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BioResources, Volume 6, Issue 4
NOTE: Each current issue of BioResources continues to build as new articles are approved.
A challenge in producing wood-plastic composites (WPCs) with a high wood content using extrusion processes is the poor processability, which gives rise to inadequate properties of the resulting WPC. Plasticizing the stiff wood cell walls can be a strategic response to this challenge. Two thoughts are addressed herein on improving the plasticity of wood particle cell walls: use of ionic liquids or use of low molecular weight organic thermal conductors. An ionic liquid can dissolve the cell wall surface and therefore reduce the stiffness of cell wall during an extrusion process. Organic thermal conductors can be incorporated into the cell wall (bulking) to improve the thermal conductivity, thereby sufficiently softening the lignin, a native plasticizer embedded in the cell walls. The potential issues that may arise as a result of these approaches are also presented and discussed. PDF
Santos, R. B., Capanema, E. A., Balakshin, M. Y., Chang, H.-M., and Jameel, H. (2011). "Effect of hardwoods characteristics on kraft pulping process: Emphasis on lignin structure," BioRes. 6(4), 3623-3637.
In an attempt to explain variations in delignification behaviors among different hardwood species, the kraft pulping delignification rates of Eucalyptus urograndis, E. nitens, E. globulus, sweet gum, maple, red oak, birch, red alder, cottonwood, and acacia were obtained and correlated with their respective lignin chemical structures. Since H-factor for hardwood is calculated based on the softwood activation energy (Ea) value, a comparison between softwood vs. hardwood activation energy was also performed. Lignin was isolated by a modified isolation protocol, using alkaline pretreatment of the wood prior to isolation. The lignin preparations were analyzed via quantitative 13C NMR spectroscopy. Substantial variations were found among the hardwood species studied. A linear correlation between the kraft delignification rate and the amount of syringyl units was found. Activation energy values obtained for kraft pulping of hardwoods were very similar and almost identical to the value obtained for softwood. Birch was the only species with outlier behavior. PDF
1-octadecanol is known to be a highly effective agglomerating agent for nonimpact-printing toners. However, it was found that some xerographic toners did not agglomerate under alkaline conditions. The effect of alkali on the agglomeration was studied with two different toners, one carrying no surface charge and one carrying a negative charge. The effect of the addition of a cationic surfactant on the agglomeration under neutral and alkaline conditions was then studied using two different cationic surfactants. It was found that both toners agglomerated better under neutral conditions than under alkaline conditions. The toner carrying no surface charge agglomerated much better than the toner carrying a negative charge under either alkaline or neutral conditions. The addition of a cationic surfactant greatly improved the agglomeration of the toner carrying a negative charge but had relatively small effect on that of the toner carrying no surface charge. It is recommended that agglomeration of mixed office waste with 1-octadecanol should be carried out under neutral conditions with the addition of a small amount of a cationic surfactant. PDF
The present study deals with the utilization of a cellulosic material, i.e. fungal biomass of Mucor heimalis, for the removal of cadmium from aqueous solution in a batch system. Effects of various parameters such as pH, biomass dosage, contact time, and initial metal concentrations were investigated. The sorption of cadmium followed pseudo-second-order rate kinetics (R2=0.998). Intraparticle diffusion was found not to be the sole rate-controlling step. Thermodynamic studies revealed that the sorption of cadmium was feasible, spontaneous, and exothermic. Various isotherm models viz. Langmuir, Freundlich, Redlich–Peterson, Dubinin-Radushkevich, and Temkin isotherms were applied. The Langmuir and Redlich–Peterson models were found to be in good agreement with experimental data with high R2, low RMSE, and low χ2 values. The Redlich–Peterson isotherm constant g was found to be unity, which implies a good fit to the Langmuir model. The maximum sorption capacity calculated from the Langmuir isotherm was 85.47 mg/g at optimum conditions of pH 6.0, contact time of 35 min, biomass dosage of 1g/L, and temperature of 25 oC. PDF
An inexpensive methodology is proposed to identify and locate a single defect within a wooden beam using free a flexural vibration technique. A similar approach has been introduced in the literature based on free longitudinal vibration, which was selected to be a leading frontier for the present research. The flexural vibration technique was tested for five groups of the absolutely clear specimens while holding a manually drilled hole at 0.1, 0.2, 0.3, 0.4, and 0.5 of their total span. The beams were tested in free flexural vibration with both ends in a free condition before and after drilling, and relative shifts of modal frequencies due to the presence of the defects were measured and compared to their mathematically calculated values in a sinusoidal equation. Using the method of least squares, a coincidence factor was developed based on the differences of the measured and calculated shifts of the four initial resonance frequencies where the minimum district of the coincidence factor curves successfully indicated the defected area. Though the longitudinal vibration approach was promising enough to estimate the position of the defect, its combination with the flexural vibration might increase the degree of confidence in the identifications. PDF
In this work the multi-factor, non-linear dependencies between main (tangential) FC (N) and normal (radial) FN (N) cutting forces and eight machining parameters by sawing simulation of wood of Pinus sylvestris L. were evaluated. The relationships are graphically illustrated and discussed. Evidence of several contradictions was found relative to results from available literature. PDF
Santiagoo, R., Ismail, H., and Hussin, K. (2011). "Mechanical properties, water absorption, and swelling behaviour of rice husk powder filled polypropylene/recycled acrylonitrile butadiene rubber (PP/NBRr/RHP) biocomposites using silane as a coupling agent," BioRes. 6(4), 3714-3726.
The performance of rice husk powder (RHP) filled polypropylene (PP)/ recycled acrylonitrile butadiene rubber (NBRr) biocomposites with and without coupling agent, γ-aminopropyltrimethoxysilane (APS), were investigated. The composites with different RHP filler loading (0 to 30 phr) were prepared in a Haake internal mixer. Mechanical properties, swelling behavior, and water absorption of PP/NBRr/RHP were studied. Increasing RHP loading in PP/NBRr/RHP biocomposites increased processing torque, tensile modulus, water absorption, and swelling in oil but decreased the tensile strength and elongation at break of the biocomposites. The γ-APS treated RHP composites exhibited higher processing torque, tensile strength, and tensile modulus but lower elongation at break when compared to untreated RHP composites. This is due to strong bonding between γ-APS treated RHP filler and PP/NBRr matrices. These findings were well supported by micrographs from the morphology studies. The γ-APS treatment on RHP improved the adhesion between RHP fiber and PP/NBRr polymer matrices, which led to less water and oil absorption into PP/NBRr/RHP/ biocomposites. PDF
Rapeseed waste from biodiesel production was explored as a biosorbent for the removal of Cu(II) and Cd(II) ions from aqueous solutions under batch conditions. The optimum value of the initial pH for the sorption of both metal ions was found to be 4.5 to 5. The efficiency of Cu(II) and Cd(II) removal from aqueous solutions varied from 49% to 91% and from 61% to 97%, respectively, by increasing the rapeseed waste dose from 5 to 30 g L-1. According to the evaluation using the Langmuir equation, the monolayer sorption capacity of copper (II) and cadmium (II) ions on rapeseed waste was found to be 15.43 mg g-1 and 21.72 mg g-1, respectively at 293 K. The batch sorption systems under study were thermodynamically characterized by means of parameters such as ΔG, ΔH, and ΔS. The kinetic parameters derived from the pseudo-first-order and pseudo-second-order equations were calculated and compared. PDF
Ismail, H., Omar, N. F., and Othman, N. (2011). "The effect of kenaf fibre loading on curing characterisitics and mechanical properties of waste tyre dust/kenaf fibre hybrid filler filled natural rubber compounds," BioRes. 6(4), 3742-3756.
Waste tyre dust (WTD)/kenaf fibre (Ke) hybrid filler filled natural rubber (NR) compounds having constant 30 phr loading were prepared with increasing partial replacement of WTD by kenaf fibre at 0, 10, 15, 20, and 30 phr. Curing characteristics, mechanical properties, rubber-fibre interaction, and morphology of the NR compounds were studied after the compounds were obtained. The curing characteristics such as t2 and t90 increased with increment of kenaf fibre loading. For MHR, the increasing partial replacement of WTD by kenaf fibre showed increasing MHR value. For tensile properties, the value of tensile strength and elongation at break value decreased with increasing kenaf fibre loading. The values of M100 and M300 increased but then decreased after the addition of 15 phr of kenaf fibre loading. Besides, fatigue life value also showed a decreasing trend with increasing kenaf fibre loading. For rubber-fibre interaction, the values of Qf/Qg showed a small increment with increasing kenaf fibre loading. The SEM micrographs obtained for fractured surface of WTD/kenaf fibre hybrid filled NR compounds supported the results for the mechanical properties. PDF
Environmentally friendly polyurethane (PU) spray foam insulation was prepared by substituting petrochemical polyol with soy-based polyol. The effects of adding wood fiber and water on the cell morphologies were studied. Cell size increased with the presence of wood fiber, but it decreased with an increase of water (H2O). Still, shorter fiber decreased in foam density but increased in cell size and open cell content. PDF
Bio-based polyurethane (PU) spray foam insulation was prepared with soy polyol. The effects of adding wood fiber and water on the thermal and mechanical properties of the insulations were studied. The decomposition temperature (Td) of the foams increased with fiber reinforcement due to a higher degree of crosslinking. Alternatively, different fiber length contributed to different crosslinking. In addition, the neat foams, which didn’t contain wood fibers, had exceptional thermal stability with the increase of the amount of H2O by forming more stable polyurea adducts. In addition, PU spray foam blown with a larger content of H2O had higher compressive strength by forming a stiffer phase. Still, PU spray foam reinforced with fiber also had superior compressive strength due to the fiber framing into the foam struts. The effect of the fiber length on the compressive strength was evaluated. The degree of complex networks was influenced by the fiber length. However, the tensile strength was weakened with the addition of wood fiber. PDF
Kang, L., Wang, W., Pallapolu, V. R., and Lee, Y. Y. (2011). "Enhanced ethanol production from de-ashed paper sludge by simultaneous saccharification and fermentation and simultaneous saccharification and co-fermentation," BioRes. 6(4), 3791-3808.
A previous study demonstrated that paper sludges with high ash contents can be converted to ethanol by simultaneous saccharification and fermentation (SSF) or simultaneous saccharification and co-fermentation (SSCF). High ash content in the sludge, however, limited solid loading in the bioreactor, causing low product concentration. To overcome this problem, sludges were de-ashed before SSF and SSCF. Low ash content in sludges also increased the ethanol yield to the extent that the enzyme dosage required to achieve 70% yield in the fermentation process was reduced by 30%. High solid loading in SSF and SSCF decreased the ethanol yield. High agitation and de-ashing of the sludges were able to restore part of the yield loss caused by high solid loading. Substitution of the laboratory fermentation medium (peptone and yeast extract) with corn steep liquor did not bring about any adverse effects in the fermentation. Fed-batch operation of the SSCF and SSF using low-ash content sludges was effective in raising the ethanol concentration, achieving 47.8 g/L and 60.0 g/L, respectively. PDF
The performance of a newly developed pilot scale continuous enzymatic deinking system has been evaluated using a mixture of cellulase and xylanase enzymes in the deinking of mixed office wastepaper (MOW) and old newspaper (ONP). Optimizations of the enzymatic deinking processes were carried out, and the optimum conditions obtained for MOW and ONP were different. The highest brightness obtained from enzymatic deinking of MOW and ONP under their respective optimum conditions were about 83.6% and 41.9%, respectively. The deinking efficiency of 6.0% and 6.3% were obtained by enzymatic deinking process using MOW and ONP, respectively. On the other hand, the deinking efficiency of 2.9% and 3.5% were obtained by a chemical deinking process using MOW and ONP, respectively. The findings obtained from present work indicated that enzymes have potential to be used in deinking of MOW, which is difficult to deink by conventional chemical deinking methods. PDF
Juniper (Juniperus communis) is a slowly growing softwood species that has unusually high elasticity. To demonstrate the utilization of the material properties of juniper, conventional kraft pulping was used to prepare juniper pulp, whose handsheet and fiber properties were subsequently analyzed. A large number of uncooked fiber bundles remained after pulping, the screened yield was low, and kappa number high. Also the viscosity value of juniper pulp was lower than that of common industrial softwood pulps, due to the harsh pulping conditions required. Juniper fibres had thicker cell walls, smaller diameters, and shorter lengths than those of the more conventional softwood species, while the microfibril angle, which was measured by X-ray diffraction, was significantly higher (22-37°). Moreover, the strength properties of juniper pulp handsheets were lower than those of common softwood pulps. The intriguing elastic properties of juniper wood, however, were apparent in the handsheet properties. Tensile stiffness was determined to be merely half of the value typical for softwood pulps, whereas the breaking stretch was more than twice higher. Although a large-scale industrial use of juniper is not possible, one can speculate that it may be feasible to mimic its properties via transgenic modification to faster growing species. PDF
Ghali, L., Aloui, M., Zidi, M., Bendaly, H., M'sahli, S., and Sakli, F. (2011). "Effect of chemical modification of Luffa cylindrica fibers on the mechanical and hygrothermal behaviours of polyester/luffa composites," BioRes. 6(4), 3836-3849.
Effects of surface chemical modifications of luffa fibers on mechanical and hygrothermal behaviors of polyester/luffa composites were studied. Unsaturated polyester resin was used as matrix. Untreated, alkali-treated, treated with combined process, and acetylated luffa fibers were used. Scanning electron microscopy and infrared spectroscopy were used to characterize the morphology and chemical structure of the luffa fibers. The mechanical properties of the composites were characterized using the three-point flexural bending test. Water absorption tests were conducted on both the fibers and the composite materials by immersion in distilled water at 25°C. The acetylation treatment improved the mechanical properties. As shown by infrared analysis, the process decreased the hydrophilic behaviour of the luffa fibers, improving their adhesion to the polyester matrix. The chemical modifications at the surface of the luffa fibers also decreased the diffusion coefficient and the maximum amount of water absorbed by these fibers. Moreover, it was observed that for the fibers tested in this study, the diffusion process was “Fickian” at earlier times of immersion, but became complicated towards the end of the immersion. Similar results have been obtained for composite materials at earlier stages of water immersion. The diffusion process was found to be affected by external loads applied on the exposed composite materials. As the load increased, the amount of absorbed water increased at a higher rate of diffusion. PDF
Wheat straw is a suitable raw material for ethanol production since it has high cellulose content. The objective of this work was to evaluate the effect of cellobiase and surfactant on the enzymatic hydrolysis of lignocellulosic materials. For this purpose, wheat straw was first pretreated by organosolv digestion. The chemical composition s of raw and pretreated wheat straw were analyzed. Much of the hemicellulose and lignin were removed, and the relative cellulose content of pretreated wheat straw was 26.57% higher when compared to untreated wheat straw. Cellobiase was added into hydrolysate to improve the hydrolysis efficiency. Through experiments and analysis, the optimum cellobiase dosage was found to be 1/10 of the cellulase loading. Surfactant was also added into hydrolysate. Nonionic surfactant (Tween 80) exhibited better effect on improving enzymatic hydrolysis. When 0.06 g/g dry solids (DS) Tween 80 was also added into hydrolysate, the yield of glucose in hydrolyzate could reach 486 g/kg DS. PDF
Lee, C. K., Ibrahim, D., Ibrahim, C. O., and Wan Rosli, W. D. (2011). "Enzymatic and chemical deinking of mixed office wastepaper and old newspaper: Paper quality and effluent characteristics," BioRes. 6(4), 3859-3875.
Enzymatic and chemical deinking not only significantly influence the optical and mechanical properties of deinked paper, but also influence the pulp properties and wastewater effluent generated. Both enzymatic and chemical deinking of mixed office wastepaper (MOW) and old newspaper (ONP) showed improvement in brightness (1.4-4.7 units), tensile index (1-14%), burst index (1.2-3.8%), freeness (1.9-2.9%), and residual ink removal (31.1-51.2%) but caused loss in opacity (0.1-2.6%) and tear index (0.1-9.6%). Chemical Oxygen Demand (COD) analysis indicated that effluent produced from enzymatic deinking were about 33.9% and 33.8% lower compared to chemical deinking of ONP and MOW, respectively. Meanwhile, Biological Oxygen Demand (BOD5) obtained from enzymatic deinking of MOW and ONP were 47.1% and 39.3% lower compared to the chemical deinking process, respectively. The results obtained in this work demonstrated that the quality of the pulp and paper obtained from enzymatic deinking process was better than that from the chemical deinking process. This suggests that enzymatic deinking has high potential as an alternative to the chemical method. PDF
Singh, S., Dutt, D., and Tyagi, C. H. (2011). "Environmentally friendly totally chlorine free bleaching of wheat straw pulp using novel cellulase-poor xylanases of wild strains of Coprinellus disseminatus," BioRes. 6(4), 3876-3882.
Cellulase-poor crude xylanases of Coprinellus disseminatus, strains SH-1 NTCC 1163 (enzyme-A) and SH-2 NTCC 1164 (enzyme-B) produced under optimum conditions of solid-state fermentation (SSF), were used in bio-bleaching of wheat straw soda-AQ pulp in totally chlorine free (TCF) bleaching sequences. Kappa number reductions of 56% and 58% with respect to oxygen-delignified pulps were obtained after the sequences OXAE and OXBE, respectively. Significant increases in pulp brightness of 6.07% (enzyme-A) and 3.34% (enzyme-B) with slight decreases in some strength properties (due to the removal of hemicelluloses) were observed. Removal of hemicelluloses was further validated by an increase in pulp viscosity (6.07%, and 4.58%), COD (40%, and 38%), and facilitation of lignin removal, as indicated by colour values (48% and 45%) for OXAEQPP and OXBEQPP bleached pulps, respectively, over the control. Crude xylanases from C. disseminatus SH-1 NTCC 1163 and SH-2 NTCC 1164 can successfully be used for TCF bleaching of pulps owing to their high temperature and pH toleranance, and cellulase-poor nature, thus adding to the search for environment-friendly bleaching solutions for the pulp and paper industry. PDF
According to the Energy Information Administration two fifths of the energy used by US wood products manufacturers comes from electricity and natural gas, the costs of which have pointedly increased over the last decade. Empirical indications exist that higher energy prices affect the industry’s profitability. Together with other developments such as, for example, unfavorable trends in hardwood stumpage prices, higher transportation costs, increasing government regulations, a challenging economic situation, or the ongoing globalization of markets, the US hardwood industry has to cope with some serious challenges threatening its profit potential. To understand the impact of energy prices on wood products manufacturers’ profitability and to gain insights regarding actions the industry is taking to respond to energy-related challenges, a survey was conducted among Eastern US primary hardwood products manufacturers in late 2010. Results show that, overall, the share of energy expenses on total production costs of respondents was 7.9%. A majority of respondents (61.8%) agreed that their energy expenses have increased by an average of 18.7% during the last five years. Half of the respondents reported a 5% or higher negative impact of higher energy prices on their profits over the same period. Actions undertaken by the industry to alleviate the negative impact of rising energy prices are presented in a second paper in this two-part series. PDF
This second manuscript in the series about energy and the US hardwood industry reports results from research investigating the impact of energy prices on the US hardwood industry. The manuscript focuses on actions by the industry to improve energy performance. Most companies (63 percent) indicated that they are focusing on improving energy efficiency and/or improving productivity (41.3 and 41.9%, respectively) to cope with rising energy prices; however, only 8.6% of the survey respondents indicated that they have established energy usage baselines and energy performance indicators. Sixty-seven percent of companies indicated that they are training employees on energy saving issues. Other common initiatives for energy costs reductions were installing more efficient lighting, acquiring new high energy-efficient equipment, and measures to reduce the wastage of energy, like switching off high energy consuming equipment or close off or lit off sections with no traffic. PDF
The U.S, Forest Service regularly removes tons of dead biomass from federal forestlands to control and prevent devastating wildfires. Every year thinning young trees and brush, as well as removing dead biomass from the forest floor generates large quantities of low-grade woody material for which there is little use. Currently this biomass is either burned on-site, or at facilities to generate electricity. Finding a sustainable long-term utilization scheme for this material may generate a steady demand for this material and improve the economics of fire prevention. In this project the feasibility of substituting non-renewable materials currently used in a wide variety of highway infrastructure products, with sustainable composites utilizing low-grade woody biomass is investigated as potential alternative to burning. Devices such as traffic signs, road markers, and guardrails are installed on public roadways in high volumes. Until now, there have been no clear guidelines established for systematically assessing the viability of full or partial material substitution with more sustainable alternatives. A conceptual framework is presented, outlining necessary input information, inquiries, practical steps, and decision points necessary to determine if material substitution in a product or its individual components is viable. This procedure can assist entrepreneurs and small-scale businesses willing to enter the market, and provide opportunities in rural regions affected by the decline in the forest products industry. The application of this procedure is demonstrated on three selected highway products. Potential benefits to the environment, the economy, and local communities are discussed. PDF
Yapıcı, F., Uysal, B., Kurt, Ş., Esen, R., and Özcan, C. (2011). "Impacts of impregnation chemicals on finishing process and combustion properties of oriental beech (Fagus orientalis L.) wood," BioRes. 6(4), 3933-3943.
Effects of the impregnation materials borax, boric acid, and Tanalith-E on combustion properties of Oriental beech (Fagus orientalis Lipsky) were investigated. The immersion method was used for long-term impregnation (24 h). After the impregnation process, polyurethane as well as synthetic, acid hardening, and water-based varnishes were applied on the wood sample surfaces according to company’s suggests. The combustion test was performed according to the ASTM-E 69 standard. The mass reduction, release of gasses (CO, NO, O2), and the temperature differences of samples were determined for each 30 seconds during combustion. It was shown that the most mass reduction occurred when both polyurethane varnish and boric acid were applied. PDF
Ma, J., Zhang, Z., Yang, G., Mao, J., and Xu, F. (2011). "Ultrastructural topochemistry of cell wall polymers in Populus nigra by transmission electron microscopy and Raman imaging," BioRes. 6(4), 3944-3959.
The topochemical distribution of lignin and cellulose in individual cell wall layers of Populus nigra stem was determined by transmission electron microscopy (TEM) and confocal Raman microscopy. TEM images exhibited the fiber wall as being typically differentiated into three layers: middle lamella (ML), primary wall (P), and secondary wall (S1, S2, and S3). Higher magnification views showed the S2 layer to be differentiated into electron lucent and dense areas in the radial direction. In situ Raman images calculated by integrating over the intensity of characteristic spectral bands enabled visualization of the spatial variation in lignin and cellulose. Raman images acquired by integrating over the spectral band at 1605 cm-1 suggested that higher lignin content was visualized in the cell corner (CC), the compound middle lamella (CML), and the secondary wall of ray parenchyma. Cellulose distribution followed by taking the band regions around 2897 cm-1 into account showed the opposite pattern, with the highest content in fiber secondary wall. The SEM-EDXA provided semi-quantitative results, showing that the lignin content ratio in various cell wall layers was 1.4 (CC):1.1(CML):1(S2). PDF
The bark of black spruce was thermo-mechanically refined and used to manufacture binderless bark-based fiberboard with various pressing temperatures, times, and panel structures in order to utilize an abundant bark resource for a better value-added application. The test results indicated that it is technically feasible to manufacture binderless fiberboard with refined black spruce bark through self-bonding under elevated temperatures over a reasonable period of pressing time. Binderless bark-based fiberboards with a homogeneous structure had very poor flexural properties due to the poor strength of bark itself; however, by using a sandwich structure with 30wt% wood fiber in the surface layers and 70wt% bark in the core layer it was possible to sufficiently improve panel flexural properties so that the manufactured binderless bark-based fiberboards was able to meet the mechanical property requirements of 115-grade fiberboard according to ANSI A208.2 (2009). Refining conditions had a great impact on the mechanical properties of binderless bark-based fiberboard. PDF
Jamalirad, L., Doosthoseini, K., Koch, G., Mirshokraie, S. A., and Hedjazi, S. (2011). "Physical and mechanical properties of plywood manufactured from treated red-heart beech (Fagus orientalis L.) wood veneers," BioRes. 6(4), 3973-3986.
Effects of drying temperature and artificial UV irradiation on the pH of veneer surfaces, water absorption, thickness swelling, as well as shear strength of plywood manufactured from untreated and treated veneer sheets were evaluated. Rotary cut veneer sheets from beech (Fagus orientalis Lipsky) log were selected. The veneer sheets were dried at either 100°C or 180°C after peeling. Then the surfaces were exposed to artificial UV irradiation in an UV chamber for 1, 2, and 3 days representing a natural sun irradiation of 2, 4, and 6 months, respectively. Tests by UV microspectrophotometry showed that after high temperature drying and UV irradiation treatment, lignin condensation occurs. Also with increasing drying temperature and UV irradiation duration phenolic extractives are mainly concentrated in parenchyma cells and vessel lumens. HPLC analysis of the treated tissue showed distinct signals of catechin and 2,6-dimethoxybenzoquinon, which are two chromophoric compounds in discolored red hearted beech wood. Increasing drying temperature up to 180°C improved water absorption, thickness swelling, and shear strength of plywood samples. Especially, when veneers were exposed to UV irradiation (6 months), increased water absorption and thickness swelling and decreased the shear strength of plywood samples were observed. PDF
Fly ash was collected as a byproduct from the processing of southern pine wood chips in a pilot-scale biomass gasifier. General properties of the fly ash were determined to assess its applicability as a soil amendment. Its alkaline pH (9.5) and high concentrations of Ca, K, and Mg suggest that it could be used as both a liming agent and a fertilizer. The concentrations of most heavy metals in all ash samples in this study were lower than the ecological soil screening levels used as a guideline. A sequential extraction analysis was used to evaluate the bioavailability of selected nutrient elements and pollutant heavy metals in the fly ash. Most nutrient elements were present in exchangeable/acid extractable and easily reducible fractions. The heavy metals were generally less bioavailable, thus ameliorating concerns for land application of fly ash, with or without prior combustion. Comparison of sequential extraction test results for all of the ashes indicated that the conditions experienced during gasification, such as high processing temperatures, impacted both the total heavy metal concentrations and their potential bioavailabilities. PDF
Preliminary tests of a new hydrogen peroxide bleaching procedure for mechanical pulps were performed in a bleaching medium comprised of water and an alcohol, which is characterized by good miscibility with water, poor solvency for hemicelluloses, and good solvency for lignin. As compared with a conventional bleaching method, this modified process is aimed at reducing the removal of hemicelluloses while moderately increasing the dissolution of lignin. Results showed that an aspen CTMP pulp can be bleached to a target brightness with less bleaching chemicals and/or with a higher pulp yield. The laboratory studies demonstrate that this new bleaching process offers substantially enhanced efficiency and selectivity over the conventional peroxide bleaching. Overall, the brightness increased by about 5 ISO units for a given peroxide consumption and the yield increased by 2 to 3 percent at the same target brightness. PDF
Trees in two provenance-progeny experimental sites of Pinus brutia Ten. were sampled to study variation in wood density and its components among and within six populations and to estimate heritability of wood density and ring components. Wood increment cores (12 mm thick) were collected from 29-year-old trees at breast height. A total of 1023 wood strips were scanned with the X-ray densitometry technique. There were significant differences among populations and among families (within populations) in all the characters studied. Murtbeli (M) population from the middle altitude (486 m asl) had the highest values in both ring-area-weighted density and late wood proportion (500 ± 2.7 kg/ m3 and 49 ± 0.3 %, respectively), whereas Hacibekar (H) population from the highest altitude (1032 m asl) exhibited the lowest values (468 ± 3.0 kg/ m3, 42 ± 0.3 %). Relatively high heritability values (hi2 between 0.45 and 0.74; hhs2 between 0.68 and 0.80) for investigated characters (except latewood density) suggest that these characteristics are under moderate to strong genetic control, and thus, by selecting populations (and families within populations) having high wood density, genetic improvement can be achieved in P. brutia. Correlations between wood density and other growth traits have indicated that simultaneous selection of desired genotypes for most of the wood density components is possible for the species. Latewood percentage and earlywood density present an optimal target for selection to improve wood density. PDF
Marashdeh, M. W., Hashim, R., Tajuddin, A. A., Bauk, S., and Sulaiman, O. (2011). "Effect of particle size on the characterization of binderless particleboard made from Rhizophora spp. mangrove wood for use as phantom material," BioRes. 6(4), 4028-4044.
Experimental binderless particleboards were made from various sizes of Rhizophora spp. particles. The experimental samples were made by cold pressing the particles to a target density of 1 gm/cm3. The internal bond strength and dimensional stability of the disks were evaluated based on Japanese standards. The experimental results showed that the internal bond strength and dimensional stability of the samples were enhanced as the particle size decreased. The microstructure of samples was investigated by field emission scanning electron microscopy (FE-SEM coupled with energy dispersive X-ray analysis (EDXA). An X-ray diffraction (XRD) procedure was used to study the crystalline structure of binderless particleboard samples. The results indicated that different particle size did not change the crystalline structure, but the degree of crystallinity decreased when the particle size was decreased. The profile density distribution was estimated using an X-ray computed tomography (CT) scanner. The CT results indicated that samples having smaller particle size had lower variation of density distribution profile compared with those samples made with larger particle size. Based on the overall results of this study, raw material from Rhizophora spp. wood can be used to fabricate binderless particleboard without using any adhesives, and these could be used as a phantom in a radiotherapy center. This study indicated that particle size affected the sample properties. PDF
Wang, Z., Lin, W., and Song, W. (2011). "Theoretical study of the conversion from 5-hydroxymethylfuran-2-carbaldehyde to 2-hydroxy-5-methylene-2,5-dihydro-furan-2-carbaldehyde in the levulinic acid formation process," BioRes. 6(4), 4045-4054.
A novel reaction route was proposed from 5-hydroxymethylfuran-2- carbaldehyde (HMFCA) to 2-hydroxy-5-methylene-2,5-dihydro-furan-2-carbaldehyde (HMDFC) on the basis of the mechanism previously offered by Horvat, to account for the formation mechanism of levulinic acid. The probabilities of the two mechanisms were compared by Gaussian 03 software. It was found that the conversion from HMFCA to HMDFC in the newly deduced mechanism has a lower net energy requirement than that in the original mechanism, and thus should be more preferable. The mechanism indicates that HMFCA is initially protonized by H+ addition at the position 5 of the furan ring, and then combines with OH-, thereby completing the hydration process after isomerization. Finally, an H2O molecule is released, forming the intended intermediate product of HMDFC. PDF
This study described a process of making ultra-low density fiberboard (ULDF) and investigated the properties of samples of ultra-low density fibreboard made from wood fiber using a liquid frothing approach. The fiberboard had a density of 56.3 kg/m3 and a layered cross-linked interior structure. Density profiles showed a relatively high density in the surface layers and low density in the core layer. The results showed that the fiberboard had an internal bond strength of 0.15 MPa, a modulus of rupture of 0.70 MPa, a modulus of elasticity of 8.91 MPa, and a compressive strength of 0.17 MPa at 10% deformation. Thickness swelling after 24 hours water immersion was 0.57%. It had a low thermal conductivity of 0.035 W/mK, and a high sound reduction coefficient of 0.67. Resin was uniformly distributed on the fiber surface. The fiberboard can be used as buffer material for packaging and insulation material for building. PDF
Taghiyari, H. R., Rangavar, H., and Farajpour Bibalan, O. (2011). "Effect of nano-silver on reduction of hot-pressing time and improvement in physical and mechanical properties of particleboard," BioRes. 6(4), 4067-4075.
Effects were studied of 200 ppm nano-silver suspension on physical and mechanical properties of particleboard made on an industrial scale at the Iran-Choob Factory. Nano-silver suspension was added to the mat at two levels of 100 and 150 milli-liters/kg dry weight wood particles and compared with control boards; all the other manufacturing variables remained constant. Results showed that hot-pressing time was reduced by 10.9% and 10.1% when 100 and 150 mL of nano-silver were used, respectively. Also, both levels of nano-silver consumption had improving effects on physical and mechanical properties, although in some cases not statistically significant. It can be concluded that heat-transfer property of nano-silver particles in the mat can be used to reduce the hot-press time as the bottle-neck of nearly all wood-composite factories, as well as to reduce the heat gradient and consequently to improve physical and mechanical properties of composite-boards. PDF
The unknown nature of the future requires us to question our decisions and seek reliable methods. The artificial neural networks approach, which is one of the methods used to best predict the future and one that is important for decision making has been thought of, particularly in recent years, as a method with a high level of validity in the fields of economy and financial prediction. The Istanbul Stock Exchange (ISE), at which millions of national and international investors operate, is among the developed stock exchanges of the world. The ISE has the attributes of being appropriate for making predictions regarding financial returns, without any sector differentiation, as a whole. In this study, it was aimed to predict monthly stock yields of 14 different paper companies dealing with the ISE (Istanbul Stock Exchange) by using artificial neural network. Four different variables (the gold price, ISE daily trading volume, exchange rate purchase-sale average, and monthly deposit interest rates by utilizing) and 127 months data were used. Results show that the monthly stock yields of the paper sector can be predicted correctly to account for 95% of the variability of data with the artificial neural network model, and the average absolute percentage failure value was 6.85%. PDF
Ni/CeO2-ZrO2 catalysts were prepared via co-precipitation and characterized by N2 adsorption–desorption, XRD, SEM, and TPR techniques. The effects of reaction temperature, carbon-equivalent space velocity (GC1HSV), and steam-to-carbon ratio (S/C) on the performance of the catalysts for ethanol steam reforming (ESR) were investigated. It was found that the best catalytic performance was obtained over the Ni/Ce0.75Zr0.25 catalyst with GC1HSV=345 h-1 and S/C=9.2. Under these conditions, H2 selectivity reached its highest value of 98% at T=725 °C, and carbon conversion reached 100% at T=825 °C. The performances of Ni/Ce0.75Zr0.25 and Ni/Ce0.5Zr0.5 were also compared at S/C ranging from 2.5 to 9.2. The results showed a higher carbon conversion for the Ni/Ce0.75Zr0.25 catalyst than for Ni/Ce0.5Zr0.5. PDF
Akpinar, O., Levent, O, Sabanci, S., Uysal, R. S., and Sapci, B. (2011). "Optimization and comparison of dilute acid pretreatment of selected agricultural residues for recovery of xylose," BioRes. 6(4), 4103-4116.
Two different agricultural wastes, sunflower stalk and tobacco stalk, were evaluated for the production of xylose, which can be used as a raw material and converted to xylitol, a highly valued product. The objective of the study was to determine the effects of H2SO4 concentration, temperature, and reaction time on the production of sugars (xylose, glucose, and arabinose), and on the reaction by-products (furfural and acetic acid) from sunflower stalk and tobacco stalk and to compare the hydrolysis conditions of these wastes. Since both agricultural wastes had different structures, they had different responses to experimental conditions. Response surface methodology (RSM) was used to optimize the hydrolysis process in order to obtain high xylose yield and selectivity. The optimum reaction temperature, reaction time and acid concentration were 120 oC, 30 min and 4% of acid concentration for sunflower stalk and 133 oC, 27 min and 4.9% of acid concentration for tobacco stalk. PDF
Adeogun, A. I., Ofudje, A. E., Idowu, M., and Kareem, S. O. (2011). "Equilibrium, kinetic, and thermodynamic studies of the biosorption of Mn(II) ions from aqueous solution by raw and acid-treated corncob biomass," BioRes. 6(4), 4117-4134.
Biosorption was carried out in a batch process to test the suitability of corncob for the removal of manganese ion (Mn(II)) from aqueous solution. The amount of metal ions removed from solution depended on the metal ion-substrate contact time, ion concentration, temperature, and pH. The adsorption capacity of the biosorbent from corncob was also enhanced by treatment with acid. Kinetic modeling of the data obtained from the study showed that the biosorption of Mn(II) ions by the untreated and acid-treated corncob followed the Largergren pseudo-first order model. The adsorption capacity of the raw biomass was found to be 6.54 mg/g, while acid-treated biomass showed an adsorption capacity of 7.87 mg/g. The data obtained from this study fitted well with the Freundlich and Langmuir adsorption isotherms. PDF
The Raffia textilis fiber has interesting specific mechanical properties among other vegetables fibers. But its production remains entirely based on empirical knowledge. The fibers are dried in the open air and in the shade for about 48 hours. This study explores the effect of the drying temperature, from 30° to 70°C, on its drying kinetics. It was found that the drying duration passes from 55 min at 30 °C to 20 min at 70 °C. Among the three models used to simulate the drying kinetics, the Page model yields the best results. The values of the parameters of this model agree with the hypothesis that the water diffusion is one-dimensional. The activation energy of water in the fiber varies from 49 to 71 KJ/mol, depending on the model used. The effective diffusion coefficient is about 3x10-14 m2.s-1 at 30 °C. This low value justifies the traditional use of the raffia leaves for house roofs. PDF
To investigate the effect of organic bound Na groups on pyrolysis and gasification behaviors of alkali lignin, an experimental study was carried out by Thermogravimetric Analyzer coupled with Fourier Transform Infrared Spectrometry (TG-FTIR). Acid precipitated lignin (APL) and Alkali soluble lignin (ASL) were selected as the testing samples, and physiochemical properties were studied by FTIR, 1H NMR, and SEM analyses. The research results showed that the pyrolysis and gasification characteristics of alkali lignin depended on phenolic sodium (-CONa) and carboxylate sodium (-COONa) groups (PCSG). In pyrolysis stage, PCSG improved the yields of alcohols and hydrocarbons but inhibited benzenes. During gasification stage, in the present of PCSG, the peak value of gasification rate increased, yet the initial gasification temperature decreased. Meanwhile, CO releasing was relatively concentrated and intensively increased from 37 min (740 oC) to 42 min (840 oC). PDF
With the rapid development of the packaging industry, the requirements for physical properties of corrugated paperboard tend to become higher and higher, especially for the strength properties. A water glass-starch compound system was employed as a surface sizing agent to improve the strength of linerboard in this work. The viscosity of water glass-starch compound system, and its impacts on ring-crush strength and bursting strength of linerboard were evaluated. Cobb value and contact angle were used to characterize the waterproof performance of paper after surface sizing. Compared with conventional surface sizing agents, water glass-starch compound system overcame the defects of low coating weight and inadequate stiffness of the sizing layer, allowing ring-crush strength and bursting strength of linerboard to increase by 91% and 50%, respectively. Additionally, the compound system had higher solids content, low viscosity, and good film-forming ability, which will bring a lot of convenience to production. PDF
McLean, D., Agarwal, V., Stack, K., Horne, J., and Richardson, D. (2011). "Synthesis of guar gum-graft-poly(acrylamide-co-diallyldimethylammonium chloride) and its application in the pulp and paper industry," BioRes. 6(4), 4168-4180.
The synthesis and characterization of a novel fixative, guar gum-graft-poly(acrylamide-co-diallyldimethylammonium chloride) (GG-g-p(AM-co-DADMAC)) polymer is described. The grafted polymerproved to be effective at adsorbing hydrophobic wood resin particles onto papermaking fibre surfaces, thus removing wood resins from the water phase where they have a tendency to aggregate and form troublesome deposits. The new polymer combines the colloidal stabilising features of a natural product, guar gum, and the wood resin fixative properties of a synthetic polymer p(AM-co-DADMAC). GG-g-p(AM-co-DADMAC was effective over the entire pH range as compared to other commercially available polymeric fixatives that were evaluated. PDF
The drying process of Norway spruce (Picea abies [L.] Karst) wood exposed to infrared heat radiation was studied by measuring the moisture profiles of the wood samples at controlled temperature during drying. The thermal treatment was executed in a purpose-made industrial pilot-plant containing the heat radiators covered by infrared (IR) transmition filters. The moisture content of the samples was detected at certain stages of the process. Based on the results of exposing the samples to IR radiation for 15, 25, 35, and 45 hours, the drying mechanism of wood is discussed. The moisture transport mechanism was explained by a semipermeable membrane process considering the moisture content as a dilute aqueous solution. If the semipermeable cell wall allows only the passage of water but not that of solute molecules, water diffusing from the region of higher (center) to lower (periphery) water content produces osmotic pressure difference between the two sides of the cell walls. The importance of this osmosis was considered in the approach of moisture migration. PDF
In this study the effect of virgin and recycled plastics on water absorption of nanocomposites from newsprint fiber and organoclay was studied. Newsprint fiber was mixed with either virgin or recycled polypropylene (PP) at 30% by weight fiber loading. The samples were made by melt compounding and then injection molding. The concentration was varied as 0, 2.5, and 5% for nanoclay. The amount of coupling agent was fixed at 10% for all formulations. The long-term water absorptions of samples were evaluated by immersing them in water at room temperature for several weeks, and water diffusion coefficients were also calculated by evaluating the water absorption isotherms. The results indicated that whether or not virgin plastic is used has a significant effect on the water absorption of composites. The water absorption of the newsprint fiber/recycled plastic composites was higher than those of virgin plastics. Furthermore, with addition of nanoclay content in composites, water absorption decreased. Water absorption of all formulations was proved to follow the kinetics of a Fickian diffusion process. Morphological findings showed the formation of intercalated morphology and better dispersion with 2.5% of nanoclay. PDF
The objective of this work was to compare the adsorption of different polysaccharides and cellulose derivatives on cellulose nanofibril films. Cellulose films having the native cellulose I structure were prepared from hardwood kraft pulp by extensive mechanical disintegration. Further fractionation enabled the preparation of reproducible, nanometer-scale thickness films. Systematic comparison by Quartz Crystal Microbalance with Dissipation (QCM-D) showed that various industrially available galactomannans have almost as good affinity to cellulose surface as xyloglucan and that most of the polysaccharides attach irreversibly to cellulose nanofibrils at low pH (4.5) and intermediate ionic strength (10 mM). SPR results support the QCM-D findings. Atomic Force Microscopy (AFM) imaging and Digital Pulsed Force Mode (DPFM) measurements further confirmed that a uniform non-aggregated layer of polysaccharides was formed that changed the properties of the NFC film. PDF
100% natural tannin-based rigid foams were synthesized. Tannin-furfuryl alcohol networks were polymerized in an acid environment applying a temperature between 120° and 160°C. The process was developed in two ways: in a ventilated oven and in between the heated plates of a press. The foams produced showed a high homogeneity in both cases. By modifying the formulation in terms of type and amount of components it was possible to produce two kinds of foams: (1) light with density of approximately 50 Kg/m³, and (2) resistant having a density of approximately 180 Kg/m³. The compression resistance and the water absorption of these materials were evaluated. The results of these tests, in comparison with those of formaldehyde-reinforced tannin foams, indicated that these lightweight foams have lower mechanical strength but higher water affinity. The latter was also demonstrated with moisture uptake measurements. Particular attention was dedicated to the press-produced foams for their possible application as core-layer for lightweight composite panels. PDF
Kinetic modeling of enzymolysis of pulp fiber waste pretreated by a wet oxidation process was studied. First, a wet oxidation pretreatment of fiber waste was carried out. It was found that hemicellulose were removed efficiently, yielding material with a pentosan content of 4% (based on the o.d. biomass). A statistical kinetic model was developed based on the experimental results of the enzymatic hydrolysis of wet oxidation pretreated material. The model can be described as follows: RSY (reducing sugar yield)=12.48×C0.4261×(1-e-0.2021t) ×100%, an equation that can be used to predict the reducing sugar yield in an enzymolysis process. The RSY by enzymatic loading of 35FPU/g achieved almost the highest yield after 48 h, and there was no significant improvement with further extension of the enzymolysis time. The modeling was validated within the enzymatic loading range of 15 to 35FPU/g and provided a satisfactory interpretation of the experimental data. PDF
Effects of alkali treatment of rice straw flour on the mechanical properties of rice straw flour-polypropylene composites were investigated. Rice straw flour (40 mesh) was first treated with sodium hydroxide using two concentrations of sodium hydroxide, 5 and 10% (W/W), and two treatment times (45 and 90 min) for a total of four treatments. The composites were then made with the rice straw flour as a filler (30%), polypropylene (65%) as a matrix, and maleic anhydride (5%) as a coupling agent. The polypropylene/rice straw flour mixtures were blended in an internal Haake mixer and made into molds that were later used for mechanical testing. The results showed that the treatment of rice straw flour with 5% alkali (W/W) increased the tensile modulus and impact strength. Longer treatment time also resulted in a higher tensile modulus and impact strength. The fiber/matrix interaction was analyzed from the mechanical data and morphological (SEM) studies. Treatment of rice straw flour with 10% alkali (W/W), however, decreased these properties even under a longer treatment time. Increasing the alkali concentration and treatment time increased the flexural modulus, flexural strength, and tensile strength of the composites. The SEM results showed greater adhesion between the rice straw flour and the polypropylene matrix at higher alkali concentrations and longer treatment times. PDF
The effects of different circular saws on surface roughness were determined for heat-treated wood, including Scots pine (Pinus sylvestris L.), eastern beech (Fagus orientalis L.), Uludağ fir (Abies bornmülleriana Mattf.), and sessile oak (Quercus petraea L.), which are used commonly in Turkey. Samples were heat-treated for 3, 5, or 7 hours at 140 or 160ºC, and cut with circular saws with 28, 48, 60, 72, or 96 teeth. Then, the surface roughness of the samples was determined using a scanning device (TIME TR200) with respect to the ISO 4287 standard. Heat treatment increased the surface roughness of the wood used, and changed the colour of the wood. To obtain smooth surfaces with or without heat treatment, a circular saw with 28 teeth and a double chamfered (WZ) mouth profile is recommended. PDF
Surface treatment is an important step of papermaking, namely for improving the final product quality. For uncoated printing and writing papers (P&W), surface sizing is becoming a common practice for controlling paper surface characteristics and liquid spreading and absorption. This work aims at evaluating the potential of assessing and controlling paper surface chemistry, by analyzing the impact of the application of different surface sizing formulations both on the chemical surface characteristics of the modified paper samples and on the final printing quality. For that, blends of cationic starch and minor quantities (5%, 10%, and 20% w/w) of four distinct copolymers of styrene were used, resulting in a total of 12 different surface sizing formulations. A sample surface sized only with cationic starch was taken as reference. Surface chemical properties were determined by using contact angle measurements and inverse gas chromatography. Finally, the inkjet printing quality was evaluated. The results revealed that the surface sizing treatments tested have a substantial influence on the surface energetics and partially explain the differences detected in the inkjet printing quality. PDF
Nanocrystalline cellulose (NCC) with small particle size and high crystallinity was prepared via the combined method of ultrasonication and acid hydrolysis from bleached softwood kraft pulp (BSKP). Scanning electron microscopy, transmission electron microscopy, X-ray diffraction (XRD), and Fourier transform infrared spectroscopy were used for determination of morphology, crystal structure, and surface chemical groups. Thermal behavior was analyzed by thermogravimetric analysis. The analyses revealed that rod-shaped NCC particles with diameter of 10 to 20 nm can be obtained. Ultrasonication can induce cellulose folding, surface erosion, and external fibrillation of BSKP, together with the shorter average length of NCC (96 nm) than that prepared without ultrasonication (150 nm). Due to the smaller size and larger number of free ends of chains, the thermal stability of NCC was lower than BSKP. The degradation of BSKP exhibited one significant pyrolysis stage within the range of 300 to 420 °C. In contrast, UH-NCC exhibited three pyrolysis stages within the range of 210 to 450 °C. NCC prepared with ultrasonication decomposed at lower temperature and over a wider temperature range, together with higher char yield of 43% (compared with 27% for that without ultrasonication). The obtained NCC had similar surface chemical structures but higher crystallinity (82%) compared with that of the starting BSKP (74%). PDF
Empty fruit bunches (EFB) from palm oil were characterized. The holocellulose (66.97%), α-cellulose (47.91%), and lignin (24.45%) are similar to wood materials, and various non-wood materials, but the fiber length is shorter (0.53 mm). The influence of operational variables in the EFB pulping [formic acid (75-95%), hydrochloric acid (0.05-0.15%), and time (30-150 min)], on the yield, kappa number, viscosity, and brightness of the pulps was studied. By using a factorial design, equations that reproduced the experimental results for the dependent variables, errors less than 10% were obtained. These equations could be used to find suitable conditions, so that operating with not too high values of operating variables (with minor costs of capital and of operation), pulps could be obtained with acceptable properties. In this way, a cellulosic pulp with a 42.3% yield, 22.7% brightness, and a 512 mL/g viscosity was obtained under the following conditions: 92.5% of formic acid, 0.075% of hydrochloric acid, and a time of 60 min. A pulp (31.1 kappa number and 606 mL/g viscosity) was bleached by EPabOPoP sequence, achieving a brightness of 69.4%, a loss of viscosity and yield of 34.8% and 13.1%, respectively. The residual liquor from the pulping with formic acid 95%, 0.05% hydrochloric acid and 30 min, provides a liquor with 18.2% residual lignin, 4.1% glucose, 9.8% xylose, and 1.2% arabinose, all on dry weight of original material. PDF
Xylose-extracted corncob residue (X-ER), a byproduct from the xylose production industry, is a potential cellulose-rich energy resource. However, attempts to achieve large-scale production of cellulosic ethanol using X-ER have been unsatisfactory due to a lack of understanding of the substrate. This study presents the first characterization of the X-ER to evaluate its potential utilization in the sequential production of cellulosic ethanol. The current dilute acid treatment procedures used for the corncobs by the xylose-production industry were insufficient for efficient deconstruction of cellulose structure to release available sugars for subsequent cellulosic ethanol conversion. After a secondary dilute acid hydrolysis of the X-ER, an additional 30% hemicellulose was recovered. In addition, a more efficient enzymatic hydrolysis of X-ER was observed resulting in a significantly higher yield of glucose conversion compared with an untreated X-ER control. These results suggest X-ER can be utilized for cellulosic ethanol production. However, improved corncob pretreatment procedures are needed for economical cellulosic ethanol conversion. PDF
A novel manganese peroxidase (MnP) produced by an indigenous white rot fungal strain Trametes versicolor IBL-04 in solid state medium of corncobs was puriﬁed and characterized. The fungus produced 964U/mL MnP in the presence of additional carbon (glucose) and nitrogen (yeast extract) supplements added at a C:N ratio of 25:1, 1mM Tween-80 (1mL), 1mM MnSO4 (1mL), and 1mM CuSO4 (1mL). The MnP was purified by ammonium sulfate fractionation (65% saturation) and dialysis, followed by Sephadex G-100 gel ﬁltration chromatography. Purification procedures resulted in 2.4-fold purification with an overall yield and specific activity of 3.4% and 660 U/mg, respectively. The purified MnP was monomeric of molecular weight of 43 kDa, showing a single band on sodium dodecyl sulfate poly acrylamide gel electrophoresis (SDS-PAGE). The enzyme was optimally active at pH 5 and 50oC and was stable for 1 h over a broad range of pH (4-7) and temperature (40-65oC). Kinetic constants KM and Vmax of purified MnP were 70 µM and 540 U/mL for MnSO4 substrate. The effect of possible activators and inhibitors of enzyme were also investigated, and it was observed that EDTA, Cystein, and Ag+ caused MnP inhibition and inactivation to different extents, whereas MnP was activated by 4 and 3 mM of Cu2+ and Fe2+, respectively. High thermo-stability, low KM and high Vmax features of this novel MnP isolated from culture filtrate of T. versicolor IBL-04 suggests its suitability for various industrial and biotechnological applications. PDF
Finland currently has tremendous enthusiasm to increase decentralised pellet production alongside of large-scale factories. The aim of research is to promote the development of eco-/cost-efficient Nordic wood-based pellet production by means of multidisciplinary research. Using Finnish conifer stem wood (bark-free Scotch pine sawdust and shavings) as a model raw material, the total functionality of a pilot-scale pellet facility combined with an extensive chemical toolbox was tested in this study to promote future development of eco- and cost-efficient wood-based pellet production in both quantitative and qualitative senses. Lignosulphonate, residual potato flour, and potato peel residue were used as adhesive binding agents. A pilot-scale pellet facility was equipped with a data logger for temperature and power measurements. The chemical toolbox included also novel specific staining and optical microscope methods and respirometric BOD Oxitop measurements. The results showed that adhesive binding agents increased the quality of pellets and changed inorganic characteristics, but did not have a significant effect on their calorimetric heat values. Lignosulphonate even increased the rate of production. Valuable information about both the pelletizing process and pellets is necessary in the future when developing good-quality pellets, a prime biofuel, from low-value and/or moist biomass that has undergone a cost-efficient drying process. PDF
In order to determine the quantitative relationship between sheet strength and lignin coverage at the fiber surface, CTMP was blended with softwood bleached kraft pulp (BKP), refined softwood BKP, and hardwood BKP. The morphology of the fibers, fibers properties, fiber surface components and relative bonded area of sheets were investigated. Multi-linear regression equations of tensile strength index and internal bond strength were established. The results indicated that unbleached aspen CTMP fiber surfaces were covered by granules of lignin, and BKP fiber surfaces were predominated covered by microfibrils. Fiber properties have a significant impact on tensile strength index. RBA had a greater impact on IBS than lignin coverage. For the pulp samples tested, a 1% increase in lignin coverage at fiber surfaces would lead to a 0.48N·m/g decrease in tensile strength index and 5.32×10-3 J/m2 decrease in internal bond strength. PDF
Spence, K. L., Venditti, R. A., Rojas, O. J., Pawlak, J. J., and Hubbe, M. A. (2011). "Water vapor barrier properties of coated and filled microfibrillated cellulose composite films," BioRes. 6(4), 4370-4388.
Microfibrillated celluloses (MFCs) have mechanical properties sufficient for packaging applications, but they lack water vapor barrier properties in comparison to petroleum-based plastics. These properties can be modified by the use of mineral fillers, added within the film structure, or waxes, as surface coatings. In this investigation it was found that addition of fillers resulted in films with lower densities but also lower water vapor transmission rates (WVTR). This was hypothesized to be due to decreased water vapor solubility in the films. Associated transport phenomena were analyzed by the Knudsen model for diffusion but due to the limited incorporation of chemical factors in the model and relatively large pore sizes, accurate prediction of pore diameters for filled films was not possible with this model. Modeling the filled-films with Fick’s equation, however, takes into account chemical differences, as observed by the calculated tortuosity values. Remarkably, coating with beeswax, paraffin, and cooked starch resulted in MFC films with water vapor transmission rates lower than those for low density polyethylene. These coatings were modeled with a three-layer model which determined that coatings were more effective in reducing WVTR. PDF
Rasat, M. S. M., Wahab, R., Sulaiman, O., Moktar, J., Mohamed, A., Tabet, T. A., and Khalid, I. (2011). "Properties of composite boards from oil palm frond agricultural waste," BioRes. 6(4), 4389-4403.
Properties of composite boards from oil palm frond agricultural waste were researched. Phenol and urea formaldehyde resins were used as the binders. The oil palm fronds were obtained from 20 year-old trees in an oil palm plantation in Kota Belud, Sabah. The fronds were segregated into three groups of matured, intermediate, and young oil palm fronds and further subdivided into bottom, middle, and top sections. The leaflets and the epidermis were removed from the fronds before they were sliced longitudinally into thin layers. The layers were then compressed into uniform thickness of 2 to 3 mm. The layers were air-dried and later mixed with resins using 12 to 15% of phenol and urea formaldehyde and recompressed with other layers, forming composite boards. The composite boards samples were then tested for their physical and mechanical properties. Testing was conducted in accordance with the International Organization for Standardization (ISO) standard. The results for physical and mechanical properties showed that the oil palm composite boards were better than composite boards from oil palm trunks and slightly worse than the rubberwood. Statistical analysis indicated significant differences between composite boards made from each group and section, but no differences were observed in the type of resin used. The composite boards from oil palm fronds agricultural residues has the potential to be used as an alternative to wood to overcome the shortage in materials in the wood industry. PDF
Funalia trogii and Trametes versicolor were grown on agro byproduct wheat bran moistened with various natural moistening agents, and their effects on laccase production under solid substrate condition were investigated. Laccase was the main enzyme detected under this condition. High levels of laccase activity were obtained with solid substrate cultures moistened with olive oil mill wastewater (OOMW) or alcohol factory wastewater (vinasse). Among the cultures without inducer, T. versicolor culture was detected as a more effective laccase producer than F. trogii culture. Copper and xylidine were used as laccase inducers, and copper induced laccase production more than xylidine. The maximum laccase activity was detected as 14.18 U/mL with F. trogii grown on wheat bran moistened with 5 mM CuSO4.5H2O added 25% vinasse. Azo dye decolorization activity of the supernatants from solid substrate cultures was also tested. While the use of 0.063 U/mL F. trogii laccase in reaction solution gave 66% decolorization in a minute, it was 14% for T. versicolor. This method can be a possible alternative for valorization of lignocellulosic materials and industrial wastewaters during solid substrate fermentation and for obtaining enzyme source with very high decolorization activity. PDF
Xylo-oligosaccharides were obtained from Miscanthus x giganteus. The process was designed as a biorefinery scheme, which seeks the separation of the three main components: cellulose, hemicelluloses, and lignin. To extract the hemicelluloses, particularly xylans, in an efficient way, Miscanthus was subjected to autohydrolysis. The system was evaluated for the effects of temperature (160 to 200oC) and reaction time (15 to 60 min) on various parameters, reflecting the changes undergone during the process. The results showed that autohydrolysis is a suitable method for obtaining high yields of xylo-oligosaccharides, reaching values close to 65% of the dissolved xylans (based on the initial amount of potential xylose). Analysis of the process by using the severity factor (RO) allowed for the identification of a set of time-temperature values for which the fractionation was optimal. PDF
Zhang, H., Zhang, J., Song, S., Wu, G., and Pu, J. (2011). "Modified nanocrystalline cellulose from two kinds of modifiers used for improving formaldehyde emission and bonding strength of urea-formaldehyde resin adhesive," BioRes. 6(4), 4430-4438.
In this study, nanocrystalline cellulose (NCC) was used for increasing the bonding strength of urea-formaldehyde (UF) resin adhesive, with a reduction of formaldehyde (HCHO) emissions. The surface of NCC was modified by 3-aminpropyltriethoxysilane (APTES) and 3-methacryloxy-propyltrimethoxysilane (MPS) for the lack of compatibility with UF resin adhesive. The modified NCC was characterized by X-ray powder diffraction (XRD), thermogravimetric analysis (TG), and wetting property. HCHO emission and bonding strength of the UF resin adhesive with modified NCC were tested according to Chinese National Standards GB/T 17657-1999 and GB/T 9846-2004. The results of XRD, TG, and wetting property from NCC modified by APTES showed more significant improvements than that from NCC modified by MPS. The HCHO emission of UF resin adhesive with 1.5% NCC modified by APTES decreased by 53.2% and bonding strength increased by 23.6%, while the results from the NCC modified by MPS were 21.3% and 7.0%, respectively. PDF
Mancera, C., El Mansouri, N.-E., Ferrando, F., and Salvado, J. (2011). "The suitability of steam exploded Vitis vinifera and alkaline lignin for the manufacture of fiberboard," BioRes. 6(4), 4439-4453.
The main objective of this study was to explore the suitability of Vitis vinifera as a raw material and alkaline lignin as a natural binder for fiberboard manufacturing. In the first step, Vitis vinifera was steam- exploded through a thermo-mechanical vapor process in a batch reactor, and the obtained pulp was dried, ground, and pressed to produce the boards. The effects of pretreatment factors and pressing conditions on the chemical composition of the fibers and the physico-mechanical properties of binderless fiberboards were evaluated, and the conditions that optimize these properties were found. A response surface method based on a central composite design and multiple-response optimization was used. The variables studied and their respective variation ranges were: pretreatment temperature (Tr: 190-210ºC), pretreatment time (tr: 5-10 min), pressing temperature (Tp: 190-210ºC), pressing pressure (Pp: 8-16MPa), and pressing time (tp: 3-7min). The results of the optimization step show that binderless fiberboards have good water resistance and weaker mechanical properties. In the second step, fiberboards based on alkaline lignin and Vitis vinifera pulp produced at the optimal conditions determined for binderless fiberboards were prepared and their physico-mechanical properties were tested. Our results show that the addition of about 15% alkaline lignin leads to the production of fiberboards that fully meet the requirements of the relevant standard specifications. PDF
Asgher, M., Ahmed, N., and Iqbal, H. M. N. (2011). "Hyperproductivity of extracellular enzymes from indigenous white rot fungi (P. chrysosporium IBL-03) by utilizing agro-wastes," BioRes. 6(4), 4454-4467.
An indigenous locally isolated white rot fungal strain Phanerochaete chrysosporium IBL-03was investigated for the hyper-production of ligninolytic enzymes from different agro-industrial wastes including wheat straw, rice straw, banana stalks, corncobs, corn stover, and sugarcane bagasse as substrate material in still culture fermentation technique. Screening experiments were performed at 30oC from 1 to 10 days and maximum enzyme activities were recorded after the 5th day of incubation on banana stalk. P. chrysosporium IBL-03 produced highestactivities of lignin peroxidase (LiP) and manganese peroxidase (MnP) but no laccase activity was detected in any fermented culture media. Production of ligninolytic enzymes was substantially enhanced through the optimization process. When banana stalk at 66.6 % moisture level and pH 4.5 was inoculated with 5mL spore suspension of P. chrysosporium IBL-03 at 35oC in the presence of molasses (1%) as carbon source, ammonium sulfate (0.2%) as nitrogen supplement, (1%) Tween-80 (0.3 mL) as surfactant and mediators (MnSO4 and veratryl alcohol) enhanced the LiP and MnP production up to 1040 and 965 (U/mL), respectively. PDF
This study demonstrated the use of a pressurized mechanical refining system for the continuous steam explosion pretreatment of wheat straw. Wheat straw was first impregnated with either dilute acid (0.5% sulfuric acid) or water and then steam exploded in an Andritz pressurized refiner. The effect of a range of pretreatment conditions, including refining retention time and steam pressure/temperature on the resulting substrate composition and hydrolysability as well as overall sugars yield was investigated. For autohydrolysis, the optimum conditions, 198 oC/6 min gave an enzymatic hydrolysis yield of 93.3% and an overall glucose yield of 85.8%, while 198 oC/4 min gave an enzymatic hydrolysis yield of 88.7% and overall glucose yield of 88.4%. Longer retention time increased the enzymatic hydrolysability but reduced the overall glucose yield owing to the degradation reaction during pretreatment. For acid pretreatment, the most favourable condition for enzymatic hydrolysis and overall glucose yield coincided at 178 oC /6 min. PDF
Fiber dimensions, chemical composition, and soda and soda-AQ pulping of tobacco stalks were examined to assess if they were suitable for pulp and paper production. The results showed that the morphological characteristics of tobacco stalks were similar to those of nonwoods and hardwoods. The average values of length, diameter, and cell wall thickness of tobacco stalks fibers were determined as 1.23 mm, 24.31 μm, and 8.93 μm, respectively. The holocellulose and alpha-cellulose in tobacco stalks were lower than those of hardwoods and common nonwoods. In addition, lignin content of tobacco stalks was lower than that of hardwood. The holocelluloses, alpha-cellulose, lignin, and ash contents of tobacco stalks were examined to be 67.79, 39.20, 18.90, and 6.86 wt%, respectively. The optimum cooking conditions for a bleachable pulp of tobacco stalks were found to be as follows: active alkali 25%, temperature 165°C, cooking time 180 min, and 0.2% anthraquinone. Addition of anthraquinone resulted in lower screening rejects and lower kappa number, higher screen yield, and higher brightness. The bleaching of tobacco stalk pulp did not respond very well. The brightness of pulp made by tobacco stalks reached about 73.06% on DED and 78.2% on DEDD bleaching sequences. PDF
Li, L., Yu, S.-T., Liu, F.-S., Xie, C.-X., and Xu, C.-Z. (2011). "Efficient enzymatic in situ saccharification of cellulose in aqueous-ionic liquid media by microwave pretreatment," BioRes. 6(4), 4494-4504.
Several representative ionic liquids (ILs) were synthesized, and [Emim]OAc was chosen as environment-friendly solvent for enzymatic in situ saccharification in view of its biocompatibility with both natural and microcrystalline cellulose, as well as its enzymatic activity. With the microwave pretreatment of natural and microcrystalline cellulose, directly enhancing the in situ enzymatic saccharification, the rate was compared versus an untreated control by the detection of dinitrosalicylic acid (DNS). It is suggested that the molecular structure of cellulose in the process of pretreatment was changed, e.g. intramolecular hydrogen bonds were broken (detected by FT-IR), and the crystallinity (monitored by SEM and XRD) changed significantly from a crystalline to an amorphous pattern. These changes of cellulose led to an increase of reducing sugar conversion during cellulose enzymatic hydrolysis. PDF
Ahmed, I., Zia, M. A., Iftikhar, T., and Iqbal, H. M. H. (2011). "Characterization and detergent compatibility of purified protease produced from Aspergillus niger by utilizing agro wastes," BioRes. 6(4), 4505-4522.
A study was conducted to purify and characterize a novel protease produced from Aspergillus niger using different lignocellulosic agro-based by-products including corncobs, wheat bran, and rice bran as substrates under SSF. Maximum protease activity was recorded on wheat bran fermented culture media after the 3rd day of incubation. The optimal conditions found for protease production using wheat bran were cultivation period (3 days), substrate concentration (10 g), pH (7), incubation temperature (45oC), inoculum size (4 mL), and 3% surfactant Tween-80 (2 mL). A purification fold of 2.41 with 29 U/mg specific activity and 70.73 % recovery was achieved after purification. Purified protease from A. niger had a molecular weight of 47 kDa on SDS-PAGE. The enzyme activity profile showed that purified protease was optimally active at pH 7 and 45oC as optimum values. A. niger protease was reasonably stable in the pH range 5-8 and 35-60oC for up to 1 h incubation. Protease was activated by various metal ions/inhibitors tested, Mn2+, Cd2+, Mg2+, Cu2+, PMSF, Pepstatin and Iodoacetic acid at 1 mM, proving the enzyme as metalloprotease, whereas an inhibitory effect was shown by certain agents including EDTA and SDS. The purified protease was compatible with five local detergents with up to 25 days of shelf life at room temperature. The maximum production of protease in the presence of a cheaper substrate at low concentration and its potential as a detergent additive for improved washing makes the strain and its enzymes potentially useful for industrial purposes, especially for the detergent and laundry industry. PDF
In this study, glyoxalated alkaline lignins with a non-volatile and non-toxic aldehyde, which can be obtained from several natural resources, namely glyoxal, were prepared and characterized for its use in wood adhesives. The preparation method consisted of the reaction of lignin with glyoxal under an alkaline medium. The influence of reaction conditions such as the molar ratio of sodium hydroxide-to-lignin and reaction time were studied relative to the properties of the prepared adducts. The analytical techniques used were FTIR and 1H-NMR spectroscopies, gel permeation chromatography (GPC), differential scanning calorimetry (DSC), and thermogravimetric analysis (TGA). Results from both the FTIR and 1H-NMR spectroscopies showed that the amount of introduced aliphatic hydroxyl groups onto the lignin molecule increased with increasing reaction time and reached a maximum value at 10 h, and after they began to decrease. The molecular weights remained unchanged until 10 h of reaction time, and then started to increase, possibly due to the repolymerization reactions. DSC analysis showed that the glass transition temperature (Tg) decreased with the introduction of glyoxal onto the lignin molecule due to the increase in free volume of the lignin molecules. TGA analysis showed that the thermal stability of glyoxalated lignin is not influenced and remained suitable for wood adhesives. Compared to the original lignin, the improved lignin is reactive and a suitable raw material for adhesive formulation. PDF
Abdul Khalil, H. P. S., Fizree, H. M., Jawaid, M., and Alattas, O. S. (2011). "Preparation and characterization of nano-structured materials from oil palm ash: A bio-agricultural waste from oil palm mill," BioRes. 6(4), 4537-4546.
Oil palm ash (OPA), a bio-agricultural waste from oil palm mills, was subjected to high-energy ball milling for 30 h and was converted into a nano-structured material. The nano-structured OPA was characterized for its particle size and crystallinity index by using Transmission Electron Microscopy (TEM) and X-ray Diffraction (XRD) analysis. The crystallite size obtained from TEM and XRD was found to be 50 nm and 54.32 nm respectively, and the crystallinity index of OPA was 66.54%. The shape and texture of raw and nano-structured OPA were studied using scanning electron microscopy. The raw OPA had an irregular shape with spongy and porous structure, while the nano-structured powder had a mostly irregular and crushed shape. The elemental studies of OPA used Energy Dispersive X-ray (EDX) analysis, XRD, and Fourier Transform Infrared Spectroscopy (FT-IR). The elemental compositions found in OPA were silica, potassium oxide, calcium oxide, magnesium oxide, aluminium oxide, and iron oxide. PDF
Non-isothermal crystallization of neat high density polyethylene (HDPE), wood flour (WF)/HDPE composite (WPC), virgin Kevlar fiber (KF) reinforced WPC (KFWPC), and grafted Kevlar fiber (GKF) reinforced WPC (GKFWPC) was investigated by means of differential scanning calorimetry (DSC) and wide angle X-ray diffraction (WAXD). Several theoretical models were applied to describe the process of non-isothermal crystallization. The results showed that the Avrami analysis modified by Jeziorny and a method developed by Mo and coworkers successfully described the non-isothermal crystallization behavior of HDPE and composites. The Ozawa analysis, however, failed to provide an adequate description of non-isothermal crystallization. The values of crystallization peak temperature (Tp), half-time of crystallization (t1/2), and kinetic parameters KJ and F(T) showed that the crystallizability followed the order: FKWPC > GKFWPC > HDPE > WPC. The effective activation energy for non-isothermal crystallization of HDPE and composites based on both Kissinger and Friedmen methods was evaluated. WAXD indicated that the crystalline thickness perpendicular to the reflection plane (Lhkl) increased with the addition of KF. The results demonstrated that KF and GKF can act as nucleating agents and increase the crystallization rate of HDPE. Compared with GKF, KF is a more effective nucleating agent for HDPE, and wood flour cannot act as a nucleating agent for HDPE. PDF
Lignin recovered from the near-neutral hemicellulose extraction process was investigated as a precursor suitable for production of carbon fiber. Crude lignin was precipitated from the wood extract by adding sulfuric acid to lower the pH value to 1.0. The crude lignin extract was then upgraded by using hydrolysis to cleave lignin-carbohydrate bonds and to remove carbohydrates that contaminate the lignin. The precipitated solids were separated by filtration, washed with water, and then dried. Lignin recovered using the hydrolysis method was found to be high in carbon, high in total lignin, low in inorganic contamination, and low in insoluble material, but high in volatile material. The recovered lignin could be thermally spun into lignin fibers, but the spun fibers proved to be brittle, which was thought to be due to its low-molecular mass and the glassy nature of lignin. Micrographs obtained using scanning electron microscopy (SEM) illustrated imperfections on the surface and in the interior microstructure of the carbon fiber when compared to micrographs taken of commercial carbon fiber manufactured using PAN and pitch. These imperfections were thought to be related to the high volatile material content in the samples and the slow rate of heating during the carbonization process. Baker (2011) suggests that increasing the rate of heating during carbonization can reduce the degree of brittleness and improve mechanical properties. PDF
This study was performed to determine the effects of thermal aging on the film hardness of some wood varnishes. For this purpose, Scots pine (Pinus sylvestris L.), Eastern beech (Fagus orientalis L.), and oak (Quercus petraea L.) samples coated with synthetic (alkyd), two-part polyurethane (urethane-alkyd), and waterborne (self cross-linked polyurethane) varnishes were evaluated at a moisture content of 8% and 12%. Afterwards, thermal aging processes were performed for periods of 25, 50, 75, and 100 days at 25 ºC, 50 ºC, 75 ºC, and 100 ºC. Hardness changes in the varnish films were measured in accordance with ISO 1522-2006. According to the test results, the samples prepared with polyurethane varnishes at 8% moisture content give the best results. PDF
In a biorefinery context it is an advantage to fractionate and extract different wood components in a relatively pure form. However, one major obstacle for efficient extraction of wood polymers (lignin, polysaccharides etc.) is the covalent lignin-polysaccharide networks present in lignified cell walls. Enzymatic catalysis might be a useful tool for a controlled degradation of these networks, thereby enhancing the extraction of high molecular weight polymers. In this work, a methanol-alkali mixture was used to extract two different wood samples treated with endoxylanase and gammanase, respectively. Wood chips were pretreated with alkali prior to enzymatic treatment to enhance the cell-wall accessibility to enzymes. Extractions were also carried out on non-enzyme-treated samples to evaluate the enzymatic effects. Results showed that the enzymatic treatment increased the extraction yield, with gammanase as the more efficient of the two enzymes. Furthermore, polymers extracted from xylanase-treated wood had a higher degree of polymerization than the reference. PDF
In this study the effect of processing parameters on different types of wood raw material in extrusion was examined. The study consisted of two parts: the first part was to break and separate individual fibers from wood chips during the extrusion process; in the second part the effect of chemical pre-treatment and screw elements on wood raw material was evaluated. Statistical analysis was performed to evaluate the most important factors affecting wood particle size in extrusion. The statistical analysis showed that the screw speed is the main factor affecting wood fiber length in twin-screw extrusion of wood chips. This study showed that a twin-screw extruder can be used to separate individual fibers from wood chips, and the separated fibers have higher aspect ratios than the wood flour particles typically used in wood-polymer composites. When more fibrous and chemically softened wood raw material was used, fibers with even higher aspect ratios were obtained. PDF
Iran is facing a severe lack of fibrous raw materials for paper production. Kenaf (Hibiscus cannubinus L.) is a superior complement to wood as a source of fiber. Kenaf bast fibers are excellent for making pulp and paper of various grades due to the presence of high alpha cellulose (56.43), holocellulose (77.71), and ultimate fiber length (2.77 mm). Fiber length is an important factor in the development of tear and tensile properties. The aim of this work is to study the effect of charge alkali (20 and 25% oven dried, as NaOH) and cooking time (30, 60, 90, 120, 150, and 180 min) of kenaf bast fiber on soda and soda-anthraquinone (AQ) pulp yield, kappa number, rejects, and strength properties of their handsheets. Results indicated that alkali charge and cooking time had significant influence on kappa number, yield, and rejects of pulps, whereas PFI revolution had only a minimal effect, especially at higher cooking times. The soda method was modified by adding 0.2% anthraquinone, and the resultant pulps displayed an increase in pulp yield and reduction in both kappa number (by 6 to 9 units) and screening rejects. The strength properties obtained with the two cooking processes used were compared, and those provided by soda-AQ process were found to be best. Regarding handsheet properties, a significant improvement in tensile index could be obtained by the soda-AQ process, compared to the soda process. PDF
Cellulose/chitosan homogeneous solutions were prepared in 1-ethyl-3-methylimidazolium acetate ([EMIM]Ac) ionic liquid. Steady and oscillatory dynamic rheological properties were studied with a Haake Mars-ΙΙΙ rotational rheometer. Rheological results show that cellulose/chitosan [EMIM]Ac solutions are a pseudoplastic liquid, and the viscosity of the solution decreases with increasing of chitosan content. The zero shear rate viscous activation energy of solution is about 52.10 to 62.50KJ/mol, calculated from the Cross and Arrhenius equation. The structural viscosity index of the solution is similar to that of cellulose/N-methylmorpholine-N-oxide solution, which indicates a potential spinnability. The dynamic rheological responses reveal that the Cox-Merz rule holds well with the solutions, and the crossover point of loss modulus and storage modulus shifts to a higher frequency range with increasing temperature. PDF
Gautam, G., Adhikari, S., Thangalazhy-Gopakumar, S., Brodbeck, C., Bhavnani, S., and Taylor, S. (2011). "Tar analysis in syngas derived from pelletized biomass in a commerical stratified downdraft gasifier," BioRes. 6(4), 4652-4661.
A study was conducted to quantify tar formation in a stratified downdraft gasifier using wood pellets. The effect of biomass flow rate on tar concentration was also analyzed, and more than thirty compounds in tar were quantified. Among the different compounds in tar, tertiary condensed products such as toluene, o/p-xylene, naphthalene, phenol, styrene, and indene were observed in significant amounts. Tar concentration in the syngas was found to be in the range of 340 to 680 mg/Nm3. These concentrations were found to be much higher when compared to a similar gasifier using woodchips. PDF
A composite of themoplastic polyurethane (TPU) reinforced with short kenaf (Hibiscus Cannabinus L.) fiber (KF) was prepared by a melt-mixing method. Mixing was followed by compression molding to produce sheets for specimen cutting. Five samples were cut from the composite sheet. A mean value was taken for each sample according to ASTM standards. The aims of this study were to optimize the processing parameters and fiber size of TPU/KF composite. The method used to develop this composite consisted of two main steps. First, the influence of processing parameters such as temperature, time, and speed on tensile properties was studied. Second, effects of different fiber size on tensile properties, flexural properties, and impact strength were tested. The optimum blending parameters were 190°C, 11 min, and 40 rpm for temperature, time and speed, respectively. TPU/KF composites with different fiber sizes were prepared, namely, <125, 125-300, and 300-425 µm. Tensile and flexural strength and modulus were best for fiber size range between 125 and 300 µm. Impact strength showed a slight increasing trend with an increase in fiber size. PDF
Bhat, I.-u.-H., Abdul Khalil, H. P. S., Ismail, H., and Alshammari, T. (2011). "Morphological, spectroscopic, and thermal properties of alkali-treated and chemically modifed oil palm empty fruit bunch fibers and oil palm frond fibers: A comparative study," BioRes. 6(4), 4673-4685.
The effect on morphological, spectroscopic, and thermal properties of oil palm empty fruit bunch fibers (OPEFB fibers) and oil palm frond fibers (OPF fibers) following treatment and modification with sodium hydroxide and succinic anhydride, respectively, were investigated. The evidence of treatment was observed by weight gain and FT-IR. The effect of the treatment upon the fiber surfaces was examined using scanning electron microscopy (SEM), which indicated that succinic anhydride treatment led to smoother surfaces as compared to the sodium hydroxide. The thermal degradation was carried out by thermal gravimetric analysis, which exhibited a different degree of mass loss due to different treatments. PDF
Solution behaviors and adsorption characteristics of sodium lignosulfonate (NaLS) were studied under different pH conditions. The changes of Mw and particle size of NaSL with solution pH were detected by laser light scattering (LLS). Film thickness was determined with a spectroscopic ellipsometer, and surface roughness was measured by atomic force microscopy (AFM). The results showed that NaSL aggregated in acidic water, and the degree of aggregation decreased with increasing pH. When solution pH increased, the Mw of NaLS decreased, indicating that the intermolecular aggregates of NaLS were disaggregated at high pH. In the meantime, the ratio of Rg/Rh decreased, suggesting that the intrastructure of NaSL was changed from compact to loose. When the NaSL with loose structure and low degree of aggregation was adsorbed on a solid substrate, the adsorption thickness and the surface roughness decreased correspondingly. PDF
The objective of this research was to evaluate the influence of steam-heat treatment on the decay resistance of Chinese white poplar and Chinese fir wood against the wood-rotting fungi Gloeophyllum trabeum (Pers.:Fr.) Murrill. The Chinese white poplar and Chinese fir specimens were obtained from Shandong and Hunan provinces, respectively. They were steam-heat-treated at 170, 185, 200, 215, or 230 oC with time duration of 1, 2, 3, 4, and 5 hrs in an air-tight chamber that comprised less than 2 per cent oxygen. According to the standard GB/T 13942.1-92, the decay resistance experiments were completed with the wood-rotting fungi G. trabeum on an agar block test with 12-week incubation. The results of steam-heat treatment indicated that, compared to a weight loss of 56% for untreated samples, a weight loss of 45% decreased to just 2% for Chinese white poplar with an increase in temperature from 170 to 230℃. No weight loss was observed in the steam-heat-treated China-fir heartwood, sapwood, and untreated sapwood specimens, while only a weight loss of 4.739% in untreated China-fir heartwood specimens was found. PDF
Kang, P., Zheng, Z., Qin, W., Dong, C., and Yang, Y. (2011). "Efficient fractionation of Chinese white poplar biomass with enhanced enzymatic digestability and modified acetone-soluble lignin," BioRes. 4705-4720.
Fractionation using concentrated phosphoric acid is a cost-effective pretreatment approach due to production of highly reactive amorphous cellulose under modest reaction conditions. Chinese white poplar biomass was used as feedstock. The effects of pretreating temperature and liquid/solid ratio of H3PO4/poplar (v/w, ml/g) on poplar fractionation, enzymatic hydrolysis efficiency (EHE), and supramolecular structural change were investigated. Only 31% (w/w, g/g) cellulose was retained in the solid phase at the higher liquid/solid ratio of 10:1 for 60 min, while 38 % cellulose was retained at 8:1. Temperature played an important role in lignin removal, xylan hydrolysis, and enzymatic hydrolysis, which may eventually influence cellulose conversion. More than 40% lignin could be removed after 60 min pretreatment at above 50 oC. A majority of the xylan hydrolysis could be detected in mixed rinsing liquid after 80 min pretreatment at 50 oC and liquid/solid ratio of 10:1. Up to 96.37% EHE could be obtained after 24 h enzymatic hydrolysis at 50 oC. The optimal pretreatment condition was 50 oC, liquid/solid ratio 8:1 (v/w), and 60 min. After pretreatment the CrI index decreased from 39.9 % to 27.7 %, suggesting a decrease of crystalline area percentage. Pyrolysis-GC-MS results of precipitated lignin indicated that nearly 48% of the lignin was phenolic, such that it can be used as a natural antioxidative material. PDF
Buyuksari, U.., Akbulut, T., Guler, C., and As, N. (2011). "Wettability and surface roughness of natural and plantation-grown narrow-leaved ash (Fraxinus angustifolia Vahl.) wood," BioRes. 6(4), 4721-4730.
Plantation-grown wood species are becoming more important. Their anatomical, physical, and mechanical properties are different and generally more variable than wood grown in natural stands. The objective of this study was to investigate the wettability and surface roughness (SR) of natural and plantation-grown narrow-leaved ash (Fraxinus angustifolia Vahl.) wood. The logs were cut from a natural stand versus three different spacings of plantation-grown narrow-leaved ash wood stands. Plantation spacings were 3 x 2 m, 3 x 2.5 m, and 4 x 4 m. The wetting behavior of the wood samples was characterized by the contact angle (CA) method (goniometer technique). A stylus type profilometer was used for the SR measurement according to the DIN 4768 (1990) standard. The SR and CA measurements were done on both the radial and tangential surfaces of the samples. Individual values of both SR and CA of ash wood showed statistically significant differences. Based on the findings, it appears that the natural-grown ash wood have higher (less favorable) SR and lower (more favorable) CA values compared to all the plantation-grown ash wood on both radial and tangential surfaces. Tangential surfaces had lower SR values and higher CA values than the radial surfaces for all groups. In conclusion, plantation-grown narrow-leaved ash wood can be utilized for bonded wood products such as plywood, laminated veneer lumber, and glulam. PDF
Mashkour, M., Tajvidi, M., Kimura, T.., Kimura, F., and Ebrahimi, G. (2011). "Fabricating unidirectional magnetic papers using permanent magnets to align magnetic nanoparticle covered natural cellulose fibers," BioRes. 6(4), 4731-4738.
This paper reports a simple innovative method to align magnetic cellulose fibers by using a simple permanent magnet to fabricate unidirectional magnetic papers. Magnetic cellulose fibers were made by in situ synthesis of magnetite nanoparticles on alpha cellulose pulp extracted from American southern pine. Scanning electron microscope micrographs and energy dispersive X-ray spectroscopy maps indicated that magnetite nanoparticles completely covered the cellulose fibers. Suspensions of magnetic cellulose fibers were prepared at three levels of concentration (0.02, 0.04, and 0.08 g/L) and poured into the designed magnetic forming machine. Flow rate of suspension into the forming column was adjusted at 0, 0.3, 0.5, and 1 cm/s. The strength of the applied external magnetic field was the same in all cases and lower than 0.18 T. Orientation analysis indicated that the designed magnetic forming machine has a high performance to be used for aligning magnetic cellulose fibers and fabricating unidirectional magnetic cellulose papers. Observed anisotropic magnetic and mechanical properties confirmed the unidirectional structure. PDF
Enzymatic hydrolysis of sludge from a bleached tissue mill generates glucose that can be sold as a product or sent to an ethanol plant. Hydrolysis rates using enzymes from two sources are reported, and a configuration for the industrial conversion of sludge to glucose is proposed. The system combines a set of stirred tank reactors with ash removal and membrane filtration to give a glucose concentrate. The economics of the conversion are attractive. PDF
Wood pyrolysis oil consists of hundreds of complex compounds, many of which are phenolic-based and exhibit hydrophobic properties. Southern yellow pine was impregnated with a pyrolysis oil-based penetrant using both a high pressure and vacuum impregnation systems, with no significant differences in retention levels. Penetrant concentrations ranging from 5-50% pyrolysis oil/methanol on a volume basis were used to determine the threshold concentration for significant physical property improvement. Wood impregnated with penetrant concentration of at least 10% exhibited significant reduction in both moisture sorption and tangential swelling when exposed to a 90% relative humidity and 21°C environment. When exposed to liquid water in a 24-hour soak test, analysis revealed a negative linear relationship between penetrant concentration and both moisture sorption and tangential swell. However, during the course of the 24-hour soak test, a significant linear relationship between penetrant concentration and leachate was determined. PDF
Ahmad, M. N., Mokhtar, M. N., Baharuddin, A. S., Hock, L. S., Ali, S. R. A., Abd-Aziz, S., Rahman, N. A. A., and Hassan, M. A. (2011). "Changes in physicochemical and microbial community during co-composting of oil palm frond with palm oil mill effluent anaerobic sludge," BioRes. 6(4), 4762-4780.
The aims of this study were to investigate the physicochemical changes and microbial population during co-composting of 1 ton oil palm frond (OPF) with 1,000 L palm oil mill effluent (POME) anaerobic sludge. In the first 30 days of composting, the temperature of the composting piles was observed in the thermophilic phase, within a range of 50 - 56oC. Meanwhile, the oxygen level, moisture content, and pH profiles of the compost were maintained at 2.0 to 12%, 60 to 70%, and 7.9 to 8.5, respectively, throughout the composting process. The total bacteria count was estimated to be about 55 x 1010 CFU/mL in the mesophilic phase, and then it increased up to 66 x 1010 CFU/mL in the thermophilic phase, and finally decreased to 9.0x1010 CFU/mL in the curing phase. The initial C/N ratio, 64, decreased to 18 after 60 days of composting process, indicating the maturity of compost product from OPF-POME anaerobic sludge. The diversity of the bacterial community was investigated using polymerase chain reaction-denaturing gradient gel electrophoresis (PCR-DGGE) analysis. The results suggested that the co-composting process of OPF with POME anaerobic sludge was dominated by Pseudomonas sp. PDF
Using standard methods for the determination of approximate analysis, ultimate analysis, and calorific value, the thermochemical properties of driftwood have been analyzed in the present study. The preliminary results showed that woody waste obviously comprised a large percentage of volatile matter at 72.56 ± 4.58 wt%. The molar ratio of hydrogen to carbon (H/C) was about 1.1, which was lower than those of cellulose (H/C = 1.67) and hemicellulose (H/C = 1.6), and seemed to be in accordance with its higher heating value (18.7 MJ/kg). However, the content of nitrogen was slightly higher, suggesting that the emissions of nitrogen oxide gases from biomass-to-heat facilities will arouse concern. Under the carbonization temperature of around 500 oC, the calorific value (25.5 MJ/kg) of the resulting biochar from driftwood was relatively enhanced. Based on the 1,000,000 tons driftwood in Taiwan and the Tier 1 method recommended by the Intergovernmental Panel on Climate Change (IPCC), the environmental benefit of mitigating greenhouse gas emissions and the economic benefit of selling electricity were preliminarily calculated to be around 1.5 × 10 6 tons and US$ 7.0 × 10 7, respectively. PDF
Ionic liquids that dissolve cellulose provide an option to pretreat lignocellulosic biomass. In this study, potential application of three ionic liquids in pretreating rice husk and their abilities in dissolving rice husk cellulose were investigated. The ionic liquids applied were 1-butyl-3-methylimidazolium chloride ([BMIM]Cl), 1-ethyl-3-methylimidazolium acetate ([EMIM]OAc), and 1-ethyl-3-methylimidazolium diethyl phosphate ([EMIM]DEP). Dissolution of rice husk was conducted by heating 1.5% (w/v) rice husk-ionic liquid mixture at 100oC for 20 hours. The dissolved cellulose was subsequently regenerated with deionised water. All the ionic liquids were able to dissolve rice husk cellulose to varying extents, with the highest dissolution (36.7%) given by [EMIM]OAc followed by [BMIM]Cl (31.3%) and [EMIM]DEP (16.0%) at the 10th hour of heating. All the regenerated cellulose were found to be more amorphous as compared to the untreated rice husk. The energy study showed that both [EMIM]OAc and [BMIM]Cl had lower energy requirement compared to [EMIM]DEP. The results of energy requirement complemented the findings of dissolution ability of the ionic liquid. Both [EMIM]OAc and [BMIM]Cl are potential ionic liquids to be used in the pretreatment of rice husk, as they dissolved rice husk equally well. PDF
Ten industrial fully bleached hardwood pulps representing very different brightness reversion profiles were evaluated. The pulps were characterized before and after brightness reversion. The aging method (dry, wet, high/low RH, high/low temperature, short/long time) had, in most cases, no effect on overall brightness reversion trends, but affected the absolute reversion values significantly. Relative humidity in the range of 50 to 90% influenced reversion much more than temperatures in the range from 30 to 45°C. Dry and wet heat-induced brightness reversion correlated positively and significantly with hexenuronic acid (HexA) content in the pulp. The brightness reversion causes a significant decrease in pulp viscosity values, and HexA thus causing decrease of kappa number. Modern pulps produced by TCF and light ECF bleaching technologies were more prone to brightness reversion than regular ECF pulps, partly due to the higher content of HexA. At a pH level above 8, the brightness reversion process was strongly retarded for pulps with a very high HexA content. PDF
Bachtiar, D., Salit, M. S., Zainudin, E., Abdan, K., and Mohd. Dahlan, K. Z. H. (2011). "Effects of alkaline treatment and a compatibilizing agent on tensile properties of sugar palm fibre-reinforced high impact polystyrene composites," BioRes. 6(4), 4815-4823.
The effects of alkaline treatment and a compatibilizing agent on the tensile properties of sugar palm fibre-reinforced high impact polystyrene (HIPS) composites were studied. Two concentrations of an alkali solution (4% and 6%) and two percentages of a compatibilizing agent (2% and 3%) were used in this study. The alkaline treatment was carried out by immersing the fibres in 4% and 6% alkali solutions for 1 hour. A 40 wt. % of sugar palm fibre (SPF) was blended with HIPS and the compatibilizing agent using a Brabender melt mixer at 165 °C. All the treated fiber composites showed tensile strength enhancement compared with untreated composites. The maximum strength increase was 35%, which was achieved by 4% alkali treatment; however, there was no improvement in the tensile modulus. PDF
In this research, char was prepared from Switchgrass (Panicum virgatum) cave-in-rock species and characterized from the perspective of value addition either as a soil amendment or as a feedstock for energy production. Char from torrefaction/pyrolysis was produced in a fixed bed lab-scale reactor, using a N2 flow at three temperatures (300, 400, and 500°C) and for two residency times (2.5 and 5 minutes). Proximate and ultimate analyses as well as calorific value tests were done on each of the chars obtained. Chars scanning electron microscopy (SEM) pictures were taken. Organic composition of char leachates was characterized using gas chromatography-mass spectrometry (GC-MS) following a Soxhlet extraction with dichloromethane. Char was analyzed using FTIR-ATR. No significant difference was observed in most char characteristics between 2.5 and 5 min residency times, for each temperature studied. Among the compounds identified, two may be of particular interest with respect to the biochar domain. 1-undecanol, a compound commonly used as a growth regulator in agriculture, was observed in 300 and 400°C chars for 5 and 2.5 min residence time, respectively. Naphthalene, commonly used as an ingredient in pesticide products, was the only polycyclic aromatic hydrocarbon (PAH) observed in chars and was found solely in the extracts obtained from the char produced at 500 °C (for both residency times). PDF
Samarghandy, M. R., Hoseinzade, E., Taghavi, M., and Hoseinzadeh, S. (2011). "Biosorption of Reactive Black 5 from aqueous solution using acid-treated biomass from potato peel waste," BioRes. 6(4), 4840-4855.
The goal of this study was to survey the feasibility of the biosorption of Reactive Black 5 (RB5) from aqueous solutions using biomass prepared from potato peel waste. Adsorption isotherms were constructed, and the kinetics of dye adsorption were studied. Langmuir and Freundlich isotherms were constructed, and pseudo-first order, pseudo-second order, and modified pseudo-first order kinetic models were studied. Maximum adsorption (85.5%) was observed at a pH of 3, and uptake decreased with increasing pH. The biosorption of RB5 increased with increasing contact time and reached equilibrium after two hours. RB5 removal efficiency decreased with an increase in the initial dye concentration, but the uptake of dye increased. Adsorption data conformed to the Langmuir isotherm model and pseudo-first order kinetics. PDF
Biomass pretreatment by autohydrolysis uses hot-water to extract soluble components from wood prior to converting the woody residuals into paper, wood products, or fuel, etc. Mixed hardwood chips were autohydrolyzed in hot-water at 150, 160, 170, and 180 ºC, for 1 and 2 h. The tradeoff between fermentable sugar yield and caloric value of the residual solids was studied for a process that will be referred to as “value prior to combustion”. The extracted liquid was treated with dilute sulfuric acid to break down sugar oligomers into fermentable monomers. Material balances were performed around autohydrolysis to evaluate the role of temperature and residence time on sugar production and residual solid heating value. The composition (sugars and byproducts) of the extracted liquid was determined. As the autohydrolysis temperature increased, the material balance became less precise, presumably due to more volatile byproducts being formed that were not quantified. More hemicelluloses were extracted from the wood by the hot water extraction process under higher temperature and longer residence time, but a greater degree of sugar degradation was also observed. After hot-water extraction the heating value of the solid residues was higher than the original wood. The total energy content of the residual solid after extraction ranged from 74 to 95% of the original energy content of the feed. PDF
The Young’s modulus and the in-plane shear modulus of medium-density fiberboard (MDF) were obtained by conducting a flexural vibration test under the free-free condition based on Timoshenko’s vibration theory using specimens with various depth/length ratios and performing a subsequent numerical analysis. The results obtained by the experiment and numerical analysis revealed that the Young’s modulus was independent of the specimen configuration. In contrast, the in-plane shear modulus was significantly dependent on the specimen configuration and could not be measured properly based on Timoshenko’s theory when the specimen had a small depth/length ratio. The numerical analysis also revealed that the Poisson’s ratio has a significant influence on the measurement of shear modulus as well as the specimen configuration. A statistical analysis on the results experimentally obtained suggested that the length of the specimen must be less than 7.5 times the depth to measure the in-plane shear modulus appropriately. PDF
Kurt, R., Cil, M., Aslan, K., and Cavus, V. (2011). "Effect of pressure duration on physical, mechanical, and combustibility characteristics of laminated veneer lumber (LVL) made with hybrid poplar clones," BioRes. 6(4), 4886-4894.
Experimental eight-ply laminated veneer lumbers (LVLs) from rotary peeled I-214 (Populus x Euramericana) and I-77/51 (Populus deltoides)fast growing hybrid poplar clones were successfully manufactured using three different press durations (18, 24, and 30 min) with a melamine urea formaldehyde (MUF) adhesive. The effect of press durations on LVLs’ selected physical, mechanical, and combustibility characteristics were determined. The results showed that press duration affected dimensional stability (thickness swelling and water absorption), modulus of rupture, and/or compression strength parallel to grain, depending on the clone types. Improvement in dimensional stability and some mechanical properties of LVLs can be achieved by proper curing of the MUF adhesive. On the other hand, the press durations did not affect oven-dry densities, modulus of elasticity, and the combustibility (weight loss after completion of the test). For improved physical and mechanical properties, up to a 30 min press duration can be recommended. This is necessary for LVLs when they are to be used under conditions where water and/or high humidity is present. PDF
In this study we analyze changes in United States imports of wood furniture over the 39-year period from 1972 to 2010. In 1972, Canada and the former Yugoslavia were the most important sources of imported wood furniture, and Europe accounted for nearly 60 percent of total imports. Shipments of low-cost wood furniture from Taiwan started to increase in the 1970s, and by 1978, Taiwan was the most important source of imported wood furniture. Overall, low-cost sources in Asia displaced Europe in 1987. Taiwan continued to be the most important source until 1994. Canada became the most important source of imported wood furniture from 1994 to 2000 as the Canadian dollar declined in value against the United States dollar. In 2001, China became the most important source of wood furniture imports. More recently furniture imports from an emerging source, Vietnam, have increased dramatically. One reason why Asian manufacturers have been so successful in the U.S. market has been that furniture consumers were influenced mainly by price. By contrast, success in some segments of the U.S.-based furniture industry indicates that models enabling consumers to make styling and pricing decisions also can be competitive. PDF
Shahriarinour, M., Wahab, M. N. A., Ariff, A. B., Mustafa, S., and Mohamad, R. (2011). "Kinetics of cellulase production by Aspergillus terreus at various levels of dissolved oxygen tension in a stirred tank bioreactor," BioRes. 6(4), 4909-4921.
In this study the effect of different levels of dissolved oxygen tension (d.o.t) on the production of three main components of extracellular cellulases (FPase, CMCase and β-glucosidase) at a fixed agitation speed by Aspergillus terreus was investigated. Growth of A. terreus and cellulase production were modeled based on logistic and Luedeking-Piret equations. The results from the model fit well with the experimental data, confirming that the models were appropriate for describing and representing growth and cellulase production at various d.o.t levels. The models showed that the production of FPase and CMCase were growth-associated processes. Cell growth and cellulase production were approximately two-fold higher in a stirred tank bioreactor compared with a shake-flask culture. At a d.o.t of 55% air saturation, cell growth and cellulase production were higher than at low d.o.t (40% air saturation) or high d.o.t (80% air saturation). The highest activities of FPase (2.33 U ml-1), CMCase (51.10 U ml-1), and β-glucosidase (16.18 U ml-1) were obtained at a d.o.t of 55% air saturation, yielding overall productivities of 19.40, 425.00, and 67.40 U l.h-1, respectively. PDF
Martín-Sampedro, R., Martín, J. A., Eugenio, M. E., Revilla, E., and Villar, J. C. (2011). "Steam explosion treatment of Eucalyptus globulus wood: Influence of operational conditions on chemical and structural modifications," BioRes. 6(4), 4922-4935.
This study evaluates the use of steam explosion (SE) as a pre-treatment of Eucalyptus globulus chips, aimed at making this wood suitable as feedstock in biorefineries or alternative processes such as biopulping. Several SE treatments were applied, modifying the following variables: previous hydration of the chips, number of SE cycles, and duration of the first cycle. Chemical composition and structural properties were analyzed after all treatments. Our results show that acetone and hot water extractives contents increased between 1.0% and 6.2% and between 3.6% and 7.1%, respectively, depending on SE operational conditions. Holocellulose content was also observed to decrease (9.4 to 15.6%), while the Klason lignin underwent a slight solubilization. Furthermore, greater water retention capacity and new bigger sized pores were found in the exploded samples. It is reasonable to expect that these changes would facilitate the subsequent implementation of chemical or biological treatments of the cellulose fraction in the biorefinery design. PDF
Olivella, M. À., and del Rio, J. C. (2011). "Suberin composition from different bark layers of Quercus suber L. by PY-GC/MS in the presence of tetramethylammonium hydroxide (TMAH)," BioRes. 6(4), 4936-4941.
In previous studies we found significant differences in the suberin content with respect to the bark layer of Quercus suber samples. In this study the monomer composition of suberin from the two bark layers (i.e., back and cork) of three provenances (Extremadura, Castile-la Mancha, and Portugal) was investigated using pyrolysis in the presence of tetramethylammonium hydroxide (TMAH) with gas chromatography-mass spectrometry (GC/MS). The major compounds released were octadec-9-enedioic acid, docosanedioic acid, and 9,10-epoxyocta-decanedioic acid with mean values of 17%, 14.5%, and 11%, respectively. The former is more abundant in back than in cork, and the latter in cork than in back with mean differences, in terms of percentages, between the back and cork of 4.3 ± 0.81 and 2.2 ± 0.52, respectively. PDF
A novel class of hydrogel was prepared by graft copolymerization of acetic acid lignin (AAL) and N-isopropylacrylamide (NIPAAm) in the presence of N,N'-Methylenebisacrylamide (MBAAm) as the crosslinker and H2O2 as the initiator. The impact of AAL content on the hydrogel properties were investigated in terms of their swelling behavior, thermal behavior, and interior morphology. The data showed that these newly synthesized hydrogels were temperature-sensitive. Differential scanning calorimetry (DSC) curves demonstrated that the lower critical solution temperature (LCST) of the lignin-based hydrogels was approximately 31°C. The thermogravimetric analysis (TGA) data revealed that the temperature of rapid decomposition of all the hydrogel samples was within a narrow range of 400 to 410°C. Furthermore, the scanning electron microscopy (SEM) images showed that the pore size of the hydrogel increased with increasing the AAL content. PDF
Norway spruce specimens 50x30x30mm with initially determined ultrasonic characteristics in the longitudinal, radial, and tangential directions were subjected to bio-attacks with the brown-rot fungi Serpula lacrymans, Coniophora puteana,or Gloeophyllum trabeum, and the white-rot fungus Trametes versicolor, respectively. Bio-attacks lasted 4, 8, 12, or 16 weeks. Decreases of the ultrasonic wave velocities (Dc) and the dynamic modulus of elasticity (DMOEd) depended more or less closely on the enlarged degrees of rot in the spruce wood, and as the dynamic modulus of elasticity decreased approx. 1.7 to 2.3 times more than corresponding weights (Dm from 2.01 to 42.35%) or 2.1-3.4 times more than corresponding densities (Dr from 2.42 to 26.63%). Two sample t-test analyses of slopes “a” in the linear regressions Dc or DMOEd = a.(Dm) or a.(Dr) showed that drops of the ultrasonic and elastic characteristics of wood having the brown rot were not influenced by the fungus species. On the other hand, the velocity of ultrasonic waves in the longitudinal direction and the dynamic modulus of elasticity appeared to be suitable for distinguishing the brown rot from the white rot at known decreases of wood density. The anatomical direction of wood was a significant factor only for the white rot, when approx. 2-times higher decrease of the ultrasonic wave velocities was determined in the radial and tangential directions compared to the longitudinal one. PDF
The chemical composition of Astragalus armatus contains quite a high amount of extractives in organic solvents (close to 13%), but a low percentage of lignin (around 17%) and an acceptable content of holocellulose (54%). The α-cellulose content is around 35%, and the ash content is around 3%. Using the insight of such data, the soda-anthraquinone cooking of Astragalus armatus produced lignocellulosic fibres. Different cooking temperatures (100, 120, 140, and 160°C) were tested and the delignification duration was 2 h. A yield of about 30% w/w was obtained, and the obtained pulps had a kappa number of 25. Finally, the isolated fibres were used to produce paper samples with a basis weight of 60 g/m2. The structural and mechanical properties of the prepared samples were close to those of other common annual plant-based fibre mats. PDF
Zhang, J., Rizvi, G. M., and Park, C. B. (2011). "Effects of wood fiber content on the rheological properties, crystallization behavior, and cell morphology of extruded wood fiber/HDPE composites foams," BioRes. 6(4), 4979-4989.
When increasing the wood fiber (WF) content in extruded wood fiber/plastic composites (WPC) foams, a good balance between reducing the cost and obtaining good cell morphology should be maintained. This study examines the relationship between WF content and the foam morphology in WPC foams. The role of WF as cell nucleating agent at low concentrations (10 wt.%) was observed, as WPC foam with 10 wt.% WF had lower average cell size and higher cell density than neat HDPE foams. Increasing the WF content further, decreased the average cell size and cell density, and increased the foam density of WPC foams. These results were linked to the rheological properties and crystallization behavior of HDPE and WPC with different WF content. PDF
This article describes a facile method for the preparation of cellulosic catalyst paper: the in situ synthesis of gold nanoparticles (AuNPs) on zinc oxide (ZnO) whiskers, the preferential support for AuNPs, preloaded into a paper matrix. The ZnO paper composites were fabricated using a high-speed and low-cost paper-making technique, and immersed in an aqueous solution of HAuCl4. After drying, fine 5 nm AuNPs were successfully formed on the ZnO whiskers inside the paper matrix. As-prepared AuNPs@ZnO whisker-containing paper (AuNPs@ZnO paper) is similar to ordinary paper products, being flexible, lightweight, and easy to handle. The AuNPs@ZnO paper exhibited a high catalytic efficiency towards the reduction of 4-nitrophenol to 4-aminophenol in aqueous media. Furthermore, the addition of a polyamideamine epichlorohydrin resin provided a wet strength to the AuNPs@ZnO paper, which enables several catalyst recycles with no significant losses in catalytic activity. PDF
Liu, Y., Wang, G., Xu, J., Zhang, Y., Liu, C., and Yuan, Z. (2011). "Effect of sulfite pretreatment to overcome the recalcitrance of lignin (SPROL) on enzymatic saccharificaiton of corn stalk," BioRes. 6(4), 5001-5011.
In order to maximize the glucose yield in the subsequent enzymatic hydrolysis, corn stalk was pretreated with sulfite to overcome the recalcitrance of lignocellulose (SPORL) under different operational conditions (pretreatment temperature, bisulfite charge, and pH). The parameters optimized included sodium bisulfite charge from 0 to 7% (w/w) on od dry (od) substrate, pretreatment temperature 160 to 190 oC, and pH 2.2 to 6.7 required in the process. The results indicated that after the SPORL pretreatment of corn stalk with 7% bisulfite at 180 oC for 30 min, about 69% and 62% of enzymatic conversion efficiency and glucose yield were achieved, respectively, with emzyme loading of about 5 FPU cellulase per gram of cellulose plus β-glucosidase after 72 h hydrolysis. Temperature had a positive effect on enzymatic hydrolysis. The enzymatic conversion efficiency was reached 81.04% with 7% sodium bisulfite at 190 oC for 30 min. The pH of pretreatment liquor plays a crucial role in enhancing enzymatic digestibility of SPORL substrate. PDF
Zhu, Z.-S., Li, X.-H., Zheng, Q.-M., Zhang, Z., Yu, Y., Wang, J.-F., Liang, S.-Z., and Zhu, M.-J. (2011). "Bioconversion of a mixture of paper sludge and extraction liquor from water prehydrolysis of Eucalyptus chips to ethanol using separate hydrolysis and fermentation," BioRes. 6(4), 5012-5026.
Paper sludge and extraction liquor from water prehydrolysis of Eucalyptus chips before pulping are potential raw materials for ethanol production in an integrated forest biorefinery concept. Ethanol production from paper sludge, extraction liquor from water prehydrolysis of Eucalyptus chips, and a mixture of both using separate hydrolysis and fermentation were investigated. The hydrolysate composed of 51.01±0.72 g/L glucose, 30.11±0.09 g/L xylose, and 13.65±0.94 g/L cellobiose, which was obtained by enzymatic saccharification of the mixture at an initial consistency of 6% (w/v, expressed in terms of total carbohydrate mass), was used for ethanol production by yeast SHY07-1 without prior detoxification and nutrient supplementation. A final ethanol concentration of 36.82±0.35 g/L was achieved, corresponding to an ethanol yield of 0.45±0.04 g/g with a fermentation efficiency of 80.71±0.03% and an ethanol productivity of 0.31±0.01 g/(L h). This confirmed the feasibility of co-fermentation of these two materials for bioconversion to ethanol. PDF
Güler, C., and Büyüksarı, Ü. (2011). "Effect of production parameters on the physical and mechanical properties of particleboards made from peanut (Arachis hypogaea L.) hull," BioRes. 6(4), 5027-5036.
In this study, effects of panel density and adhesive ratio on some physical and mechanical properties of peanut (Arachis hypogaea L.) hull particleboards for general purposes were investigated. Panels were manufactured with various densities (0.5, 0.6, 0.7, and 0.8 g/cm3) and adhesive ratios (core layer 8-9% and face layer 10-11%) using urea-formaldehyde (UF) as an adhesive. All panels were tested for some mechanical (internal bond, modulus of elasticity, and modulus of rupture) and physical (water absorption and thickness swelling) properties. Results indicated that increase in the panel density and adhesive ratio, resulted in an improvement in mechanical and physical properties. Only the panels with 0.8g/cm3 density almost met the requirements for the TS-EN 312 Standard for general purposes. Also, the boards having the lower mechanical properties tested in this study can be used as insulating material in buildings because such materials would not be subjected to any mechanical stress. PDF
Stone groundwood (SGW) is a fibrous matter commonly prepared in a high yield process, and mainly used for papermaking applications. In this work, the use of SGW fibers is explored as reinforcing element of polypropylene (PP) composites. Due to its chemical and superficial features, the use of coupling agents is needed for a good adhesion and stress transfer across the fiber-matrix interface. The intrinsic strength of the reinforcement is a key parameter to predict the mechanical properties of the composite and to perform an interface analysis. The main objective of the present work was the determination of the intrinsic tensile strength of stone groundwood fibers. Coupled and non-coupled PP composites from stone groundwood fibers were prepared. The influence of the surface morphology and the quality at interface on the final properties of the composite was analyzed and compared to that of fiberglass PP composites. The intrinsic tensile properties of stone groundwood fibers, as well as the fiber orientation factor and the interfacial shear strength of the current composites were determined. PDF
Several timbers and crop by-products were subjected to an enzymatic treatment to obtain a xylo-oligosaccharides-enriched preparation. The process was performed by means of the commercial endo-β-1,4-xylanase Buzyme 2511®. The enzymatic cocktail was applied onto the raw ground materials with yield up to 5.3 ± 1.0 g/L xylo-oligosaccharides for apple pomace. In order to make the materials more accessible to enzymatic hydrolysis, they were subjected to thermal-alkaline treatment. The biocatalysis process over the thermo-alkaline treated materials yielded xylo-oligosaccharide solutions with the following concentrations (g/l): 1.3 white poplar (Populus alba), 2.9 giant cane (Arundo donax), 3.7 apple pomace (Malus domestica), and 6.5 stalk of grapes (Vitis vinifera). The preparation resulting from biotransformation of grape stalk contained mostly xylo-oligosaccharides (96% w/v) with a small amount of xylose (3% w/v). The same ratio was obtained when pure xylan from birchwood was used as feedstock. PDF
Sharma, A. K., Dutt, D., Upadhyaya, J. S., and Roy, T. K. (2011). "Anatomical, morphological, and chemical characterization of Bambusa tulda, Dendrocalamus hamiltonii, Bambusa balcooa, Malocana baccifera, Bambusa arundinacea, and Eucalyptus tereticornis," BioRes. 6(4), 5062-5073.
Due to scarcity of cellulosic wood fibers five bamboo species, namely B. tulda, D. hamiltonii, B. balcooa, M. baccifera, and B. arundinacea, and two eucalyptus species, namely E. tereticornis and E. grandis, were grown under North Indian climatic conditions in order to sustain fiber supply through social forestry. After four years of cultivation, these cellulosic raw materials were evaluated for anatomical structures, fibre dimensions, chemical characterization, and pulp and paper making characteristics. B. balcooa and M. baccifera contained higher holocellulose and α-cellulose contents compared to other bamboo species and lower ash contents, indicating that they are likely to pose less problem during chemical recovery. E. grandis contained higher holocellulose, α-cellulose, and lower lignin contents than that of E. tereticornis. Morphologically, bamboo species did not show much difference in fiber dimensions and their derived values. E. grandis showed problems of kink and curl due to longer fiber length than E. tereticornis. Based on pulp yield, brightness, and pulp viscosity B. balcooa, M. baccifera and E. grandis are better options for social forestry among other species. PDF
Soda pulping was performed using kenaf stalk, core, and bast as raw materials. It was observed that all these components could yield good paper characteristics when the resulting pulps were beaten to a freeness of 200 to 300 mL. Soda pulp made from the stalk was comparable to the frond from oil palm in sheet properties, but the latter would require higher beating energy to reach similar freeness as compared to the former. PDF
Si, C.-L., Lu, Y.-Y., Qin, P.-P., Sun, R.-C., and Ni, Y.-H. (2011). "Phenolic extractives with chemotaxonomic significance from the bark of Paulownia tomentosa var. tomentosa," BioRes. 6(4), 5086-5098.
Chemotaxonomy, also known as chemosystematics, can be regarded as a hybrid science which can classify plants based on their unique extractives (secondary metabolites). In this work, we investigated the chemotaxonomic marks of Paulownia species by studying the extractives of Paulownia tomentosa (Thunb.) Steud. var. tomentosa, a hardwood species widely used in Chinese medicine and pulping industries. Nine phenolic extractives, including two flavonoids (naringenin (1), and quercetin (2)), two phenolic acids (cinnamic acid (3), and gallic acid (4)), and five phenylpropanoid glycosides (cistanoside F (5), acteoside (6), isoacteoside (7), campneoside II (8), and isocampneoside II (9)), were isolated from the n-BuOH soluble fraction of P. tomentosa var. tomentosa bark, by repeated sephadex LH-20 open column chromatography coupled by Thin Layer Chromatography detection. The structures of the phenolic extractives were elucidated and characterized on the basis of their spectroscopical data and physiochemical properties. This was the first time to report the nine extractives from P. tomentosa var. tomentosa bark. Our chemotaxonomic analysis demonstrated that phenylpropanoid glycosides in P. tomentosa var. tomentosa were interesting and phenylpropanoid glycosides may possibly be considered as a useful chemotaxonomic marker within the species of Paulownia. PDF
Zhang, H., Yuan, Z., Gilbert, D., Ni, Y., and Zou, X. (2011). "Use of a dynamic sheet former (DSF) to examine the effect of filler addition and white water recirculation on fine papers containing high-yield pulp," BioRes. 6(4), 5099-5109.
With increased interest in using high-yield pulps (HYP) in uncoated and coated wood-free paper, there is a need to evaluate the effects of HYP under the conditions similar to commercial paper machine operations. Such tests were carried out by means of a Dynamic Sheet Former (DSF) sheet with white water recirculation, considering the high fines content of HYP and the usually high filler content in fine papers. In this study, we evaluated the use of a DSF that is equipped with a white water recirculation tank for making oriented sheets under various conditions. The effects of different factors such as operational variables, use of retention aids, and recirculation of white water were examined and clarified in terms of retention of fines and fillers as well as their impact on paper properties. The effect of HYP content on filler retention was also examined. PDF
Graft copolymerization of acrylamide (Am) onto rubberwood fibre (RWF) was carried out by free radical initiation. Ceric ammonium nitrate was used as an initiator system. The effects of temperature, dose of initiator, ratio of monomer to fibre, and nitric acid concentration, on the grafting percentage were investigated. The optimum reaction temperature was found to be about 50°C for 4h and with an appropriate ratio of monomer to fibre of 3:1 wt/wt. The optimum concentration of initiator and nitric acid were 0.007 M and 0.2 M, respectively. The polyacrylamide (PAm) homopolymer was removed from the graft copolymer by Soxhlet extraction using distilled water. The pre-treatment RWF before the grafting procedure showed that grafting of acid-treated had a higher efficiency than alkali- treated and untreated RWF. Fourier transform infrared spectroscopy was used to confirm and characterize the PAm-graft-RWF. PDF
Crude tall oil (CTO) soap, purified and neutralised CTO, and neutralised distilled tall oil (DTO) were pyrolysed (at 750ºC for 20 s) by pyrolysis gas chromatography with mass-selective and flame ionisation detection (Py-GC/MSD and FID) to clarify their thermochemical behaviour. In each case, the pyrolysates were characteristically dependent on the feedstock, and a wide range of volatile aliphatic and aromatic compounds with some chemically bound oxygen formed. The CTO soap pyrolysate was typically composed of initial extractives-type compounds together with a significant amount of unsaturated aliphatic hydrocarbons and aromatics, whereas the DTO pyrolysate contained mostly just unsaturated aliphatic hydrocarbons and aromatics. These data are of importance when considering the suitability of various extractives-derived resources for producing bioliquids and chemicals. PDF
Mixed US southern hardwood chips were impregnated and cooked under various conditions in the laboratory. Kappa numbers between 15 and 55 were obtained. The reject content, kappa number, and yield were studied as a function of time, temperature, and alkali charge in the cooking. The results indicate that by using modern cooking technology, i.e. CompactCookingTM, an optimal point with respect to the studied pulp parameters can be found. Selected pulps were bleached to high brightness with several different bleaching sequences. These pulps were beaten in a PFI mill and their physical properties were compared at a constant bulk. High kappa, well impregnated fully bleached pulps exhibited improved yield with equivalent or better physical properties as compared to conventional kraft pulps. The high kappa, well impregnated pulps were also found to have improved bleachability as compared to conventionally cooked, bleachable grade kappa number pulps. PDF
Shi, Z.-J., Xiao, L.-P., Deng, J., Xu, F., and Sun, R.-C. (2011). "Isolation and characterization of soluble polysaccharides of Dendrocalamus brandisii: A high-yielding bamboo species," BioRes. 6(4), 5151-5166.
Nine soluble polysaccharide fractions were sequentially extracted with hot water at 80, 100, and 120 °C for 3 h, and 60% aqueous ethanol containing 0.25, 0.50, 1.00, 2.00, 3.00, and 5.00% NaOH at 80 °C for 3 h from dewaxed bamboo (Dendrocalamus brandisii) sample, and their chemical compositions and physicochemical properties were examined. The sequential treatments yielded 20.6% soluble polysaccharides of the dry dewaxed bamboo material. Molecular weight and neutral sugars analysis revealed that the soluble polysaccharides were mainly composed of arabinoglucuronoxylans and amylose starch. Spectroscopy (FT-IR, 1H, 13C, and 2D-HSQC NMR) analyses suggested that the isolated arabinoglucuronoxylans from bamboo (D. brandisii) could be defined as a linear (1→4)-β-linked-xylopyranosyl backbone to which α-L-arabinofuranose units and/or short chains of 4-O-methyl-glucuronic acid were attached as side residues via α-(1→3) and/or α-(1→2) linkages. In addition, it was found that the thermal stability of polysaccharides increased with an increment of their molar mass. PDF
The effects of moulding pressure and initiator content on the performances of kraft fibre-reinforced UPE composites were investigated by means of tensile evaluation, DMA analysis, SEM analysis, and short-term creep tests. The results indicated that the prepared composites had much higher tensile strength and modulus and better creep resistance than traditional thermoplastic wood plastic composites (WPCs). These improved properties resulted from the incorporation of the strong kraft fibres as reinforcement. The combination of the fibers with the thermosetting UPE matrix produced enhanced kraft-UPE interfacial adhesion. Changes in moulding pressure and initiator level produced various effects in the properties of composites. As the moulding pressure increased from 6 MPa to 25 MPa, the mechanical properties and creep resistances increased gradually until a moulding pressure of 20 MPa was reached; after this point, the values decreased. With an increase in the initiator content from 0.3 PHR (parts per hundred parts of resin) to 1.0 PHR, the tensile strength and interface adhesion first increased, then decreased, while the instantaneous strain and maximum strain values (measured in the creep tests) decreased gradually. PDF
Safdari, V., Khodadadi, H., Hosseinihashemi, S. K., and Ganjian, E. (2011). "The effects of poplar bark and wood content on the mechanical properties of wood-polypropylene composites," BioRes. 6(4), 5180-5192.
Bark, as a residue from trees, is mostly used for thermal energy production, but a better utilization of this resource was considered as an alternative raw material for wood-plastic composites (WPCs). The influence of bark, wood, and blending of bark and wood flour content of the poplar tree on the mechanical characteristics of WPCs were investigated. Wood and bark flours with 2% maleic anhydride-grafted polypropylene (MAPP) and polypropylene were compounded into pellets using a counter-rotating twin-screw extruder, and test specimens were prepared by injection molding. The results showed that both bark fiber and wood flour increased mechanical strength (flexural strength (MOR), flexural modulus (MOE), tensile modulus, and tensile strength) significantly (P<0.05). Composites made with bark flour exhibited lower mechanical strength compared to those made with wood flour and wood flour/bark flour. Differences in chemical composition between bark and wood, fines, low aspect ratio (length/width) of bark flour, delamination between fines and matrix, and the lower intrinsic fiber strength of bark fibers compared to wood fibers are good explanations for this demarcation. The notched impact strength of all reinforced composites was significantly lower than neat polypropylene (P < 0.05). PDF
Pretreatment of straw separated from cattle and horse manure using N-methylmorpholine oxide (NMMO) was investigated. The pretreatment conditions were for 5 h and 15 h at 120 °C, and the effects were evaluated by batch digestion assays. Untreated cattle and horse manure, both mixed with straw, resulted in 0.250 and 0.279 Nm3 CH4/kgVS (volatile solids), respectively. Pretreatment with NMMO improved both the methane yield and the degradation rate of these substrates, and the effects were further amplified with more pretreatment time. Pretreatment for 15 h resulted in an increase of methane yield by 53% and 51% for cattle and horse manure, respectively. The specific rate constant, k0, was increased from 0.041 to 0.072 (d-1) for the cattle and from 0.071 to 0.086 (d-1) for the horse manure. Analysis of the pretreated straw shows that the structural lignin content decreased by approximately 10% for both samples and the carbohydrate content increased by 13% for the straw separated from the cattle and by 9% for that separated from the horse manure. The crystallinity of straw samples analyzed by FTIR show a decrease with increased time of NMMO pretreatment. PDF
Abdul Khalil, H. P. S., Marliana, M. M., and Alshammari, T. (2011). "Material properties of epoxy-reinforced biocomposites with lignin from empty fruit bunch as curing agent," BioRes. 6(4), 5206-5223.
Lignin was obtained from black liquor samples from soda-AQ pulping of oil palm empty fruit bunch (EFB) fiber. Oil palm EFB reinforced epoxy composite samples with varying lignin content of 15, 20, 25, and 30% as curing agent were prepared. The chemical structures of lignin were characterized by FT-IR, and CHN analysis. FT-IR and CHN analysis confirmed structural changes of epoxy resin after use of EFB-lignin as curing agent in epoxy resin. Thermal analysis of composites was carried out by thermogravimetric analysis (TGA). The TGA graphs showed that crosslinking of epoxy and lignin as curing agent may induce relatively high-chain rigidity in the polymer and may result in an enhanced thermal stability of the EFB/lignin-epoxy composite systems. The mechanical properties (tensile, flexural, and impact behavior) and physical properties (water absorption) of the composite samples were evaluated. Mechanical properties of epoxy composites cured with 25% lignin were found to be higher than that of the composite prepared from a commercial curing agent. Scanning electron micrographs showing tensile fracture of the composites showed evidence of good fiber–matrix interaction, induced by the curing agent. PDF
Isroi, Millati, R., Syamsiah, S., Niklasson, C., Cahyanto, M. N., Lundquist, K., and Taherzadeh, M. J. (2011). "Biological pretreatment of lignocelluloses with white-rot fungi and its applications: A review," BioRes. 6(4), 5224-5259.
Lignocellulosic carbohydrates, i.e. cellulose and hemicellulose, have abundant potential as feedstock for production of biofuels and chemicals. However, these carbohydrates are generally infiltrated by lignin. Breakdown of the lignin barrier will alter lignocelluloses structures and make the carbohydrates accessible for more efficient bioconversion. White-rot fungi produce ligninolytic enzymes (lignin peroxidase, manganese peroxidase, and laccase) and efficiently mineralise lignin into CO2 and H2O. Biological pretreatment of lignocelluloses using white-rot fungi has been used for decades for ruminant feed, enzymatic hydrolysis, and biopulping. Application of white-rot fungi capabilities can offer environmentally friendly processes for utilising lignocelluloses over physical or chemical pretreatment. This paper reviews white-rot fungi, ligninolytic enzymes, the effect of biological pretreatment on biomass characteristics, and factors affecting biological pretreatment. Application of biological pretreatment for enzymatic hydrolysis, biofuels (bioethanol, biogas and pyrolysis), biopulping, biobleaching, animal feed, and enzymes production are also discussed. PDF
Retting is the main challenge faced during the processing of bast plants for the production of long fibre. The traditional methods for separating the long bast fibres are by dew and water retting. Both methods require 14 to 28 days to degrade the pectic materials, hemicellulose, and lignin. Even though the fibres produced from water retting can be of high quality, the long duration and polluted water have made this method less attractive. A number of other alternative methods such as mechanical decortication, chemical, heat, and enzymatic treatments have been reported for this purpose with mixed findings. This paper reviews different types of retting processes used for bast plants such as hemp, jute, flax, and kenaf, with an emphasis on kenaf. Amongst the bast fibre crops, kenaf apparently has some advantages such as lower cost of production, higher fibre yields, and greater flexibility as an agricultural resource, over the other bast fibres. The fibres produced from kenaf using chemical retting processes are much cleaner but low in tensile strength. Enzymatic retting has apparent advantages over other retting processes by having significantly shorter retting time and acceptable quality fibres, but it is quite expensive. PDF
To deeply understand the factors that affect the conversion of lignocellulosic biomass to fermentable sugars, experimental results should be bridged with process simulations. The objective of this paper is to review published research on modeling of the pretreatment process using leading technologies such as dilute acid, alkaline, and steam explosion pretreatment, as well as the enzymatic hydrolysis process for converting lignocellulose to sugars. The most commonly developed models for the pretreatment are kinetic models with assumptions of a first-order dependence of reaction rate on biomass components and an Arrhenius-type correlation between rate constant and temperature. In view of the heterogeneous nature of the reactions involved in the pretreatment, the uses of severity factor, artificial neural network, and fuzzy inference systems present alternative approaches for predicting the behavior of the systems. Kinetics of the enzymatic hydrolysis of cellulosic biomass has been simulated using various modeling approaches, among which the models developed based on Langmuir-type adsorption mechanism and the modified Michaelis-Menten models that incorporate appropriate rate-limiting factors have the most potential. Factors including substrate reactivity, enzyme activity and accessibility, irreversible binding of enzymes to lignin, and enzyme deactivation at high conversion levels, need to be considered in modeling the hydrolysis process. Future prospects for research should focus on thorough understanding of the interactions between biomass reactants and chemicals/enzymes — the key to developing sophisticated models for the entire conversion process. PDF
Paper aging and conservation are matters of concern to those responsible for archives and library collections. Wood-derived fibers are mainly composed of cellulose, hemicelluloses, and lignin, but paper composition can also include additives, such as starch, minerals, and synthetic polymers. Therefore, paper is a multi-component material, and because of its complex and varied nature, research findings in paper chemistry can be difficult to interpret. Deterioration of paper is caused by many factors such as acid hydrolysis, oxidative agents, light, air pollution, or the presence of microorganisms. The origin of the cellulosic material, as well as pulping and papermaking procedures, additives, and storage conditions play a crucial role. The chemical changes occurring within paper thus involve multi-parameter processes. The purpose of this review, which mainly focuses on the most recent decade, is to provide a description of the more important changes produced by aging and an update of the new tools available for the study of paper deterioration and its conservation. PDF