NC State
  • Editorialpp 1508-1509Hubbe, M. A. (2013). "Life in the Forest Canopy," BioRes. 8(2), 1508-1509.AbstractPDF
    Scientists have been devoting increased time and attention to the tops of trees. As made clear by results of their studies, the environment of the forest canopy is teeming with life. Perhaps because the crowns of trees are difficult for people to reach, and due to the micro-climates within them, they hold a rich and diverse collection of life forms. Advances in the use of ropes, ladders, and suspended walkways is now making it possible for humans to be more frequent visitors to these realms.
  • Editorialpp 1510-1512Zhu, S., Yu, P., Wang, Q., Cheng, B., Chen, J., and Wu, Y. (2013). "Breaking the barriers of lignocellulosic ethanol production using ionic liquid technology," BioRes. 8(2), 1510-1512.AbstractPDF
    Although the use of ionic liquids (ILs) has provided a potentially effective technical tool to improve the lignocellulosic ethanol production process, the technology still is facing great challenges with respect to its efficiency and economic viability. This editorial gives a systematical analysis of the potential and limitations of lignocellulosic ethanol production using IL technology. The use of ILs establishes a new platform for fractionation of lignocellulosic biomass. The IL pretreatment of lignocellulosic biomass can greatly increase its saccharification rate and the fermentable sugar yield. Use of ILs can also intensify the ethanol fermentation process and improve ethanol separation efficiency from its fermentation broth. However, many technical difficulties still exist in reducing the process costs and alleviating the environmental and ecological effects. More research and financial support are needed to overcome these difficulties.
  • Editorialpp 1513-1516Reeb, C. W., Lucia, L. A., and Venditti, R. A. (2013). "Novel screening technique: Integrated combinatorial green chemistry & life cycle analysis (CGC-LCA)," BioRes. 8(2), 1513-1516.AbstractPDF
    The integration of combinatorial green chemistry (CGC), a more benign approach to combinatorial chemistry, with environmental life cycle assessment (LCA) methodologies as an improved process development methodology is discussed. It is expected that the CGC approach will require less labor and result in more globally optimized assay results, leading to more optimized unit process design. The technique utilizes chemical assay stage information to rapidly predict globally optimized process conditions based on techno-economic and LCA indicators. A simplified kraft pulping case study of the application of CGC-LCA is demonstrated herein, but CGC analyses could be applied to virtually any chemical-based project development and implementation project.
  • Editorialpp 1517-1519Li, J., Shen, J., Qian, X., and Ren, W. (2013). "Engineering of cellulosic cigarette paper to reduce the toxic emissions of smoking," BioRes. 8(2), 1517-1519.AbstractPDF
    The prevalence of smoking around the world is well known. During the smoking of cigarettes, various toxins in both the mainstream smoke and sidestream smoke are huge threats to people’s health. In this context, the reduction of toxic emissions is indeed a global concern. Engineering of cigarette-related components, including cigarette paper and tobacco, is important for mitigating the negative impacts of smoking. In the case of cigarette paper, such concepts as decreasing the amount of cellulosic fibers, use of burn-promoting additives, increasing the permeability of paper, and use of catalysts, adsorbents, and/or reductants, have been proposed in the literature. The commercialization of technologies for the engineering of cellulosic paper is expected to result in the production of “healthier” cigarettes. A possible blueprint is to tailor cigarette paper to help smokers to completely quit smoking.
  • Researchpp 1520-1538Dion, L.-M., Lefsrud, M., Orsat, V., and Cimon, C. (2013). "Biomass gasification and syngas combustion for greenhouse CO2 enrichment," BioRes. 8(2), 1520-1538.AbstractPDF
    Greenhouse carbon dioxide (CO2) enrichment from biomass residues was investigated using exhaust gas from the combustion of syngas produced by gasification. Near complete syngas combustion is essential to achieve CO2 levels which increase plant yields while maintaining a safe environment for workers. Wood pellets were supplied to a downdraft gasifier to produce syngas fed to a steel swirl burner. The preliminary results were encouraging and represented a first step toward a successful development of this technology. The burner required an equivalence ratio (the actual air to fuel ratio relative to the stoichiometric air to fuel requirements) of 2.6 for near complete combustion. Concentrations of sulphur dioxide (SO2) and ethylene (C2H4) emissions were either below critical concentrations or negligible. In 60% of the trials, carbon monoxide (CO) emissions were below ASHRAE standards for indoor air quality. However, the average nitrogen oxide (NOx) emission was 23.6 ppm, and it would need to be reduced below the 0.05 ppm to meet ASHRAE standards. Proposed improvements to the syngas burner design to lower NOx emissions and increase efficiency are: integration of a low swirl design, mesh catalysers, a higher quality refractory material, and a more efficient heat exchanger. Theoretically, combustion or gasification of biomass could provide more CO2 for greenhouse enrichment than propane or natural gas per unit of energy.
  • Researchpp 1539-1550Safwan, M. M., Lin, O. H., and Akil, H. M. (2013). "Preparation and characterization of palm kernel shell/polypropylene biocomposites and their hybrid composites with nanosilica," BioRes. 8(2), 1539-1550.AbstractPDF
    Hybrid composites are characterized by a variety of properties that are of interest to automotive applications, including strength, mechanical, and thermal properties. In this work, palm kernel shell-filled maleated polypropylene composites and palm kernel shell/nanosilica-filled maleated polypropylene hybrid composites were produced using a Brabender Internal Mixer. The results showed that the usage of the two types of filler in the PP matrix enhanced the tensile strength, elongation at break, and impact strength but reduced the tensile modulus of the PP composites. Thermal studies confirmed that the improved nucleating ability of the hybrid fillers contributed to the superb mechanical properties of the hybrid composites. A lower percentage of water absorption was observed in hybrid composites compared to the palm kernel shell/PP composite system.
  • Researchpp 1551-1562Ai, N., Zeng, G., Zhou, H., and He, Y. (2013). "Co-production of activated carbon and bio-oil from agricultural residues by molten salt pyrolysis," BioRes. 8(2), 1551-1562.AbstractPDF
    The feasibility of co-producing activated carbon and bio-oil from rice stalk through molten salt pyrolysis is reported in this work. The results indicated that: (1) mixed ZnCl2-KCl molten salt could considerably improve the solid and liquid yield as well as the ratio of H2 and CH4 selectively (compared to the traditional ZnCl2 method), (2) an increase of pyrolysis temperature had the same impact on the yield as mixed molten salt, except for a decrease of the liquid yield, which may have a negative effect on the adsorption ability of activated carbon, and (3) the adsorption capability of activated carbon varied significantly with the activation temperature and, to a lesser degree, with the pyrolysis temperature. The conclusion can be drawn that pyrolysis in molten salt is a potential technology for agricultural residue utilization because of its capability of co-production, especially in activated carbon and bio-oil.
  • Researchpp 1563-1572Ren, Q., Huang, Y., Ma, H., Wang, F., Gao, J., and Xu, J. (2013). "Conversion of glucose to 5-hydroxymethylfurfural catalyzed by metal halide in N,N-dimethylacetamide," BioRes. 8(2), 1563-1572.AbstractPDF
    A simple strategy is reported for catalytic conversion of glucose to 5-hydroxymethylfurfural (HMF) over AlI3 in N,N-dimethylacetamide (DMAC). When the reaction was conducted in DMAC at 120°C for 15 min over AlI3 catalyst, HMF was obtained with a yield of 52%. The reaction course was monitored by 13C NMR spectroscopy and HPLC analysis. The results suggest that AlI3 catalyzes the three consecutive reactions consisting of mutarotation of α-glucopyranose to β-glucopyranose, isomerization of glucose to fructose, and dehydration of fructose to HMF.
  • Researchpp 1573-1581Abe, H., Murata, Y., Kubo, S., Watanabe, K., Tanaka, R., Sulaiman, O., Hashim, R., Mhd Ramle, S. F., Zhang, C., Noshiro, S., and Mori, Y. (2013). "Estimation of the ratio of vascular bundles to parenchyma tissue in oil palm trunks using NIR spectroscopy," BioRes. 8(2), 1573-1581.AbstractPDF
    In order to use oil palm trunks more effectively, a new method was investigated to estimate the weight-based ratio of vascular bundles (VB) to parenchyma tissue (PT) in study materials taken from oil palm trunks, by using near infrared (NIR) spectroscopy based on chemical analyses of the composition. The VB and PT were carefully separated by hand from oil palm trunks using a polarizing microscope to ensure purity, and then they were mixed at certain ratios. As the VB ratio was increased, extractives, lignin, hemicellulose, and starch contents decreased, while the alpha-cellulose content increased. By using NIR spectroscopy coupled with partial least squares regression analysis, we could predict the ratio of VB to PT with an accuracy of R2 = 0.99. Absorption peaks significantly affecting estimation were observed at 1929, 2104, 2276, and 2335 nm, which were assigned to the chemical compositions of cellulose and starch. The NIR absorbance is considered to reflect the ratio of VB to PT, according to the compositions of cellulose and starch in oil palm trunks.
  • Researchpp 1582-1590Korkut, D. S., Hiziroglu, S., and Aytin, A. (2013). "Effect of heat treatment on surface characteristics of wild cherry wood," BioRes. 8(2), 1582-1590.AbstractPDF
    Heat treatment effects on surface properties of wild cherry (Prunus avium) including surface roughness, glossiness, and color stability were evaluated. Samples were exposed to a temperature of 212 °C for 1.5 and 2.5 h. A stylus type profilometer, glossmeter, and spectrophotometer were employed to determine surface characteristics of heat-treated specimens. Glossiness and surface roughness values of the samples decreased with heat treatment compared to those of control specimens. The glossiness and values of surface roughness decreased for the samples with all treatment combinations. The samples had significant discoloration as a result of heat exposure. Color difference of the specimens increased as a result of all treatment schedules.
  • Researchpp 1591-1603Kiew, K. S., Hamdan, S., and Rezaur Rahman, M. (2013). "Comparative study of dielectric properties of chicken feather/kenaf fiber reinforced unsaturated polyester composites," BioRes. 8(2), 1591-1603.AbstractPDF
    The electrical properties of chicken feather fiber (CFF) and kenaf fiber (KF) unsaturated polyester (UP) composites have been studied with reference to fiber loading and frequency. Tests were carried out to compare the suitability of the two different composites as a dielectric material. The chicken feather fiber unsaturated polyester composite exhibited an overall lower dielectric constant, dissipation factor, and loss factor compared to the kenaf fiber unsaturated polyester composites. The values were high for the composites with fiber contents at 40%. The dielectric value increments were high at low frequencies, and they gradually reached significantly lower values at higher frequencies. Based on the results it was judged that chicken feather fiber composites would be suitable for application as high speed printed circuit board (PCB) material with good frequency stability at 1 MHz. Finally, an attempt was made to correlate the experimental values with theoretical calculations.
  • Researchpp 1604-1614Zhang, A. P., Liu, C. F., Sun, R. C., and Xie, J. (2013). "Extraction, purification, and characterization of lignin fractions from sugarcane bagasse," BioRes. 8(2), 1604-1614.AbstractPDF
    Three-step extraction of lignin fractions from ball-milled sugarcane bagasse (SCB) was studied with 96% dioxane, 50% dioxane, and 80% dioxane containing 1% NaOH at boiling temperature followed by purification to remove hemicelluloses. The total yields of hemicelluloses and lignin were 15.8% and 7.2% based on dried SCB, respectively. In the first step, 5.1% lignin (70.8% of the total extracted lignin) was isolated with 96% dioxane, which is higher than the traditional MWL procedure (3.3% lignin). In the second step, 10.4% hemicelluloses (65.8% of the total extracted hemicelluloses) were obtained with 50% dioxane. The obtained lignin fractions were characterized with FT-IR, 31P-NMR, and 2D 1H-13C HSQC. The results suggested that the ‘core’ of the lignin structure did not change dramatically during the sequential neutral and alkaline dioxane treatment processes. The contents of phenolic hydroxyl groups in the three lignin fractions based on 31P-NMR analysis were 1.66, 4.46, and 9.42 mmol/g lignin, respectively, higher than those from wood. The results also indicated that the lignin fractions obtained from SCB contained some amount of p-coumaric acid and ferulic acid, significantly different from those extracted from softwood and hardwood.
  • Researchpp 1615-1624Luppold, W. G., and Bumgardner, M. S. (2013). "Factors influencing changes in U.S. hardwood log and lumber exports from 1990 to 2011," BioRes. 8(2), 1615-1624.AbstractPDF
    Domestic consumption of hardwood products in the United States since 2000 has trended downward, making exports the single most important market for higher grade hardwood lumber and a major market for higher value hardwood logs. Between 1990 and 2011, hardwood lumber exports increased by 46%. During most of this period, Canada was the largest export market for U.S. lumber, but in 2009 China/Hong Kong became the most important market. Nearly 60% of the lumber exported in 1990 was red or white oak, but the proportion of exports of these species had decreased to 38% by 2011. By contrast, exports of yellow-poplar lumber increased by 381% over this period. The volume of hardwood logs exported grew by 62% between 1990 and 2011, and Canada remained the largest customer. Several factors can affect the export of hardwood lumber and logs. In the 1990s, changes in exchange rates and economic activity in importing countries could be linked with changes in lumber and log exports. Since 2000, China, Vietnam, and other East Asian furniture-producing countries have become important export markets as overseas manufacturers seek lumber of species familiar to U.S. consumers. Conversely, the large decrease in hardwood lumber and log exports to Canada between 2006 and 2009 coincides with a similar decrease in wood furniture imports from Canada.
  • Researchpp 1625-1633Mahmood, Z., Ahmed, I., Saeed, M. U. Q., and Sheikh, M. A. (2013). "Investigation of physico-chemical composition and antimicrobial activity of essential oil extracted from lignin-containing Cupressus sempervirens," BioRes. 8(2), 1625-1633.AbstractPDF
    New, cost-effective source materials are being sought to enable the development of essential oils for potential use in pharmaceutical and commercial applications. The present study was aimed at investigating such features of Cupressus sempervirens, which despite its exotic legendary attributes has been almost ignored up until now. Gas liquid chromatography (GLC) was used to determine the various physico-chemical composition parameters (specific gravity, refractive index, acid and ester values profile) of the selected lignin-containing plant. The essential oil was extracted by a steam distillation technique using needles and twigs of C. sempervirens. The antimicrobial properties of the oil were investigated against a wide spectrum of microorganisms by flask culture and diffusion methods. In the flask culture method, only three strains, viz. A. niger, A. flavous, and A. fumigates, while in diffusion method seven strains, viz. A. niger, A. flavous, A. fumigatous, F. solani, F. oxysporum, Penecillium digitatum, and Candida uterus, and three strains of bacteria, viz. E. coli, M. leutius, B. lacto, exhibited 100% effectiveness in the presence of newly extracted C. sempervirens oil.
  • Researchpp 1634-1645Hassan, K. T. S., Horáček, P., and Tippner, J. (2013). "Evaluation of stiffness and strength of Scots pine wood using resonance frequency and ultrasonic techniques," BioRes. 8(2), 1634-1645.AbstractPDF
    The aim of this paper was to predict the static bending modulus of elasticity (MOES) and modulus of rupture (MOR) of Scots pine (Pinus sylvestris L.) wood using three nondestructive techniques. The mean values of the dynamic modulus of elasticity based on flexural vibration (MOEF), longitudinal vibration (MOELV), and indirect ultrasonic (MOEUS) were 13.8, 22.3, and 30.9 % higher than the static modulus of elasticity (MOE S ), respectively. The reduction of this difference, taking into account the shear deflection effect in the output values for static bending modulus of elasticity, was also discussed in this study. The three dynamic moduli of elasticity correlated well with the static MOE S and MOR; correlation coefficients ranged between 0.68 and 0.96. The correlation coefficients between the dynamic moduli and MOE S were higher than those between the dynamic moduli and MOR. The highest correlation between the dynamic moduli and static bending properties was obtained by the flexural vibration technique in comparison with longitudinal vibration and indirect ultrasonic techniques. Results showed that there was no obvious relationship between the density and the acoustic wave velocity that was obtained from the longitudinal vibration and ultrasonic techniques.
  • Researchpp 1646-1656Cobas, A. C., Felissia, F. E., Silvia Monteoliva, S., and Area, M. C. (2013). "Optimization of the properties of poplar and willow chemimechanical pulps by a mixture design of juvenile and mature wood," BioRes. 8(2), 1646-1656.AbstractPDF
    Forest plantations of Salicaceae (poplars and willows) in Argentina are mainly used for the manufacture of pulp for newsprint. The rapid growth of these species results in a decrease in rotation age, which increases the proportion of juvenile wood. The aim of this work was to define the proportions of juvenile wood (JW) and mature wood (MW) of these species that can optimize the mechanical and optical properties of chemimechanical pulps for newsprint production. A two-component mixture type experimental design was used with proportions (JW:MW) of 0:100%, 25:75%, 50:50%, 75:25%, and 100:0%. When the mechanical properties were optimized, the highest desirability function was obtained with a JW:MW ratio of 100:0%, and the optimal ratio for optical properties was 0:100%. The pattern of variation of mechanical properties can be attributed to the higher density of MW, whilst that of the optical properties can be attributed to the higher content of extractives in the JW.
  • Researchpp 1657-1664Severo, E. T. D., Sansígolo, C. A., Calonego, F. W., and Barreiros, R. M. (2013). "Kraft pulp from juvenile and mature woods of Corymbia citriodora," BioRes. 8(2), 1657-1664.AbstractPDF
    Kraft pulp produced from juvenile and mature wood from thirty-two-year-old Corymbia citriodora trees was evaluated. The stem was subdivided into regions of juvenile and mature wood, and then it was transformed into chips. These materials were then cooked in the Laboratory of Pulp and Paper at São Paulo State University (UNESP, Botucatu, SP, Brazil) and the physico-mechanical properties of the pulps were determined. The results showed that: (1) the pulp yields of mature wood were up to 4.4% greater in comparison to the juvenile wood, (2) the juvenile wood pulp required a shorter refining time than mature wood to reach the same Schopper-Riegler degree, (3) the juvenile wood pulp presented lower specific volume, and (4) the mature wood pulp presented greater air resistance, tensile, tear and burst index values, stress-strain factor, and stretch than the juvenile wood pulp.
  • Researchpp 1665-1674Özdemir, F., and Tutus, A. (2013). "Effects of fire retardants on the combustion behavior of high-density fiberboard," BioRes. 8(2), 1665-1674.AbstractPDF
    The objective of this study was to determine the effects of certain fire-retardant chemicals on the combustion resistance of high-density fiberboard (HDF). Borax (BX), boric acid (BA), ammonium polyphosphate (APP), and alpha-x (AX) were added into the fibers made from 50% scots pine (Pinus sylvestris L.) and 50% beech (Fagus orientalis Lipsky) woods at 3%, 6%, and 9% levels based on oven-dry fiber weight. HDF panels were produced in 6.5 mm thickness. HDF panels’ combustion behavior was explored. To detect combustion resistance, the panels were tested according to the ASTM-E 69 and thermogravimetric analysis (TGA) tests. It was determined that fire-retardant (FR) chemicals enhanced the combustion resistance of the panels to varying degrees. As a result, the FR chemicals’ type and concentrations are effective for determining the combustion resistance of HDF panels.
  • Researchpp 1675-1696Wan Nadhari, W. N. A., Hashim, R., Sulaiman, O., Sato, M., Sugimoto, T., and Selamat, M. E. (2013). "Utilization of oil palm trunk waste for manufacturing of binderless particleboard: Optimization study," BioRes. 8(2), 1675-1696.AbstractPDF
    Utilization of oil palm trunk waste for production of environmental friendly binderless particleboard was studied. Response surface methodology was used to optimize the manufacturing conditions. The steaming temperature (100 to 120˚C), steaming time (25 to 50 min), hot pressing temperature (180 to 220˚C), and hot pressing time (15 to 30 min) were optimized in the ranges shown. The optimum conditions for making the particleboard were found to involve steaming for 46 min at a temperature of 120˚C before it was compressed using a pressure of 12 MPa, at a temperature 215 ˚C for 29 min. The internal bond (IB) strength, modulus of rupture (MOR), thickness swelling (TS), and water absorption (WA) were 0.54 MPa, 8.18 MPa, 22%, and 51%, respectively. The residual values of actual and model-based calculated IB, MOR, TS, and WA were found to be 0.1 MPa, 0.23 MPa, 2%, and 4%, respectively, which shows the significance of the study.
  • Researchpp 1697-1708González, I., Alcalá, M., Arbat, G., Vilaseca, F., and Mutjè, P. (2013). "Suitability of rapeseed chemithermomechanical pulp as raw material in papermaking," BioRes. 8(2), 1697-1708.AbstractPDF
    The use of chemithermomechanical (CTMP) pulp from rapeseed residues as raw material for the manufacturing of linerboard and fluting medium grades was investigated. For this purpose, different alternatives for improving mechanical and optical properties of rapeseed CTMP were studied, and the addition of nanofibrillated cellulose (NFC) was proposed to decrease the intensity of the beating process and enhance the final mechanical properties. Handsheets from each pulp were produced, and their properties compared to those of linerboard from recycled paper. Compared to kraft linerboard from recycled paper, rapeseed CTMP required less beating to reach an optimal breaking length. This reduction in beating can be combined with the addition of NFC to improve the mechanical properties of paper. Therefore, rapeseed CTMP from crop residues is a technically affordable alternative for the production of fluting and linerboard grades.
  • Researchpp 1709-1717Akgül, M., Korkut, S., Çamlıbel, O., and Ayata, Ü. (2013). "Some chemical properties of luffa and its suitability for medium density fiberboard (MDF) production," BioRes. 8(2), 1709-1717.AbstractPDF
    This study was conducted to evaluate suitability of luffa (Luffa cylindrica) fiber for medium density fiberboard (MDF) production. For the experiment, luffa and commercially manufactured fibers (Pinus sylvestris (30%), Fagus orientalis Lipsky (35%) and Quercus robur L. (35%)) with 11% moisture content were used. Luffa was mixed with commercially manufactured fibers in the following fashion: a layer of luffa fiber (30 g) placed in the middle of the mat, two equidistantly placed layers (60 g) in the mat, three layers (90 g) instead of two in the mat, and homogenously (90 g) dispersed without a district pattern in the mat, respectively. In panel production the only variable tested was the addition of luffa fiber at various weights to the wood fibers. Commercial urea formaldehyde (UF) adhesive was used as a binder. Chemical properties, including holo-, α-cellulose, and contents, alcohol-benzene solubility in dilute alkali (1% NaOH), and hot and cold water solubility, were determined. In addition, some physical and mechanical properties, such as density, thickness swelling (TS), bending strength (BS), modulus of elasticity (MOE), and internal bond (IB) of the panel of MDF were also measured. The chemical composition and solubility of luffa were found to be similar to those of nonwoods in general. Thus, the results suggest that luffa (Luffa cylindrica Mill.) fiber can be used as an alternative raw material for MDF manufacturing.
  • Researchpp 1718-1730Todaro, L., Dichicco, P., Moretti, N., and D’Auria, M. (2013). "Effect of combined steam and heat treatments on extractives and lignin in sapwood and heartwood of turkey oak (Quercus cerris L.) wood," BioRes. 8(2), 1718-1730.AbstractPDF
    Combined treatment with steam and heat was imposed on green Turkey oak (Quercus cerris L.) wood, both for sapwood and heartwood. Steaming was carried out in an autoclave at 100, 120, or 130 °C, and then a portion of the samples was heated in an oven for 2 h at 120 or 180 °C. Extraction with ethanol provided the greatest extractive contents in sapwood, and the extractive quantity decreased as the heating temperature was increased to 180 °C. In contrast, extraction with dichloromethane provided the greatest extractive content in heartwood, and no sizeable differences were found among the various treatments. Lignin amounts increased with rising treatment temperatures combined with steaming at 100 and 120 °C until the greatest value of 31.1% lignin content was reached. However, the lignin content decreased as the steaming temperatures rose to 130 °C. In all the combined treatments, the lignin content was greater in heartwood than in sapwood. Moreover, both steaming and heating applied individually produced no significant effect on lignin content.
  • Researchpp 1731-1746Pánek, M., Reinprecht, L., and Mamoňová, M. (2013). "Trichoderma viride for improving spruce wood impregnability," BioRes. 8(2), 1731-1746.AbstractPDF
    Impregnability of poles and other products made from spruce or fir wood decreases after the closing of toruses in the pits of tracheids, which usually occurs after their drying up to the fiber saturation point. With the aim of reopening access to the pits in the tracheids, the microscopic fungus Trichoderma viride was used for the enzymatic degradation of the pits in Norway spruce. During the summer, freshly cut and debarked spruce bolts were exposed in an inoculation mycelium of T. viride for 1, 3, 6, and 9 weeks under exterior conditions. Very good permeability and impregnability of spruce sapwood was observed after 1 or 3 weeks with no apparent change in its mechanical properties (Modulus of Rupture, Impact Bending Strength). On the other hand, previously closed pits of spruce heartwood remained unchanged in all experiments. Generally, coming out from achieved results and knowledge of other researches, bio-treatments of conifers are suitable for improving the impregnability of poles and other rounded timber products with the sapwood zone intact. However, bio-treatments for squared timbers with visible heartwood are usually a less appropriate.
  • Researchpp 1747-1757Lepikson-Neto, J., Alves, A., Simões, R., Deckmann, A. C., Camargo, E. L. O., Salazar, M. M., Rio, M. C. S., do Nascimento, L. C., Pereira, G. A. G., and Rodrigues, J. C. (2013). "Flavonoid supplementation reduces the extractive content and increases the syringyl/guaiacyl ratio in Eucalyptus grandis x Eucalyptus urophylla hybrid trees," BioRes. 8(2), 1747-1757.AbstractPDF
    The Eucalyptus genus plays an important role in the worldwide forest industry, with highly productive plantations supplying high-quality raw material for pulp and paper, wood, and biomass that would otherwise come from native forests. Lignin and extractives are important components for wood structure and protection but they are disruptive elements with respect to some industrial processes involving paper, pulp, and biomass production. This work evaluated effects of supplementation of flavonoids on the wood composition of Eucalyptus grandis x Eucalyptus urophylla (E. urograndis), a commercial hybrid. The wood samples were analyzed for extractives and lignin contents by wet chemical analysis, and the composition of lignin monomers and the carbohydrate hexosan/pentosan ratio were determined by analytical pyrolysis. The results showed that supplementation with the flavonoids naringenin and naringenin-chalcone led to an overall reduction of the extractive content and altered the monomeric composition of lignins towards a higher syringyl content. Thus, the treatment of Eucalyptus with flavonoids results in the improvement of wood quality for technological purposes.
  • Researchpp 1758-1770Abdul Razak, M. N., Ibrahim, M. F., Yee, P. L., Hassan, M. A., and Abd-Aziz, S. (2013). "Statistical optimization of biobutanol production from oil palm decanter cake hydrolysate by Clostridium acetobutylicum ATCC 824," BioRes. 8(2), 1758-1770.AbstractPDF
    Oil palm decanter cake (OPDC) is a potential lignocellulosic biomass for the biofuel industry. The fermentation conditions for biobutanol production using glucose from OPDC hydrolysate by Clostridium acetobutylicum ATCC 824 were optimized via response surface methodology (RSM). An analysis of variance (ANOVA) using 2–level factorial was successfully screened. Three significant variables were found to influence the biobutanol yield: glucose concentrations in the OPDC hydrolysate, inoculum sizes, and initial pH. The concentration of yeast extract, however, showed an insignificant effect in this study. The batch fermentation was analyzed using central composite design (CCD), and it yielded significant variables and the predicted optimum conditions were 70.00 g/L of OPDC hydrolysate, 16.20% of inoculum size, and an initial pH of 5.20. The predicted yield of biobutanol was 0.09 g/g using 70.00 g/L of glucose. The optimum conditions were validated, and the actual biobutanol yield was 0.11 g/g with 54.86 g/L of glucose consumption. The biobutanol production using synthetic glucose was 15.38% higher when compared to OPDC hydrolysate, but the utilization of OPDC as alternative substrate was still comparable with other findings.
  • Researchpp 1771-1789Yoshihara, H. (2013). "Mode II critical stress intensity factor of medium-density fiberboard measured by asymmetric four-point bending tests and analyses of kink crack formation," BioRes. 8(2), 1771-1789.AbstractPDF
    Using medium-density fiberboard specimens, asymmetric four-point bending tests were conducted to obtain the Mode II critical stress intensity factor for this in-plane system. Because the medium-density fiberboard is in-plane quasi-isotropic about its board plane, the crack propagates obliquely with respect to the initial crack direction under the asymmetric four-point loading condition. A finite element analysis is required to obtain the Mode II stress intensity factor. The analysis herein was conducted to take into account the kink crack formation. In addition, a three-point bend end-notched flexure test was also conducted, and the results obtained by the experiments and numerical calculations were compared. When the initial crack’s length-to-specimen’s depth ratio ranged from 0.85 to 0.95 and when the additional crack length was taken into account, the Mode II critical stress intensity factor KIIc was appropriately obtained by the asymmetric four-point bending test.
  • Researchpp 1790-1800Min, D.-Y., Smith, S. W., Chang, H.-M., and Jameel, H. (2013). "Influence of isolation condition on structure of milled wood lignin characterized by quantitative 13C nuclear magnetic resonance spectroscopy," BioRes. 8(2), 1790-1800.AbstractPDF
  • Researchpp 1801-1812Nayeri, M. D., Md Tahir, P., Harun, J., Abdullah, L. C., Bakar, E. S., Jawaid, M., and Namvar, F. (2013). "Effects of temperature and time on the morphology, pH, and buffering capacity of bast and core kenaf fibres," BioRes. 8(2), 1801-1812.AbstractPDF
    This study investigated the effects of heating on the morphology, pH, and buffering capacity of bast and core kenaf fibre. The bast material yielded longer and thinner fibres (with a higher aspect ratio) compared to the core. Changes in fibre morphology were clearly visible when the temperature of pulping was increased. The morphology of the bast fibre displayed significant variations following treatment at different pulping temperature (150, 160, 170, and 180 °C), time (1, 2, and 3 hours), and with the interaction between both parameters. Core fibre also exhibited significant variation in length, width, and wall thickness in all parameters, but lumen diameter and aspect ratio were not significantly affected by the same processing conditions. The pH value of both fibres was reduced as the temperature increased; core fibre was more acidic compared to bast fibre. Bast fibre exhibited greater acid buffering capacity and core fibre greater alkaline buffering capacity.
  • Researchpp 1813-1830Thilagavathy, P., and Santhi, T. (2013). "Sorption of toxic Cr(VI) from aqueous solutions by using treated Acacia nilotica leaf as adsorbent: Single and binary system," BioRes. 8(2), 1813-1830.AbstractPDF
    The use of cheap and eco-friendly adsorbents prepared from freely and abundantly available Acacia nilotica leaves for the removal of highly toxic Cr(VI) from aqueous solutions in single and binary ion solutions as well as from a mixture of it with Co(II) & Cu(II) was investigated by batch methods. The effects of pH, contact time, and initial metal ion concentration of Cr(VI) onto H2SO4-treated Acacia nilotica leaves (HAN) was investigated. The linear form of the Freundlich model achieved high coefficients of determination R2 = 0.9808 for Cr(VI) adsorption. The R2 values for fitting the adsorption rate data were greater than 0.983 for Cr(VI) ion, which indicates the applicability of pseudo-second-order kinetic model. The desorption and recycling ability of Cr(VI) and HAN were found to be good. The studies showed that this low-cost adsorbent could be used as an efficient adsorbent material for the removal of Cr(VI) from aqueous solutions.
  • Researchpp 1831-1840Kean, C. W., Sahu, J. N., and Wan Daud, W. M. A. (2013). "Hydrothermal gasification of palm shell biomass for synthesis of hydrogen fuel," BioRes. 8(2), 1831-1840.AbstractPDF
    Production of hydrogen has been widely practiced to produce a CO2-neutral green fuel that can substitute for fossil fuel. One of the alternative ways in producing such fuel is to utilize biomass by the hydrolysis process. In this study the effects of reaction times (10 to 70 min), reaction temperatures (180 to 260 °C ), and biomass to water mass ratio (1:1 to 1:9) were evaluated relative to the hydrolysis of palm shell particles in a low temperature (below 300 °C) hydrolysis process. Palm shell biomass was hydrolyzed in distilled water, and the gaseous products (bio-syn gas) generated were comprised of H2 and CO2, with small amounts of carbon monoxide and methane.
  • Researchpp 1841-1851Azizi, S., Ahmad, M., Mahdavi, M., and Abdolmohammadi, S. (2013). "Preparation, characterization, and antimicrobial activities of ZnO nanoparticles/cellulose nanocrystal nanocomposites," BioRes. 8(2), 1841-1851.AbstractPDF
    Zinc oxide (ZnO) nanoparticles were synthesized within cellulose nanocrystals (CNC) as a new stabilizer by a precipitation method for antimicrobial applications. For fabrication of ZnO/CNC nanocomposites, solutions with different molar ratios of Zn to CNC were prepared in ethanol as the solvent. ZnO/CNC was separated from the suspension and then dried at 120 °C for 1 hour. The nanocomposites were characterized using Fourier transform infrared (FTIR), ultraviolet-visible (UV-vis), X-ray diffraction (XRD), transmission electron microscope (TEM), and thermogravimetric (TG) analyses. According to the XRD and TEM results, the ZnO nanoparticles with a hexagonal wurtzite structure were easily prepared and dispersed in the CNC with an average size of less than 20 nm. The average size of the ZnO nanoparticles increased with increasing molar ratio of ZnO to CNC. The best ratio of Zn:CNC was chosen based on the small size of the ZnO nanoparticles that yielded better antimicrobial and thermal properties. The UV-vis absorption spectra of the ZnO/CNC nanocomposites showed absorption peaks in the UV region that were ascribed to the band gap of the ZnO nanoparticles. The antibacterial effects of ZnO/CNC were stronger compared to ZnO nanoparticles.
  • Researchpp 1852-1867Demirci, Z., Sönmez, A., and Budakçı, M. (2013). "Effect of thermal ageing on the gloss and the adhesion strength of the wood varnish layers," BioRes. 8(2), 1852-1867.AbstractPDF
    The present study investigated the effect of thermal ageing of several wood varnishes on film characteristics. For this purpose, alkyd, two-part polyurethane (urethane-alkyd), and water-borne (self-cross-linked polyurethane) varnishes were applied on Scots pine (Pinus sylvestris L.), Eastern beech (Fagus orientalis L.), and sessile oak (Quercus petraea L.). The test samples had 8% or 12% moisture content. The samples were then thermally aged for 25, 50, 75, and 100 days at 25, 50, 75, and 100°C. The decrease in adhesion strength of the varnish layers and the loss in surface gloss were determined in accordance with the ISO 4624 and ISO 2813 standards. The results of the study indicated that thermal ageing caused a decrease in the adhesion strength and gloss values.
  • Researchpp 1868-1880Li, Q., Steele, P. H., Mitchell, B., Ingram, L. L., and Yu, F. (2013). "The addition of water to extract maximum levoglucosan from the bio-oil produced via fast pyrolysis of pretreated loblolly pinewood," BioRes. 8(2), 1868-1880.AbstractPDF
    Levoglucosan is one of the major polar compounds that can be initially extracted into an aqueous fraction with water as the solvent. Levoglucosan can be hydrolyzed by an acid catalysis into monomeric sugars (primarily glucose), which can be further converted biochemically into alcohols or lipids, or converted catalytically into hydrogen. It has been demonstrated that the levoglucosan yield can be greatly increased if the proper pretreatment is applied to demineralize the feedstock prior to pyrolysis. In this study, bio-oil with a high levoglucosan concentration was produced via the fast pyrolysis of a dilute acid pretreated loblolly pine wood in an auger reactor. The water-to-bio-oil ratio, temperature, and time were selected as the three parameters to investigate the optimal condition for extracting the maximum amount of levoglucosan from the bio-oil. A response surface design (Box Behnken Design) was utilized to determine the direct and interactive effects of the three parameters on the extraction yield of the levoglucosan from the bio-oil. The optimal condition for the levoglucosan extraction was found to be 1.3:1 (water-to-bio-oil ratio), 25 oC, and 20 min, with a levoglucosan yield of 12.7 wt%.
  • Researchpp 1881-1892Nejad, M., Shafaghi, R., Ali, H., and Cooper, P. (2013). "Coating performance on oil-heat treated wood for flooring," BioRes. 8(2), 1881-1892.AbstractPDF
    Thermal modification of wood in a hot-oil bath is a green process, which improves wood properties using natural products. The process imparts a uniform brown color to the wood and increases its dimensional stability. The improved properties create value-added opportunities for some wood species to be used for high performance applications such as flooring products. This study focused on the optimization of the oil-heat-treatment process to find different approaches for saving energy and also evaluating the performance of water-based coatings on oil-heat treated wood. Effects of process variables on development of wood drying defects such as, checking, cupping, crooking, bowing, twisting, and grain raise were evaluated. This included investigation of effects of Initial wood moisture content and delayed cooling of treated wood in an oven or under a thermal blanket. Our results showed that wood can be treated at an initial moisture content around 8 to 10 percent and cooled in a blanket instead of in an oven without increasing wood defects. Testing the performance of four commercially formulated water-based coatings on heat-treated wood showed that the coatings had an overall better color retention, abrasion, and scratch resistance on the heat-treated wood than on the untreated wood. However, the adhesion of all of the coatings was lower on the heat-treated wood when compared with untreated wood samples.
  • Researchpp 1893-1908Rosli, N. A., Ahmad, I., and Abdullah, I. (2013). "Isolation and characterization of cellulose nanocrystals from Agave angustifolia fibre," BioRes. 8(2), 1893-1908.AbstractPDF
    Cellulose nanocrystals were extracted from Agave angustifolia fibres by alkali and bleaching treatments followed by acid hydrolysis. The chemical composition of the Agave fibres was determined at different stages of chemical treatment. The structural analysis was carried out by a Fourier Transform Infrared spectroscopy and X-ray diffraction. The morphology and thermal stability of the Agave fibres at different stages of chemical treatment were investigated by field emission scanning electron microscopy and thermogravimetric analysis, respectively. The results indicated that the hemicellulose and lignin were removed extensively from the extracted cellulose. The two peaks at 1735 cm-1 and 1247 cm-1, which were attributed to the C=O stretching and C-O out of plane stretching vibration of the hemicellulose and lignin in raw Agave, completely disappeared in the spectra of chemically treated fibres. The X-ray diffraction data showed enrichment in the portion of crystalline cellulose from 59% to 82% in the raw and cellulose nanocrystals, respectively. Thermogravimetric analysis showed that the thermal stability improved significantly by various chemical stages. The size reduction of the Agave cellulose into nano-sized particles from 7 µm to 8 nm in diameter by acid hydrolysis was confirmed with transmission electron microscopy images.
  • Researchpp 1909-1917Vaysi, R., and Kord, B. (2013). "The effects of H2O2 bleaching and DTPA spraying on the brightness stability of hornbeam CMP pulp following accelerated irradiation aging," BioRes. 8(2), 1909-1917.AbstractPDF
    In this research, hornbeam chips were cooked under chemimechanical pulp (CMP) conditions, and the pulps were prepared at a yield level of 85%. The CMP pulps were separately bleached with hydrogen peroxide and sodium dithionite with and without treatment with DTPA. Then 60 gr/m2 handsheets were made. The goal was to determine whether complementary bleaching with sodium dithionite improves optical behavior of the handsheets. Following DTPA solution spraying on the surface of hand sheets, brightness, opacity, and yellowness were improved, and the K/S ratio and PC number were decreased. Among different samples and following optical aging, it was found that in long-term aging, DTPA spray has considerable effect on improving the stability of brightness and increasing the paper’s durability against optical deterioration.
  • Researchpp 1918-1932Ambjörnsson, H. A., Schenzel, K., and Germgård, U. (2013). "Carboxymethyl cellulose produced at different mercerization conditions and characterized by NIR FT Raman spectroscopy in combination with multivariate analytical methods," BioRes. 8(2), 1918-1932.AbstractPDF
    Carboxymethyl cellulose (CMC) is produced commercially in a two-stage process consisting of a mercerization stage followed by an etherification stage. In this work, extended mercerization stages were used when producing CMC from a spruce dissolving pulp. Near infra-red (NIR) Fourier transform (FT) Raman spectroscopy was used to analyse the molecular structures of the CMC and the gel fractions formed in the CMC preparation. Three different CMC groups were obtained, representing backbone structures of cellulose I, cellulose II, and amorphous cellulose. By applying principal component analyses (PCA) to the spectral data, two CMC classes were identified with different degrees of substitution (DS). Thus, a low degree of substitution was obtained in the CMC if the alkaline concentration in the mercerization stage was only 9.0%, and the backbone structure was cellulose I or II. However, if the alkaline concentration was higher (18.25% or 27.5%), then the degree of substitution in the CMC was also higher, and the backbone structure was more amorphous.
  • Researchpp 1933-1945Lin, C.-H., Yang, T.-H., Lai, W.-J., and Lin, F.-C. (2013). "Anisotropic physical and mechanical performance of PF-impregnated oriented strand board," BioRes. 8(2), 1933-1945.AbstractPDF
    This study investigated several key mechanical and physical properties of oriented strand board (OSB) made from China fir strands impregnated with phenol-formaldehyde (PF) resin. Results showed that accumulated percentages of strand alignment angles between strand length direction and mechanical alignment direction on OSB face and bottom layer were within 0° and 30° vs. 88.2% and 76.2%, respectively. Ultrasonic velocity at 0° strand angle (V0) was the highest, decreasing rapidly with increasing aligned angle (θ). The lowest ultrasonic velocity was found at 90° of strand’s angle (V90). The relationship between θ and V could be represented by Hankinson's formula, where the optimal n exponential values were between 1.59 and 1.88. The anisotropic properties of the OSBs, defined as the ratio of V0/V90, were 2.23 to 2.45 for the bending specimens. The ratios of MORp/MORv and MOEp/MOEv were 3.79 to 4.15 and 4.18 to 5.42, respectively. Effects of PF-impregnation on the bending properties showed superior performance. The parallel bending strength (MORp) was 64.7 to 84.8 MPa and the MOEp was 13.0 to 15.9 GPa, respectively. After accelerated deterioration testing, the retention rates of MORp and MOEp (%) were 78.3% to 88.2% and 68.0 to 83.1%, respectively. Further, the dimensional stability of PF-impregnated OSB showed good performance in thickness swelling (TS) and linear expansion (LE).
  • Researchpp 1946-1962Xu, J.-K., Sun, Y.-C., Xu, F., and Sun, R.-C. (2013). "Characterization of hemicelluloses obtained from partially delignified Eucalyptus using ionic liquid pretreatment," BioRes. 8(2), 1946-1962.AbstractPDF
    Lignocellulosic biomass is a relatively inexpensive and abundant feedstock for biofuel production. The key to unlocking the recalcitrance of lignocelluloses is an effective pretreatment process. A promising new pretreatment method for lignocellulosic biomass is the use of ionic liquids (ILs). In this study, wood flour was partially dissolved in the novel ionic liquid 1-butyl-3-methylimidazolium acesulfamate ([BMIM]Ace) mixed with different organic solvents (1,4-dioxane, acetone, methanol, DMSO, and DMF) followed by precipitation in water. Hemicelluloses were successfully extracted from the carbohydrate-enriched residues by an alkaline ethanol solvent. Sugar analysis of the hemicellulosic fractions indicated that xylose (63.25-74.85%) was the major sugar component, while small amounts of glucose (4.85-14.40%) and galactose (4.49-7.32%) were also observed. Molecular weights of these fractions varied between 49.330 and 60.760 g/mol as determined by GPC. NMR studies revealed that the hemicelluloses had a backbone of β-(1→4)-linked-D-xylopyranosyl units and were branched mainly through 4-O-methyl-α-D-glucuronic acid. The thermal degradation behavior of the hemicellulosic fractions showed that the most significant degradation occurred between 242 and 300 °C.
  • Researchpp 1963-1975Zhang, Y., Tong, D., and Song, K. (2013). "A comparative analysis on the longitudinal compression characteristics of juvenile and mature northeast Chinese ash (Fraxinus mandshurica Rupr.) subjected to alkaline treatment," BioRes. 8(2), 1963-1975.AbstractPDF
    Longitudinal compression can help wood form some folds on the wood cell walls after a suitable softening procedure. These folds can enhance the one- and multi-dimensional bending performances of wood. The longitudinal compression properties of alkali-treated juvenile and mature northeast Chinese ash (Fraxinus mandshurica Rupr.) were analyzed. Elastic and elastic-plastic stages were inferred from the longitudinal compression curves. Scanning electron microscopy images showed that some folds formed in the wood cell wall vessels and fibers. X-ray microdensitometer test results showed a decrease in the fluctuation of the wood cell wall density of the specimens. The swelling and degradation or extraction of hemicellulose, lignin, and extractive occurred after alkaline treatment. Slippage between cellulose chains and curving within a cellulose chain were inferred during longitudinal compression. Juvenile wood specimens had higher modulus of elasticity and larger variability than mature wood after alkaline treatment. This finding can be attributed to the higher extent of degradation or extraction of hemicelluloses, lignin, and extractive, as well as the smaller microfibril angle and the similar cellulose crystallinity of treated juvenile wood compared to those of mature wood specimens after alkaline treatment.
  • Researchpp 1976-1985Sapci, Z., Morken, J., and Linjordet, R. (2013). "An investigation of the enhancement of biogas yields from lignocellulosic material using two pretreatment methods: Microwave irradiation and steam explosion," BioRes. 8(2), 1976-1985.AbstractPDF
    Two pretreatment methods, microwave irradiation and steam explosion, were investigated in this work. The aim of the study was to investigate whether these methods would improve the biodegradability of wheat straw as a lignocellulosic feedstock. Microwave pretreatment was carried out on milled straw with an irradiation time of 15 minutes, at a temperature of either 200 or 300 °C in the oven. The steam explosion pretreatment was carried out on milled straw at 210 °C for 10 minutes. To determine the methane production potential, anaerobic digestion batch trials were run under mesophilic conditions for 60 days. The methane yields of the microwave-pretreated straw decreased by 65% for an attained temperature of 200 °C and by 92% for 300 °C. After steam explosion pretreatment, however, the methane yields of the straw increased by approximately 20% when compared to untreated straw samples. These results indicate that microwaving does not optimize methane production from wheat straw, while steam explosion yields positive results.
  • Researchpp 1986-1996Wang, X., Deng, Y., Wang, S., Liao, C., Meng, Y., and Pham, T. (2013). "Nanoscale characterization of reed stalk fiber cell walls," BioRes. 8(2), 1986-1996.AbstractPDF
    Reed (Phragmites australis) is a natural biological material that has great potential as reinforcing material in bio-composites. In order to evaluate the potential of reed stalk for reinforcement, the microstructure, elemental composition, microfibril angle (MFA), and mechanical properties of fiber cell walls were investigated by means of scanning probe microscopy (SPM), energy dispersive analysis of X-rays (EDAX), X-ray diffraction (XRD), and nanoindentation, respectively. The effects of elemental composition and microfibril angle of reed fibers on the mechanical properties were also considered. The results indicated that reed fiber cells have a multilayered structure. The observed increase in lignin content and decrease in MFA may contribute to the increase of mechanical properties. The elastic modulus and hardness of fibers in the upper part of the reed stalk were higher than those of the lower part. Based on nanoindentation results found in the literature, reed fibers have higher elastic modulus and hardness than poplar and spruce fibers.
  • Researchpp 1997-2009Landry, V., Blanchet, P., and Cormier, L. M. (2013). "Water-based and solvent-based stains: Impact on the grain raising in yellow birch," BioRes. 8(2), 1997-2009.AbstractPDF
    Water-based finishes are slowly replacing solvent-based finishes in the wood industry. Wood grain raising is an important issue associated with the use of water-based stains. In this paper, water-based and solvent-based stains were applied on yellow birch veneers and hardwood samples that had been previously sanded. Grain raising phenomena were studied by profilometry and microscopy. This study demonstrated that the appearance of wood surfaces treated with water-based and solvent-based stains is affected by a number of factors, including grain raising, surface preparation quality, and substrate type. Main observations are: 1) the sanding method has an important role in the grain raising generation and finish quality; 2) profilometry experiments revealed that developed interfacial area parameter can provide valuable information, as it captures both grain roughness and small-scale roughness due to raised fiber fragments; 3) differences between sawn lumber and peeled veneer appeared minor, although the lumber exhibited less significant differences between water-based and solvent-based finishing systems; and 4) wood fragments on the wood surface would be difficult to eliminate.
  • Researchpp 2010-2017Ng, S. H., Tahir, P. M., Mohamad, R., Abdullah, L. C., Choo, A. C. Y., and Liong, Y. Y. (2013). "Effect of pretreatment process on bioconversion of kenaf (Hibiscus cannabinus L.) core to glucose," BioRes. 8(2), 2010-2017.AbstractPDF
    Kenaf (Hibiscus cannabinus L.) is a renewable carbon-rich lignocellulosic resource for fermentable sugars. In this study, kenaf cores cultivar V36 from four-month-old stems were pretreated by i) physical, ii) physical and thermal, and iii) physical and chemical methods. The celluloses of pretreated kenaf core particles were then hydrolyzed into fermentable sugars by cellulase from Trichoderma reesei (C2730). The pretreated kenaf core particles were incubated for 48 h at 37 °C. The efficiency of bioconversion was mainly dependent on the pretreatments applied prior to the hydrolysis process. The effects of the pretreatments on kenaf core’s lignin, holocellulose, and cellulose contents were also determined. Kenaf cores without pretreatment had 19.4% lignin, 86.2% holocellulose, and 47.4% alpha-cellulose. The combination of physical and chemical pretreatment on kenaf cores cultivar V36 resulted in a higher cellulose content (92.49%) and produced 50 times higher sugar concentration than the physical pretreatment.
  • Researchpp 2018-2032Zhang, Z., Li, J., Feng, F., Liu, D., Pang, Q., Li, M., and Chen, K. (2013). "Optimization of nutrition constituents for xylanase activity by Rhizopus stolonifer under solid-state fermentation on corncob," BioRes. 8(2), 2018-2032.AbstractPDF
    This study aims to optimize the medium for xylanase activity by a newly isolated strain of Rhizopus stoloniferJS-1008 (R. stolonifer JS-1008) under solid-state fermentation (SSF) on corncob. Four quantitative variables impacting the enzyme activity were selected through one-factor-at-a-time design. They were nitrogen source, initial moisture content (IMC), inorganic salt, and surface active agent. In addition, the interaction among these factors was further investigated by response surface methodology (RSM). Statistical analysis revealed that among these factors, IMC and urea significantly affected the xylanase activity. Our data indicate that the optimal medium contains (g/g dry corncob): urea, 0.15; ZnSO4, 0.022; Tween-80, 0.08; IMC, 3. Under the optimal condition, the xylanase activity reached its maximum, 13.90 U/g dry substrate (DS), on the 10th day of fermentation. This work provides a new potential strain to synthesize xylanase for biofuel production.
  • Researchpp 2033-2046Moya, R., Tenorio, C., and Bond, B. (2013). "Energy balance for three lignocellulosic residues using different drying techniques," BioRes. 8(2), 2033-2046.AbstractPDF
    The main goal of this research was to establish the energy balance from the drying of oil palm empty fruit bunches (EFB), pineapple plant leaves (PL), and sawdust from Gmelina arborea (GAD). Three drying techniques (air, solar, and hot air drying) were tested. The initial moisture content (MCi), drying time, moisture content (MC) variation with time, transformation energy, transportation and drying energy, drying critical point, and the energy balance were measured. MCi was higher for PL (over 79%), followed by EFB (over 47%), and GAD (under 47%). Drying time varied from 27 to 342 hours depending on the technique used. PL presented the longest drying time, followed by GAD, and finally EFB. The transformation energy input was only applied to PL, and the values ranged from 0.041 to 0.09 kWh/kg. Energy used for transportation ranged from 0.051 to 0.090 kWh/kg. Energy consumption ranged from 0.20 to 1.90 kWh/kg, and its mathematical model regarding MC was β1MC3+β2MC2+β3MC+β4 (polynomial) or β1ln (MC) +β2 (logarithmic). A critical value of MC was found, where an inflection of energy consumption occurs during the drying process for all residues. The critical MC for GAD was 10%. For EFB it varied from 11 to 13%. For PL it varied from 4% to 13%. The best energy balance was obtained for GAD and EFB (4.0 to 4.5 kWh/kg) when MC was less than 10%. The best energy balance for PL was obtained when MC varied from 30 to 40%.
  • Researchpp 2047-2063Conde, E., Fang, W., Hemming, J., Willför, S., Moure, A., Domínguez, H., and Parajó, J. C. (2013). "Water-soluble components of Pinus pinaster wood," BioRes. 8(2), 2047-2063.AbstractPDF
    Aqueous fractionation of wood has been proposed as a suitable processing method for biorefineries. When treatments are performed under low severity conditions, water-soluble components (which could be detrimental in further processing stages) are removed, whereas polysaccharides, lignin, and other water-insoluble constituents remain in solid phase with little alteration. In order to explore the presence of added-value products in aqueous extracts from Pinus pinaster wood, different samples (heartwood and sapwood with and without knots) were extracted with water at 130 to 140 ºC, and the resulting solutions were assayed for yield and composition (by GC-FID, GC-MS, and HPLC). The major extract components, such as polysaccharide-derived products, simple phenolics, stilbenes, lignans, flavonoids, organic acids, jubaviones, steryl esters, and triglycerides, were identified and quantified. In order to assess a possible application of the extracts, their antioxidant activity was measured using the Trolox Equivalent Antioxidant Capacity assay.
  • Researchpp 2064-2073Luo, S., Cao, J., and Wang, X. (2013). "Investigation of the interfacial compatibility of PEG and thermally modified wood flour/polypropylene composites using the stress relaxation approach," BioRes. 8(2), 2064-2073.AbstractPDF
    Stress relaxation has been proven to be a good measure for studying the interaction between the constituents in wood flour/polymer composites by evaluating the internal bonding quantitatively. In order to investigate the combination effect of polyethylene glycol (PEG) impregnation and heat treatment on the interfacial compatibility of wood flour/polypropylene composites, the stress relaxation of PEG and/or thermally modified wood flour/polypropylene composites was determined at three temperatures (26, 40, and 60 °C). The apparent activation energy (DE) was also calculated according to Eyring’s absolute rate reaction theory. The results showed that PEG treatment accelerated the stress relaxation rate of the composites and decreased the DE. However, heat treatment resulted in an alleviation of the increasing rate of stress relaxation caused by PEG modification and an increase in the DE of the composites. These results suggested that PEG treatment had a negative effect on the interfacial compatibility between wood flour and polypropylene in the composites, and heat treatment could compensate for this effect to a certain extent.
  • Researchpp 2074-2083Németh, R., Ott, Á., Takáts, P., and Bak, M. (2013). "The effect of moisture content and drying temperature on the colour of two poplars and Robinia wood," BioRes. 8(2), 2074-2083.AbstractPDF
    The colour change of wood has been the topic of numerous research activities worldwide. This study investigates the colour change of Robinia (Robinia pseudoacacia L.) and two hybrid poplars, namely Pannónia poplar (Populus x euramericana cv. Pannónia) and I-214 poplar (Populus x euramericana cv. I-214). The sapwood and heartwood were investigated separately for each of the poplars. The heartwood of Robinia was also investigated. The timbers were dried in a climate chamber at four different temperatures (20 °C, 40 °C, 60 °C, and 80 °C), as the relative humidity was reduced in 5 steps (95%, 80%, 65%, 40%, and 20%) at each temperature. The colour co-ordinates L*, a*, and b* were measured according to the CIELab system. Differences in terms of colour change between wood species and sapwood versus heartwood are discussed in the paper. The effect of wood moisture content and heat on the colour co-ordinates is provided. The colour of Robinia is more sensitive to heat than poplar.
  • Researchpp 2084-2098Temiz, A., Akbas, S., Panov, D., Terziev, N., Alma, M. H., Parlak, S., and Kose, G. (2013). "Chemical composition and efficiency of bio-oil obtained from giant cane (Arundo donax L.) as a wood preservative," BioRes. 8(2), 2084-2098.AbstractPDF
    This study aimed at determining the chemical composition of bio-oil from giant cane (Arundo donax L.), as well as its performance as a wood preservative. The performance was determined through water absorption, tangential swelling, and resistance to fungi and termites. Bio-oil was obtained by pyrolysis at 450 to 525 ºC. The yield of liquid, char, and gas was determined to be 45, 30, and 25%, respectively. The most abundant chemical compounds found in the bio-oil were acids, ketones, furans, benzenes, phenols, sugars, and guaiacols. Scots pine sapwood was impregnated with the obtained bio-oil at concentrations of 10 and 20%. Additionally, treated samples were impregnated with epoxidized linseed oil to study its effect on bio-oil leachability. The retention of the giant cane bio-oil was in the range of 50 to 100 kg m-3. Leached samples were exposed to white- and brown-rot fungi, according to European standard EN 113. Wood impregnated with only cane oil demonstrated a durability that classifies the treatment as very effective (mass loss less than 3%). Epoxidized linseed oil treatment significantly reduced water absorption of the treated samples with bio-oil and further improved the durability. A termite test showed that bio-oil was also effective against Reticulitermes flavipes.
  • Researchpp 2099-2117Brodin, F. W., Sonavane, Y., and Theliander, H. (2013). "Preparation of absorbent foam based on softwood kraft pulp: Advancing from gram to kilogram scale," BioRes. 8(2), 2099-2117.AbstractPDF
    Absorbent foams were produced at both the gram scale and the kilogram scale by treating bleached softwood kraft pulp fibers to TEMPO oxidation, followed by washing, fiber disintegration, and freeze drying. Two reaction temperatures and three different dosages of primary oxidant were evaluated to find suitable oxidation conditions. It was found that the absorption and retention capacities were 50 to 70% lower for kilogram-scale foams than for gram-scale foams. SEM studies showed that the kilogram-scale foams had larger pores than the gram-scale foams; this explains the major differences in absorption and retention. The oxidation treatments performed in both scales resulted in a major increase in the amount of carboxylate groups and a major decrease in DPV, but only minor differences in these factors were found in a comparison between pulps from gram- and kilogram-scale experiments. However, the kilogram-scale dispersing equipment appeared to cause more fiber cutting, while the equipment used in the gram-scale experiments promoted the liberation of microfibrils to a greater extent. Furthermore, in both the gram- and kilogram-scale samples, a high dosage of primary oxidant and a low oxidation temperature were found to maximize the retention of liquid.
  • Researchpp 2118-2134Bigand, V., Pinel, C., Da Silva Perez, D., Rataboul, F., Petit-Conil, M., and Huber, P. (2013). "Influence of liquid or solid phase preparation of cationic hemicelluloses on physical properties of paper," BioRes. 8(2), 2118-2134.AbstractPDF
    Cationizations of galactomannan- and xylan-type hemicelluloses were performed in a solid state, with 2,3-epoxypropyltrimethylammonium chloride (ETA) as the cationic reagent under alkaline conditions. By this method, the reaction efficiency was significantly increased for all hemicellulose types, up to 90% in the case of xylan. The consumption of reagents was reduced by a factor of ten when compared to the reaction in liquid phase, while comparable values of the degree of substitution (DS) were obtained. By reducing the number of purification steps, the consumption of solvents was limited, and high mass yields were preserved. By all aspects, this method constitutes an economical and environmental gain for the cationization reaction of hemicelluloses. Native hemicelluloses and their cationic derivatives were tested as additives to the pulp slurry in order to increase the dry strength of the paper formed. The cationization of hemicelluloses had a beneficial effect on the mechanical properties of paper, with a supplementary gain of properties compared to the unmodified polysaccharides. Cationic derivatives of a DS 0.3 gave the best results for both polysaccharides, with the galactomannan-type being more efficient than the xylan-type with a 90% increase of the burst index.
  • Researchpp 2135-2144Liu, Z., Liu, Y., and Shen, J. (2013). "Influence of the vibrational properties of the resonance board on the acoustical quality of a piano," BioRes. 8(2), 2135-2144.AbstractPDF
    The vibrational properties of eight resonance boards made from Picea glehnii, Picea jezoensis, Picea spinulosa, and Picea sitchensis were analyzed. The modulus of elasticity and the vibration transmission velocity of the resonance board, the modulus of elasticity of the beam samples cut from the edge of the resonance board, and the vibration response time of the soundboard (TL, TR: times for the longitudinal and radial directions, respectively) were calculated. After the resonance boards were incorporated into the pianos, the sound intensity of loud (LL) and soft playing (LS), sound length (S), and the dynamic range of volume (Vd) were measured. Then the influence of the vibrational properties of the resonance board on the acoustical quality of a piano was investigated preliminarily, and the results showed that the acoustical quality would improve notably with improvements in the vibrational properties in the y-direction of the resonance board, and that the TR affected acoustical quality more obviously than did TL.
  • Researchpp 2145-2160Gao, J., Kong, D., Wang, Y., Wu, J., Sun, S., and Xu, P. (2013). "Production of mesoporous activated carbon from tea fruit peel residues and its evaluation of methylene blue removal from aqueous solutions," BioRes. 8(2), 2145-2160.AbstractPDF
    Removal of methylene blue by activated carbon produced from tea fruit peel (Camellia sinensis L.) residue using agents ZnCl2 (AC-1) and H3PO4 (AC-2) was investigated in this work. Mesoporous activated carbons with desirable surface areas and total pore volumes were obtained. Meanwhile, the characteristics of the activated carbon were examined. The effects of solution pH (2 to 10), contact time (0 to 480 min), and adsorbate dosage (0.5 to 3.5 g L-1) were studied. Equilibrium adsorption data were found to be in good agreement with the Langmuir isotherm model. The maximum monolayer adsorption capacities of methylene blue onto activated carbons were 291.5 and 342.5 mg g-1 for AC-1 and AC-2, respectively. The intraparticle diffusion model indicated that intraparticle diffusion was not the sole rate-determining step. The results demonstrated that the easily available tea fruit peel activated carbon is an excellent adsorbent for the removal of methylene blue from aqueous solutions.
  • Researchpp 2161-2172Nazir, M. S., Wahjoedi, B. A., Yussof, A. W., and Abdullah, M. A. (2013). "Eco-friendly extraction and characterization of cellulose from oil palm empty fruit bunches," BioRes. 8(2), 2161-2172.AbstractPDF
    Cellulosic fibers in Oil Palm Empty Fruit Bunches (OPEFB) are tightly packed with lignin, hemicelluloses, small depositions of wax, and inorganic elements. In the present work, eco-friendly reagents with low concentrations of 20% (v/v) formic acid and 10% (v/v) of 30% hydrogen peroxide were employed at 85 ºC for the extraction of cellulose from OPEFB. The yield of 64% (w/w) achieved was among the highest ever reported. Based on the XRD, the alpha-cellulose content was 93.7% with a high crystallinity of 69.9%. The average diameter was 13.5 μm with structural evidence of separated fibrils as investigated by FESEM. The TEM analysis suggested that the material was crystalline and its geometry was a monoclinic structure. The FTIR spectral peaks representing wax and hemicelluloses at 1735 cm-1 and 1375 cm-1, respectively, and lignin at 1248 cm-1 and 1037 cm-1, were not observed in the extracted OPEFB-cellulose spectra. Based on the TGA results, thermal stability at 325 ºC with a single degradation curve suggests the purity of OPEFB-cellulose.
  • Researchpp 2173-2185Cheng, F., Li, Y., and Chen, D. (2013). "Energy consumption and morphological development of eucalyptus alkaline peroxide mechanical pulp by carboxymethyl cellulose-assisted refining," BioRes. 8(2), 2173-2185.AbstractPDF
    Carboxymethyl cellulose (CMC)-assisted refining was shown, by means of tests with a PFI mill, to have potential to save energy compared with conventional refining techniques. Previously it was thought that the energy-saving effect of CMC-assisted refining was caused by resultant lubrication that reduced friction. In this work, the refined fiber of eucalyptus alkaline peroxide mechanical pulp was analyzed. The mechanism of CMC-assisted refining is that the cell wall is fibrillated to peel and weaken cell wall strength. Then CMC permeates into the cell wall and swells it, and the fiber becomes more pliable. CMC-assisted refining is helpful in maintaining fiber length through resultant hydration to avoid more fiber cutting. In this work, fiber morphological changes in the course of PFI refining for different numbers of revolutions were shown in relation to CMC-assisted refining. The purpose of the research was to determine whether energy savings could be achieved by CMC-assisted refining and to study its influence on fiber morphological development. The study showed a linear relationship between fiber length and energy consumption, as well as an exponential relationship between fines and fiber length. These results are helpful for obtaining ideal fiber morphology in pulp and paper making, man-made board, natural nano-fibers and specialty fibers, and the food industry.
  • Researchpp 2186-2194Wen, S., Liu, L., Nie, K. L., Deng, L., Tan, T. W., and Fang, W. (2013). "Enhanced fumaric acid production by fermentation of xylose using a modified strain of Rhizopus arrhizus," BioRes. 8(2), 2186-2194.AbstractPDF
    An enhanced, xylose-utilizing strain of Rhizopus arrhizus was successfully developed via modification using media with increasing concentrations of xylose. Xylose, a relatively cheap monosugar that can be easily obtained from corncobs, rice straw, and vinasse, was the sole carbon source used for both the seed culture phase and the fermentation process. After modification, this newly improved strain showed tremendous industrial potential for fumaric acid production using xylose. The fumaric acid production increased to 28.48 g/L (parental strain was 13.23 g/L) at 8% initial xylose, a carbon:nitrogen ratio of 200, and a residence time of 7 days. The volumetric productivity was 169.52 mg/L (78.75 mg/L) per hour.
  • Researchpp 2195-2208Winarni, I., Oikawa, C., Yamada, T., Igarashi, K., Koda, K., and Uraki, Y. (2013). "Improvement of enzymatic saccharification of unbleached cedar pulp with amphipathic lignin derivatives," BioRes. 8(2), 2195-2208.AbstractPDF
    Synthesized amphipathic lignin derivatives comprised of acidic acid lignin (AL) with poly(ethylene glycol) diglycidyl ether (PEGDE), ethoxy-(2-hydroxy)-propoxy-poly(ethylene glycol) glycidyl ether (EPEG) or dodecyloxy-poly(ethylene glycol) glycidyl ether (DAEO) were added before the enzymatic saccharification of unbleached cedar pulp along with two commercially available cellulases, Meicelase and Genencor GC220. At the same filter paper unit (FPU) dosage, GC220 showed higher sugar yield than Meicelase. The difference was attributed to the composition of processive and non-processive endoglucanase activities per FPU; GC220 had higher such activities than Meicelase. The sugar yield was significantly improved by the addition of the lignin derivatives. In addition, residual activities after the saccharification were maintained at the higher level by their addition than with polyethylene glycol (PEG) 4000. In particular, EPEG-AL yielded the complete recovery of cellulase activity when using 20 FPU/g of substrate. It was found that the lignin derivatives were directly associated with Cel6A, one of cellulase components, whereas PEG 4000 was not. Thus, it is evident that the lignin derivatives are promising agents to improve the enzymatic saccharification of cellulase.
  • Researchpp 2209-2221Ariño, R., Brodin, M., Boldizar, A., and Westman, G. (2013). "Thermal and viscoelastic properties of cellulosic gels with different ionic liquids and coagulation agents," BioRes. 8(2), 2209-2221.AbstractPDF
    Thermal and viscoelastic properties of three-component gels consisting of microcrystalline cellulose, ionic liquid, and coagulation agent were studied. The amount and type of components was varied to obtain different gel properties. The absorption of coagulation agent (13 to 35 %wt of water or ethanol) was found to depend on the types of ionic liquid and cellulose. Surface hydrophobization of cellulose prior to preparation of the gel remarkably resulted in the gels containing the most coagulation agent (35%wt). Rheological studies indicated a linear viscoelastic behavior in storage modulus but not in loss modulus, which is a behavior that, according to our knowledge, has not been seen before for gels. Increasing the cellulose concentration from 1:20 to 1:10 increased the stiffness of the gels. The highest critical stress value (1050 Pa) was obtained for a gel containing 1-butyl-3-methylimidazolium chloride and water. Finally, it was confirmed by dynamic-mechanical experiments that the gels had a cross-linked structure.
  • Researchpp 2222-2233Ma, J., Zhou, X., Zhang, X., and Xu, F. (2013). "Label-free in situ Raman analysis of opposite and tension wood in Populus nigra," BioRes. 8(2), 2222-2233.AbstractPDF
    Label-free in situ confocal Raman microscopy has been used to investigate the differences in cell morphology and components distribution between opposite wood (OW) and tension wood (TW) in Populus nigra. In the Raman images showing the ratio of the 1657 cm-1 to the 1603 cm-1 band, the spatial heterogeneity in coniferyl alcohol and coniferyl aldehyde (Lignin-CAA) was visualized within both samples. Enrichment of Lignin-CAA was visualized in the CC and CML regions where there was the highest lignin concentration. In fiber S2, which had the highest content of cellulose, there was apparent deficiency in the Lignin-CAA concentration. Raman spectra analysis revealed that the band at 1097.0 cm-1 in OW fiber S2 shifted to lower wavenumbers in TW fiber S2 (1094.4 cm-1) and GL (1094.0 cm-1), which resulted from the stretch of the glycosidic C-O-C bond of the cellulose molecular. The negative band shift at 1097 cm-1 indicated that the microfibrils in the TW fiber S2 and GL were stretched during TW formation and the microfibrils still kept the tensional deformation even after the fibers were transversally cut. The sub-cellular localization of cellulose and lignin together with the variation in molecular deformation will contribute to understanding the morphological and chemical properties of TW as a desirable woody biomass, as well as the development of its high tensile strength.
  • Researchpp 2234-2245Khosravani, A., and Rahmaninia, M. (2013). "The potential of nanosilica - cationic starch wet end system for applying higher filler content in fine paper," BioRes. 8(2), 2234-2245.AbstractPDF
    Multiple studies have considered the nanosilica-cationic starch system to be a retention/drainage aid; however its potential to improve strength has previously been neglected. This research focused on the effect of both nanosilica and cationic starch on certain crucial physical and mechanical properties of fine paper compared with a paper sheet containing no additives to evaluate how this system can compensate for using more filler in fine paper. In previous studies, it was suggested that the cationic starch-nanosilica system induces much tinier flocs and thus possibly results in better strength properties. In this respect, results revealed that cationic starch did, however, improve tensile index; this effect weakened at higher filler levels. Cationic starch and nanoparticles both improved internal bonding, while cationic starches’ effect was more prominent. With more filler, tear index suffered. Although addition of cationic starch partly compensated this negative effect with filled papers, nanoparticles did not seem to have an obvious effect. Therefore, cationic starch provided the limited potential of using more filler and nanoparticles may do it indirectly.
  • Researchpp 2246-2256Pereira, H. (2013). "Variability of the chemical composition of cork," BioRes. 8(2), 2246-2256.AbstractPDF
    The chemical composition of cork was determined, following a sampling that covered the whole production area in Portugal (29 provenances from six regions) with samples taken at cork stripping. To analyse between population variations, a more intensive sampling was made in two locations. The overall mean chemical composition of cork was: extractives 16.2% (dichloromethane 5.8%, ethanol 5.9%, water 4.5%), suberin 42.8% (long-chain lipids 41.0%, glycerol 3.8%), and lignin 22.0% (Klason 21.1%, acid soluble 0.9%). The suberin compositional ratio of long chain lipids to glycerol, LCLip:Gly, was 11.3. The proportion of neutral sugars in the polysaccharides was: glucose 46.1%, xylose 25.1%, arabinose 18.0%, mannose 3.0%, galactose 7.3%, and rhamnose 0.5%. The range of values was large and the variation between individual trees seemed to be the major factor of the differences. Geographical location of cork production was statistically significant only in a few cases when considering site and not when considering regions. The population variation in two sites was important and the absolute difference between the site mean values was small. This research covers the natural variability of cork’s chemical composition and discusses the contribution of the structural compounds to the variation of cork properties.
  • Researchpp 2257-2269Liu, X., Zhu, H., Qin, C., Zhou, J., Zhao, J. R., and Wang, S. (2013). "Adsorption of heavy metal ion from aqueous single metal solution by aminated epoxy-lignin," BioRes. 8(2), 2257-2269.AbstractPDF
    This study investigated the adsorption of the heavy-metal ions Cu(II) and Pb(II) onto a lignin derivative. The lignin derivative was obtained by treating bagasse soda lignin with epichlorohydrin, and subsequently grafting an amine functional group by the Mannich reaction. The morphology of aminated epoxy-lignin was a layered structure with pores characterized by SEM. The heavy-metal ion adsorption data could be described well with the pseudo-first order model for Pb(II) ion and the pseudo-second order model for Cu(II) ion; diffusion was found to be the rate-limiting step when approaching equilibrium. FTIR spectroscopy was used to study the mechanism of heavy-metal adsorption by the derivatized lignin. The results show that the sites for adsorption are related to hydroxyl and amido groups.
  • Researchpp 2270-2282Helander, M., Theliander, H., Lawoko, M., Henriksson, G., Zhang, L., and Lindström, M. E. (2013). "Fractionation of technical lignin: Molecular mass and pH effects," BioRes. 8(2), 2270-2282.AbstractPDF
    Today, lignin from kraft pulping is used mainly as fuel, with only very small amounts being used as raw material for chemicals and materials. This work focuses on using a convenient method for separating large amounts of low molecular weight lignin from the kraft process. Low molecular weight lignin contains larger amounts of phenolic structural units, which are possible modification sites and can be used as antioxidants. Moreover, a product that has reduced polydispersity, low molecular weight, and purified lignin could be a potential material for new applications. The studied process for separating lignin from weak black liquor used a membrane with a cut-off of 1000 Da. During precipitation of the 1000 Da permeate, it is necessary to prevent formation of fairly large, rigid particles/agglomerates of lignin by keeping the temperature low. To improve the dead-end filtration, higher ionic strength is needed for the weak black liquor. Additionally, reducing the end pH will cause more material to precipitate. More sulfur was found in the low molecular weight lignin and at lower precipitation pH, indicating that most sulfur left in the lignin samples might be bound to low molecular weight lignin.
  • Researchpp 2283-2299Huang, R., Kim, B.-J., Lee, S., Yang, Z., and Wu, Q. (2013). "Co-extruded wood-plastic composites with talc-filled shells: Morphology, mechanical, and thermal expansion performance," BioRes. 8(2), 2283-2299.AbstractPDF
    The effect of unmodified talc particles on the mechanical and thermal expansion performance of talc-filled high density polyethylene (HDPE) and co-extruded wood plastic composite (WPC) with talc-filled shells was studied. The use of talc in HDPE helped enhance its tensile, bending, and dynamic modulus, but lowered its tensile and impact strength. The selected models for composite modulus and tensile strength fit the data well after adjusting the model parameters. Talc-filled HDPE had lower linear coefficient of thermal expansion (LCTE) values in comparison with the neat HDPE values, and the LCTE reduction rate increased after the talc loading levels increased above the 30 wt%. Extruding a relatively thick, less-stiff HDPE shell with a large LCTE value over a stiff and thermally stable WPC core decreased overall composite modulus and increased the LCTE values. The composite modulus and strength increased and LCTE values decreased with increase of the talc loading levels in the shell. The impact strength of co-extruded WPC was greatly enhanced with unfilled- and filled HDPE shells.
  • Researchpp 2300-2309Li, T., Huang, B., Wang, S., Chen, C., Tang, L., Lu, Q., and Lin, W. (2013). "Covalent grafting of organic molecules onto activated carbon by a single step," BioRes. 8(2), 2300-2309.AbstractPDF
    Activated carbon appended with organic groups was obtained by a grafting technique using a one-step reaction with diazonium salts. Using the organic aryl amines of 4-bromo aniline and 4-aminoantipyrine as precursors for the corresponding functional diazonium reagents, the bromobenzene and antipyrine molecules were bonded to the surface of carbon. The modified activated carbon was characterized by Fourier transform infrared spectroscopy, X-ray and photoelectron spectroscopy, and BET methods. The results provided evidence of covalent grafting of the organic groups onto the activated carbon by aryldiazonium cations. The present method may provide a convenient and efficient procedure for the preparation of various functionalized activated carbons by means of a single step process.
  • Researchpp 2310-2324Salim, N., Hashim, R., Sulaiman, O., Nordin, N. A., Ibrahim, M., Akil, H. M., Sato, M., Sugimoto, T., and Hiziroglu, S. (2013). "Effect of steaming on some properties of compressed oil palm trunk lumber," BioRes. 8(2), 2310-2324.AbstractPDF
    Compressed lumber is considered to be a superior structural material due to its uniform properties and higher strength than other solid timbers. This study presents the effect of steaming on some properties of compressed lumber of oil palm (Elaeis guineensis) trunks (OPT). The specimens were steamed at a temperature of 130 ⁰C for 2 hours before being compressed in a hot press and evaluated for their physical and mechanical properties. Compressed OPT without steaming was used as a comparison sample to compare the effect of steaming on compressed OPT. The average modulus of rupture of steamed compressed OPT samples was 31.36 MPa, which was 8.7% higher than the compressed OPT without steaming samples. The modulus of elasticity was determined to be 8919 MPa, 9.9% higher than the compressed OPT samples. Steaming enhanced the dimensional properties of the samples. Thickness swelling and water absorption of the steamed compressed OPT samples were 6.57% and 33.84%, respectively, lower than those of the samples without steaming. Some other properties such as compression strength, dynamic bending strength, and the compression and recovery ratios were also evaluated. Scanning electron micrographs taken from the cross section of the samples showed a clear difference between the compressed and uncompressed oil palm.
  • Researchpp 2325-2336Mou, H., Iamazaki, E., Zhan, H., Orblin, E., and Fardim, P. (2013). "Advanced studies on the topochemistry of softwood fibres in low-consistency refining as analyzed by FE-SEM, XPS, and ToF-SIMS," BioRes. 8(2), 2325-2336.AbstractPDF
    The influence of low-consistency refining on the surface chemical and morphological properties of softwood chemical pulp was investigated using a special laboratory refining station and advanced topochemical analyses. Refined pulp was fractionated in order to investigate the refining effect on fibres separately, without fines. The morphological properties of whole pulp and fibre fraction were studied by field-emission-SEM. X-ray photoelectron spectroscopy and time-of-flight secondary ion mass spectrometry (ToF-SIMS) were used to analyze the surface chemistry of the pulp fibres before and after refining. As a result of refining, fibre shape changed from tubular to flat. The surface coverage by extractives increased during refining together with increasing refining energy both in the whole pulp and in the fibre fraction; the increase was more significant in the whole pulp. This is probably due to leakage of hydrophobic components from the pulp fines. In the fibre fraction, surface coverage by lignin increased in the course of refining, but in the whole pulp the trend was the opposite. Similar trends were detected by observing the ToF-SIMS peaks of polysaccharides, lignin, and extractives. Refining modifies the surface chemistry and morphology of fibres, presumably by making structural changes in the fibre cell wall composition. Eventually, these changes induce increased fibre-to-fibre bonding capability and decreased scattering of light.
  • Researchpp 2337-2350Hietanen, T. M., Österberg, M., and Backfolk, K. A. (2013). "Effects on pulp properties of magnesium hydroxide in peroxide bleaching," BioRes. 8(2), 2337-2350.AbstractPDF
    High alkalinity in peroxide bleaching has traditionally been achieved using sodium hydroxide and sodium silicate. In the present work, partial and total substitution of traditional sodium-based peroxide bleaching auxiliary chemicals with a highly pure magnesium hydroxide-based bleaching additive was studied on two high-brightness mechanical pulp types from Norwegian spruce (Picea abies): pressure groundwood and thermomechanical pulp. Peroxide bleaching with 3.0% charge was carried out on both pulps to a given brightness level. The bleached pulp was studied with respect to electrical conductivity, zeta potential, and water retention value. The bleaching filtrate was measured for total organic carbon content, biological and chemical oxygen demand, cationic demand, extractives content, and turbidity. The main results from this study were that the cationic demand and electrical conductivity of the bleaching filtrate were significantly lowered for both pulps when a magnesium-based bleaching process was used. At the same time, the zeta potential of the dilute pulp suspension was only slightly affected. Magnesium hydroxide-based peroxide bleaching seems to increase the water retention value of the pulp, especially on fines-rich pressure groundwood, predicting a good strength potential of the pulp. The bleaching filtrate from the magnesium hydroxide-based process was significantly cleaner in all categories measured, which indicates that this is an environmentally sound concept.
  • Researchpp 2351-2365Pereira, P. H. F., Benini, K. C. C. C., Watashi, C. Y., Voorwald, H. J. C., and Cioffi, M. O. H. (2013). "Characterization of high density polyethylene (HDPE) reinforced with banana peel fibers," BioRes. 8(2), 2351-2365.AbstractPDF
    Lignocellulosic fibers from banana peels were washed with water in order to increase their compatibility with a polymeric matrix, and their properties were compared with unwashed fibers. Washed banana fibers were mixed with high density polyethylene (HDPE) and placed in an injector chamber to produce specimens for tensile tests. Samples of washed banana fibers/HDPE composites were characterized by tensile tests and thermal analysis. The chemical composition of unwashed and washed banana fibers was analyzed by thermogravimetric analysis, scanning electron microscopy, and X-ray diffraction. The treatment with water was effective at removing extractives and increasing the surface roughness, thereby increasing the thermal stability of the fibers. However, results showed that the addition of washed banana fibers decreased the thermal stability of composites, while increasing the melting and crystallization temperatures of composites. The addition of 5 wt% fibers also provided an improvement in mechanical properties of composites in comparison with pure HDPE.
  • Researchpp 2366-2375Ma, X., Jiang, M., Wu, Y., and Wang, P. (2013). "Effect of wood surface treatment on fungal decay and termite resistance," BioRes. 8(2), 2366-2375.AbstractPDF
    Surface treatments, such as immersion, brushing, spraying, dipping, and steeping have been extensively used to treat wood for use in low hazard class areas or as an on-site remedial/supplemental treatment of in-service wooden structures to extend their service life. In the present study the wood was subjected to steeping with three preservative formulations, i.e., copper azole type C (CA-C), alkaline copper quat type C (ACQ-C), and tebuconazole-propiconazole combo (TP), and the effect of surface treatment on fungal decay and termite resistance was evaluated. The results showed that the depth of chemical penetration into the wood and the surface absorption primarily depends on the permeability of the wood species. The efficacy of decay and termite resistance was determined by surface retention per unit area of the surface-treated wood. The surface treatment with CA-C, ACQ-C, and TP significantly enhanced the decay and termite resistances of the wood. But for low-permeability wood species such as Picea asperata, a higher concentration of preservatives or periodic re-surface-treatment is necessary to maintain resistance to decay and to termites.
  • Researchpp 2376-2385Zhang, S.-Y., Wang, C.-G., Fei, B.-H., Yu, Y., Cheng, H.-T., and Tian, G.-L. (2013). "Mechanical function of lignin and hemicelluloses in wood cell wall revealed with microtension of single wood fiber," BioRes. 8(2), 2376-2385.AbstractPDF
    Chinese Fir wood (Cunninghamia lanceolata (Lamb.) Hook) was subjected to extraction treatments with sodium chlorite (NaClO2) for delignification, as well as with sodium hydroxide (NaOH) at different concentrations for extraction of hemicelluloses. The wood was examined using a Fourier Transform Infrared (FT-IR) spectrometer and microtension technique to track changes in the chemical and the micromechanical properties of the cell wall. The results of the microtensile tests indicated that the hemicelluloses caused more damage to the mechanical properties of the cell wall than lignin. The micromechanical properties that occurred with degradation of chemical components underlined the key role of hemicelluloses in maintaining the integrity of the cell wall.
  • Researchpp 2386-2397Safinas, M. S. A., Bakar, A. A., and Ismail, H. (2013). "Properties of kenaf bast powder-filled high density polyethlene/ethylene propylene diene monomer composites," BioRes. 8(2), 2386-2397.AbstractPDF
    High-density polyethylene (HDPE)/ethylene-propylene-diene monomer (EPDM) blend was prepared by mixing HDPE and EPDM in an internal mixer. Kenaf fibers were then added to the mixture with a few minutes of mixing. The tensile properties of the HDPE/EPDM/kenaf composites were investigated using tensile testing and scanning electron microscopy. Treated kenaf bast powder was prepared using hydrochloric acid (HCl). Hydrolysis was carried out to study the effect of HCl on the structure, composition, and properties of the fibers. HCl treatment removed the impurities in the fibers, resulting in smooth fibers with a small particles size. Fourier transform infrared analysis showed a reduction in lignin, wax, and hemicellulose but no modification in surface chemical composition. The treated filled HDPE/EPDM composites had high tensile strength, elongation at break, and modulus than the untreated filled HDPE/EPDM composites.
  • Researchpp 2398-2416Meng, Q., Wan, J., Ma, Y., and Wang, Y. (2013). "Effects of different deinking processes on fiber morphology, hydrogen bond models, and cellulose supramolecular structure," BioRes. 8(2), 2398-2416.AbstractPDF
    Deinked pulp fibers produced by three kinds of deinking processes, alkaline deinking, neutral deinking, and enzymatic deinking, were studied by Scanning Electron Microscope (SEM), Fourier Transform Infrared Spectrometer (FTIR), X-ray Diffraction (XRD), and Cross-Polarization Magic Angle Spinning Carbon-13 Nuclear Magnetic Resonance (CP/MAS 13C-NMR). There were remarkable differences in both macroscopic and microscopic structure between the samples. SEM images showed that the effects of deinking processes on fiber morphology were obvious and the influences of alkaline deinking were the most apparent. FTIR analysis indicated that the content of intermolecular hydrogen bonds increased by 22.63%, 9.42%, and 14.40% after the alkaline deinking process, neutral deinking process, and enzymatic deinking process, respectively. XRD revealed that the average width of crystallite size in the (002) lattice plane was decreased after different deinking processes, in accordance with the change tendency of cellulose crystallinity. CP/MAS 13C NMR combined with spectral fitting demonstrated that the content of different cellulose polymorphs changed during deinking processes. The increase of WRV was attributed to changes in the hydrogen bonding patterns and cellulose supramolecular structure.
  • Researchpp 2417-2428Takahashi, S., Tanifuji, K., Shiell, K., Fatehi, P., Jahan, M. S., Ohi, H., and Ni, Y. (2013). "Removal of acetic acid from spent sulfite liquor using anion exchange resin for effective xylose fermentation with Pichia stipitis," BioRes. 8(2), 2417-2428.AbstractPDF
    Acetic acid is one of the major inhibitors of spent sulfite liquor (SSL) fermentation for ethanol production. The objective of this study was to remove acetic acid from hardwood SSL using anion exchange resin in order to achieve effective fermentation with Pichia stipitis CBS6054. Lignosulfonate, as well as sulfate and sulfite ions in the SSL hindered the removal of acetic acid by anion exchange resins. CaO treatment was an effective method for removing these materials from SSL, which facilitated the removal of acetic acid in the subsequent ion exchange resin treatment. A two-stage strong base ion exchange resin (OH- form) treatment removed approximately 90% of the acetic acid from CaO-treated SSL, which decreased the acetic acid concentration to less than 1 g/L. The combined treatment of CaO and ion exchange resin treatments in a relatively short time achieved the selective removal of acetic acid from SSL and significantly increased the ethanol production from SSL.
  • Researchpp 2429-2441Valdés, L., Gullón, P., Salazar, N., Rios-Covián, D., González-Muñoz, M. J., Parajó, J. C., Ruas-Madiedo, P., Gueimonde, M., and de los Reyes-Gavilán, C. G. (2013). "Population dynamics of some relevant intestinal microbial groups in human fecal batch cultures with added fermentable xylooligosaccharides obtained from rice husks," BioRes. 8(2), 2429-2441.AbstractPDF
    Xylooligosaccharides (XOS) obtained by autohydrolysis of rice husks were demonstrated in a previous study to act as fermentable substrates by the intestinal microbiota in human fecal slurry cultures, leading to the generation of acetic and lactic acids and supporting the growth of bifidobacteria (Gullón et al. 2011). The purpose of the present study was to provide new insights into other possible targets of XOS action by determining (in the same fecal cultures) the levels of some relevant intestinal microbial groups and the profile of Bifidobacterium species by quantitative and qualitative polymerase chain reaction (PCR), respectively. XOS-containing concentrates promoted the growth of Lactobacillus-Weissella, Bacteroides-Prevotella, and Clostridium cluster XIVa groups, as well as Faecalibacterium prausnitzii species. Preliminary results point to possible variation in the profile of some bifidobacteria species in fecal cultures caused by XOS that should be further investigated. These results support XOS as potential prebiotics for the design of functional food products.
  • Researchpp 2442-2452Grünewald, T., Grigsby, W., Tondi, G., Ostrowski, S., Petutschnigg, A., and Wieland, S. (2013). "Chemical characterization of wood-leather panels by means of 13C NMR spectroscopy," BioRes. 8(2), 2442-2452.AbstractPDF
    Intelligent resource usage is one of the most challenging tasks for the wood-based panels industry. With respect to this issue, leather shavings, derived during leather preparation, are a promising new raw material, as they offer not only high availability, but also potentially enhance material properties such as panel fire retardancy. In order to improve the performance of these emerging panel binder materials, an understanding of chemical interactions between the different constituents is crucial. This paper investigates the chemical changes that occur during hot-pressing of wood and leather in combination with lignin by means of solid state 13C NMR spectroscopy. These constituents, their binary mixtures, and the influences of panel pressing temperature and pressure commonly used in panel production were investigated. The study showed characteristic chemistry and features of these constituents, quantifying the impacts of both heat and pressure on their interactions. Primarily, analysis revealed that lignin readily connects with both the wood and leather components. Lignin induces chemical change within the protein structure of leather, resembling tanning reactions, or protein complexation. By analogy, it was deduced that this interaction also takes place between leather and the lignin-rich wood fibre surface. This effect may be beneficial in industrial-scale production through improving resin binding properties during panel consolidation.
  • Researchpp 2453-2469Mao, A., Hassan, E. B., and Kim, M. G. (2013). "Investigation of low mole ratio UF and UMF resins aimed at lowering the formaldehyde emission potential of wood composite boards," BioRes. 8(2), 2453-2469.AbstractPDF
    Urea-melamine-formaldehyde (UMF) resins with 2.5% and 5.0% melamine levels added at the beginning of the third step of the typical urea-formaldehyde (UF) synthesis procedure were synthesized with an F/(U+M) mole ratio of 1.05 and evaluated as particleboard binders to investigate the positive effects of melamine on the formaldehyde content and physical performance of boards. Resins were tested for storage properties and analyzed by 13C NMR. Curing catalysts were studied, curing rates were measured, and laboratory particleboards were prepared and tested for formaldehyde contents as well as strength and water-soak test values. The UMF resins resulted in slower curing rates but had adequate board strength values. The formaldehyde content values were within the newly created California emission law (5.2 to 8.0 mg/100 g board). Another objective of this work was to establish the baseline performance of these resins for use in subsequent studies that will aim to reveal the effects of methylene-ether group contents on formaldehyde emissions.
  • Researchpp 2470-2486Mao, A., Hassan, E. B., and Kim, M. G. (2013). "Low mole ratio UF and UMF resins entailing uron-type methylene-ether groups and their low formaldehyde emission potentials," BioRes. 8(2), 2470-2486.AbstractPDF
    The previous study on low mole ratio urea-formaldehyde (UF) and urea-melamine–formaldehyde (UMF) resins synthesized in the typical way as particleboard binders was repeated with the inclusion of a strong acidic reaction step at a mole ratio of 2.7 in the beginning of the resin synthesis procedure. The resulting UF and UMF resins showed longer storage- and pot-lives, longer gel times, and the particleboards gave higher internal bond and lower water-soak absorption values. However, the free formaldehyde contents of boards were increased with UF resins and decreased with UMF resins, indicating that the uron-type methylene-ether groups formed from the strong acidic step resulted in enhancement of the bonding, but they give off some extra formaldehyde, which is captured more effectively in UMF resins because of the higher reaction capacity of melamine. The extra acidic reaction step could be useful in UMF resin syntheses. The generation of extra formaldehyde by uron-type methylene-ether bonds is documented.
  • Researchpp 2487-2498Feng, L., Li, Y., Chen, C., Liu, X., Xiao, X., Ma, X., Zhang, R., He, Y., and Liu, G. (2013). "Biochemical methane potential (BMP) of vinegar residue and the influence of feed to inoculum ratios on biogas production," BioRes. 8(2), 2487-2498.AbstractPDF
    Vinegar residue, a typical agro-industrial by-product in the vinegar production process, constitutes a huge environmental problem in China. Though utilization of vinegar residue has drawn much attention, there is still no effective, economical, and environmentally friendly method to deal with it. Anaerobic digestion is an effective method widely used in organic waste processing which might be an alternative to convert this acidic waste into biogas energy. A biochemical methane potential assay was conducted, and the influence of different feed to inoculum ratios (F/I) was determined. The highest methane yield of 242.69 mL g VS-1 was achieved at a F/I of 1, while the lowest methane yield of 182.94 mL g VS-1 was obtained at a F/I of 6. The TVFA/TA ratio was higher than the limiting value (0.4) at F/I ratios of 5 and 6, which demonstrated destabilization during the anaerobic digestion process. The modified Gompertz equation was developed to calculate the cumulative methane yields from different F/I ratios. The results suggested that the vinegar residue had extensive potential in biogas production and anaerobic digestion as a promising method that may be applied to deal with such waste, thus it is worth doing further research in the future.
  • Researchpp 2499-2509Mohamad, N. L., Mustapa Kamal, S. M., Abdullah, N., and Ismail, I. (2013). "Evaluation of fermentation conditions by Candida tropicalis for xylitol production from sago trunk cortex," BioRes. 8(2), 2499-2509.AbstractPDF
    Xylitol production from sago trunk cortex hydrolysate using Candida tropicalis was evaluated in shake flasks and a bioreactor. The fermentation and kinetic behaviours of this microorganism were investigated using sago trunk cortex hydrolysate and commercial xylose as substrate. Results obtained for sago trunk hydrolysate were close to the commercial xylose with xylitol yield of 0.82 gg-1 and productivity of 0.39 gL-1h-1. The maximum specific growth rate, µmax for sago trunk cortex was higher (0.24 h-1) compared to commercial xylose (0.17 h-1). The bioreactor study showed an increase of about 6% (w/v) of xylitol concentration and 10% (v/v) of volumetric productivity when compared to the results obtained under the shake flasks, keeping xylitol yield above 0.8 g g-1.
  • Researchpp 2510-2520Xu, G., Ren, S., Wang, D., Su, L., and Fang, G. (2013). "Fabrication and properties of alkaline lignin/poly (vinyl alcohol) blend membranes," BioRes. 8(2), 2510-2520.AbstractPDF
    Membranes were prepared from alkaline lignin and poly(vinyl alcohol) (PVA) by a film casting method, and their properties were evaluated. These blend membranes can aptly be termed as green by nature as they are totally non-toxic and eco-friendly. The optimal mass ratio was determined based on the mechanical properties of membranes. The microstructure, mechanical properties, oxygen and carbon dioxide transmission, light transmittance, and thermal stability of the membranes were investigated. The blend membrane exhibited better thermal stability and barrier performance to oxygen and carbon dioxide than a PVA membrane due to the incorporation of alkaline lignin. Both tensile strength and elongation at break were increased with increasing mass fraction of alkaline lignin up to 15%, at which point the maximum of tensile strength and elongation at break were 43.65 MPa and 211.6%, respectively. The blockage of visible light at 600 nm was 62.36%, which was an improvement of 314.90% compared with the PVA membrane (13.36%). Based on this result, we suggest that the mechanical properties of blend membrane containing 15% alkaline lignin are excellent and better than PVA membrane (40.26 MPa, 179.37%). Thus, an alkaline lignin/PVA blend membrane was judged to be potentially suitable as an eco-friendly packing material.
  • Researchpp 2521-2536Wang, L., and Li, J. (2013). "Removal of methylene blue from aqueous solution by adsorption onto crofton weed stalk," BioRes. 8(2), 2521-2536.AbstractPDF
    Crofton weed stalk (CWS) was used as an adsorbent to remove methylene blue (MB) from aqueous solution. The adsorbent was analyzed by FT-IR and observed by SEM. The porosity and pHzpc were measured. The effects of adsorbent dose, initial dye concentration, solution pH, and solution temperature were investigated. Models of the adsorption kinetics and isotherms were analyzed, and thermodynamic parameters were calculated at different temperatures. The results showed that the adsorption capacity of MB on CWS increased with increasing initial concentration from 10 to 40 mg/L and pH from 2 to 7. The amount of MB removed increased as the adsorbent dosage was increased from 0.2 to 1.2 g/L. The maximum dye adsorption capacity of 28 mg/g was reached at around 120 min in a solution of 40 mg/L. A pseudo-second-order kinetic model described the kinetics well, and the experimental data followed the Freundlich model. The calculated values of standard free energy (ΔGo) and standard enthalpy (ΔHo) were negative, which indicates the adsorption process is spontaneous and exothermic. The values of both free energy and ΔGo indicate that the adsorption is a physical process. This work shows CWS could be utilized as an effective adsorbent for treating dye wastewater.
  • Researchpp 2537-2546Liu, X.-J., Guo, M.-L., Huang, J., and Yin, X.-Y. (2013). "Improved fluorescence of carbon dots prepared from bagasse under alkaline hydrothermal conditions," BioRes. 8(2), 2537-2546.AbstractPDF
    A simple and effective route to improve the fluorescence of carbon dots is reported. A weak fluorescent solution was obtained by a diminution step to obtain tiny particles from bagasse-based carbonaceous blocks. This solution was subjected to hydrothermal treatment under alkaline conditions to improve its fluorescent performance. The luminescence was found to be improved by more than 20-fold after hydrothermal treatment. The ultraviolet absorption and the surface structure were also significantly changed. The alkaline hydrothermal process was shown to involves hydrolysis, isomerization, dehydration, and polymerization that causes the formation of the C=C double bonds and conjugated structures. The optimum hydrothermal conditions were at 200 °C for 8 h, and the most appropriate ratio of NaOH to the amount of the weak fluorescent solution was 38-40 mg to 1 mL.
  • Researchpp 2547-2557Chong, Y. H., Wan Daud, W. R., and Leh, C. P. (2013). "Effect of hydrogen peroxide and anthraquinone on the selectivity and hexenuronic acid content of mixed tropical hardwood kraft pulp during oxygen delignification," BioRes. 8(2), 2547-2557.AbstractPDF
    In this study, the bleachability of commercial mixed tropical hardwood brown kraft pulp by oxygen delignification (O stage) was examined. It was found that the effective reduction of kappa number was limited to about 35%, and the pulp viscosity was 20.3 cP with a selectivity less than 0.60 and ISO brightness of ca. 43%. The selectivity and pulp brightness of the O stage were improved by adding H2O2 (OP stage) because it decreased the kappa number to a greater extent. However, the addition of hydrogen peroxide caused more serious cellulose degradation. In order to minimize the drop of pulp viscosity during the OP stage, a small amount (0.04%) of anthraquinone (AQ) was added. The results showed that the AQ-aided OP stage was capable of preventing cellulose degradation and thus improved the bleaching selectivity about 60%, in comparison to the ordinary O stage. Moreover, the AQ-OP pulps retained significantly less hexenuronic acid than the pulps from O and OP stages.
  • Researchpp 2558-2567Wang, X., Xu, M., Liu, Z., and Cao, Y. (2013). "Impact of oxygen-reinforced alkali extraction on eucalyptus sulfate pulp for viscose fiber production," BioRes. 8(2), 2558-2567.AbstractPDF
    Some pulp mills expect to produce viscose fiber by means of pre-existing pulp production lines as used for conventional kraft pulp having a relatively high content of hemicellulose. In the present study oxygen-reinforced alkali extraction was used to dissolve the oxidized lignin, which increased the content of alpha cellulose and increased the degree of mercerization. This paper considers the influence of alkalinity, time, temperature, oxygen pressure, and borax additive on oxygen-reinforced alkali extraction. According to the experimental results, the optimal oxygen-reinforced alkali treatment conditions were 120 g/L alkali for 30 min at a temperature of 40 °C. Single factor experiment results showed that oxygen pressure was beneficial to the process of alkali extraction, and 0.4 Mpa was selected as the optimal oxygen pressure. Kappa number, alpha cellulose, carboxyl content, and degree of polymerization (DP) were 1.2, 99.18%, 0.00965 mmol/g, and 1505, respectively, under the optimal reaction conditions. Results for the oxygen-alkali treatment showed that borax was important for affecting DP and the amount of cellulose II. DP was decreased to 1282 and the amount of cellulose II was increased to 36% when the borax was added.
  • Researchpp 2568-2582Ding, W., Li, W., Gao, Q., Han, C., Zhang, S., and Li, J. (2013). "The effects of sealing treatment and wood species on formaldehyde emission of plywood," BioRes. 8(2), 2568-2582.AbstractPDF
    Urea-formaldehyde (UF) resin (F/U: 1.25), melamine-urea-formaldehyde (MUF) resin (F/(U+M): 1.05), and three kinds of wood species including poplar (Populus davidianaDode), beech (Fagus englerianaSeem.), and eucalyptus (Eucalyptus robusta Smith) were used to produce plywood. The effects of sealing treatment and wood species on the formaldehyde emissions were studied. The anatomical characteristics of different wood species were measured. The results showed that: (1) formaldehyde emission of plywood treated by surface sealing was higher than without treatment; (2) formaldehyde emission of nine-ply poplar plywood bonded by UF resin decreased by 74.4% to 1.98 mg/L after edge sealing treatment; (3) compared with beech and poplar plywood, the formaldehyde emission of five-ply eucalyptus plywood bonded by MUF resin was the lowest obtained, at 0.19 mg/L; (4) formaldehyde emission of poplar plywood from the surface changed slightly in spite of different layers. The contact angle and spreading-penetration coefficient, K, analyses showed that the cell arrangement of eucalyptus was dense. Scanning electron micrographs indicated that the pore sizes of eucalyptus samples were the smallest in contrast to poplar and beech.
  • Researchpp 2583-2593Liu, Z., Hunt, J. F., and Cai, Z. (2013). "Fire performance of fiber board coated with nano kaolin-clay film," BioRes. 8(2), 2583-2593.AbstractPDF
    Fiberboard is a common interior material used both in China and the United States of America. The increase in demand for interior materials has raised concerns regarding combustibility of the materials. The pyrolysis characteristics of fiber, phenolic resin (PF), and nano kaolin-clay (NK) were investigated using thermogravimetry. The fire performances of samples coated with a mixture of NK and PF were determined using a cone calorimeter. The pyrolysis process of fiber included three phases dependent on chemical composition. The initial temperature of PF pyrolysis was about 100 °C and it stopped at 280°C. The major mass loss of NK was observed between 400 to 600 °C due to the gradual oxolation of the metakaolin. In comparison with fiber board, samples coated with a mixture of NK and PF achieved a better fire performance. The results showed a longer TTI, lower HRR, and THR, and less CO and CO2 yield, especially from a mixture of NK (90%) and PF (10%). The application of an NK and PF mixture to fiber board as a flame retardant is an effective method for enhancing fire safety and resistance.
  • Researchpp 2594-2604She, Y., Zhang, H., Song, S., Lang, Q., and Pu, J. (2013). "Preparation and characterization of waterborne polyurethane modified by nanocrystalline cellulose," BioRes. 8(2), 2594-2604.AbstractPDF
    Nanocrystalline cellulose (NCC) was used as a modifier for waterborne polyurethane (WPU) to investigate the water and ethanol resistance of WPU-NCC composites. The NCC surface was modified with γ-glycidoxypropyltrimethoxysilane (GPTMS) and γ-ammnonimpropylmethyldimethoxysilane (APMDS) to improve its compatibility with waterborne polyurethane (WPU), as indicated by the contact angle (CA). The characteristic properties of WPU modified by NCC and a control group were compared by a Fourier-transform infrared spectroscope (FTIR), X-ray powder diffraction (XRD), and scanning electron microscopy (SEM). The CA between the modified NCC and WPU was decreased by 31.2% (with 8.0% APMDS (v/v)), and the NCC modified by GPTMS resulted in a 33.8% decrease of the CA. Compared to the original WPU, the crystal structure and crystallinity of the modified WPU showed a slight alteration. The SEM micrographs showed that the NCC particles modified by GPTMS were dispersed more uniformly. The FT-IR results showed that the addition of modified NCC led to the reduction of the characteristic absorption peak of the hydroxyl group. The water resistance of WPU with 1.5% NCC modified by GPTMS was increased by 47.2%, and the ethanol resistance decreased by 67.0%, while the modification from APMDS led to a 38.1% increase in water resistance and a 56.9% decrease in ethanol resistance.
  • Researchpp 2605-2619Zhou, Y., Pan, S., Wei, X., Wang, L., and Liu, Y. (2013). "Immobilization of β-glucosidase onto magnetic nanoparticles and evaluation of the enzymatic properties," BioRes. 8(2), 2605-2619.AbstractPDF
    This paper reports on a novel and efficient β-glucosidase immobilization method using magnetic Fe3O4 nanoparticles as a carrier. Based on response surface methodology, the optimal immobilization conditions obtained were: glutaraldehyde (GA) concentration, 0.20%; enzyme concentration, 50.25 μg/mL; cross-linking time, 2.21 h; and the maximum activity recovery reached 89.35%. The magnetic immobilized enzyme was characterized by Fourier transform infrared spectroscopy (FTIR), transmission electron microscope (TEM), and vibrating sample magnetometer (VSM). FTIR revealed that β-glucosidase was successfully immobilized on the magnetic nanoparticles. TEM showed that enzyme-magnetic nanoparticles possessed nano-scale size distribution. VSM confirmed that the enzyme-magnetic nanoparticles were superparamagnetic. The properties of the immobilized β-glucosidase were improved, and the immobilized β-glucosidase exhibited wider pH and temperature ranges of activation, higher accessibility of the substrate, better thermal stability, and better storage stability than that of the free enzyme. The enzyme-magnetic nanoparticles could be separated magnetically for easy reuse. Immobilization of β-glucosidase onto the magnetic nanoparticles has the potential for industrial application.
  • Researchpp 2620-2630Espigulé, E., Puigvert, X., Vilaseca, F., Mendez, J. A., Mutjé, P., and Girones, J. (2013). "Thermoplastic starch-based composites reinforced with rape fibers: Water uptake and thermomechanical properties," BioRes. 8(2), 2620-2630.AbstractPDF
    Fully biodegradable composite materials were obtained through reinforcement of a commercially available thermoplastic starch (TPS) matrix with rapeseed fibers (RSF). The influence of reinforcement content on the water sorption capacity, as well as thermal and thermo-mechanical properties of composites were evaluated. Even though the hydrophilic character of natural fibers tends to favor the absorption of water, results demonstrated that the incorporation of RSF did not have a significant effect on the water uptake of the composites. DSC experiments showed that fibers restricted the mobility of the starch macromolecules from the TPS matrix, hence reducing their capacity to crystallize. The viscoelastic behaviour of TPS was also affected, and reinforced materials presented lower viscous deformation and recovery capacity. In addition, the elasticity of materials was considerably diminished when increasing fiber content, as evidenced in the TMA and DMTA measurements.
  • Researchpp 2631-2640Lu, Y., and Liang, Q. (2013). "Removal of Pb(II) from vanillin solution by acid-modified cattail biomass," BioRes. 8(2), 2631-2640.AbstractPDF
    The use of the aquatic plant cattail to produce an adsorbent for heavy metals will add value to wetlands. Cattail adsorbents were treated with multi-valent carboxylic acids to facilitate adsorption of Pb(II) from a vanillin solution. Fourier transform infrared (FTIR) spectroscopic analysis confirmed the formation of acid modifications by esterification. While unmodified cattail had a Pb(II) adsorption capacity of 3.21 mg/g, citric acid-, malic acid-, tartaric acid-, oxalic acid-, and iminodiacetic acid-modified cattail absorbents were able to adsorb 66.10, 55.42, 44.53, 52.32, and 36.82 mg/g, respectively, at the optimum pH of 4.9. The Pb(II) adsorption capacity increased as the concentration of Pb(II) increased without loss of vanillin during the adsorption process. Desorption of Pb(II) and regeneration of the adsorbents was achieved by 0.1 M HCl elution, which showed that the cattail adsorbents were regenerated easily and could be used repeatedly. The results suggest that acid-modified cattail biomass may be a promising adsorbent for heavy metal ion uptake in water-based cosmetics.
  • Researchpp 2641-2656Gandolfi, S., Ottolina, G., Riva, S., Fantoni, G. P., and Patel, I. (2013). "Complete chemical analysis of Carmagnola hemp hurds and structural features of its components," BioRes. 8(2), 2641-2656.AbstractPDF
    As interest in lignocellulosic biomass as a feedstock for conversion into biofuels is steadily growing, analysis of its components becomes ever more important. The complete chemical composition of waste hemp hurds from the industrial variety “Carmagnola” has been determined to optimize its utilization as a raw material. The results from chemical analysis show that hemp hurds contain 44.0% alpha-cellulose, 25.0% hemicellulose, and 23.0% lignin as major components, along with 4.0% extractives (oil, proteins, amino acids, pectin) and 1.2% ash. Structural and physicochemical properties of hurds components were analysed by FTIR or GC/MS. The data revealed that isolated components are pure and comparable to standard components. Acetone extractives show higher total phenolic content and antioxidant capacity compared with lignin and dichloromethane extractives. Water extractive shows the presence of proteins (1.6%), free amino acids (0.02%), and pectin (0.6%). The degree of esterification of pectin was estimated to be 46.0% by FTIR and enzymatic hydrolysis. The results of this study show that Carmagnola hurds contain low amounts of ash and high amounts of carbohydrates compared with other varieties of hemp hurds; therefore they can be considered as a potential feedstock for biorefinery.
  • Researchpp 2657-2668Cao, S., Ma, X., Luo, X., Huang, F., Huang, L., and Chen, L. (2013). "Effect of hydroxyl radical on the selectivity of delignification during oxygen delignification of bamboo pulp," BioRes. 8(2), 2657-2668.AbstractPDF
    The main challenge in the oxygen delignification process is the improvement of selectivity. To further understand the effect of the amount of hydroxyl radicals on the selectivity of oxygen delignification, in this work, the hydroxyl radicals were generated by the improved Fenton reaction system and were quantified by UV spectrophotometry. Antioxidants such as ascorbic acid were applied for the scavenging of hydroxyl radicals so that the amount of hydroxyl radicals could be regulated. The bamboo kraft pulps were treated with the Fenton system or the Fenton system combined with ascorbic acid. The results indicated that the improved Fenton reaction system could be used for the determination of hydroxyl radicals by UV spectrophotometry. The amount of hydroxyl radicals could be regulated to a suitable extent by the hydroxyl radical scavengers during oxygen delignification so that the delignification selectivity improvement was achieved.
  • Researchpp 2669-2680Buehlmann, U., Bumgardner, M., and Sperber, M. (2013). "How small firms contrast with large firms regarding perceptions, practices, and needs in the U.S. secondary woodworking industry," BioRes. 8(2), 2669-2680.AbstractPDF
    As many larger secondary woodworking firms have moved production offshore and been adversely impacted by the recent housing downturn, smaller firms have become important to driving U.S. hardwood demand. This study compared and contrasted small and large firms on a number of factors to help determine the unique characteristics of small firms and to provide insights into useful areas for support. Small firms were found to be similar to large firms with respect to the perceived importance attributed to manufacturing capabilities as a business success factor. However, small firms differed substantially from large firms in other ways, such as less attention to information seeking and planned investments. Small firms also tended to make greater use of distribution yards in the hardwood lumber purchasing value chain and requested fewer services from their hardwood lumber suppliers than did larger firms. Small firms were found to be keen on developing their marketing capabilities, including e-commerce, to further their information exchange with customers to successfully produce made-to-order products. Small firms considered the individual characteristics of company owners/managers to be a relatively important success factor to business, more so than larger firms. The results are summarized and discussed through the lens of small firm reliance on niche markets for survival (including fully made-to-order production) and their need to find new revenue during economic downturns.
  • Researchpp 2681-2695Xue, B., and Hu, Y. (2013). "Analysis of the microstructure and mechanical properties of laminated veneer lumber," BioRes. 8(2), 2681-2695.AbstractPDF
    In this paper, four different nondestructive testing (NDT) methods and static bending tests were done on poplar (Populus ussuriensis Kom.) and birch (Betula platyphylla Suk.) Laminated Veneer Lumber (LVL). The effects of compression ratio on the modulus of elasticity (MOE) and modulus of rupture (MOR) of LVL with vertical load and parallel load were investigated. There were four compression ratios: 8.1%, 18.3%, 26.5%, and 33.1%. The microscopic structure of LVL was analyzed with a scanning electron microscope (SEM). Results showed a strong correlation between each dynamic Young’s modulus and the static MORof LVL; the MOE and MOR of LVL changed with the increase of compression ratio. MOE and MOR were greatly increased when the compression ratio increased from 18.3% to 26.5%, and the microstructure of LVL changed greatly between different compression ratios by birch and poplar species.
  • Researchpp 2696-2707Lei, T., Wang, Z., Li, Y., Li, Z., He, X., and Zhu, J. (2013). "Performance of a diesel engine with ethyl levulinate-diesel blends: A study using grey relational analysis," BioRes. 8(2), 2696-2707.AbstractPDF
    The combustion and emission characteristics of ethyl­ levulinate (EL)–diesel blended fuels were investigated using engine bench tests. Blended fuels properties, including the kinematic viscosity (KV), density, EL proportions, oxygen content, cetane number (CN), and lower heating value (LHV) were considered. The combustion and emission characteristics of brake-specific fuel consumption (BSFC), as well as hydrocarbon (HC), nitrogen oxide (NOx), carbon monoxide (CO), and carbon dioxide (CO2) emissions, as well as smoke opacity, were tested. The relationship between the blended fuel properties and the combustion–emission characteristics were analyzed using grey relational analysis (GRA). The correlation degree between the fuel properties and the combustion–emission results indicated that the BSFC was influenced most by the density of the blended fuels. NOx, CO, and CO2 emissions were influenced most by the oxygen content. The KV was the most influential parameter for HC emissions and the opacity of the blended fuels. The oxygen content was the foremost influential parameter. The results show that GRA could be used to increase the comprehensiveness of combustion–emission blended-fuel studies, by providing a reference for the reasonable use of biofuel-diesel mixtures.
  • Researchpp 2708-2718Luo, P., Cao, C., Liang, Y., Ma, X., Xin, C., Jiao, Z., Cao, J., and Zhang, J. (2013). "Kinetic study of the acetylation of cotton linter pulp," BioRes. 8(2), 2708-2718.AbstractPDF
    The kinetics of the reaction of cotton linter pulp with acetic anhydride catalyzed by sulfuric acid at temperatures ranging from 30 to 45 °C have been investigated. A kinetic model considering the dissolution of the sufficiently sulfated cellulose chains on the surface of the solid fibers, and the subsequent reactions in the liquid phase was proposed for the acetylation process. The kinetic parameters were regressed from the measured degree of substitution using a nonlinear regression method. With the optimum values of the rate constants, the proposed model can predict the acetylation process very well. The chemical activation energy of the reactions of the cellulose hydroxyl groups with acetic anhydride was estimated as 39.6 kJ/mol. The dissolution rate of the sulfated chains can be represented by the equation r/r0=1-kt. A similar equation, the Arrhenius expression, k=Aexp(-E/RT) was used to predict the dissolution rate constants. The corresponding activation energy for the dissolution was evaluated as 19.6 kJ/mol.
  • Researchpp 2719-2737Joutsimo, O. P., and Asikainen, S. (2013). "Effect of fiber wall pore structure on pulp sheet density of softwood kraft pulp fibers," BioRes. 8(2), 2719-2737.AbstractPDF
    In this study fiber cell wall porosity was altered by fiber line simulation in a laboratory. The changes in the fiber cell porosity were analyzed with a water retention value (WRV) test. Pore size distributions were measured by differential scanning calorimetry (DCS), and atomic force microscopy (AFM) was used to determine the cell wall pore area from cross sections of the S2 layer of the cell wall. WRV was shown to correlate with the amount of water in the pores with a diameter of at least 200 nm. Changes in the non-freezing and total bound water did not affect the WRV. The calculated shrinkage forces generated by the capillary forces in different pore cell wall structures correlated with the sheet densities generated by fiber networks. It was observed that the swelling of the cell wall, defined as an increase in the diameter of the cell wall, was most likely not occurring or was very difficult to detect.
  • Researchpp 2738-2751Marques, T. L., Alves, V. N., Coelho, L. M., and Coelho, N. M. M. (2013). "Assessment of the use of Moringa oleifera seeds for removal of manganese ions from aqueous systems," BioRes. 8(2), 2738-2751.AbstractPDF
    Moringa oleifera seeds were investigated for the removal of manganese ions from aqueous solutions. The seeds utilized were obtained from plants grown in Uberlândia, Brazil. After being dried and pulverized, the seeds were treated with 0.1 mol L-1 NaOH. Using the optimized methodology (50 mL of 4.0 mg L-1 Mn(II), pH range of 4.0–6.0, contact time of 5 min, and biosorbent mass of 0.5 g) it was found that 100% of Mn(II) could be removed from water samples. In order to remove up to 95% of Mn ions in 50 mL of a laboratory residue produced during biochemical oxygen demand determinations with 112.0 mg L-1 of manganese, the contact time and pH were maintained, but a mass of 3.0 g was used. The kinetic data were fitted to a pseudo-second-order kinetic model. The sorption data were fitted satisfactorily to the Langmuir and Freundlich isotherm models. Evaluation applying the Langmuir equation gave the monolayer sorption capacity as 5.61 mg/g. In this application the method was found to be efficient, fast, simple, and economical.
  • Researchpp 2752-2767Sammons, R. J., Harper, D. P., Labbé, N., Bozell, J. J., Elder, T., and Rials, T. G. (2013). "Characterization of organosolv lignins using thermal and FT-IR spectroscopic analysis," BioRes. 8(2), 2752-2767.AbstractPDF
    A group of biomass-derived lignins isolated using organosolv fractionation was characterized by FT-IR spectral and thermal property analysis coupled with multivariate analysis. The principal component analysis indicated that there were significant variations between the hardwood, softwood, and grass lignins due to the differences in syringyl and guaiacyl units as well as the different processing temperatures and times used to isolate the lignins. Partial least squares regression revealed that the concentration of syringyl units was the foremost factor behind the variation in glass transition temperature (Tg) for each lignin sample. It was concluded that structural variations resulting from altering the processing time and temperature and the lignin species directly affect the thermal properties of the lignin. Therefore, by determining the thermal properties of a lignin sample, a basic understanding of its structure can be developed.
  • Researchpp 2768-2779Zhang, M., Song, S., Wang, J., Sun, J., Li, J. Z., Ni, Y., and Wei, X. (2013). "Using a novel fly ash based calcium silicate as a potential paper filler," BioRes. 8(2), 2768-2779.AbstractPDF
    A novel calcium silicate filler can be made from fly ash. This new filler, known as fly ash based calcium silicate (FACS), has a highly porous surface structure, high brightness (91% ISO), low bulk density (0.31 g/cm3), and high specific surface area (121 m2/g). In this paper, its potential application as a paper filler was studied and its effect on drainage, retention, and paper properties was investigated. The results from dynamic drainage tests showed that FACS had similar drainage and retention behaviors to the conventional precipitated calcium carbonate (PCC). Physical tests indicated that FACS-filled paper had higher tensile, burst, and tear indices, but lower brightness and opacity than those loaded with PCC. A more important finding was that the bulk of paper can be increased by 56.4% with 20% FACS content in paper relative to the control (no filler addition).
  • Researchpp 2780-2791Chen, T., Liu, W., and Qiu, R. (2013). "Mechanical properties and water absorption of hemp fibers-reinforced unsaturated polyester composites: Effect of fiber surface treatment with a heterofunctional monomer," BioRes. 8(2), 2780-2791.AbstractPDF
    Hemp fibers–reinforced unsaturated polyester (UP) composites were prepared by hand lay-out compression molding. Hemp fibers were treated with isocyanatoethyl methacrylate (IEM), using dibutyltin dilaurate as a catalyst. The results indicated that fiber treatment significantly increased tensile strength, flexural strength, flexural modulus, and water resistance of the resulting composites, and yet decreased the impact strength of the composites. The water absorption characteristics for composite samples immersed in water at room temperature followed Fickian behaviour, but for those evaluated at temperature 100 °C, there was a deviation from Fickian behaviour. Scanning electron microscope graphs of the tensile-fractured surface of hemp–UP composites revealed that fiber treatment with IEM greatly improved the interfacial adhesion between hemp fibers and UP resins. Fourier transform infrared analysis of the treated fibers showed that some IEM was covalently bonded onto hemp fibers.
  • Researchpp 2792-2804Lai, L.-W., and Idris, A. (2013). "Disruption of oil palm trunks and fronds by microwave-alkali pretreatment," BioRes. 8(2), 2792-2804.AbstractPDF
    In this study, lignocellulosic biomass from oil palm trunk (OPT) and oil palm frond (OPF) of oil palm tree, Elaeis guineensis, were treated using the microwave-alkali (Mw-A) method, and their chemical constituents, namely cellulose, hemicellulose, and lignin, were analyzed. A number of instruments, i.e. FESEM, FT-IR, and XRD, were employed to analyze the morphology and structural changes of biomass. After the Mw-A pretreatment, it was revealed that the amount of cellulose released was up to 41.55% for OPT and 64.42% for OPF. There was also a huge degree of reduction in hemicellulose, up to 64%, but lignin removal saw a fair reduction with only 15.33% for OPT and 17.97% for OPF. The results revealed that the Mw-A pretreatment is capable of disrupting the OPT and OPF.
  • Researchpp 2805-2826Yilgor, N., Dogu, D., Moore, R., Terzi, E., and Kartal, S. N. (2013). "Evaluation of fungal deterioration in Liquidambar orientalis Mill. heartwood by FT-IR and light microscopy," BioRes. 8(2), 2805-2826.AbstractPDF
    The chemical and morphological changes in heartwood specimens of Liquidambar orientalis Mill. caused by the white-rot fungus Trametes versicolor and the brown-rot fungi Tyromyces palustris and Gloeophyllum trabeum were studied by wet chemistry, FT-IR, GC-MS analyses, and photo-microscopy. According to GC-MS results, 26 extracts identified in the ethanol/toluene extraction and 17 in the ethanol extraction were found. Heartwood specimens of L. orientalis were highly susceptible to the fungi tested. While 1% NaOH solubility increased 35% in the specimen decayed by T. palustris, only an 8% increase was seen in the specimen exposed to T. versicolor when compared to the control specimen. Decayed wood by T. palustris showed a 5.5% increase in the Klason lignin content when compared to control specimens; however, the Klason lignin content decreased after a T. versicolor attack for 12 weeks. A T. versicolor attack in the cell walls was seen both from the lumina and from the cell corners, and the attack from the cell corners was mainly clear in ray parenchyma cells. An excessive destruction was detected in the wood structure attacked by T. palustris. The cell collapse was caused by a distortion in the plane of the wood cells. This extensive degradation was seen in all types of cell walls. Cracks in the cell walls were also detected in the specimens.
  • Researchpp 2827-2838Chen, H., Cheng, H., Jiang, Z., Qin, D., Yu, Y., Tian, G., Lu, F., Fei, B., and Wang, G. (2013). "Contact angles of single bamboo fibers measured in different environments and compared with other plant fibers and bamboo strips," BioRes. 8(2), 2827-2838.AbstractPDF
    The objective of this paper was to investigate the contact angles of single bamboo fibers at different temperatures and relative humidities in comparison to terylene fibers. Comparative tests were done for three other natural fibers (ramie, jute, and kendir) under the same conditions. Contact angles were also measured for bamboo strips. The results showed that with increasing temperature and constant relative humidity, the contact angles of bamboo fibers decreased, whereas those of terylene fibers increased. The contact angle of the bamboo fiber increased significantly, while that of the terylene fibers rose a little with increasing relative humidity at constant temperature. The contact angles of the single bamboo fibers were higher than those of ramie fibers, but lower than jute and kendir fibers after the same chemical treatment because of different diameters, surfaces, and chemical components. In comparison with bamboo strips, the contact angles of single bamboo fibers were much higher and changed with a different trend. Meanwhile the contact angles of cross-section, radical section, and tangential section of bamboo also changed differently.
  • Researchpp 2839-2854Hu, Y., and Xue, B. (2013). "Analysis of nondestructive testing for mechanical properties of LVL at different relative humidities based on fuzzy and classical mathematics," BioRes. 8(2), 2839-2854.AbstractPDF
    Laminated veneer lumber (LVL) panels made from poplar (Populus ussuriensis Kom.) and pine (Pinus sylvestris L. var. mongolica Litven.) veneers were tested for mechanical properties in this work. Four different nondestructive testing (NDT) methods and the static bending test were conducted on the LVL. The NDT methods included the longitudinal vibration method, longitudinal transmission method, and in-plane and out-plane flexural vibration methods. The effects of relative humidity on the modulus of elasticity (MOE) and bending strength (MOR) of LVL with vertical load were investigated. Four relative humidities were tested, namely 40%, 50%, 60%, and 70%. The feasibility of NDT testing on LVL was analyzed by fuzzy and classical mathematics. The results showed that the MOE and MOR of LVL diminished with an increase of relative humidity, and the analysis results of fuzzy neartude and correlation coefficients were same. There was a good linear correlation between NDT results and MOE or MOR of poplar and pine LVL.
  • Researchpp 2855-2866Fonseca, M. I., Fariña, J. I., Sanabria, N. I., Villalba, L. L., and Zapata, P. D. (2013). "Influence of culture conditions on laccase production, growth, and isoenzymes patterns in native white rot fungi from the Misiones rainforest (Argentina)," BioRes. 8(2), 2855-2866.AbstractPDF
    Many biotechnological processes pursuing sustainability aim for effective, inexpensive, and environmentally friendly alternatives to replace conventional practices. Laccase-containing lignocellulolytic systems from white rot fungi have been shown to be an efficient enzymatic tool for ecofriendly biological treatments. One objective of the biotechnological enzymes production process is to find optimum growing and secretion conditions for a selected fungus. In this work, different fungi isolated from the Misiones rainforest (Coriolus versicolor f. antarcticus BAFC-266, Ganoderma applanatum strain F, Phlebia brevispora BAFC-633, and Pycnoporus sanguineus BAFC-2126) were incubated at different temperatures (25, 29, 33 °C) and pH values (3.5, 4.5, 5.5) under static conditions for 7, 10, and 14 days to evaluate their growing ability and laccase (Lac) production. Results revealed specific favorable conditions for growth and protein secretion depending on the fungus under consideration, making it necessary to adjust these parameters for each particular case. The combined effect of these cultivation parameters showed a marked influence on the secreted Lac activity by P. brevispora BAFC 633, with the highest activity (~ 240 U/l) at 29 ºC and pH 4.5 at the 10th day of cultivation. The presence of Lac isoenzymes also depended on the pH, temperature, and time of cultivation for the different tested fungi.
  • Researchpp 2867-2880Li, X., He, X., Li, Z., and Wang, F. (2013). "Combined strategies for improving the production of recombinant Rhizopus oryzae lipase in Pichia pastoris," BioRes. 8(2), 2867-2880.AbstractPDF
    We have developed a yeast Pichia pastoris system for the high-level expression of recombinant Rhizopus oryzae lipase (ROL), which is a potentially effective catalyst in the solvent-free production of biodiesel fuel. In the glycerol fed-batch phase, the combination of the dissolved-oxygen-stat and gradient-control glycerol feeding strategies resulted in a higher cell biomass in the P. pastoris culture, with shorter feed times. In the methanol fed-batch phase, a constant methanol concentration of 0.3-0.5% (v/v) was found to be optimal for high ROL activity, maximum protein concentration, and a maximum biomass. Cells were grown at 30 °C and induced by methanol at 22 °C and a pH of 6.0 with the addition of 0.5% (w/v) casein, which reduced the proteolytic degradation of ROL. Using a combined glycerol step-increasing, on-line methanol feeding strategy and these reducing proteolytic degradation methods, a maximum biomass of 96 g DCW/l, a maximum concentration of 2.0 g/L, and an activity of 1302.2 U/mL ROL were attained. The simple culture process is the highest level of ROL expression reported in P. pastoris. Our results strongly demonstrate that the efficiency of the recombinant ROL expression is directly dependent on feed strategies, lower induction temperature, maintaining the proper pH, and the addition of casein.
  • Researchpp 2881-2896Rahnama, N., Mamat, S., Md Shah, U. K., Ling, F. H., Abdul Rahman, N. A., and Ariff, A. B. (2013). "Effect of alkali pretreatment of rice straw on cellulase and xylanase production by local Trichoderma harzianum SNRS3 under solid state fermentation," BioRes. 8(2), 2881-2896.AbstractPDF
    Use of alkali-pretreated rice straw and untreated rice straw as substrates for enzyme production under solid-state cultivation was investigated. Cellulase produced from untreated rice straw showed higher activity of FPase, CMCase, β-glucosidase, and xylanase at 6.25 U/g substrate, 111.31 U/g substrate, 173.71 U/g substrate, and 433.75 U/g substrate respectively, as compared to 1.72 U/g substrate, 23.01 U/g substrate, 2.18 U/g substrate, and 45.46 U/g substrate for FPase, CMCase, β-glucosidase, and xylanase, respectively, when alkali-pretreated substrate was used. The results of the X-ray diffractogram analysis showed an increase in relative crystallinity of cellulose in alkali-pretreated rice straw (62.41%) compared to 50.81% in untreated rice straw. However, the crystalline structure of cellulose was partially disrupted after alkali pretreatment, resulting in a decrease in absolute crystallinity of cellulose. The higher the crystallinity of cellulose, the more cellulase production was induced. The structural changes of rice straw before and after alkali pretreatment were compared by using Scanning Electron Microscopy. Fungal mycelial growth was also observed for both untreated and alkali-pretreated substrates. The results of this study indicated that untreated rice straw is a better substrate for cellulase and xylanase production under solid-state fermentation with low environmental impact.
  • Researchpp 2897-2909Wang, Q., Wang, S., Li, X., and Guo, L. (2013). "Hydrogen production via acetic acid steam reforming over HZSM-5 and PdHZSM-5 catalysts and subsequent mechanism studies," BioRes. 8(2), 2897-2909.AbstractPDF
    Acetic acid (HOAc) was selected as a bio-oil model compound for the steam reforming of bio-oil for hydrogen production. The influence of temperature and steam-to-carbon ratio (S/C) on the steam reforming of HOAc over hydrogen-type Zeolite Socony Mobil-5 (HZSM-5) and the catalyst with added Pd (Pd/HZSM-5) have been investigated in a fixed-bed reactor. Brunauer–Emmett–Teller surface area measurements, scanning electron microscopy, and transmission electron microscopy were performed to characterize the texture and structure of the catalysts. Upon addition of Pd to HZSM-5, the selectivity of the products was modified and the H2 yield was greatly increased. The hydrogen yield and potential hydrogen yield from the steam reforming of HOAc were as high as 60.2% and 87.5%, respectively, under optimized reaction conditions. Both the conversion of HOAc and the H2 yield over Pd/HZSM-5 were significantly enhanced with increasing S/C ratio and reaction temperature below 600 °C, whereas the H2 yield did not significantly increase at temperatures above 600 °C. The mechanism of HOAc decomposition on the Pd(111) surface was calculated via density functional theory. The optimal decomposition route was found to be CH3COOH* → CH3CO* → CH3* + CO*.
  • Researchpp 2910-2923Yeng, C. M., Husseinsyah, S., and Ting, S. S. (2013). "Chitosan/corn cob biocomposite films by crosslinking with glutaraldehyde," BioRes. 8(2), 2910-2923.AbstractPDF
    Corn cob (CC) was used as a filler in chitosan (CS) biopolymer films. The effect of glutaraldehyde (GLA) as a crosslinking agent was studied in an effort to improve the properties of CS/CC biocomposite films prepared via solvent casting. The tensile strength and elongation at break values decreased, but the modulus of elasticity increased with CC content. However, the tensile properties of CS/CC biocomposite films improved when modified with GLA. The Fourier transform infrared (FTIR) results indicated the presence of imine bonds (C=N) and ethylenic groups due to the cross-linking reaction between CS and GLA. The thermal stability of CS/CC biocomposite films reduced with increasing CC content. The modification of CS/CC with GLA enhanced the thermal stability of the biocomposite films. Moreover, the wettability and adhesion of the CC-CS system were enhanced by modification with GLA, as demonstrated by a morphological study. The crosslinking agent glutaraldehyde positively affected the tensile strength, modulus of elasticity, and thermal stability of the biocomposite films.
  • Researchpp 2924-2933Abia, J. A., and Ozer, R. (2013). "Development of polyoxometalate-ionic liquid compounds for processing cellulosic biomass," BioRes. 8(2), 2924-2933.AbstractPDF
    A unique approach was used in which polyoxometalate-based ionic liquids (POM-IL) were synthesized and employed for the one-pot dissolution and conversion of biomass. A library of four functional POM-IL compounds was synthesized using two cationic organic groups (1-butyl-3-methylimidazolim and 1-ethyl-3-methylimidazolium) and two anionic POMs (phosphotungstate and tungstosilicate). The POM-IL compound serves a dual-purpose. First, it dissolves approximately 30 wt% of cellulosic biomass in 2 h at 200 °C. Second, analysis using HPLC confirmed that the POM-ILs catalyze conversion of biomass into commodity monosaccharides such as glucose and xylose. All of the prepared POM-IL compounds demonstrated dynamic thermal stabilities exceeding 300 °C and were characterized using IR and thermogravimetric analysis.
  • Researchpp 2934-2949Elenga, R. G., Djemia, P., Tingaud, D., Chauveau, T., Maniongui, J. G., and Dirras, G. (2013). "Effects of alkali treatment on the microstructure, composition, and properties of the Raffia textilis fiber," BioRes. 8(2), 2934-2949.AbstractPDF
    The Raffia textilis fiber has a specific strength of 660 MPaŸcm3/g and scales and hollows on its surface. Thus, this fiber is a potential composite reinforcement. The objective of this study was to evaluate the effect of alkaline treatment at room temperature on its microstructure, structure, composition, thermal behavior, mechanical properties, and color. To this end, slack raw fibers were soaked in three NaOH solutions (2.5%, 5%, and 10% by weight) for 12 hours. SEM observations revealed that fibers got more and more clean and smooth when the solution concentration was increased. In comparison with the raw fiber, it was found that fiber treated with 5% NaOH solution exhibited enhanced tensile strength (129%) and strain to failure (175%), in addition to increased yellowness, redness, and thermal stability. Contrariwise, the Young modulus and lightness slightly decreased with the treatment. The Fourier transform infrared spectra and the XRD patterns suggested an incipient allotropic transformation of cellulose for 10% NaOH-treated fibers. These changes could be explained by the gradual dissolution of non-cellulosic components as revealed by the Fourier transform infrared attenuated total reflection spectra and thermal analysis.
  • Researchpp 2950-2966Hesas, R. H., Arami-Niya, A., Wan Daud, W. M. A., and Sahu, J. N. (2013). "Preparation and characterization of activated carbon from apple waste by microwave-assisted phosphoric acid activation: Application in methylene blue adsorption," BioRes. 8(2), 2950-2966.AbstractPDF
    Activated carbons (ACs) prepared from apple pulp and apple peel with phosphoric acid as an activation agent under microwave radiation were investigated. The effects of microwave radiation power and time on the adsorption capacities of the ACs were studied. The optimum AC preparation condition was identified by comparing the MB adsorption capacities of the produced ACs. The obtained results show that the microwave radiation power and time had strong effects on the adsorption capacities. Relative to conventional heating methods, microwave-prepared ACs showed higher BET surface areas and mesopore volumes after a shorter activation time due to differences in the type of heat transfer between these two methods. The N2 adsorption isotherms at −196°C and SEM and FTIR results were used to characterize the properties of the prepared ACs. The N2 adsorption results revealed BET surface areas of 1552 m2/g and 1103 m2/g for apple-peel and apple-pulp-based AC, respectively.
  • Researchpp 2967-2980Lourenço, A., Gominho, J., Marques, A. V., and Pereira, H. (2013). "Comparison of Py-GC/FID and wet chemistry analysis for lignin determination in wood and pulps from Eucalyptus globulus," BioRes. 8(2), 2967-2980.AbstractPDF
    The kraft pulps produced from heartwood and sapwood of Eucalyptus globulus at 130 ºC, 150 ºC, and 170 ºC were characterized by wet chemistry (total lignin as sum of Klason and soluble lignin fractions) and pyrolysis (total lignin denoted as py-lignin). The total lignin content obtained with both methods was similar. In the course of delignification, the py-lignin values were higher (by 2 to 5%) compared to Klason values, which is in line with the importance of soluble lignin for total lignin determination. Pyrolysis analysis presents advantages over wet chemical procedures, and it can be applied to wood and pulps to determine lignin contents at different stages of the delignification process. The py-lignin values were used for kinetic modelling of delignification, with very high predictive value and results similar to those of modelling using wet chemical determinations.
  • Researchpp 2981-2997Li, C., Yang, X., Zhang, Z., Zhou, D., Zhang, L., Zhang, S., and Chen, J. (2013). "Hydrothermal liquefaction of desert shrub Salix psammophila to high value-added chemicals and hydrochar with recycled processing water," BioRes. 8(2), 2981-2997.AbstractPDF
    Bio-oil and hydrochar were produced through the hydrothermal liquefaction (HTL) of Salix psammophila (SP) branch residues with recycled processing water, in order to address the lack of water in deserts or sandy lands and the difficulty of water treatment in a batch reactor. The results indicated that the recycling of the HTL processing water could significantly improve the yield of bio-oil from 30.3% to 46.9%. The gas chromatography and mass spectrometry analyses of the obtained bio-oil confirmed the presence of value-added chemicals, such as phenolics, acetic acid, and furans. The acetic acid in the processing water played a key role in the HTL. The heavy oil had a high content (maximum of 42.7 wt%) of the low boiling point fraction (<300 °C), indicating its potential for further applications. The higher heating value of the hydrochar was about 27 MJ/kg, equivalent to the heating value of medium-rank and high-rank coals. These results show that HTL using recycled processing water has great potential for utilization of desert biomass wastes.
  • Researchpp 2998-3016Kittikorn, T., Strömberg, E., Ek, M., and Karlsson, S. (2013). "Comparison of water uptake as function of surface modification of empty fruit bunch oil palm fibres in PP biocomposites," BioRes. 8(2), 2998-3016.AbstractPDF
    Empty fruit bunch oil palm (EFBOP) fibres were surface modified by four different methods, propionylation, vinyltrimethoxy silanization, PPgMA dissolution modification, and PPgMA blending, and integrated into a polypropylene (PP) matrix. The designed biocomposites were subjected to an absorption process at different temperatures. Their water uptake behaviour was compared with the unmodified fibre biocomposites. An increased fibre content and temperature resulted in increased water uptake for all of the biocomposites. The biocomposites containing modified fibres showed a reduction in water uptake, rate of diffusion, sorption, and permeation in comparison with unmodified fibre composites. Comparing the 20 wt% fibre composites at ambient temperature, the performance in water absorption followed the sequence silanization < propionylation < PPgMA dissolution modification < PPgMA blending < no modification. Furthermore, the lowest water absorption was obtained from the silanized fibre/PP composite with 40% fibre content at ambient temperature. Dissolution or blending of PPgMA gave similar water uptake results. The reduction of diffusion, sorption, and permeation confirmed that the modification of fibres was potentially effective at resisting water penetration into the composites.
  • Researchpp 3017-3026Wang, W., Liu, J., Zhuang, X., Qi, W., Yu, Q., Wang, Q., and Yuan, Z. (2013). "Reuse of enzymatic hydrolyzed residues from sugarcane bagasse to cultivate Lentinula edodes," BioRes. 8(2), 3017-3026.AbstractPDF
    In the conversion process of lignocellulose into fuel ethanol, the enzymatic hydrolyzed or fermented lignocellulosic residues are produced as byproducts. In order to further recycle these byproducts, this study used the enzymatic hydrolyzed residues of sugarcane bagasse (EHR-SCB) as the media for culturing Lentinula edodes. The sugarcane bagasse (SCB), pretreated by liquid hot water (LHW), was hydrolyzed for 120 h with cellulase to obtain the EHR-SCB. The EHR-SCB was mixed with wheat bran and gypsum powder in a certain proportion to make six kinds of media. The media containing 50% and 60% EHR-SCB could cultivate Lentinula edodes, due to their rational ratio of carbon to nitrogen and mineral contents. Compared with Lentinula edodes sold in the market, the one cultured in the medium containing 50% EHR-SCB had a little higher content of amino acids except cysteine and proline, and mineral elements except zinc, while that cultured in the medium containing 60% EHR-SCB had a lower content of amino acids except serine, glutamic acid, glycine, methionine, tyrosine, and arginine, and mineral elements except selenium, copper, chromium, and manganese. After harvesting Lentinula edodes, the mushroom residues might be further used as media for obtaining value-added products or composting for manure.
  • Researchpp 3027-3037Stajić, M., Vukojević, J., Knežević, A., and Milovanović, I. (2013). "Influence of trace elements on ligninolytic enzyme activity of Pleurotus ostreatus and P. pulmonarius," BioRes. 8(2), 3027-3037.AbstractPDF
    Trace elements, at tolerable concentrations, are either part of the active site or act as an activity modulator of ligninolytic enzymes of white-rot mushrooms. They are usually in plant raw materials in a non-toxic amount or non-available and extractable forms. This study evaluated the effects of Fe, Zn, and Se on the activity of laccase and Mn-oxidizing peroxidases of P. ostreatus and P. pulmonarius during solid-state fermentation of grapevine sawdust. The studied species showed different levels of tolerance to the trace elements. A stimulatory effect of the microelements on laccase activity was demonstrated in P. ostreatus, while Fe and Zn were strong inhibitors of the activity of P. pulmonarius, which was contrary to Se, independent of the cultivation period. With the exception of SeO2, activity of Mn-oxidizing peroxidases in P. ostreatus was suppressed in various levels by the elements. However, in P. pulmonarius, activity against phenol red oxidation in the presence of external Mn2+ was stimulated by the elements on day 7, while on day 10, activity inhibition by Fe and Zn and stimulation by Se was noted. The effect on activity against phenol red oxidation in the absence of external Mn2+ was the opposite.
  • Reviewpp 3038-3097Hubbe, M. A., Rojas, O. J., Fingas, M., and Gupta, B. S. (2013). "Cellulosic substrates for removal of pollutants from aqueous systems: A Review. 3. Spilled oil and emulsified organic liquids," BioRes. 8(2), 3038-3097.AbstractPDF
    Water-insoluble oils, including crude petroleum and a wide variety of refined organic liquids, can cause major problems if spilled or leaked to aqueous environments. Potential environmental damage may be reduced if the spilled oil is promptly and efficiently removed from the water. This article reviews research that sheds light on the use of cellulose-based materials as sorbents to mitigate effects of oil spills. Encouraging results for oil sorption have been reported when using naturally hydrophobic cellulosic fibers such as unprocessed cotton, kapok, or milkweed seed hair. In addition, a wide assortment of cellulosic materials have been shown to be effective sorbents for hydrocarbon oils, especially in the absence of water, and their performance under water-wet conditions can be enhanced by various pretreatments that render them more hydrophobic. More research is needed on environmentally friendly systems to handle oil-contaminated sorbents after their use; promising approaches include their re-use after regeneration, anaerobic digestion, and incineration, among others. Research is also needed to further develop combined response systems in which biosorption is used along with other spill-response measures, including skimming, demulsification, biodegradation, and the use of booms to limit the spreading of oil slicks.
  • Reviewpp 3098-3121Paunonen, S. (2013). "Strength and barrier enhancements of cellophane and cellulose derivative films: A Review," BioRes. 8(2), 3098-3121.AbstractPDF
    Cellulose derivatives, i.e. cellulose functionalized in a solvent state with various side groups, are an important source of biomaterials for food packaging. This review considers the following materials: i) cellophane, ii) cellulose acetate, iii) methylcellulose, and iv) carboxymethylcellulose. Mechanical and barrier properties are important for freestanding packaging films as well as for coatings. The potential of the selected cellulose derivatives and cellophane is thus examined from the viewpoint of their tensile properties as well as their moisture and oxygen barrier properties. The capacity of microcrystalline cellulose and nano-sized celluloses to reinforce the films and to help impede gas diffusion is examined for microfibrillar celluloses, nanocrystalline celluloses, and whiskers. Very good oxygen barrier properties have been reported for cellophane. Nanocellulose fillers have regularly been shown to enhance the tensile properties of several cellulose derivatives, but the effects on the water vapor permeability (WVP) have been studied less often.
  • Reviewpp 3122-3135Naylor, A., and Hackney, P. (2013). "A review of wood machining literature with a special focus on sawing," BioRes. 8(2), 3122-3135.AbstractPDF
    In this review, fundamental wood machining research is evaluated to determine the general cutting mechanics of simple, orthogonal, and oblique cutting tools. Simple tool force trends and chip formation characteristics are indentified here, along with the cause and effects of tool wear. In addition to this, specific methods of evaluating sawing processes have been investigated. These include the use of piezoelectric dynamometers to record tool forces and high speed photography to evaluate chip formation. Furthermore, regression analysis has been previously used to identify tool force trends with respect to both tooth geometry parameters and work-piece properties. This review has identified the original findings of previous research. This will allow for further original research to be conducted.
  • Reviewpp 3136-3156Dungani, R., Jawaid, M., Abdul Khalil, H. P. S., Jasni, Aprilia, S., Hakeem, K. R., Hartati, S., and Islam, M. N. (2013). "A review on quality enhancement of oil palm trunk waste by resin impregnation: Future materials," BioRes. 8(2), 3136-3156.AbstractPDF
    Oil palm trunk (OPT) is a solid waste obtained in large quantities after the felling of oil palm trees and is available year-round. Scientists and industrialists face difficulties in utilizing these solid wastes for different applications due to great variations in their physical and mechanical properties. Because OPT consists of lignocellulosic materials, its cellulosic material is utilized in the production of panel products such as particleboard, medium density fibreboard, mineral-bonded particleboard, block board, and cement board. In order to control the OPT waste, it is essential to consider its alternative utilization inside buildings as lightweight construction materials and furniture. The impregnation of different resins in wood and non-wood materials can improve the quality of the OPT, making it possible to utilize OPT as raw materials for different applications. The enhanced properties and good appearance of impregnated OPT have found use in high-grade furniture and housing materials. In order to further evaluate its potential, this review has been compiled for the detailed study of various properties, characteristics, and applications of OPT.
  • Reviewpp 3157-3176Iqbal, H. M. N., Kyazze, G., and Keshavarz, T. (2013). "Advances in the valorization of lignocellulosic materials by biotechnology: An overview," BioRes. 8(2), 3157-3176.AbstractPDF
    In view of the worldwide economic and environmental issues associated with the extensive use of petro-chemicals, there has been increasing research interest during the past decade in the value of residual biomass. Because of its renewable nature and abundant availability, residual biomass has attracted considerable attention as an alternate feedstock and potential energy source. To expand the range of natural bio-resources, significant progress related to the lignocellulose bio-technology has been achieved, and researchers have been re-directing their interests to biomass-based fuels, ligninolytic enzymes, chemicals, and biocompatible materials, which can be obtained from a variety of lignocellulosic waste materials. This review article focuses on the potential applications of lignocellulosic materials in biotechnology, including the production of bio-fuels, enzymes, chemicals, the pulp and paper, animal feed, and composites.