, as the SAR increased. Additionally, the acidity increased the selectivity of unsubstituted aromatic compounds, but decreased the selectivity of substituted aromatic compounds. Moreover, ex situ catalytic pyrolysis more effectively enhanced the aromatic hydrocarbon yield and selectivity (69 wt.%) compared with in situ catalytic pyrolysis (27.51 wt.%), and in situ catalytic pyrolysis generated more polyaromatics and solid residue.

  • Researchpp 8306-8319Huang, C., Huang, C., Lai, C., Wu, X., Huang, Y., He, J., Li, X., and Yong, Q. (2017). "Strategy to utilize the high ash content biomass feedstock for fermentable sugars," BioRes. 12(4), 8306-8319.AbstractArticlePDF

    A prewashing step was used to remove ash from straw pulping solid residue (waste wheat straw, WWS) prior to pretreatment and enzymatic hydrolysis. The effects of prewashing on the effectiveness of liquid hot water pretreatment (LHWP) and dilute acid pretreatment (DAP) were investigated. Prewashing effectively removed the ash in raw WWS. However, a certain amount of polysaccharides was also removed. The decreased pH of hydrolyzate after pretreatment suggested that both the prewashing and DAP could destroy the buffering effect of ash and thus improve the pretreatment efficiency. Consequently, the highest enzymatic hydrolysis yields of 79.4% and 76.1% could be obtained for LHWP and DAP, respectively. In addition, the LHWP resulted in the highest sugar recovery of 84.4% at 180 °C, and a sugar recovery of 86.8% was also reached by DAP at 160 °C. LHWP combined with prewashing strongly facilitated the enzymatic digestibility of WWS pretreated at 180 °C. However, for pretreatment at low temperature, DAP was more suitable.

  • Researchpp 8320-8339Song, W., Wei, W., Wang, D., and Zhang, S. (2017). "Preparation and properties of new plywood composites made from surface modified veneers and polyvinyl chloride films," BioRes. 12(4), 8320-8339.AbstractArticlePDF

    To reduce the formaldehyde emissions of plywood used in furniture and interior decorations, new plywood composites made from surface modified veneers and polyvinyl chloride films were developed. These films were used as formaldehyde-free adhesives, and the veneer surfaces were modified with 3-aminopropyl(triethoxy)silane to enhance the compatibility with the films. Hot-pressing of composites was optimized using a response surface methodology. The effects of 3-aminopropyl(triethoxy)silane modification on various properties of veneers and composites were studied by Fourier transform infrared spectroscopy, contact angle, physico-mechanical, scanning electron microscope, dynamic mechanical, and thermogravimetric analyses. The optimum hot-pressing process for the composites was 183 °C (temperature), 74 s/mm (duration), and 312.5 g/m2 (adhesive). The modification with 3-aminopropyl(triethoxy)silane enhanced the hydrophobicity of veneer surfaces and improved the interfacial adhesion and physico-mechanical properties of composites. Adding 3% 3-aminopropyl(triethoxy)silane resulted in approximately 40% of decrease in water adsorption of composites and 30% increase in wet shear strength. The 3-aminopropyl(triethoxy)silane modification also improved the thermal stability of composites. The physico-mechanical properties of both the unmodified and modified composites met the requirements in Chinese national standard GB/T 9846 (2015) for the water-resistant plywood, indicating the potential of proposed composites as new building materials.

  • Researchpp 8340-8358Lenske, A., Müller, T., Penter, L., Schneider, M., Hauptmann, M., and Majschak, J. (2017). "Evaluating the factors influencing the friction behavior of paperboard during the deep drawing process," BioRes. 12(4), 8340-8358.AbstractArticlePDF

    Deep drawing of paperboard with rigid tools and immediate compression has only a small presence in the market for secondary packaging solutions due to a lack of understanding of the physical relations that occur during the forming process. As with other processes that deal with interactions between two solids in contact, the control of the factors that affect friction is important due to friction’s impact on runnability and process reliability. A new friction measurement device was developed to evaluate the factors influencing the friction behavior of paperboard such as under the specific conditions of the deep drawing process, which differ from the standard friction testing methods. The tribocharging of the contacting surfaces, generated during sliding friction, was determined to be a major influence on the dynamic coefficient of friction between paperboard and metal. The same effect could be examined during the deep drawing process. With increased contact temperature due to the heating of the tools, the coefficient of friction decreased significantly, but it remained constant after reaching a certain charging state after several repetitions. Consequently, to avoid ruptures of the wall during the forming process, tools that are in contact with the paperboard should be heated.

  • Researchpp 8359-8367Leminen, V., Pesonen, A., Tanninen, P., & Varis, J. (2017). "Effect of elevated heat sealing pressure on the gas tightness of press-formed paperboard trays," BioRes. 12(4), 8359-8367.AbstractArticlePDF

    The quality of press-formed paperboard trays and its effect on the leakproof heat-sealability of the lidding film is known to depend on the quality of the sealed trays and the parameters of the sealing process. In this study, the elevation of the sealing pressure and its effect on the leak-proof heat-sealing of press-formed trays with reduced surface quality were investigated. Trays with varying quality were manufactured and heat-sealed with a lidding film, using three different sealing pressures. The quality of the sealed trays was evaluated using oxygen content measurements, leak detection by a coloring solution, and microscopic analysis. The results showed that using a higher, elevated pressure resulted in a lower oxygen content in the packages during the analysis. The results also showed that even a high sealing pressure was not enough to achieve a leakproof seal if the quality of the sealed trays was not in a satisfactory level, for example as a result from a low forming force.

  • Researchpp 8368-8377Cai, H., Yuan, Z., Zhang, X., Jun, S., Zhang, H., and Olson, J. (2017). "The influence of consistency and fibre length on the yield stress of OCC pulp fibre suspensions," BioRes. 12(4), 8368-8377.AbstractArticlePDF

    The effect of fibre length on the yield stress of recycled old corrugated containers (OCC) pulp fibre suspensions was investigated. Two types of OCC pulps were divided into four fractions based on the fibre length with a Bauer-McNett classifier. The yield stress of each fraction was measured using the shear stress ramp method at pulp consistency ranging from 0.5% to 2.5% (w/v). The results showed that both pulp consistency and fibre length had significant effects on the yield stress of OCC pulp suspensions, and the yield stress was greater with increasing fibre length and pulp consistency. Moreover, the effect of consistency in OCC pulp suspension with long fibres on the yield stress was stronger than in the slurry with short fibres.

  • Researchpp 8378-8389Louhelainen, J., Lehto, J., Kłosińska, T., Drożdżek, M., and Alén, R. (2017). "Characterization of pre-treatments on wood chips prior to delignification by near infrared spectroscopy," BioRes. 12(4), 8378-8389.AbstractArticlePDF

    A near infrared (NIR) spectroscopy-based method for predicting yields and lignin contents of differently pre-treated silver/white birch (Betula pendula/B. pubescens) and Scots pine (Pinus sylvestris) chips was developed. The approach was to create multivariate calibration models from the NIR data by the partial least squares (PLS) method. Both parameters are important factors when adjusting adequate conditions for pre-treatments either with hot-water (HW) as such and slightly acidified HW (collectively referred to as autohydrolysis) or dilute alkaline aqueous solutions prior to alkaline pulping. Pre-treatment conditions were varied with respect to temperature (130 °C and 150 °C) and treatment time (from 30 min to 120 min). In the case of alkaline pre-treatments, the NaOH charge was 1% to 8% NaOH on wood dry solids (DS). The yields varied in the range 81.2% to 99.3% (in autohydrolyses) and 83.5% to 97.9% (in alkaline pre-treatments). High correlation coefficients and low prediction errors in relation to conventional yield and lignin content data clearly indicated the suitability of NIR spectroscopy combined with the multivariate modeling as an effective and fast tool for this purpose. This technique also showed promising possibilities for developing practical process control methods to follow such pre-treatments.

  • Researchpp 8390-8401Yu, H., Du, C., Liu, H., Wei, J., Zhou, Z., Huang, Q., and Yao, X. (2017). "Preparation and characterization of bamboo strips impregnation treated by silver-loaded thermo-sensitive nanogels," BioRes. 12(4), 8390-8401.AbstractArticlePDF

    Silver-loaded thermo-sensitive nanogels (STSNGs), having a pH value of 6.8, were used as an anti-fungal agent at ambient temperature. To determine the optimal impregnation process, bamboo strips were infused with STSNG by air- and vacuum-pressurization. Scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDX), and X-ray diffraction were employed to characterize the properties and morphology of the resulting impregnated bamboo strips. The results showed that the loading dosage of bamboo strips increased with either prolonged impregnation treatment time, increasing hybrid nanogels concentration, or increasing the intensity of vacuum and pressure. Vacuum-pressurized impregnation remarkably improved the dosage of the hybrid nanogels in the bamboo strips. An increase in the loading dosage resulted in an increase in Ag content. The optimum parameters of impregnation treatment were as follows: 90 min impregnation treatment time, 0.90 wt.% concentration, and 0.5 MPa applied pressure. SEM observations revealed that the STSNGs were successfully saturated in bamboo cell cavities or covered on the cell walls. The results of the mildew proof test showed that the STSNGs had a good anti-mildew effect.

  • Researchpp 8402-8418Penín, L., Peleteiro, S., Yañez, R., Parajó, J. C., and Santos, V. (2017). "Kinetics of 5-hydroxymethylfurfural production from monosaccharides in media containing an ionic liquid and a solid acid catalyst," BioRes. 12(4), 8402-8418.AbstractArticlePDF

    Glucose and mannose, the major structural units found in softwood hemicelluloses, were used to produce 5-hydroxymethylfurfural (HMF) in the ionic liquid 1-butyl-3-methylimidazolium chloride, in the presence of a commercial zeolite (which acted as an acidic catalyst), and in the presence or absence of co-catalysts. Experiments were performed under diverse operational conditions, and the reaction kinetics were interpreted by a mechanism involving three major reactions (non-productive substrate conversion, HMF generation, and HMF decomposition). Activation energies were determined for the best reaction medium.

  • Researchpp 8419-8442Hong, G., Meng, Y., Yang, Z., Cheng, H., Zhang, S., and Song, W. (2017). "Mussel-inspired polydopamine modification of bamboo fiber and its effect on the properties of bamboo fiber/polybutylene succinate composites," BioRes. 12(4), 8419-8442.AbstractArticlePDF

    A bio-inspired approach to coating polydopamine (PDA) onto bamboo fiber (BF) was developed to enhance the poor interfacial bonding of BF/polybutylene succinate (PBS) biocomposites. The macroscopic features, functional groups, nanoscale topography, and crystallinity of the PDA-coated BF (D-BF) were investigated with digital photography, Fourier transform infrared (FTIR) spectroscopy, atomic force microscopy (AFM), and X-ray diffraction (XRD), respectively. The effects of the PDA loading rate on the performance of the D-BF/PBS biocomposites were also evaluated through the mechanical properties tests, differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), dynamic mechanical analysis (DMA), and scanning electron microscopy (SEM). Treating BF with an optimum concentration of dopamine (DOPA) decreased the polarity of the bamboo fiber, while maintaining the crystal structure of the cellulose. The thermal stability, mechanical properties, and storage modulus of the D-BF/PBS biocomposites were noticeably enhanced because of the good interfacial compatibility. Moreover, the glass transition temperature (Tg) and crystallinity of the biocomposites increased with higher DOPA loading rates. The best properties were observed with a DOPA concentration of 1.0 mg/mL. These findings exhibited the feasibility for the application of PDA in the biomass fiber-reinforced biodegradable polymer composites industry.

  • Researchpp 8443-8450Thomas, R. E., Stanovick, J. S.,  and Conner, D. (2017). "The presence and nature of ellipticity in Appalachian hardwood logs," BioRes. 12(4), 8443-8450.AbstractArticlePDF

    The ellipticity of hardwood logs is most often observed and measured from either end of a log. However, due to the nature of hardwood tree growth and bucking practices, the assessment of ellipticity in this manner may not be accurate. Trees grown on hillsides often develop supporting wood that gives the first few feet of the log butt a significant degree of ellipticity, while the rest of the log may be more circular. Good log bucking methods dictate that a log be bucked near a fork or a large knot, creating a higher-valued lower log and a jump cut or a lower-valued upper log. This practice and the additional supporting (buttress) wood below the knot can make the upper end of a log exhibit ellipticity. In this study, 703 hardwood logs from Appalachian forests were scanned using a high-resolution laser scanner, and the ellipticity and the angle of the greater axis was recorded for every foot along each log. Approximately one-third of the logs exhibited moderate to severe eccentricity on the small end. However, most logs (99%) did not exhibit significant ellipticity along the entire length. Furthermore, the mean length of the elliptical zone for all species was 3.3 feet.

  • Researchpp 8451-8467Gašparík, M., Makovická Osvaldová, L., Čekovská, H., and Potůček, D. (2017). "Flammability characteristics of thermally modified oak wood treated with a fire retardant," BioRes. 12(4), 8451-8467.AbstractPDF

    Flammability characteristics were determined for oak wood (Quercus robur L.), which was thermally modified at 160, 180, and 210 °C. Subsequently, the thermally modified and unmodified wood was treated with a fire retardant. The effect of the thermal modification (TM) and fire retardant treatment (FRT) on the weight loss (WL), burning rate (BR), maximum burning rate (MBR), and time to reach the maximum burning rate (TRMBR) were evaluated. The FRT had an expected positive effect on all of the flammability characteristics, where the WL, BR, and MBR decreased, and the TRMBR increased. The TM temperature did not have a clear effect. As the TM temperature increased, the WL and BR decreased. The highest differences were found at 160 and 180 °C. As the TM temperature increased for the wood without the FRT, the TRMBR decreased. During the burning of the thermally modified wood with the FRT, the trend was the exact opposite.

  • Reviewpp to be addedGhiyasinasab, M., Lehoux, N., and Ménard, S. (2017). "Production phases and market for timber gridshell structures: A state-of-the-art review," BioRes. 12(4), Page numbers to be added.AbstractPDF

    Timber gridshell is a structure with a doubly curved shape that is made of grid timber laths. Gridshell structure can be a solution of interest in modern free-form structures that are environmentally sustainable. However, there is a lack of academic research focusing on the potential markets and the production stages based on this construction technology. The aim of this literature review is to investigate the gridshell structure to identify its global production process, as well as the partners involved in the architectural examples studied. A review of both peer-reviewed scientific articles and grey literature resources (e.g., magazines, web pages, etc.) was conducted to gather information about timber gridshells. The design examples found were categorized as small, medium, and large gridshells. The categorization is based on the size and level of complexity of the design examples. Production phases and partners involved in the design and construction of these structures were identified for each category. Furthermore, the motivations and barriers to using gridshell designs in construction, and the potential market segments were determined.

  • Researchpp 8468-8489Oszust, K., Pawlik, A., Siczek, A., Janusz, G., Gryta, A., Bilińska-Wielgus, N., and Frąc, M. (2017). "Efficient cellulases production by Trichoderma atroviride G79/11 in submerged culture based on soy flour-cellulose-lactose," BioRes. 12(4), 8468-8489.AbstractPDF

    The microbiological hydrolysis of lignocellulose waste materials, using enzymatic biopreparations and its anaerobic processing, is a promising strategy for the efficient use of renewable energy sources. This article presents the optimization of microbiological media to improve cellulase production by Trichoderma atroviride G79/11 for further application as a cellulolytic biopreparation. The characterization of T. atroviride phenotypic microarrays was performed using the Biolog® PM plates approach. The optimization investigations were aimed at increasing the efficiency of the cellulolytic enzyme production involved in the solid-state fermentation type medium. This medium was based on dried sugar beet and wheat bran, as well as two liquid media based on mineral and soy flour, cellulose, and lactose (MSCL). The basic components of the MSCL were optimized. The study involved optimization of the content of the carbon and nitrogen source and the detergent additive. In order to increase the cellulase production, proper T. atroviride G79/11 culture conditions were established.

  • Researchpp 8490-8504Zhao, H., Feng, Q., Xie, Y., Li, J., and Chen, X. (2017). "Preparation of biocompatible hydrogel from lignin-carbohydrate complex (LCC) as cell carriers," BioRes. 12(4), 8490-8504.AbstractPDF

    Two poplar lignin-carbohydrate complexes (LCCs), LCC-48 and LCC-72, were isolated at different milling times, 48 h and 72 h, respectively. A new hydrogel carrier was prepared from these LCCs in the presence of polyethylene glycol diglycidyl ether as the crosslinker for cell (human hepatocyte (L-02)) culture. The effects of the structure of LCC on the carrier were investigated. The FT-IR spectra indicate that the two LCC samples were composed of lignin and polysaccharide, and showed a typical LCC structure. The galactose contents of LCC-48 and LCC-72 were 3.02% and 5.67%, respectively. The results of cell culture show that a large number of hepatocytes adhered to the porous carriers. Hepatocytes grown on the LCC carriers outperformed the control group in every observed category, including cell proliferation rate and metabolic activity. These results indicate that poplar LCC might be a great potential precursor of biological carriers for human hepatocytes culture.

  • Researchpp 8505-8518Al-Shorgani, N. K., Al-Tabib, A. I., and Kalil, M. S. (2017). "Production of butanol from acetyl chloride-treated deoiled rice bran by Clostridium acetobutylicum YM1," BioRes. 12(4), 8505-8518.AbstractPDF

    Butanol was produced from pretreated deoiled rice bran (DRB) in a batch culture of Clostridium acetobutylicum YM1. The DRB was pretreated by acetyl chloride to produce fermentable sugars prior to butanol fermentation. Pretreatment of DRB using 1% acetyl chloride (AC-DRB) resulted in sufficient fermentable sugars (30.88 g/L), which was comparable to that produced by using 1% sulfuric acid (33.5 g/L). Pretreated AC-DRB contained 18.08 g/L glucose, 9.95 g/L xylose, and 2.86 g/L cellobiose. Detoxification of AC-DRB was performed to remove the fermentation inhibitors, such as furfural, 5-hydroxymethyl furfural (HMF), acetic acid, formic acid, and levulinic acid with the removal efficiencies of 92.98%, 98.82%, 51.53%, 38.72%, and 96.21%, respectively, using charcoal. The detoxification with charcoal was more efficient compared to that with XAD-4 resin. Acetone-butanol-ethanol (ABE) fermentation of detoxified AC-DRB (with 1% AC) by XAD-4 produced 5.64 g/L butanol, while detoxification with charcoal of AC-DRB (with 1% AC) produced 6.48 g/L butanol. In detoxified AC-DRB with charcoal, the maximum butanol and ABE yield of 6.48 g/L and 11.82 g/L, respectively, were achieved. This study is the first reported treatment of biomass using acetyl chloride, which was used as a pretreatment method for successful butanol production.

  • Researchpp 8519-8538Bhardwaj, N., Chanda, K., Kumar, B., Prasad, H., Sharma, G., and Verma, P. (2017). "Statistical optimization of nutritional and physical parameters for xylanase production from newly isolated Aspergillus oryzae LC1 and its application in the hydrolysis of lignocellulosic agro-residues," BioRes. 12(4), 8519-8538.AbstractPDF

    Xylanase is a key enzyme in the conversion of lignocellulosic biomass into various oligosaccharides and simpler monomeric units through the hydrolysis of hemicellulose. Rice straw is readily available around the world and is a rich source of hemicellulose. Recently, there has been growing interest in the exploitation of rice straw as a low-cost substrate for the production of hemicellulolytic enzyme, i.e., xylanase. This study aimed to optimize the nutritional components (rice straw, magnesium sulphate, and calcium chloride concentrations) and physical parameters (temperature and pH) for xylanase production with a newly isolated Aspergillus oryzae LC1 under submerged fermentation using central composite design based response surface methodology. The optimum media constituents were 1% rice straw (w/v), 1.0 g/L calcium chloride, and 0.3 g/L magnesium sulphate, and the optimum physical parameters were pH 5 and 25 °C. The statistical design showed increased xylanase production with a maximum activity of 935 ± 2.3 IU/mL. The enzyme production was 3.8-fold higher than for the un-optimized Mendel’s Stenberg Basal Salt medium (245 ± 1.9 IU/mL). The enzyme was stable over wide ranges of pH (3 to 10) and temperature (25 to 60 °C). The partially purified xylanase enzyme was used for the enzymatic hydrolysis of different lignocellulosic agro-residues.

  • Researchpp 8539-8549Ferrandez-Garcia, C., Garcia-Ortuño, T., Ferrandez-Garcia, M., Ferrandez-Villena, M., and Ferrández García, C. (2017). "Fire-resistance, physical, and mechanical characterization of binderless rice straw particleboards," BioRes. 12(4), 8539-8549.AbstractPDF

    Binderless rice straw particleboards were successfully manufactured by hot pressing at low temperatures (110 °C) while under pressure (2.6 MPa) using a three-step process. Two particle sizes were used: 0.25 to 1.00 mm and 0.00 to 0.25 mm. Three pressing times (15 min, 30 min, and 60 min) were studied. Eighteen types of boards were made. The physical and mechanical properties were assessed in accordance with the European Standards for wood-based particleboards, namely density, thickness swelling, water absorption, thermal conductivity, modulus of rupture, modulus of elasticity, internal bonding strength, and reaction to fire. Two panels exceeded the requirements for general uses. The panels had a low thermal conductivity (0.076 W/mK to 0.091 W/mK). The panels were classified in the same class as the fire retardants (class Bd0, according to EN ISO 11925-2:2002).

  • Researchpp 8550-8564Zhang, L., and Chen, K. (2017). "Low-temperature alkali-anthraquinone pretreatment of wheat straw: Gradual dissolution of lignin and carbohydrate retention in pretreated solids,"  BioRes. 12(4), 8550-8564.AbstractPDF

    This paper presents a comprehensive study of wheat straw that was alkali-pretreated with NaOH loadings from 60 to 220 mg NaOH/g dry straw and a 0.5% anthraquinone (AQ) loading at 90 °C for 1, 2, and 3 h. Images of the residual solids were taken with a scanning electron microscope. A full compositional analysis of the raw material and residual solids, yield of compounds dissolved in the black liquor (BL), and molecular weight (Mw) after the different pretreatments were presented to track the dissolution process of lignin and carbohydrates. The ratio of the lignin fraction to carbohydrates dissolved in the BL was used for an analysis of the reaction selectivity. The cellulose retained 90% of the carbohydrates in the pretreated straw, while 75% of the lignin was dissolved in the BL gradually with an intermediate value of Mw. Low-molecular weight lignin (Mw ~ 1800 and degree of polymerization ~ 1.05) was dissolved out with the 60 mg NaOH/g dry straw loading. When the NaOH loading was increased to 220 mg NaOH/g dry straw, the Mw of the lignin was 4300 to 4700.

  • Researchpp 8565-8580Oleszek, M., and Matyka, M. (2017). "Nitrogen fertilization level and cutting affected lignocellulosic crops properties important for biogas production," BioRes. 12(4), 8565-8580.AbstractPDF

    The influence of the nitrogen fertilization level was investigated relative to the chemical composition of lignocellulosic energy crops and their usefulness as a substrate for the purpose of biogas production. In the case of perennial crops, such as Virginia mallow (VM) and reed canary grass (RCG), the impacts of individual swath and cutting frequency were examined. The results showed that raised nitrogen fertilization improved the biomass quality. This was important for biogas production, primarily through decreased lignin content, and for an increased ratio of structural carbohydrates to lignin. It is believed that this tendency may facilitate the digestion of the tested substrate and increase the methane fermentation efficiency. Likewise, the swath of perennial crops differed significantly in terms of the analyzed properties, which also may have been reflected in the suitability of biomass as a feedstock for biogas plants.

  • Researchpp 8581-8594Lovrić, A., Zdravković, V., Popadić, R., and Milić, G. (2017). "Properties of plywood boards composed of thermally modified and non-modified poplar veneer," BioRes. 12(4), 8581-8594.AbstractPDF

    Possibilities for use of thermally modified poplar veneer were evaluated for the production of plywood boards in industrial conditions. Formats of poplar veneer were treated at temperatures of 190 °C, 200 °C, 210 °C, and 215 °C for 1 h. By combining the treated and non-treated formats of veneer, thirteen different types of board were made. Analyses showed that the examined physical and mechanical properties were influenced by both the type of construction and the applied thermal treatment. Boards composed only of thermally modified veneer achieved the best results regarding moisture absorption and dimensional stability, and boards composed of the combined veneers had better mechanical properties. Treatments at 200 °C and 210 °C proved to be optimal, while the treatment at 215 °C was too harsh and should not be used for the thermal modification of poplar veneer.

  • Researchpp 8595-8611Spîrchez, C., Lunguleasa, A., and Antonaru, C. (2017). "Experiments and modeling of the torrefaction of white wood fuel pellets," BioRes. 12(4), 8595-8611.AbstractPDF

    The main purpose of this study was to find the optimal conditions for thermal treatment of white wood pellets. Other goals of this study were to compare torrefied and white pellets and to model the treatment process. Three types of pellets acquired from different manufacturing companies in the pellet market, representing distinct wood species, were torrefied at different temperatures of 160, 180, 200, and 220 °C, for 1, 2, and 3 h. After thermal treatment, the properties of the treated pellets were determined, including their mass loss, calorific value, ash content, and shear strength, and compared with those of the non-torrefied pellets. The calorific value increase was modeled based on the thermal degradation of hemicellulose and cellulose of the pellets and the correlation between the calorific value and mass loss. It was concluded that torrefied pellets have an increase in calorific value up to 22%, because of hemicelluloses degradation.

  • Researchpp 8612-8628Liu, J., Shi, J., Qian, C., Zhao, Y., Chen, L., Huang, L., and Luo, X. (2017). "Decolorization of Rhodamine-B from aqueous solutions by spent mushroom substrate," BioRes. 12(4), 8612-8628.AbstractPDF

    The adsorption of Rhodamine-B (Rh-B) from aqueous solutions onto spent mushroom substrate (SMS) and mushroom substrates prior to use (MSP) were comparatively studied in terms of the adsorption parameter effects, isotherms, and kinetics. It was found that an acidic pH of the dye solution was detrimental for basic Rh-B dye adsorption, which favored the electrostatic attraction between the cationic Rh-B and negative SMS and MSP. The adsorption isotherms of Rh-B onto the SMS and MSP followed the Langmuir model rather than the Freundlich or Temkin models. The fitted adsorption capacity of the SMS (107.5 mg/g) was approximately double that of the MSP (47.6 mg/g), which indicated a higher surface area and the presence of more adsorption functional sites that were created during edible fungus (Grifola frondosa) cultivation. Moreover, the experimental adsorption data of the SMS and MSP obeyed pseudo-second-order kinetics. The intraparticle diffusion plots revealed the multilinear adsorption nature of the SMS, which included boundary layer adsorption, intraparticle diffusion, and pore diffusion. However, only intraparticle diffusion played a major role in the adsorption of Rh-B onto MSP. It was concluded that the utilization of agricultural waste for edible fungus cultivation would not only improve the value of the agricultural waste itself, but can also remove Rh-B from aqueous solutions.

  • Researchpp 8629-8640Yang, W., Wu, S., Wang, H., Ma, P., Shimanouchi, T., Kimura, Y., and Zhou, J. (2017). "Effect of wet and dry torrefaction process on fuel properties of solid fuels derived from bamboo and Japanese cedar," BioRes. 12(4), 8629-8640.AbstractPDF

    Torrefaction is a promising pretreatment process to convert biomass into high energy density solid fuel for further thermal conversion systems. In this study, the effects of wet and dry torrefaction on the properties of solid fuels prepared from bamboo and Japanese cedar were investigated in a batch reactor. The yields of solid fuels decreased with increasing treatment temperature in both torrefaction processes, mainly due to the decomposition of cellulose and hemicellulose. Cellulose showed higher reactivity than hemicellulose in both biomasses. The higher heating values (HHV) of solid fuels prepared at the treatment temperatures higher than 240 °C in both torrefaction processes reached the same level as those of commercial coals. Wet torrefaction was better than dry torrefaction for decomposing bamboo and Japanese cedar. Dry torrefaction had more favorable impact than wet torrefaction on improving the fuel properties of bamboo and Japanese cedar because of its lower energy input, higher solid fuel yield, higher energy yield, and similar HHV under the same conditions. The crystalline structure of solid fuel had no great change below 260 °C in both torrefaction processes and was completely destroyed at 300 °C during dry torrefaction.

  • Researchpp 8641-8652Geng, J., Li, L., Wang, W., Chang, J., Xia, C., Cai, L., and Shi, S. (2017). "Fabrication of activated carbon using two-step co-pyrolysis of used rubber and larch sawdust," BioRes. 12(4), 8641-8652.AbstractPDF

    Characteristics of the char produced in the co-pyrolysis of used rubber and larch sawdust were studied in the conversion of low-valued pyrolysis char into value-added activated carbon using two-step co-pyrolysis, namely pyrolysis and activation processes. The physicochemical characteristics of the chars were examined by X-ray diffraction (XRD), Brunauer–Emmett–Teller (BET), and scanning electron microscopy (SEM). The results revealed that after the two-step co-pyrolysis, the upgraded carbon had BET surface areas ranging from 600 m2 g−1 to 900 m2 g−1, which were higher than the requirements for activated carbon (American Water Works Association B600 standard). Additionally, as the sawdust/rubber ratio increased, the BET value increased accordingly. A possible reaction mechanism is proposed based on the experimental results during the activation process.

  • Researchpp 8653-8671Li, J., Wang, B., Chen, K., Tian, X., Zeng, J., Xu, J., and Gao, W. (2017). "The use of lignin as cross-linker for polyurethane foam for potential application in adsorbing materials," BioRes. 12(4), 8653-8671.AbstractPDF

    Lignin was extracted from wheat straw and used for its crosslinking function in the synthesis of polyurethane foam (PUF). The effects of lignin’s addition on the cross-linking structure and macroscopic properties of the PUFs were investigated. A morphological examination, Fourier transform infrared (FT-IR) spectroscopy, and thermogravimetric analysis (TGA) were conducted to measure the performance of the polyurethanes. Kinetic models were simulated to analyze the oily solvent adsorption mechanism of the polyurethane. The results showed that an increase in the cross-linking density was conducive to an improvement of the physical properties of the polyurethane. Moreover, the process of oily solvent adsorption was in accordance with the quasi-second-order kinetic model. Both physical and chemical adsorption occurred during the adsorption process. This work demonstrated a highly effective method for imparting PUFs with an excellent performance and proper lignin content.

  • Researchpp 8672-8682Yu, L., Meng, J., Tang, Z., Zhu, L., Zhu, J., and Ma, X. (2017). "Investigation of the dimensional stability of ACQ-treated southern pine when supplemented with wax and different types of nano-SiO2," BioRes. 12(4), 8672-8682.AbstractPDF

    Southern pine (Pinus spp.) wood cubes were treated with amine copper quaternary (ACQ) solutions supplemented with wax and different types of nano-SiO2 particles. The effects of various types of nano-SiO2 on the dimensional stability of ACQ-treated wood were investigated, including water absorption, swelling, and shrinkage. The results showed that nano-SiO2/wax treatments improved the hydrophobicity of the ACQ-treated wood; various types of nano-SiO2 particles had different effects on the water absorption by the wood. The best water absorption resistance was observed with the ACQ-treated wood modified with nano-SiO2 that had a specific surface area of 380 m2/g. However, the nano-SiO2/wax treatment had a negligible effect on the swelling and shrinkage resistance of the ACQ-treated wood; various types of nano-SiO2 did not affect the swelling and shrinkage of the wood.

  • Researchpp 8683-8703Song, W., Wei, W., Ren, C., and Zhang, S. (2017). "Effect of heat treatment or alkali treatment of veneers on the mechanical properties of eucalyptus veneer/polyethylene film plywood composites," BioRes. 12(4), 8683-8703.AbstractPDF

    New plywood composites for furniture and interior decoration were developed with eucalyptus veneers using polyethylene films as formaldehyde-free adhesives. To enhance the interfacial adhesion, the veneers were modified with an oven treatment (temperature: 100, 120, 140, and 160 °C; time: 0.5, 1.0, 1.5, and 2.0 h) or by soaking in a sodium hydroxide (NaOH) solution (concentration: 3%, 7%, and 11%; time: 12, 24, and 36 h). The effects of these treatments on the mechanical properties (flexural strength, MOR; flexural modulus, MOE; wet shear strength, WSS) of the composites were studied. Both treatments improved the three properties of the composites. The heat treatment was better at improving the shear property, while the alkali treatment was better at improving the flexural properties. For the heat treatment, the highest WSS was 81.1% higher than the untreated group. The optimum conditions for the heat treatment were 140 °C and 1.0 h. For the alkali treatment, the highest MOR and MOE were 267.5% and 173.7% higher than the untreated group, respectively. The optimum conditions for the alkali treatment were 3% and 36 h. The changes to the veneer surfaces were determined by scanning electron microscopy.

  • Researchpp 8704-8724Watchman, M., Potvin, A., and Demers, C. (2017). "A post-occupancy evaluation of the influence of wood on environmental comfort," BioRes. 12(4), 8704-8724.AbstractPDF

    Emerging research on the impact of interior finishes, more specifically wood, is beginning to shed light on informed design opportunities. As a natural building material with unique features, wood creates warm and pleasant atmospheres and has the potential of enhancing the well-being of occupants. This research attempted to better understand how occupants perceive wood in built environments and whether its indoor use influenced the satisfaction of occupants. The comfort of occupants may have been influenced by factors that were unrelated to the indoor environmental quality, which caused difficulties in comparing interior finishes in existing environments and limited research in this field. An exploratory comparative study, within a post-occupancy evaluation framework, investigated the subjective perception of occupants in relation to physical comfort factors. Thirty-six occupants completed a questionnaire to examine comfort satisfaction in a multifunctional room with extensive wooden interior finishes in comparison with a similar space without wood surfaces. The results indicated that occupants were more satisfied in the extensive wood surfaced room in terms of lighting, noise, and temperature, despite the similar environmental conditions in both spaces. Adjectives often used to describe the wood room included bright, pleasant, modern, and warm. Architects should consider the subjective qualities of wood when designing comfortable buildings.

  • Researchpp 8725-8733Yue, X., Xu, Y., Li, X., and Xu, Y. (2017). "Purification of cellulose from bleached pulp by Lewis Base-enhanced high-temperature liquid water treatment," BioRes. 12(4), 8725-8733.AbstractPDF

    Applications of cellulose-based materials that require high-purity cellulose as a feedstock are becoming increasingly common. However, reported methods for hemicellulose removal are comparatively complicated. In this study, a Lewis base-enhanced high-temperature liquid water (HTLW) treatment was used to purify cellulose. The variation of carbohydrate content, average degree of polymerization (DP), and the crystalline index of specimens of the purified cellulose were investigated. After primary HTLW treatment, the alpha-cellulose content of specimens increased distinctly; also, the alkali solubility decreased. The DP of the specimens decreased dramatically after HLTW treatment. The incorporation of a Lewis base was beneficial for maintaining DP and for removing hemicellulose selectively. Simultaneously, the results of Fourier transform infrared spectroscopy (FTIR) and X-ray diffraction (XRD) showed that the chemical and crystal structure of the specimens were unchanged. Based on the experimental results, Lewis base-enhanced HTLW is a promising method to prepare high-purity cellulose.

  • Researchpp 8734-8754Ilyas, R. A., Sapuan, S. M., Ishak, M. R., and Zainudin, E. S.  (2017). "Effect of delignification on the physical, thermal, chemical, and structural properties of sugar palm fibre," BioRes. 12(4), 8734-8754.AbstractPDF

    Eco-friendly composites can be prepared by substituting man-made synthetic fibres with various types of cellulosic fibres. Sugar palm-derived nanocrystalline cellulose is a potential substitute. The most important factor in determining a good nanofiller reinforcement agent that can be used in composites is the character of the nanofiller itself, which is affected during a preliminary treatment. Thus, to gain better nanofiller properties, the delignification (NaClO2 and CH3COOH) and mercerization (NaOH) treatments must be optimized. The main objective of this study was to identify the effects of the delignification and mercerization treatments on sugar palm fibre (SPF). In addition, the characteristics of the SPF for the preparation of the hydrolysis treatment to produce nanocrystalline cellulose (NCC) for reinforcement in polymer composites were examined. Sugar palm cellulose (SPC) was extracted from the SPF, and its structural composition, thermal stability, functional groups, and degree of crystallinity were determined via field emission scanning electron microscopy (FESEM), thermogravimetric analysis (TGA), Fourier transform infrared (FTIR) spectroscopy, and X-ray diffraction (XRD), respectively. The density, moisture content, chemical composition, and structure of the SPC were also analysed.

  • Researchpp 8755-8774Guo, H., Zhang, H., Tang, W., Wang, C., Chen, P., Chen, X., and Ouyang, X. (2017). "Furfural hydrogenation over amorphous alloy catalysts prepared by different reducing agents," BioRes. 12(4), 8755-8774.AbstractPDF

    The catalytic hydrogenation of furfural was studied over a series of Ni-B, Co-B, and Ni-Co-B amorphous alloy catalysts that were prepared by the chemical reduction method using KBH4 and NaBH4 as reducing agents. These catalysts were characterized by N2 adsorption/desorption, XRD, XPS, FE-SEM, and TEM. The results showed that NaBH4 had a much stronger reduction ability to enhance the surface concentration of the metallic active sites for furfural hydrogenation and electron transfer capability, leading to much higher hydrogenation activity. In the Ni-Co-B amorphous alloy catalyst, the equilibrium between the isolated Ni-B/Co-B active sites and the combined Ni-Co-B active sites was important in regulating furfural conversion and products distribution.

  • Researchpp 8775-8785Wu, Y., Cao, F., Jiang, H., and Zhang, Y. (2017). "Carboxyl cellulose nanocrystal extracted from hybrid poplar residue," BioRes. 12(4), 8775-8785.AbstractPDF

    Ammonium persulfate (APS) oxidation was employed to isolate carboxyl cellulose nanocrystals (CNCs) from hybrid poplar residue. Structure changes resulting from APS oxidation were investigated by Fourier transform infrared (FTIR) spectroscopy and X-ray diffraction (XRD). The further oxidation of the ensuring CNCs with sodium periodate manifested selective oxidation of hydroxyl groups at the C6 position of cellulose into carboxyl groups during APS oxidation. The introduction of active carboxyl groups resulted in lower thermal stability. Transmission electron microscopy (TEM) and width distribution showed that the produced CNCs ranged from 10 nm to 24 nm. Carboxyl CNCs with a yield of 63.2% were isolated via APS oxidation, and they were suitable for large-scale CNCs production.

  • Researchpp 8786-8802Hu, Y., Zhang, L., Hu, J., Zhang, J., Shen, F., Yang, G., Zhang, Y., Deng, S., Qi, H., Yan, J., and Bai, S. (2017). "Assessments of Erianthus arundinaceus as a potential energy crop for bioethanol and biomethane production," BioRes. 12(4), 8786-8802.AbstractPDF

    Six varieties of Erianthus arundinaceus were assessed as potential energy crops and compared with switchgrass. Bioethanol and biomethane were produced as well. The chemical composition, elemental composition, and heating values were close to those of switchgrass except for a higher cellulose content. All varieties scored higher than 110, suggesting excellent potential as an energy crop. Pretreatment resulted in almost complete hydrolysis and achieved a higher glucose yield. In particular, E33 and E19 yielded 337.4 g and 332.4 g glucose, respectively, from 1.0 kg of feedstock compared with 312.1g/kg for switchgrass. E33, E49, and E19 exhibited a higher ethanol yield of 144.2 g/kg, 146.9 g/kg, and 149.6 g/kg feedstock, respectively, at a solids loading of 15%. No obvious influences could be observed on anaerobic digestion performances. A 16.3%, 14.6%, 14.0%, and 13.1% higher yield on cumulative methane could be obtained from E17, E23, E33, and E6, respectively, compared to switchgrass. Bioethanol and biomethane could be maximally obtained from E19 (6820 kg/ha) and E17 (3916 m3/ha), respectively. Thus, they are specially recommended for bioethanol and biomethane production, respectively. E33 can be suggested as a flexible variety for yielding relatively high bioethanol (6008 kg/ha) and biomethane (3409 m3/ha).

  • Researchpp 8803-8812Ochoa, D. R. H., Rojas-Vargas, J. A., and Costa, Y. (2017). "Characterization of NaOH-treated Colombian silverskin coffee fiber as a composite reinforcement," BioRes. 12(4), 8803-8812.AbstractPDF

    The effects of an alkali treatment with NaOH (5%, 10%, and 15%) was studied relative to the tensile and flexural mechanical properties of Colombian coffee silverskin fiber (CCSF)/polyester biocomposites. The CCSF was treated with NaOH for 30 min and then dried at 50 °C for 5 h. Laminates with a 35.1% volume fraction of fiber were prepared using a hand lay up manufacturing technique. Scanning electron microscopy was used to study the fiber morphology. The results revealed that the specific maximum tensile and flexural strengths increased by 36.3% and 25.1%, respectively, the specific tensile and flexural moduli increased by 31.6% and 147.0%, respectively, and the tensile toughness was 67.9% higher compared with the untreated biocomposite. The flexural toughness decreased by 62.0%. The results suggested that mercerization is an effective method to treat CCSF/polyester biocomposites.

  • Researchpp 8813-8826Wang, Y., Wang, M., Zhang, W., and He, C. (2017). "Performance comparison of different plant fiber/soybean protein adhesive composites," BioRes. 12(4), 8813-8826.AbstractPDF

    To compare the properties of different plant fiber/soybean protein adhesive composites, six types of plant fibers (rice straw, wheat straw, peanut straw, rice husk, wheat husk, and peanut shell) were selected as reinforced materials, and soybean protein adhesive was used as the adhesive. Six types of different bio-composites were prepared by the compression molding process. The Fourier transform infrared (FTIR) spectra, mechanical properties, moisture absorption, and thermal stability of the composites were measured. The tensile cross-section microstructure of the composites was examined. Results showed that the peanut straw/soybean protein adhesive composite contained more hydrophilic groups. The wheat fiber-based composites possessed more hydrogen bonds, leading to the best binding interface compatibility and mechanical properties. The wheat straw/soybean protein adhesive composite had the highest tensile strength, flexural strength, and impact strength, which were 337.7%, 638.6%, and 483.4%, compared to those of the rice husk/soybean protein adhesive composite, respectively. The peanut shell/soybean protein adhesive composite’s equilibrium moisture content was the lowest (8.70%). The rice husk/soybean protein adhesive composite had the highest equilibrium moisture content (14.23%), and the best thermal stability as the initial temperature of pyrolysis was 283.4 °C and the residual mass was 34.45%.

  • Researchpp 8827-8837Tripathi, J., and Rice, R. (2017). "Thermal conductivity values for laminated strand lumber and spruce for use in hybrid cross-laminated timber panels," BioRes. 12(4), 8827-8837.AbstractPDF

    This study examined the thermal conductivity as a function of specific gravity and moisture content for laminated strand lumber (LSL) and red spruce. As part of a larger study of heat and mass transfer in cross-laminated timber panels using laminate comprised of both LSL and spruce, the authors measured the thermal conductivity at four moisture content levels. The results showed that the LSL had a higher thermal conductivity value across the entire moisture content range tested. The average difference was just over 8% and the range for both LSL and spruce was from 0.081 W /m-K to 0.126 W / m-K. Comparisons with published solid wood thermal conductivity values across the range were good. There were no reported values of LSL thermal conductivity at various moisture content levels.

  • Researchpp 8838-8847Wang, Q., Yuan, T., Liu, S., Yuan, G., Chen, J., Li, W., Yang, R., and Fatehi, P. (2017). "Recycling immobilized laccase for lignin removal from prehydrolysis liquor of kraft-based dissolving pulp," BioRes. 12(4), 8838-8847.AbstractPDF

    Laccase treatment of prehydrolysis liquor (PHL) produced in a kraft-based dissolving pulp production may allow for purification of its hemicelluloses. In this work, a magnetic support of magnetic silica particle (Fe3O4/SiO2) was synthesized to immobilize laccase from Trametes versicolor. The laccase treatment led to increases in the molecular weight of lignin, which facilitated its removal from PHL. The results showed that laccase activity remained at 65% after seven successive recycle runs. The combination of 10 wt.% fresh immobilized laccase and 90 wt.% recycled immobilized laccase at the overall dosage of 1 U/mL led to 34% lignin removal, irrespective of the recycling runs. The laccase treatment caused 13 wt.% sugar losses from PHL. Based on the results, a process for removing lignin from PHL was proposed based on the application and recovery of an immobilized laccase system.

  • Researchpp 8848-8861Liu, L., Xiang, Y., Zhang, R., Li, B., Yu, J., and Fang, B. (2017). "TEMPO-media oxidation combined with laccase for effective degumming pretreatment of hemp fibers," BioRes. 12(4), 8848-8861.AbstractPDF

    TEMPO-media oxidation and laccase have been successfully used in fiber degumming, but the combination of the two methods in the hemp degumming process has not yet been reported. In this paper, an alternative and efficient way for the pretreatment of hemp degumming was proposed as a combination of TEMPO-media oxidation with laccase and was a TEMPO-laccase system. A chemical composition analysis, Fourier transform infrared spectroscopy (FT-IR), X-ray diffraction (XRD), and scanning electron microscopy (SEM) were applied to systematically analyze and compare the degumming efficiency between the TEMPO-laccase system and other pretreatments. The results showed that after the TEMPO-laccase system degumming process, a clean and smooth surface of the degummed fibers could be observed and the non-cellulosic materials were greatly removed without any crystalline transformation. The hemp fibers after the TEMPO-laccase system degumming process had the most desirable linear density of 6.64 dtex and a tenacity value of 3.41 cN/dtex. This new pretreatment had a considerable effect on hemp degumming, which holds promise for use of high-value textiles.

  • Researchpp 8862-8869Özdemir, F., Serin, Z. O., and Tutuş, A. (2017). "Investigation of the effect of some fire retardant chemicals and mineral materials used in surface coating on combustion performance of particleboard," BioRes. 12(4), 8862-8869.AbstractPDF

    The combustion resistance was investigated for dolomite, melamine (MEL), and ammonium polyphosphate used in the surface coating of particleboard. The surface coating materials consisted of a mixture of dolomite, melamine dust, ammonium polyphosphate, calcite, and water. The ratio of dolomite, melamine dust, and ammonium polyphosphate in the mixture was determined to be 10% based on the amount of calcite. The resulting mixture was applied to the surface of the particleboard at a thickness of 0.20 mm. Combustion tests were carried out according to ASTM E 69 standard. As a function of weight loss, the temperature values, amount of oxygen, amount of carbon dioxide, and nitrogen oxides of the test samples were determined. The results showed that the coating increased the combustion resistance of particleboard. Samples containing a 70% dolomite, 25% melamine dust, and 5% ammonium polyphosphate mixture or 100% dolomite produced the best results. The use of ammonium polyphosphate and dolomite positively affected combustion resistance.

  • Researchpp 8870-8885Idan, I., Abdullah, L., Jamil, S., Obaid, M., and Choong, T. (2017). "Fixed-bed system for adsorption of anionic acid dyes from binary solution onto quaternized kenaf core fiber," BioRes. 12(4), 8870-8885.AbstractPDF

    Water pollution due to the effluents from textile industries causes serious concern around the world. During the coloration process, the excess synthetic dyes are discharged into the wastewater stream. In the present research, kenaf core fiber (KCF) residue was chemically modified with (3-chloro-2-hydroxypropyl) trimethylammonium chloride (CHPTAC) to alter the surface properties and increase the surface area to develop more active sites that capture anionic dyes from aqueous solution. Fixed-bed adsorption studies were conducted to investigate the performance of using quartenized kenaf core fiber (QKCF) as an adsorbent for the removal of anionic acid dyes from a binary system. The effects of operational parameters, including inlet dye concentration, flow rate, and bed height, were studied in a fixed-bed column system, while other process parameters were fixed, i.e. pH and temperature at 7.5 and 27 ºC, respectively. The fixed-bed column performed better with lower influent dye concentration, less flow rate of the influent, and a higher adsorbent bed depth. Overall, the present study showed that QKCF is a potential adsorbent for anionic dye removal from aqueous solutions in a fixed-bed column system.

  • Researchpp 8886-8900Ahmad Yahaya, A. N., Hossain, M. S., and Edyvean, R. (2017). "Thermal degradation and morphological changes of oil palm empty fruit bunch vermicompost," BioRes. 12(4), 8886-8900.AbstractPDF

    Vermicompost produced from oil palm empty fruit bunch (EFB) was analysed to examine its thermal degradation and morphological appearance. The thermal degradation of vermicompost produced from untreated EFB and EFB treated with oyster mushrooms was characterised via thermogravimetric analysis (TGA) and differential thermogravimetric analysis (DTGA). It was observed that vermicomposting accelerated the thermal degradation of EFB and minimized the lignin content, but reduced lignin degradation of raw EFB. However, the thermal degradation of lignin increased in treated EFB vermicompost. The structural characterization of EFB vermicomposting revealed that the surface of the treated EFB was more fragmented than the untreated EFB vermicompost and raw EFB.

  • Researchpp 8901-8919Guo, M., Zhang, G., Du, L., Zheng, H., Liu, G., and Li, Y. (2017). "Multifunctional water-soluble polymeric fluorescent whitening agents based on 4,4'-bis (1,3,5-triazinyl)- diamino stilbene-2,2'-disulfonic acid structure," BioRes. 12(4), 8901-8919.AbstractPDF

    A series of multifunctional water-soluble polymeric fluorescent whitening agents (PFWAs, 5a-f) based on 4,4′-diamino-stilbene-2,2′-disulfonic acid (DSD acid)-triazine structure were successfully synthesized using a nucleophilic substitution reaction with cyanuric chloride, DSD acid, amino compounds, polyethylene glycol (PEG), and/or polyvinyl alcohol (PVA) as raw materials. The structure of the PFWAs was characterized by FT-IR, and the substitution degree was calculated from the results of an elemental analysis. The optical properties of the PFWAs were measured by the UV-vis spectra and fluorescence spectra when the PFWAs were applied to paper fiber to serve the roles of light stabilizer, fluorescent whitener, and surface-sizing agent. Then the performance of the PFWAs on paper was evaluated by measuring the surface strength and smoothness of paper, brightness degree of paper, and the yellowness value (value of PC) of paper. The results indicated that the PFWAs had better light stability in water solution than that of a conventional fluorescent whitening agent (FWA) as a light stabilizer. According to the surface-sizing experiment and UV aging experiment, it was concluded that not only could the PFWAs enhance the surface strength and smoothness of paper, but also have a better effect on anti-UV aging than that of FWA as a light stabilizer and fluorescent whitener agent.

  • Researchpp 8920-8936Konopka, D., Bachtiar, E., Niemz, P., and Kaliske, M. (2017). "Experimental and numerical analysis of moisture transport in walnut and cherry wood in radial and tangential material directions," BioRes. 12(4), 8920-8936.AbstractPDF

    The diffusion properties of walnut (Juglans regia L.) and cherry (Prunus avium L.) wood perpendicular to the grain are presented. The wet and dry cup tests were carried out in normal climate conditions. Simultaneously, inverse analyses by means of the finite element (FE) method were conducted based on the experimental sorption data. The results show that the numerically derived diffusion model can predict the mass changes during the experiments with sufficient accuracy with a maximum global relative error of 0.43%. However, the numerically determined diffusion coefficients do not show an agreement with the experimental data.

  • Researchpp 8937-8952Zhan, P., Sun, J., Wang, F., Zhang, L., and Chen, J. (2017). "Process optimization of β-glucosidase production by a mutant strain, Aspergillus niger C112," BioRes. 12(4), 8937-8952.AbstractPDF

    Enzymatic saccharification is a key step in the green conversion of lignocellulose to biofuels and other products. A key deficiency in common biocatalytic systems, such as Trichoderma reesei, is the insufficient presence of β-glucosidase (BGL). This study intended to develop an efficient process of BGL production as an enhancement to the T. reesei system. The authors investigated the process optimization of BGL by the mutant strain Aspergillus niger C112, which was previously developed in the authors’ laboratory. The culture medium and process (carbon, nitrogen, temperature, and pH) were optimized for cost-effective BGL production, which led to a maximum BGL activity of 8.91 ± 0.35 U/mL. In addition, the dynamics of the physio-chemical parameters (zeta potential and dissolved organic matter) of the process were studied and showed good correlations to the yield of BGL. Furthermore, a three-dimensional excitation-emission matrix fluorescence spectroscopy was successfully applied for analyzing the component, origin, and dynamics of dissolved organic matter, which contributed to a further understanding and optimization of BGL production.

  • Researchpp 8953-8969Yang, S., Su, C., Song, L., and Yuan, Q. (2017). "Composite process and electrothermal properties of a new-type electric heating plywood made with melamine resin adhesive film," BioRes. 12(4), 8953-8969.AbstractPDF

    A new type of electric heating plywood used for indoor heating products was made using melamine resin adhesive film (MRAF) as the bonding material and carbon fiber paper (CFP) as the electric heating material. Hot-press pressure greatly affected the permeation of the adhesive into the CFP and bonding performance, resulting in a bonding strength above 1.8 MPa. The conducting path in the electric heating layer was the main factor affecting the drop rate of resistance (DRR). Pressure of around 1.3 MPa was beneficial in controlling power deviation. Use of the MRAF improved insulation and water resistance. The plywood exhibited a surface temperature difference of 6 °C under commonly used power. Temperature rise exhibited an exponential relationship with heating time, and surface equilibrium temperature had a linear relationship with power density. The plywood had good power stability because the maximum resistance changed by only 0.44% when electricity was overloaded for 24 h at a power density of 500 W/m2. Stable resistance was presented after power was cycled 40 times, and the maximum DRR was 1.25% after 120 power cycles. This scheme offers a simple process for large-scale manufacture of the adopted MRAF, which has good bonding performance and electric heating stability.

  • Researchpp 8970-8985Zhang, H., Nie, S., Qin, C., Bowers, R., Zhang, K., Xia, N., Zhang, Q., Yang, Z., and Wang, S. (2017). "Optimization of oxidative degradation of HexA during chlorine dioxide delignification of bagasse pulp," BioRes. 12(4), 8970-8985.AbstractPDF

    Hexenuronic acid (HexA) not only influences delignification, but it is also one of the major factors producing absorbable organic halogens (AOX) during the chlorine dioxide bleaching of pulps. The efficient removal of the HexA from cooked pulp is important to minimize the need for bleaching and the pollution load from the mill effluent. Response surface analysis (RSA) was applied to determine the optimal oxidative degradation conditions for HexA in bagasse pulp. Based on the previous single-variable test results, reaction temperature, pH, and reaction time were chosen as the independent variables, with the amount of degradation of HexA being the response value in the RSA. According to the central composite experimental design principles, the type of response surface methodology with three factors and three levels was adopted and analyzed to determine the significant factors and the strength of interactions between factors. The optimal conditions determined were as follows: a reaction temperature of 94.7 °C, a pH of 3.7, and a reaction time of 124 min, which resulted in the amount of degradation of HexA at 10.5 µmol/g.

  • Researchpp 8986-9000Yao, S., Gao, C., Nie, S., Niu, F., Wang, S., and Qin, C. (2017). "Effects of formaldehyde modification of eucalyptus bark on Cr(VI) adsorption," BioRes. 12(4), 8986-9000.AbstractPDF

    The adsorption effects, thermodynamics, and kinetics of formaldehyde-modified eucalyptus bark on Cr(VI) was investigated. Scanning electron microscopy (SEM) and Fourier transform infrared spectroscopy (FTIR) were used to verify the adsorption capacity difference between unmodified and modified eucalyptus bark. The results demonstrated that the surface area and active group content was increased by modification, which was conducive to the adsorption of Cr(VI). The effects of pH, time, temperature, initial Cr(VI) concentration, and adsorbent dosage and on adsorption were investigated. The optimal adsorption capacity was 16.50 mg.g-1 under the conditions of 50 mg.L-1 initial Cr(VI) concentration, pH 2.0, 3 g.L-1 adsorbent dosage, 50 °C, and 120 min. The fitting of kinetics indicated that the adsorption was governed by multiple factors. The thermodynamic parameters △H0 > 0 showed that the adsorption process was an endothermic reaction. The value △S0 > 0 indicated that liquid-solid interface disorder increased during the adsorption process and showed a good adsorption performance.

  • Researchpp 9001-9023Meekum, U., and Wongkheeree, W. (2017). "Designing the wood foam core for manufacturing of lightweight sandwich structure engineered wood," BioRes. 12(4), 9001-9023.AbstractPDF

    Wood foam cores manufactured from Eucalyptus fiber/epoxy adhesive and 4,4′ oxybis(benzene sulfonyl hydrazide) (OBSH), ethyl acetate (EA), and microsphere polymer bead (Expancel®) as foaming agents were investigated. A 10 phr of OBSH showed superior properties of the 0.50 g/cm3 wood foam and that 0.70 g/cm3 was the optimal density. Also, 17 phr of EA loading gave rise to the better mechanical properties and was considered the optimal content. The microsphere polymer bead did not achieve significant expansion under the conditions employed. Manufacturing of single (X1) and double (X2) layer of lightweight sandwich structures engineered woods with teak/glass fiber-reinforced polymer (GFRP) skins was studied. The enhancement of the sandwich structures’ properties was mainly contributed by the core and also by the added thin interlaminated GFRP layer. In X1 and X2 sandwich structures, with the same volume fraction of core(s), marginal improvement occurred in the properties, caused by the addition of the thin inter-layer of GFRP. Small contributions of the core properties on the sandwich structures were also demonstrated. The sandwich structure derived from the OBSH core was superior in mechanical properties and heat distortion temperature (HDT). The sandwich structure made from EA was unsuccessful in achieving water resistance.

  • Researchpp 9024-9037Zhang, H., Fredriksson, M., Mravec, J., and Felby, C. (2017). "Hydration properties of briquetted wheat straw biomass feedstock," BioRes. 12(4), 9024-9037.AbstractPDF

    Biomass densification elevates the bulk density of the biomass, providing assistance in biomass handling, transportation, and storage. However, the density and the chemical/physical properties of the lignocellulosic biomass are affected. This study examined the changes introduced by a briquetting process with the aim of subsequent processing for 2nd generation bioethanol production. The hydration properties of the unprocessed and briquetted wheat straw were characterized for water absorption via low field nuclear magnetic resonance and sorption balance measurements. The water was absorbed more rapidly and was more constrained in the briquetted straw compared to the unprocessed straw, potentially due to the smaller fiber size and less intracellular air of the briquetted straw. However, for the unprocessed and briquetted wheat straw there was no difference between the hygroscopic sorption isotherms, which showed that the amount of cell wall water was not affected by the briquetting process and that the sugar yield was similar after a combined hydrothermal pretreatment and enzymatic hydrolysis. The factors which offset the benefits introduced by the briquetting process need to be further examined to optimize the processing parameters and enzyme recipe for better use of the wheat straw biomass feedstock.

  • Researchpp 9038-9049Ucuncu, T., Durmaz, E., and Kaymakci, A. (2017). "Characteristics of hot-compressed poplar wood boards," BioRes. 12(4), 9038-9049.AbstractPDF

    The influence of thermal modification by hot-compressing was investigated relative to the physical, mechanical, anatomical, crystallinity, and colour characteristics of poplar wood boards. The boards were modified by a hot-compressed method under various temperature stages. The physical and mechanical properties of hot-compressed poplar wood increased with increased pressing temperature. Likewise, the highest crystallinity index (68.7%) of X-ray diffraction (XRD) analyses was found in the samples pressed at 210 °C. Microscopic investigation, revealed that there were some structural deformations in early and late wood, annual ring, etc., of the compressed samples at 170 °C, 190 °C, and 210 °C. In a colour measurement test, it was determined that samples had different colour values in terms of temperature increase. The results achieved in this study demonstrated that the physical and mechanical properties of hot-compressed boards improved with increased press temperature. As a result, a thermal compression method could be preferred to advance end-usage features of low-density wood materials produced from fast-growing tree species like poplar, Douglas fir, spruce, yellow pine, eucalyptus, etc.

  • Researchpp 9050-9062Xu, Y., Li, S., and Chang, P. (2017). "A facile method to produce silver nanoparticle-loaded regenerated cellulose membranes via the reduction of silver nitrate in a homogeneous system," BioRes. 12(4), 9050-9062.AbstractPDF

    Regenerated cellulose (RC) membranes loaded with silver nanoparticles (AgNPs) were prepared in this study. Cellulose acted as a reducing agent, silver nitrate acted as an oxidizing agent, and N-methylmorpholine-N-oxide (NMMO) acted as a direct cellulose solvent. The AgNP-loaded RC membranes were obtained via the redox reaction between cellulose and silver nitrate. The results of scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDS) analysis suggest that AgNPs were reduced on the RC membranes during the dissolution and regeneration of cellulose. Atomic force microscopy (AFM) showed that the RC membranes exhibited high surface roughness, with a value of 7.19 nm. The Fourier transform infrared spectroscopy (FT-IR) and X-ray diffraction (XRD) results demonstrated that the crystal lattice type of RC membranes changed from cellulose I to cellulose II, without any derivatization. The detection results of atomic absorption spectrometry (AAS) indicated that the silver content of the RC membranes increased with increasing silver nitrate solution concentration. Antibacterial experiments showed that the AgNP-loaded RC membranes exhibited good antibacterial properties with respect to both Escherichia coli and Staphylococcus aureus.

  • Researchpp 9063-9074Chen, Q., Liu, G., Chen, G., Chen, T., and Mi, T. (2017). "Green synthesis of silver nanoparticles with corn straw for the preparation of antibacterial paper," BioRes. 12(4), 9063-9074.AbstractPDF

    A green method of synthesizing silver nanoparticles (AgNPs) with corn straw acting as reducing agents was used to prepare antibacterial paper. An ammonia solution, corn straw, and soluble starch were used as the silver precursor, reducing agent, and capping agent, respectively. The optimal condition for synthesizing AgNPs was obtained by varying the reactant ratio, temperature, and reaction time. The AgNPs were characterized by ultraviolet-visible (UV-vis) spectroscopy, X-ray diffraction (XRD), spray analyzer, and transmission electron microscopy (TEM). The obtained AgNPs were almost spherical and they were redispersed well in ethanol after centrifugation. Importantly, the prepared AgNPs were better applied in preparing antibacterial paper. After careful measurements, the mechanical properties and the antibacterial ability of the antibacterial paper were good. Therefore, the method of using corn straw as a reducing agent combined with AgNPs, to prepare antibacterial paper, is feasible. This method is noteworthy because corn straw is an underutilized material.

  • Researchpp 9075-9085Huang, C., Chen, Y., Zhao, Y., Xue, D., Li, C., and Zhu, M. (2017). "Physical strength improvement of Eucalyptus alkaline hydrogen peroxide mechanical pulp by low-temperature plasma treatment," BioRes. 12(4), 9075-9085.AbstractPDF

    Low-temperature plasma treatment technology is an efficient and environmentally friendly surface treatment technology that has been extensively studied for the surface chemical modification to pulp fibers. In this study, Eucalyptus alkaline peroxide mechanical pulp (APMP) fibers were modified using a low-temperature plasma generator. The tensile index of the fibers after low-temperature plasma treatment under different conditions was measured and analyzed to evaluate the relationship between the plasma treatment conditions and the physical strength improvement of APMP. It was revealed that factors such as gas source (oxygen, argon, and nitrogen gases), discharge power, vacuum level, and modification time affected the physical strength properties of APMP. In addition, the change in carboxyl group content in the pulp fibers after low-temperature plasma treatment was measured using the Headspace Gas Chromatography (HS-GC) method. The carboxyl content in the fiber increased remarkedly after low-temperature plasma treatment, which was beneficial for improving the physical strength properties of paper made from the APMP.

  • Researchpp 9086-9102Zhang, J., Liu, F., Gao, J., Chen, Y., and Hao, X. (2017). "Ordered mesoporous TiO2/activated carbon for adsorption and photocatalysis of Acid Red 18 solution," BioRes. 12(4), 9086-9102.AbstractPDF

    Ordered mesoporous TiO2, loaded on walnut shell-based activated carbon, was prepared via sol-gel and ultrasonic-assisted technology. The obtained composites (M-TiO2/AC) were characterized via X-ray diffraction, N2 adsorption-desorption isotherms, and Fourier transform infrared spectroscopy. The adsorption–photocatalytic reduction capabilities were calculated using the removal rate of Acid Red 18 solution via UV spectrophotometry. The specific area of M-TiO2/AC increased from 563 m2·g-1 to 881 m2·g-1, compared to TiO2/AC. The removal rate was 92.3% when the Acid Red 18 with a concentration of 80 mg·L-1 was subjected to illumination for 2 h with 0.15 g of M-TiO2/AC. Under this condition the removal rate of Acid Red 18 solution by M-TiO2/AC was higher than that of TiO2/AC (83.7%), or AC (73.1%), which was attributed to the regular mesoporous structure, pore-pore synergistic amplification, and TiO2 photocatalysis. Acid Red 18 might be oxidized and decomposed into small molecular substances, such as CO2 and H2O, by strong oxidizing free hydroxyl radicals provided during the photocatalytic process by M-TiO2. The adsorption and photocatalytic processes followed the pseudo-second-order kinetic model. Internal diffusion and external diffusion processes influenced the adsorption rate.

  • Researchpp 9103-9117Alias, N. F., Ismail, H., and Ab. Wahab, M. K. (2017). "Properties of polyvinyl alcohol/palm kernel shell powder biocomposites and their hybrid composites with halloysite nanotubes," BioRes. 12(4), 9103-9117.AbstractPDF

    Biocomposites composed from polyvinyl alcohol (PVOH)/palm kernel shell powder (PKSP) were prepared via a solution casting method. Halloysite nanotubes (HNTs) were used to gradually replace PKSP to study the effect of hybrid fillers and also to compare the properties of PVOH/PKSP biocomposites with a commercial filler, HNTs. The effect of HNTs’ addition on the biocomposites was investigated based on mechanical properties, physical properties, and its biodegradability. The incorporation of HNTs in the biocomposites enhanced the tensile properties. Scanning electron microscopy (SEM) studies revealed that better filler and matrix interaction was achieved after the incorporation of HNTs. Moreover, the water absorption and water vapour transmissibility (WVT) of biocomposites decreased. The biodegradability of biocomposites filled with HNT was lower compared to the biocomposites filled with PKSP.

  • Researchpp 9118-9129Zhang, J., Liang, J., Du, G., Zhou, X., Wang, H., and Wang, H. (2017). "Performance of cutting and grinding wheel based on lignin-phenolic resin matrix and aluminum oxide," BioRes. 12(4), 9118-9129.AbstractPDF

    Grinding wheels made from an easily-prepared and industrialized thermosetting PFL resin (phenol, formaldehyde, and alkali lignin) with aluminum oxide particles were prepared (i.e., PFL grinding wheel). The mechanical properties of these grinding wheels were characterized by their Brinell hardness, compression strength, and abrasiveness. The curing and heat resistance properties of the PFL resin were studied using differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA). The results indicated that the new PFL resin with 30% of the phenol replaced by alkali lignin exhibited excellent heat resistance. When using alkali lignin to replace a portion of the phenol, the curing temperature of phenol-formaldehyde resin (PF) was increased. Scanning electron microscopy (SEM) of the PFL grinding wheel showed no pores and cracks in the composite when compared to laboratory prepared PF grinding wheels; PFL grinding wheels had high hardness and compression resistance. Furthermore, the PFL grinding wheel exhibited abrasiveness that was comparable to the PF grinding wheel during laboratory tests.

  • Researchpp 9130-9142Gómez, N., Santos, S. M., Carbajo, J. M., and Villar, J. C. (2017). "Use of bacterial cellulose in degraded paper restoration: Effect on visual appearance of printed paper," BioRes. 12(4), 9130-9142.AbstractPDF

    One of the most common methods used to reinforce damaged paper is to apply a lining, using Japanese paper (JP). The reinforcing material must consolidate the paper without modifying its visual appearance. The unique properties of bacterial cellulose (BC) suggest that it could be efficiently used to reinforce degraded paper documents. The changes in the visual appearances of the printed commercial papers lined with BC and JP were examined in this study. Four commercial papers, coated and uncoated, were printed with cyan, magenta, yellow, and black offset inks. The printed samples were lined with BC and JP sheets. Print density, gloss, and CIELab coordinates were tested in the lined and unlined samples before and after aging. Lining with JP notably affected the print density and CIELab coordinates. The lining with BC resulted in lower decrements in color intensity. The gloss values of samples lined with BC differed widely amongst the papers, whereas in papers reinforced with JP these values never exceeded 6%. Subjecting the samples to an aging process did not markedly modify the results except for the BC-lined samples, in which color differences increased.

  • Researchpp 9143-9151Ozgenc, O., Durmaz, S., and Kuştaş, S. (2017). "Chemical analysis of tree barks using ATR-FTIR spectroscopy and conventional techniques," BioRes. 12(4), 9143-9151.AbstractPDF

    ATR-FTIR spectroscopy and conventional analysis techniques were performed to characterize the chemical structure of different coniferous (cedar, fir, Calabrian pine, and spruce) and deciduous (chestnut, oak, alder, and beech) tree barks. The cell wall components (holocellulose and lignin) and extractives of tree barks were determined using conventional analysis methods. Chemical analysis indicated that the polysaccharide contents of tree barks were very low compared to lignin and extractives content. Substantial dissolution of tree barks was brought about by 1% NaOH. FTIR analysis method is an easy and reliable way to determine the functional groups of tree bark components. The levels of carbohydrates and lignin, as determined by ATR-FTIR spectral analysis, were consistent with the results of conventional analysis. The highest content of lignin was in the alder species for the deciduous trees and in the cedar type for the coniferous trees.

  • Researchpp 9152-9182Mattsson, T., Azhar, S., Eriksson, S., Helander, M., Henriksson, G., Jedvert, K., Lawoko, M., Lindström, M., McKee, L., Oinonen, P., Sevastyanova, O., Westerberg, N., and Theliander, H. (2017). "The development of a wood-based materials-biorefinery," BioRes. 12(4), 9152-9182.AbstractPDF

    Several different methods for the extraction, separation, and purification of wood constituents were combined in this work as a unified process with the purpose of achieving a high overall efficiency of material extraction and utilization. This study aimed to present a laboratory-scale demonstrator biorefinery that illustrated how the different wood constituents could be separated from the wood matrix for later use in the production of new bio-based materials and chemicals by combining several approaches. This study builds on several publications and ongoing activities within the Wallenberg Wood Science Center (WWSC) in Sweden on the theme “From wood to material components.” Combining the approaches developed in these WWSC projects – including mild steam explosion, membrane and chromatographic separation, enzymatic treatment and leaching, ionic liquid extraction, and fractionation together with Kraft pulping – formed an outline for a complete materials-biorefinery. The process steps involved were tested as integral steps in a linked process. The scale of operations ranged from the kilogram-scale to the gram-scale. The feasibility and efficiency of these process steps in a biorefinery system were assessed, based on the data, beginning with whole wood.