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BioResources, Volume 8, Issue 4
NOTE: Each current issue of BioResources continues to build as new articles are approved.
Those of us whose lives have been deeply touched by the technology of papermaking – and many others besides – are in for a real treat this coming fall when the book On Paper is scheduled to be published. The author, Nicholas Basbanes, employs an engaging, personalized approach as he brings to life the story of how paper has enabled the progress of civilization throughout two millennia. I first learned about Nick’s grand project, to capture the most intriguing aspects of paper’s story, during a re-broadcast of his hour-long interview that was presented on the CSPAN TV network. His enthusiasm is infectious, and it can be an uplifting experience to have him as a tour-guide to “all things paper”. PDF
Bending wood dates back to antiquity in the form of baskets from willow branches. Fresh growth willow twigs are readily bent into practically any shape. When wood has been separated from the tree and dried it is more rigid, difficult to bend, and breakable. Bending drier wood with the help of heat and water is centuries old. Fishing hooks, barrel staves, and planks turned into boat hulls are examples. Steamed wood is less rigid, since adding moisture and heat to wood results in plasticization. Steaming at atmospheric pressure is common, wherein diffusion prevails as the predominant mechanism governing moisture movement. Applications using conventional atmospheric steaming can be time consuming, non-uniform, and can result in failures. Vacuum steam technology offers a promising method that utilizes pressure differentials to accelerate the addition of steam to wood due to water vapor bulk flow and subsequently an accelerated temperature rise. More uniform plasticization results in less breakage of the wood. PDF
Crop straw-reinforced industrial materials can be effectively used as wood replacements, so the nondestructive evaluation of the dynamic performance and the realization of in-service testing are necessary for further quality control. Three nondestructive testing methods based on fast Fourier transform analysis were used to establish the dynamic modulus of elasticity of soybean stalk-reinforced materials. The results were compared to destructive measurements of the static modulus of elasticity and modulus of rupture using a regression analysis method. Significant correlations existed between the dynamic modulus of elasticity, static modulus of elasticity, and modulus of rupture. The highest degree of correlation was obtained from the flexural vibration method. The correlation degree is similar to that between the static modulus of elasticity and the modulus of rupture. Using the regression equation, a performance prediction model was established that will enable the prediction of the mechanical properties and quality evaluation of soybean stalk board. PDF
Because of the increasing awareness of the environment and energy issues, as well as advances in technology, the areas of application for annual plant fiber functional materials are expanding. In this work, two chemical treatments, alkalization (2 h agitation with 5% NaOH) and furfurylation (graft furfuryl alcohol followed by oxidation with (1N) NaClO2 solution), were conducted on Luffa cylindrica fiber surfaces. The grafting of furfuryl alcohol followed by oxidation-generated quinines showed better results than alkaline treatment with respect to enhancement of surface area and hydrophobicity as well as wax, lignin, and hemicellulose extraction. The efficiency of chemical treatments was verified by elemental analysis and FTIR spectroscopy. Differential scanning calorimetry, thermo-gravimetric analysis, scanning electron microscopy, water absorption, and mechanical tests were performed to determine the thermal, mechanical, and morphological properties of untreated and chemically treated luffa fiber reinforced epoxy composites. Microstructures of the composites were examined to determine the mechanisms for the fiber-matrix interaction, which affects the thermal stability, water absorption, and mechanical behavior of the composites. The data from the water absorption process of composites at various temperatures were analyzed using a diffusion model based on Fick’s law. PDF
Sundman, O., and Laine, J. (2013). "Layer-by-layer adsorption of two cellulose-based polyelectrolytes on cellulose fibers. Dependence of pH and ionic strength on the resulting charge density as measured by polyelectrolyte titration," BioRes. 8(4), 4827-4836.
The charge density of a bleached Kraft hardwood pulp, subjected to layer-by-layer adsorption of the oppositely charged cellulose derivative polyelectrolytes hydroxyethylcellulose ethoxylate, quaternised (HECE), and carboxymethyl cellulose (CMC), was studied by polyelectrolyte titration as a function of pH and ionic strength. The experimental design included a simultaneous variation of the experimental parameters, and the trends were evaluated with the help of partial least squares regression. As expected from the literature, the data indicate that both pH and ionic strength influence the charge of cationic fibers. It is also obvious that CMC as an outermost layer is more sensitive to changes in pH than the deprotonation of ≡COOH groups suggests. High ionic strength seems to be beneficial for the adsorption of HECE, while the pH dependence seems much more complicated. The non-linear pH dependence indicates that, in addition to electrostatic interactions, entropy factors and hydrogen bonding between OH groups on both the substrates and ligands are responsible for the adsorption, which is in agreement with literature on the subject. PDF
Shi, Y., Yokoyama, T., Akiyama, T., Yashiro, M., and Matsumoto, Y. (2013). "Characteristics of sulfurous acid prehydrolysis and its influence on the efficiency of subsequent chemical pulping process," BioRes. 8(4), 4837-4848.
The potential of sulfurous acid prehydrolysis followed by chemical pulping was examined at the laboratory scale using radiata pine. The residue obtained by sulfurous acid prehydrolysis with base addition was sufficiently delignified in a subsequent soda pulping stage, while the delignification of the residue was completely insufficient in subsequent kraft pulping. The residues prepared by prehydrolyses of hydrochloric and sulfuric acids were not delignified sufficiently regardless of the pulping method. The yield of hemicellulose-derived monosaccharides was about 90% on a theoretical basis in the optimal sulfurous acid prehydrolysis. In subsequent soda pulping under various conditions, pulps with kappa number 21 to 34, pulp yield 37 to 41%, and high cellulose content could be prepared from the residue obtained by sulfurous acid prehydrolysis with base addition. It was suggested from these results that sulfurous acid prehydrolysis with base addition in combination with subsequent soda pulping is an effective method for the utilization of wood hemicelluloses. PDF
García-Fuentevilla, L. L., Martin-Sampedro, R., Domínguez, P., Villar, J. C., and Eugenio, M. E. (2013). "Refining and urea pretreatments to enhance biobleaching of eucalyptus kraft pulp," BioRes. 8(4), 4849-4863.
Some pretreatments that swell and/or open the structure of wood fibers could increase the effectiveness of a biobleaching process, allowing for an industrial application. To this end, a chemical pretreatment (urea, U), a physical pretreatment (refining, R), and their combinations (RU and UR) were optimized to evaluate and compare their enhancement of the LE biobleaching sequence (laccase-mediator treatment plus alkali extraction). The urea pretreatment before biobleaching (ULE) provided the highest delignification (37.5%) and the highest increase in brightness (6.1 points % ISO). As expected, adding a refining process before or after the urea pretreatment increased paper strength. However, when the refining was applied after the urea pretreatment (URLE), the delignification was higher than that obtained after RULE. Thus, URLE provided a similar Kappa number and an increase of 97%, 149%, and 98% in the tensile, tear, and burst indexes, respectively, compared with ULE treatment, but it had a reduction of 2.8 points (% ISO) in brightness, caused by the action of refining. Therefore, depending on the final use of the paper (which can require high optical properties or high strength), either ULE or URLE would be the optimal sequence. PDF
Sarmin, S. N., Zakaria, S. A. K. Y., Kasim, J., and Shafie, A. (2013). "Influence of resin content and density on thickness swelling of three-layered hybrid particleboard composed of sawdust and Acacia mangium," BioRes. 8(4), 4864-4872.
This study was carried out to determine the thickness swelling of three-layered hybrid particleboard composed of sawdust and Acacia mangium under two different testing conditions. The experimental particleboards, composed of mixed sawdust and Acacia mangium, were fabricated with different resin contents and densities within the face and back (both composed of sawdust) and the core (composed of Acacia mangium particles). Particleboards consisting of only Acacia mangium particles were used as the control. Three different resin ratios (8:10:8, 10:10:10, and 12:10:12) were tested in combination with three different board densities (500, 600, and 700 kg/m3). Urea formaldehyde (UF), with the addition of wax, was used as a binder. The thickness swelling was evaluated using two tests: water immersion, and change in relative humidity, specifically between 10 and 90%, in accordance with the ASTM D 3502-76 (ASTM 1999) standard. The results indicated that there were significant interactions between the resin contents and the densities, which had an impact on the percentage of thickness swelling of the mixed sawdust-Acacia mangium composites in both test conditions. PDF
This study focuses on the use of demountable furniture joints in combination with 38-mm-thick honeycomb panels. These fittings were incorporated into L-shaped corner joints and then tested to determine their bending moment capacity. Overall, seven combinations of demountable fittings were tested. These groups of connectors consisted of solution non-glued, partly-glued connectors, and fully-glued connectors. All of the connectors were positioned in the test samples as they are commonly located in furniture construction. The highest capacities were obtained with glued connectors, followed by partly glued and then non-glued connectors. The difference in capacity between the inside and outside positions was insignificant for the non-glued and fully-glued connectors. A large difference between connectors in different positions was found for the partly glued connectors and for the second type of unglued connectors. The modes of failure were analyzed for each connector, and the possibilities for use in construction are described. PDF
Wei, P., Wang, B. J., Zhou, D., Dai, C., Wang, Q., and Huang, S. (2013). "Mechanical properties of poplar laminated veneer lumber modified by carbon fiber reinforced polymer," BioRes. 8(4), 4883-4898.
Poplar (Populuseuramericanacv.) is one of the most important fast-growing tree species in China, but so far its utilization has been limited to nonstructural wood-based panels. The objective of this work was to develop a good understanding of how to improve the mechanical properties of poplar laminated veneer lumber (LVL) with carbon fiber reinforced polymer (CFRP). A theoretical model was successfully developed to predict the bending modulus of elasticity (MOE) of LVL reinforced by CFRP. To validate the model, two different configurations of LVL were made in the laboratory: LVL reinforced with a single layer of CFRP on one side (LVL-SR) and LVL reinforced with a single layer of CFRP on each side (LVL-DR). It was found that the model prediction of the LVL MOE agreed well with the experimental results. LVL reinforced with CFRP had a greater MOE and modulus of rupture (MOR) than the control LVL. The MOE of the LVL-SR and LVL-DR increased by 40% and 67%, respectively. PDF
Kou, X., Yang, R., Zhao, J., Lu, J., and Liu, Y. (2013). "Enzymatic saccharification and L-lactic acid fermentation of corn stover pretreated with liquid hot water by Rhizopus oryzae," BioRes. 8(4), 4899-4911.
Corn stover was pretreated with liquid hot water (LHW) to enhance its enzymatic hydrolysis and L-lactic fermentation. The cellulose conversion rate and L-lactic acid concentration were used to evaluate LHW pretreatment performance. Results showed that the optimum conditions for the LHW pretreatment of corn stover are a reaction temperature of 190 °C for 20 min and a solid-to-liquid ratio of 1:10. The cellulase loading was 30 filter paper units per gram of oven-dried, water-insoluble solid. These conditions resulted in 92.3% conversion of cellulose to glucose. Sequential hydrolysis and fermentation using pretreated water-insoluble solid (WIS) produced an L-lactic acid concentration of 45 g/L. This study indicated that LHW pretreatment of corn stover is a suitable method for achieving high cellulose conversion and L-lactic acid concentration. PDF
Kolahi, M., Jonoubi, P., Majd, A., Tabandeh, M. R., and Hashemitabar, M. (2013). "Differential expression of phenylalanine ammonia-lyase in different tissues of sugarcane (Saccharum officinarum L.) during development," BioRes. 8(4), 4912-4922.
The phenylpropanoid pathway serves as a rich source of metabolites in plants. It is required for the biosynthesis of lignin and acts as a starting point for the production of many other important compounds involved in growth and development. Phenylalanine ammonia-lyase (PAL) catalyzes the first step of the phenylpropanoid pathway. PAL gene expression changes during the growth and development of plants as it regulates the synthesis of lignin and other phenylpropanoid compounds. The gene expression of sugarcane (Saccharum officinarum L.) PAL (SoPAL) was analyzed using quantitative real-time PCR (qPCR) and the comparative ΔΔCt method in different tissues during different developmental stages. The results showed that SoPAL was expressed in all tissues and developmental stages. SoPAL mRNA levels were increased from germination to tillering stages, except in the sheath, and from tillering to grand growth stages in the leaf and stem. PAL expression decreased from the grand growth to maturation stages in all tissues except the sheath. The highest expression of SoPAL occurred in the stem during the grand growth stage, while its lowest expression occurred in the leaf during germination (p<0.05). In conclusion, PAL, as a rate-limiting enzyme of the phenylpropanoid pathway, displays critical roles in the development of sugarcane, particularly in lignified tissues. PDF
Chitosan was used as a sizing promoter to improve the sizing performance of ASA emulsion stabilized by montmorillonite. It was found that chitosan with low molecular weight significantly improved the sizing performance of ASA emulsion without inducing the flocculation of the ASA droplets when the amount was less than 0.125% based on ASA. Confocal fluorescence microscopy revealed the formation of chitosan shell around the ASA droplet. Adding ammonia into the emulsion induced desorption of chitosan from the ASA droplet surface and the ammonolysis of ASA. The former reduced the ASA emulsion stability, while the latter resulted in the secondary emulsification of ASA-water system. Meanwhile, the presence of ammonia was demonstrated to be detrimental to the sizing performance of the ASA emulsion. The hydrolysis resistance of the ASA emulsion was higher when chitosan was present. PDF
Dungani, R., Islam, M. N., Khalil, A., Hartati, S., Abdullah, C. K., Dewi, M., and Hadiyane, A. (2013). "Termite resistance study of oil palm trunk lumber (OPTL) impregnated with oil palm shell meal and phenol-formaldehyde resin," BioRes. 8(4), 4937-4950.
A phenol-formaldehyde (PF) resin treatment of OPTL with various concentrations of finely ground palm shell, together abbreviated PF-FGPS, has been used to improve termite resistance. Termite resistance was evaluated in two ways, in a laboratory test and in a field test that lasted 3 months. A feeding arena sample was prepared for the first experiment so that the responses of the subterranean termite (Coptotermes curvignathus (Holmgren)) and the drywood termite (Cryptotermes cynocephalus (Light)) to the laboratory test could be observed for 4 weeks and 12 weeks, respectively. In general, the PF-FGPS led to greater termite resistance than did the control (dried OPTL and rubberwood), and the resistance of the samples to the subterranean termite C. curvignathus was classified as moderate when the samples were treated with OPS meal. Meanwhile, the resistance of the samples to the drywood termite C. cynocephalus was classified as moderate when samples were treated with OPS meal concentrations of 0, 1, and 3%. The samples treated with 5% OPS meal were classified as resistant. In the field test, samples impregnated with OPS meal at levels of 3%, 5%, and 10% were classified as resistant, while those impregnated with OPS meal at levels of 0 and 1% were classified as moderately resistant to attack by the subterranean termite. PDF
Continuous and batch tests were conducted to evaluate fermentative biohydrogen production from starch wastewater via a mesophillic up-flow anaerobic staged reactor (UASR). The effects of organic loading rate (OLR) and food to micro-organisms ratio (F/M) on hydrogen yield (HY) and hydrogen production rate (HPR) were investigated. The bioreactor was continuously operated at a constant hydraulic retention time (HRT) of 6.7 h. The optimal OLR and F/M ratios were 54 g-COD/L.d and 1.4 g-COD/g-VSS.d, respectively. The maximum HY and HPR were 1.87 mol-H2/mol-glucose and 246 mmol-H2/L.d, respectively. Batch experimental results indicated that the optimal initial cultivation pH ranged from 5.5 to 6.5 with a hydrogen potential (P) of 1435-1420 mL-H2, while the initial substrate concentration of 20 g-starch/L showed a maximum HPR (Rm) of 300 mL-H2/h. Zero, 1st and 2nd order kinetic studies were used to develop a model of the experimental data. The 2nd order model adequately fitted with the experimental results (R2>0.97) better than those for a zero- or a 1st order kinetic reaction. PDF
Sixty-two fungal isolates were screened for lignin peroxidase production. The most potent isolates for lignin peroxidase production were identified using the DNA sequence of the internal transcribed spacer (ITS) region of Phanerochaete chrysosporium and Pleurotus ostreatus. The pretreatment of rice straw with P. chrysosporium, Pl. ostreatus, or lignin peroxidase for use in the biopulping process was studied. Great variations in the loss of pulp yield and kappa number were recorded with different fungal and enzyme treatments. Pretreatment of rice straw with P. chrysosporium for 25 days resulted in a substantial decrease in pulp yield (by 9.1%) and kappa number (by 25.6%). Losses of pulp yield and kappa number were considerably lower with lignin peroxidase treatment (3.7 and 14.1%, respectively). However, the pretreatment of rice straw with the Pl. ostreatus isolate caused moderate pulp yield losses (5.8%) and preferential lignin degradation (kappa number losses of 34.6%). This indicated that the Pl. ostreatus isolate might be superior to both the isolate of P. chrysosporium and lignin peroxidase for use in the biopulping process or other processes in which preferential lignin degradation is desired. PDF
Huang, Y.-C., Chen, C.-Y., Chen, W.-L., Ciou, Y.-P., Yang, T.-Y., and Yang, C.-H. (2013). "Production and antioxidant properties of the ferulic acid-rich destarched wheat bran hydrolysate by feruloyl esterases from thermophilic actinomycetes," BioRes. 8(4), 4981-4991.
Ferulic acid is present at relatively high concentrations in the cell walls of several plants. Agricultural lignocelluloses are now used as bioresources in industry. This study attempted to increase the free ferulic acid content present in lignocellulose by using thermostable esterase produced from thermophilic actinomycetes to hydrolyze ester bonds. Destarched wheat bran was used as a carbon source for the production of esterases from the newly isolated thermophilic actinomycetes species Thermobifida fusca. After 96 h of cultivation, the esterase activity that accumulated in the culture broth was 946.0 U/mL. Two percent of the destarched wheat bran was then hydrolyzed by crude esterase preparation for 16 h. The ferulic acid was accumulated in the culture broth at a concentration of 310.0 mM. The hydrolysate had better radical-scavenging ability for both 1,1-diphenyl-2-picrylhydrazyl and 2,2'-azino-bis(3-ethylbenzothiazoline-6-sulphonic acid) radical-scavenging ability, as well as reducing power than ferulic acid. These results showed that the ferulic acid-rich destarched wheat bran hydrolysate had good antioxidant properties. It is suggested that this process can be advantageous for the industrial production of antioxidants derived from agricultural bioresources. PDF
Melo, L. C. A., Coscione, A. R., Abreu, C. A., Puga, A. P., and Camargo, O. A. (2013). "Influence of pyrolysis temperature on cadmium and zinc sorption capacity of sugar cane straw-derived biochar," BioRes. 8(4), 4992-5004.
The effect of pyrolysis temperature on the characteristics and metal sorption capacity of sugar cane straw derived–biochar (BC) was investigated. Biochar was produced at four temperatures (400, 500, 600, and 700 °C) before characterization for yield, ash and moisture content, pH, EC, pHPZC, elemental composition, nutrient content, CEC, TGA, and functional groups (FT-IR). Biochar alone and in mixtures containing 10%, w/w biochar with one of two different tropical soils (Entisol and Oxisol) was shaken for 24 h with a 2.0 mM solution (pH 4.5) of Zn or Cd in a batch sorption test. Increasing the pyrolysis temperature led to a reduction in the O/C and H/C molar ratios. The sorption capacity of biochar pyrolyzed at 700 °C was nearly four times greater than that produced at 400 °C. In the Entisol mixture, there was an increase up to seven-fold in the sorption of both Cd and Zn compared with the control (without BC). In the Oxisol mixture, there was a maximum 20% increase in sorption compared with the control. For the remediation of Cd- and Zn-contaminated substrates, the use of higher pyrolysis temperature biochars are recommended because of their higher metal sorption capacities. PDF
The alkali-cellulase processing of biomass into glucose near where it is grown has already been demonstrated at laboratory scale. Glucose can be fermented locally or transported to distant facilities for the production of bioethanol as fuel. This renewable energy process uses materials and methods that are readily available and that can be implemented at local or regional sites near growing fields. This study evaluated the effects on glucose production of different durations and amounts of NaOH pretreatment as well as different lengths of time for adsorption of cellulase. The pretreatment of corn stover (CS) with NaOH at 0.1 g/g CS for 6 h at a temperature of 100 °C resulted in the most acceptable glucose release following enzymatic hydrolysis. The exposure of pretreated CS solids to cellulase for 1 h resulted in the most acceptable release of glucose following the volume expansion at 10-fold dilution. The residual solids remaining after 3 h of enzymatic hydrolysis can be recycled to increase yields. The resulting glucose solution can be concentrated to minimize transportation costs when delivered to conventional grain fermentation facilities. This study introduced new conditions that enhanced practicality of the alkali-cellulase processing of biomass by allowing the processing time to be reduced to 10 h. PDF
Chinese fir (Cunninghamia lanceolata) has great potential as a future bio-energy resource in China. Thermogravimetry (TG) was used to investigate the thermal decomposition process of Chinese fir, including heartwood and sapwood. The Flynn-Wall-Ozawa and Coats-Redfern (modified) methods were used to determine the activation energy. A combination of TG and Fourier transform infrared spectrometry (TG-FTIR) was used to analyze the pyrolysis products. The TG curve indicated that the degradation processes of heartwood and sapwood were similar, but the degradation temperature of heartwood was lower than that of sapwood. The main decomposition occurred within the temperature range of 500 K to 660 K, and over 70% of the mass was degraded. The activation energy of Chinese fir with heartwood and sapwood changed slightly with an increase in conversion rate from 10 to 70. That of heartwood and sapwood was 155.38 to 158.37 KJ/mol and 155.93 to 180.04 KJ/mol, respectively, using the Flynn-Wall-Ozawa method. TG-FTIR analysis showed that the main pyrolysis products included absorbed water (H2O), methane gas (CH4), carbon dioxide (CO2), carbon monoxide (CO), acids and aldehydes, nitrogen dioxide (NO2), nitric oxide (NO), and ammonia gas (NH3). The results from this study are helpful for designing a better bio-energy manufacturing process for Chinese fir via gasification and pyrolysis methods. PDF
Surfactants made from modified lignin are attracting growing attention; therefore, a lignin-phenol nonionic surfactant named ML-AL has been prepared by modifying liquefied industrial alkali lignin (L-AL). Its basic physical and chemical properties have been shown to be favorable. In this work, anionic surfactants of sodium fatty acid soap (carbon numbers 12, 16, and 18) and sulfur-containing anionic surfactants (sodium dodecyl sulfate and sodium dodecyl benzene sulfonate) were chosen to mix with ML-AL in water-soluble media. The surface properties of each binary mixed solution system with anionic surfactant were investigated. At the same time, the mixed micelles formed by ML-AL and each anionic surfactant were studied. Non-ideal mixed micelles were obtained via ML-AL and the tested anionic surfactant. The interaction parameter (βM) and excess free energy (ΔGexcess) were both negative. Meanwhile, the critical micelle concentration (CMC) values of mixed systems (formed by ML-AL and each anionic surfactant in aqueous solution) were lower than those of a single-component system (ML-AL or single anionic surfactant). There was an optimum dosage ratio of about 0.4 in terms of synergistic effects. This research could provide a foundation for practical applications of combinations with anionic surfactants in aqueous solution. PDF
Shi, Z.-J., Xiao, L.-P., Deng, J., Yang, H.-Y., Song, X.-L., and Sun, R.-C. (2013). "Isolation and structural exploration of hemicelluloses from the largest bamboo species: Dendrocalamus sinicus," BioRes. 8(4), 5036-5050.
Dendrocalamus sinicus, which is the largest bamboo species in the world, has broad prospects for use in biomass-energy and biorefinery applications. In this study, five soluble hemicelluloses fractions were sequentially isolated with 80% ethanol (containing 0.025 M HCl or 0.5% NaOH), and alkaline aqueous solutions (containing 2.0, 5.0, or 8.0% NaOH) at 75 °C for 4 h from dewaxed D. sinicus, and their structural properties were examined. Gel permeation chromatography analysis revealed that the hemicelluloses isolated from D. sinicus had a wide distribution of molecular weights. The hemicelluloses isolated by ethanol had lower weight-average molecular weights (ranging from 17380 to 19620 g/mol), while the hemicelluloses isolated using alkaline aqueous solutions had higher weight-average molecular weights (ranging from 22510 to 42150 g/mol). Neutral sugar analysis indicated that the soluble hemicelluloses were mainly composed of arabinoglucuronoxylans, followed by minor amount of starch. Spectroscopic analyses suggested that the isolated arabinoglucuronoxylans from bamboo (D. sinicus) could be defined as a linear (1→4)-β-linked-xylopyranosyl backbone to which α-L-arabinofuranose and/or 4-O-methyl-glucuronic acid units were attached as single-unit side chains via α-(1→3) and/or α-(1→2) linkages. PDF
Ferrari, S., Allegretti, O., Cuccui, I., Moretti, N., Marra, M., and Todaro, L. (2013). "A revaluation of Turkey oak wood (Quercus cerris L.) through combined steaming and thermo-vacuum treatments," BioRes. 8(4), 5051-5066.
Turkey oak is a wood species widely distributed in Southeastern Europe and in Italy, where it is mainly present in the Apennine Mountains. Compared to other oaks, Turkey oak is less valued because of its tendency to crack, its lower technological quality, and its lower durability. The aim of the present work was to improve wood quality by treating Turkey oak through combined steaming and thermal treatment under vacuum conditions. Wood was steamed at a temperature between 100 to 110 °C and thermally treated in vacuum at 160 °C using two different technologies, i.e., the press vacuum plant and the Termovuoto® plant. The treated material was characterized in terms of mass loss, color change, hygroscopicity, and compression strength for both heartwood and sapwood. Results slightly differed according to the treatment or combination of treatments adopted. In general, a significant increase in dimensional stability and an improved color homogenization were obtained together with the maintenance of a good wood quality. Concerning mechanical properties, thermo-vacuum treatment increased the compression strength, while steaming had the opposite effect. PDF
Different kinetic models have been proposed to characterize torrefaction of biomass, demonstrating dependencies on the raw material, experimental system, reaction time, and temperature. Conventionally, stationary processes have been used for kinetics studies of the torrefaction process. In this research, the torrefaction of red oak (Quercus rubra) in a bench-scale fluidized reactor was studied with emphasis on determining the kinetic parameters and improving the final material energy density. Mass loss and ultimate, proximate, and gross calorific analyses were performed on the resulting torrefied material. The primary reaction variables were the temperature (230 °C, 270 °C, 300 °C, and 330 °C) and the residence time (10 min, 20 min, and 30 min). The effect of temperature on the mass loss and energy density was much more significant than that produced by the increase in residence time. For the conditions studied, a one-step kinetic model with a first-order reaction proved adequate to describe the torrefaction of red oak in the fluidized reactor. The reaction rate constant (k) for the torrefaction reaction was found to be 0.212 min-1 at 300 °C. The activation energy and frequency factor were 11.9 kJ/mol and 2.57 min-1, respectively. PDF
Lignin was extracted from the solid coproduct of a lignocellulosic ethanol production by a solid-liquid extraction method using N,N-dimethyl formamide. This coproduct was the residue of a steam explosion pretreatment followed by enzymatic hydrolysis process. The coproduct was used as received and also after washing. Lignin content of the solid coproduct was reduced from 63% to 43% after lignin extraction. Fourier transform infrared spectroscopy (FTIR), molecular weight measurement (GPC), and elemental analysis provided information about the chemical structure and molecular weight of the fractions. The extracted lignin had lower molecular weight (~ 5000 Da.) and higher carbon content (63%) compared to the residue of extraction (Mw ≈ 8000 Da. and carbon % = 48%). Thermal stability measurements of the samples by thermogravimetry (TGA) showed that the extracted lignin had the highest carbon residue. Effects of different heating cycles on the glass transition temperature (Tg) were measured. The Tg of the soluble fraction was lower than that of the coproduct. Results of the X-ray diffraction (XRD) showed the crystalline structure of cellulose in both the coproduct and the solid residue after extraction. This extraction and material characterization is helpful for liquid processes such as solution spinning or electrospinning. The thermal properties can be used for optimization of heat treatment processes such as carbonization. PDF
Medicinal plants, such as Polyalthia longifolia (Indian mast tree), are important therapeutic sources for curing human diseases. In this work P. longifolia leaf extract was characterized by chromatographic and spectral fingerprinting techniques, phytochemical and heavy metal analyses, and microscopy. Light microscopy of a transverse section of the leaf of P. longifolia revealed the presence of various plant cells. Phytochemical screening results revealed the presence of alkaloids, triterpenoids, tannins, saponin, anthraquinones, and glycosides in the extract. The concentrations of heavy metals determined in the extract were well below the permissible limit. Nine peaks observed in the HPLC spectra showed the presence of various compounds in the extract. The GCMS method used for quantification of (3β,4α,5α,9β)-4,14-dimethyl-9,19-cycloergost-24(28)-en-3-yl acetate (i.e., cycloeucalenol acetate) in the extract was rapid, accurate, precise, linear (R2 = 0.8752), and robust. The HPTLC analysis showed ten specific peaks for the methanolic extract of P. longifolia leaf. Twelve major peaks in the range of 4,000 to 500 cm-1 were observed in the FTIR spectra, which represented various specific functional groups in the extract. PDF
Enzymatic/Mild Acidolysis Lignin (EMAL) was isolated from Cunninghamia lanceolata and eucalyptus woods. The chemical structure and thermochemical properties were characterized by means of elemental analysis, Fourier transform infrared spectroscopy (FT-IR), thermal gravimetric analysis (TG), and pyrolysis-gas chromatography combined with mass spectrometry (Py-GC/MS). The EMAL isolated from Cunninghamia lanceolata (C-EMAL) had larger HHV (higher heat value) in comparison to the EMAL isolated from eucalyptus (E-EMAL) due to the greater carbon content of the C-EMAL. The E-EMAL had more syringyl units, whereas the C-EMAL contained more guaiacyl units. It was observed that thermal decomposition occurred over a wide temperature range, and that at a given starting temperature, within the same sample, a higher heating rate produced a higher temperature at which maximum weight loss peaked. The pyrolysis products were mainly composed of carboxylic acids, alcohols, ketones, aldehydes, olefins, alkanes, esters, ethers, and phenols. At all pyrolysis temperatures, the largest components of the pyrolysis products obtained from C-EMAL were the phenols. PDF
The properties of non-treated and hydrochloric acid (HCl)-treated oil palm ash (OPA)-filled natural rubber (NR) composites were investigated in terms of swelling behavior, rubber-filler interaction, ageing resistance, dynamic mechanical analysis, and thermal stability. The incorporation of OPA resulted in a lower degree of swelling in the NR composites, which was even lower after HCl treatment. Concerning the rubber-filler interaction, the HCl-treated OPA had better interfacial interaction with the NR matrix than that of non-treated OPA, resulting in higher crosslink density and improved ageing resistance. The dynamic mechanical properties of NR composites were better with the incorporation of HCl-treated OPA compared to non-treated OPA, in that they showed a higher storage modulus and lower mechanical loss factor. Thermogravimetry analysis revealed that the HCl treatment process did not affect the thermal stability of OPA-filled NR composites. PDF
The effects of ground calcium carbonate (GCC) modification through the polyelectrolyte multilayering technique on deposition kinetics were investigated. The surface charge of GCC particles was changed from negative to positive through Layer-by-Layer (LbL) multilayering with polyelectrolytes on GCC particles. The LbL multilayered GCC particles could deposit onto negatively charged cellulose fibers due to electrostatic attraction. Deposition kinetics followed modified Langmuir kinetics, which describe the dynamic equilibrium of deposition and detachment of the particles. The multilayer that had more affinity to the fibers had the higher deposition rate constant. The multilayer with a branched polyelectrolyte showed a low detachment rate constant compared to the linear polyelectrolyte, which led to a high equilibrium deposition amount for the particle. Application of high shear had adverse effects on deposition. However, LbL multilayered GCC particles showed reversible deposition characteristics after lowering the stirring speed. PDF
Zanuncio, A. J. V., Monteiro, T. C., Lima, J. T., Andrade, H. B., and Carvalho, A. G. (2013). "Drying biomass for energy use of Eucalyptus urophylla and Corymbia citriodora logs," BioRes. 8(4), 5159-5168.
Brazil is the world’s largest producer of charcoal, mainly for the steel industry. Fresh wood has high moisture content, which reduces its use for energy. Thereby, drying is a fundamental step for charcoal production. This work aimed to determine longitudinal variation in stem diameter, wood basic density, moisture content, and calorific value of Eucalyptus urophylla and Corymbia citriodora logs. These logs were taken from different longitudinal positions on the trees and dried for 90 d; the net calorific value was determined based on the gross calorific value and moisture content. Curves and models were generated based on this data for moisture content and net calorific value during the 90-d period. The logs from the base and middle of C. citriodora trees had lower initial moisture content, and, after 90 d of drying, all logs from the top reached the equilibrium moisture. Drying the logs increased the wood calorific value, with an increase of 49.36%, 63.86%, and 85.98% for those of the base, middle, and top, respectively. The models generated had a high coefficient of determination and a low standard error. PDF
Wang, Y.-J., Ying, H., Sun, Y.-J., Jiang, J.-F., Jiang, J.-C., Gao, Y.-W., and Yu, W.-J. (2013). "Co-pyrolysis characteristics of torrefied pine sawdust with different rank coals," BioRes. 8(4), 5169-5183.
Torrefaction of sawdust has the advantages of increasing its heating value, lowering its O/C ratio, and making it more convenient to transport and crush. Torrefied sawdust has characteristics that are more similar to coal than to sawdust. The initial pyrolysis temperature and residue content of torrefied sawdust are higher than those of sawdust. With the increase of coalification degree of three different coals, the initial pyrolysis temperature and residue contents are raised. The initial pyrolysis temperatures and remaining contents of lignite, bituminous coal, and anthracite are 330, 380, and 500 °C and 61.3, 75.1, and 89.5%, respectively. The torrefied sawdust also has a synergistic effect on the conversion of anthracite and bituminous coal, but it has an inhibitory effect on lignite. The composition of gaseous products was also measured after pyrolysis. The results demonstrate that with the addition of torrefied sawdust to anthracite and bituminous coal, the gaseous products contain more combustible components, such as H2, CO, and CH4, which increase the heating value. Moreover, the effect is more obvious with the co-pyrolysis of torrefied sawdust and anthracite. However, the co-pyrolysis of torrefied sawdust and lignite leads to decreasing CO and light hydrocarbons (CnHm (n=1, 2)) in the resulting gaseous products, which has a negative effect on the quality of the gaseous products. The co-pyrolysis characteristics of torrefied sawdust with different rank coals are discussed in this paper. PDF
Wang, Z., Bo, N., Liu, Y., Yang, G., Lv, G., and Liu, Y. (2013). "Modification of bleached eucalyptus kraft pulp by p-DMA-co-ECH and its application for the removal of acid scarlet G in aqueous solution," BioRes. 8(4), 5184-5201.
Poly-epichlorohydrin-dimethylamine (p-DMA-co-ECH) was synthesized and was used to modify bleached eucalyptus kraft pulp (BEKP). The modified pulp (designated PDMAECH pulp) was characterized by zeta potential, FTIR, NMR, and SEM. Both the PDMAECH pulp and the BEKP were used as adsorbents to remove Acid Scarlet G (ASG) from aqueous solution. The effects of operational parameters on the efficiency of dye removal, including pH, adsorbent dosage, initial dye concentration, and contact time, were investigated. Results showed that modification could change the surface characteristics and effectively enhance the adsorption capacity. The optimum pH for ASG removal with the modified bleached eucalyptus kraft pulp (PDMAECH pulp) was found to be 4.0, and for BEKP it was 2.0. Under the optimized conditions, the maximum capacities for ASG adsorption were also investigated. The adsorption processes of both adsorption reactions were spontaneous and exothermic, and the adsorption capacities decreased with an increase in temperature. Freundlich and Langmuir models were used to analyze the obtained experimental data. The Langmuir model was found to be a better fit for the experimental data for both adsorbents. Kinetic studies showed that the rate of adsorption of ASG on both adsorbents obeyed a pseudo-second-order kinetics model. The desorption process for PDMAECH pulp was also explored. PDF
Birch sawdust was extracted with a pressurized hot water (PHW) flow-through system. The pH of the extract was controlled during extraction by the addition of acetic acid/sodium acetate buffer. Three different pH levels, 4.0, 4.2, and 4.6, were used. Extraction temperatures were 160, 170, and 180 °C, with a constant 4 mL/min flow rate through the 50 mL extraction vessel. During PHW extraction with plain water, the end pH of the extract dropped from 5 to below 3. Buffers kept the pH of the extracts constant during the first 30 min of extraction. Compared to plain water, the use of buffers resulted in a lower yield of xylans during the 170 °C extraction. However, with the buffered system it was possible to obtain xylans from sawdust with a higher molar mass than plain water extraction. Acetic acid/sodium acetate buffer enabled control of the hydrolysis rate of xylans during extraction. PDF
Kenaf (Hibiscus cannabinus), a fast-growing fiber crop, is a potential substitute for wood to make composition boards. This work investigated single- and three-layer kenaf core particleboards (KPBs) and kenaf core-cedar wood composite particleboard (KCPB) with polymeric methylene diphenyl diisocyanate (pMDI) and phenol formaldehyde (PF) resins. The physical and mechanical properties including bending modulus (MOE) and strength (MOR), internal bond (IB) strength, water absorption (WA), thickness swelling (TS), and linear expansion (LE) were tested following the ASTM D 1037 and ANSI A 208.1 standards. It was shown that kenaf core can be made into standard-satisfying particleboards with comparable performances to cedar-based wood panels. Three processing factors, i.e., board density, resin content, and layered construction, had significant influences on panel properties. KPBs denser than 0.70 g/cm3 and with 6% PF met with the standard specifications. The WA, TS, and LE of single-layer KPBs decreased with increased density. Three-layer KPBs showed improved MOE, MOR, and IB strengths, and effectively avoided the unbalanced structure shown in the single-layer KPBs in thickness direction. The three-layer KPBs with a 50:50 surface-to-core ratio had the best comprehensive performances. The results can be helpful for the application of kenaf residues in the wood composites industry. PDF
The process of wood drying can induce defects caused by drying stress, which limits the processing and utilization of this valuable material. Here, we investigated elastic strain, viscoelastic creep strain, and mechano-sorptive (MS) creep strain caused by shrinkage anisotropy using the image analytical method during slow conventional drying of white birch (Betula platyphylla Suk) disks. The rheological properties of wood disks with different moisture contents (MC) were analyzed together with the influences of MC and radial position on each strain. The results showed that relations between stress and strain are complex; below the fiber saturation point (FSP), the wood disk is initially subject to tangential tensile stress; with decreasing MC, the tensile stress turns into a compressive stress. MS creep strain increased with decreasing MC; however, elastic strain and viscoelastic creep strain were positively correlated with MC. Elastic strain decreased after first increasing, and then remained stable while the MS creep strain significantly increased from pith to bark, at 10% MC and 18% MC, respectively. Shrinkage anisotropy was the main reason for strain during the drying processing, and it was one of the main factors causing cracks during drying or application. PDF
Teh, C. C., Ibrahim, N. A., and Wan Yunus, W. M. Z. (2013). "Response surface methodology for the optimization and characterization of oil palm mesocarp fiber-graft-poly(butyl acrylate)," BioRes. 8(4), 5244-5260.
Oil palm mesocarp fibers (OPMFs) are left as a waste material after oil extraction. A new application of OPMF is needed to economically utilize these fibers; thus OPMFs need to be modified to render them hydrophobic. Hydrogen peroxide was used to initiate the graft copolymerization of butyl acrylate onto OPMF in aqueous solution. The duration of reaction, temperature, and amounts of butyl acrylate and initiator were optimized using response surface methodology (RSM) coupled with a four-factor central composite design (CCD). The response variable was percentage grafting (%G). A quadratic model was obtained and developed to correlate the independent variables to %G. The optimum conditions predicted through RSM were 110 min duration of reaction, 50 °C temperature, 28 mmol of monomer, and 5.99 mmol of initiator, with a %G of 116.2%. Synthesized graft copolymers were characterized by Fourier-transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), and thermogravimetric analysis. The thermal stability of OPMF improved significantly after grafting. The FTIR and SEM results showed that graft copolymerization successfully occurred onto the OPMF backbone. The tensile test results support the utilization of grafted OPMF as a potential compatibilizer. PDF
Daystar, J. S., Venditti, R. A., Gonzalez, R., Jameel, H., Jett, M., and Reeb, C. W. (2013). "Impacts of feedstock composition on alcohol yields and greenhouse gas emissions from the NREL thermochemical ethanol conversion process," BioRes. 8(4), 5261-5278.
There has been great attention focused on the effects of first and second generation biofuels on global warming. The Energy Independence and Security Act (EISA) and the Renewable Fuel Standard (RFS) have mandated production levels and performance criteria of biofuels in the United States. The thermochemical conversion of biomass to ethanol shows potential as a biofuel production pathway. The objective of this research was to examine the alcohol yields and GHG emissions from the thermochemical conversion process for six different feedstocks on a gate-to-gate basis. GHG analyses and life cycle assessments were performed for natural hardwood, loblolly pine, eucalyptus, miscanthus, corn stover, and switchgrass feedstocks using a NREL thermochemical model and SimaPro. Alcohol yield and GHG emission for the hybrid poplar baseline feedstock conversion were 105,400 L dry metric ton−1 and 2.8 kg CO2 eq. per liter, respectively. Compared with the baseline, loblolly pine produced the highest alcohol yields, an 8.5% increase, and the lowest GHG emissions per liter of ethanol, a 9.1% decrease. Corn stover, due to its high ash content, had the lowest yields and the highest GHG emissions per liter of ethanol. The results were highly sensitive to the ash and water content of the biomass, indicating that biomass properties can significantly affect the environmental impact of the thermochemical ethanol conversion process. PDF
The interactive effect of the thermo-mechanical densification and heat treatment on the set-recovery of modified wood were investigated for optimizing the combined modification process in this study. Process parameters such as thermo-mechanical densification temperature, duration of densification, and heat treatment temperature were selected as main factors; three levels of each of these factors were chosen, and then nine experiments plus one verification experiment were conducted according to the principles of the Taguchi DoE method and the results of ANOVA analysis. It was observed that the dimensional stability of combined modified Chinese fir wood in the compression direction can be effectively improved by elevating the heat treatment temperature and densification temperature, the percentage contributions of which were 76.04% and 21.18%, respectively. Meanwhile the set-recovery had no dependence on the duration of the densification process. The value of the set-recovery in the verification experiment agreed quite well with the predictions. From an economic view, the optimal condition for the combination modification of Chinese fir wood was that of a densification temperature of 170 °C, densification duration of 10 min, and heat treatment temperature of 200 °C. PDF
An oxygen-delignified eucalypt pulp (Eucalyptus grandis x Eucalyptus urophylla hybrid)was provided by a Brazilian pulp mill. It was treated with chlorite to remove lignin, or by a long acidolysis stage to remove most of the hexenuronic acid groups (HexA) followed by a chlorite treatment to remove the lignin. Three pulp samples were treated with increasing ozone charges (up to 2% on pulp) at high consistency and room temperature. The pulp containing no lignin but all of the HexA appeared to be the most affected by the ozone treatment. This indicated that the reaction of ozone with HexA generates radicals, which then react with cellulose, leading to depolymerization. It also indicated that lignin captures some of these radicals. ESR spectroscopy confirmed that hydroxyl radicals are formed when ozone reacts with maleic acid, which can be considered a HexA model compound. These findings open the way to the improvement of chlorine-free bleaching sequences containing ozone stages. PDF
The effects of the amounts of flour from the red pepper (Capsicum annuum) fruit stem (RPFS), together with coupling agent (CA), on the mechanical and physical properties of polypropylene (PP)-based composites were investigated. Pellets manufactured through single screw extruders were injection molded into composite samples. Density, mechanical property, and dimensional stability of manufactured composites were determined according to ASTM standards. Results were analyzed using central composite design (CCD). Statistical analyses showed that filler loading significantly affected the density, as well as mechanical and physical properties of thermoplastic composites. Density of the composites was increased with filler loading but not affected by coupling agent amounts. In the case of mechanical properties, tensile modulus, flexural strength, and flexural modulus were improved with increasing filler loading while the tensile strengths, elongation at break, and impact strength of the samples were decreased. The tensile strength of the thermoplastic composites was positively affected by CA contents, but other mechanical properties were not affected as much. In the case of physical properties, thickness swelling and water absorption of the composites were increased with increasing weight percent of RPFS flour. However, these properties were not significantly changed by CA addition. Overall results revealed that RPFS flour could be potentially suitable raw materials for thermoplastic composites. PDF
Álvarez-Cervantes, J., Hernández-Domínguez, E. M., Arana-Cuenca, A., Díaz-Godínez, G., and Mercado-Flores, Y. (2013). "Purification and characterization of xylanase SRXL1 from Sporisorium reilianum grown in submerged and solid-state fermentation," BioRes. 8(4), 5309-5318.
Sporisorium reilianum is a phytopathogenic fungus that produces the maize head smut. Hydrolytic enzymes such as xylanases have not been studied in this basidiomycete, although these enzymes are widely used within the industry. In this study, the characterization of a xylanase produced by S. reilianum grown in submerged and solid-state fermentation using different culture media was performed. Submerged fermentation with a medium containing birch xylan and yeast extract showed the highest xylanase activity (12.6 U/mL). The enzyme, purified through ion exchange chromatography, had a molecular weight of 42 kDa, as determined by SDS-PAGE, and a Km and Vmax of 1.72 mg/mL and 2.48 μmol/mL/min, respectively. The optimal values of pH and temperature were 5.0 and 70 °C, respectively. The enzyme showed activity over a broad range of temperatures and pHs. Zn2+, Fe3+, and Mn2+ ions increased xylanase activity. Sequence protein analysis showed 100% similarity with the theoretical protein encoded by the sr14403 gene of S. reilianum, encoding a putative endo-b-1,4-xylanase. This is the first report on the production and purification of a xylanase from this fungus, which has interesting biochemical characteristics for application in biotechnological processes. PDF
Longue Júnior, D., Ayoub, A., Venditti, R. A., Jameel, H., Colodette, J. L., and Chang, H.-m. (2013). "Ethanol precipitation of hetero-polysaccharide material from hardwood by alkaline extraction prior to the kraft cooking process," BioRes. 8(4), 5319-5332.
Hemicellulose material is an abundant and relatively under-utilized hetero-polysaccharide material present in lignocellulosic materials. In this study, an alkaline treatment was applied to sweetgum and Eucalyptus globulus chips to extract hemicelluloses prior to kraft pulping to subsequently evaluate the final product and process. An alkaline extraction (10 and 50% NaOH by weight on wood) for 60 min at 100 °C followed by precipitation in ethanol recovered 4.3% of the biomass as a predominantly xylan material (sweetgum 50% NaOH) with an average degree of polymerization around 250 and functional groups similar to a commercial xylan (sweetgum 10% NaOH). This process in comparison to autohydrolysis (water extraction at 100 °C) produced a much higher molecular weight and more pure hemicellullose. The results obtained indicate a promising combination between the effective extraction of hemicellulose from wood and a distillation process that recovers the ethanol, which may be an attractive alternative to recover liquor and ethanol after hemicellulose precipitation. Hemicellulose from sweetgum showed more thermal stability with high molecular weight compared to the hemicellulose extracted from Eucalyptus globulus. An attractive alternative looks to be to recover liquor and ethanol after hemicellulose precipitation. PDF
Alkaline precipitate isolated from red liquor of acidic magnesium sulfite pulping exhibited obvious stratification. The properties of the stratified alkaline precipitate were investigated via infrared spectroscopy, ion chromatography, thermogravimetric analysis, and high efficiency liquid chromatography. The sulfonic group of lignosulfonate showed a characteristic absorption peak from 1210 cm-1 to 1170 cm-1. There were no significant differences between the structures of the functional groups of the upper and lower layers of the precipitate. The peak time of the sulfonic group was 6.350 min, as measured by ion chromatography. Compared with the upper precipitate, the lower precipitate had more groups with high carbon and low oxygen contents and did not easily decompose. The relative molecular weight of the lower precipitate was greater than that of the upper precipitate. The difference in relative molecular weight of the precipitates gave rise to the observed stratification. PDF
Fileto-Pérez, H. A., Rutiaga-Quiñones, J. G., Aguilar-González, C. N., Páez, J. B., López, J., and Rutiaga-Quiñones, O. M. (2013). "Evaluation of Eichhornia crassipes as an alternative raw material for reducing sugars production," BioRes. 8(4), 5340-5348.
Water hyacinth was analyzed to determine its hemicellulose/lignin content, evaluating the conditions for the saccharification process with commercial microbial enzymes. Plant material, including leaves and stalks, was pretreated at several temperatures (100, 110, and 120 °C) with different sulfuric acid concentrations (0.5, 1.0, 1.5, 2.0, 2.5, and 3%) and residence times (0, 15, 30, 45, 60, 90, and 120 min). Total reducing sugars were measured by the dinitrosalicylic acid method. The optimum conditions that maximized the yield of reducing sugars included a pretreatment with 2% (v/v) sulfuric acid at 110 °C for 90 min. The optimum conditions for enzymatic saccharification used the commercial enzyme Celluclast at 50 °C for 24 h of hydrolysis. The maximum yield was 0.54 g of fermentable sugars per gram of biomass. Data demonstrated that E. crassipes is suitable as a raw material for products such as bioethanol; however, further fermentation studies are required. PDF
The vibrational properties of Japanese cedar wood at high temperature were measured. The specimen, its support system, a magnetic driver, and a deflection sensor were placed in an electric drying oven, where vibration tests were conducted. The heating temperatures ranged from 25 ºC to 200 ºC in 25 ºC increments. The resonance frequency decreased with higher heating temperature and decreased most dramatically in the temperature range of 150 ºC to 200 ºC. The loss tangent had a minimum value at 100 ºC and changed more in the temperature range from 150 ºC to 200 ºC than in the range from 25 ºC to 150 ºC. The changes in the resonance frequency and loss tangent of the specimens with larger distance from the pith (d) were smaller than those around the pith. These tendencies are believed to have occurred because the portion with a larger d had a smaller number of intercellular layers than the portion around the pith. PDF
A biodegradable planting container made with rice straw and starch adhesives modified by polyvinyl alcohol was studied in this paper. The effect of heat treatment and polyamide resin on the properties of planting containers was investigated. The physical property and biodegradibility were characterized by means of hygroscopicity, FTIR, degradability, and the thermogravimetric analysis. The results showed that the dry strength of planting containers increased as a result of both treatments. The wet strength of planting containers increased as a result of heat treatment, while the wet strength of planting containers decreased as a result of polyamide resin. The hygroscopicity of planting containers decreased with heat treatment and polyamide resin. The effect of heat treatment was more obvious than the effect of polyamide resin. It was observed that the peak intensity and position were changed for the 3400 cm-1, 2900 cm-1, 1640 cm-1, 1500 cm-1, 1400 cm-1, and 1050 cm-1 under the treatment of polyamide resin. The weight loss of specimens treated with polyamide resin was larger because of the presence of nitrogen in the resin. The appearance of planting containers showed the heat treatment containers were not easily prone to mildew when used for planting. The thermogravimetric analysis (TGA) showed that heat treatment can improve the thermal stability, while the polyamide resin was shown to promote the degradation of planting containers. PDF
In order to decrease the viscosity and improve the wet shear strength of soybean meal (SM) adhesive, in this study, SM adhesive, enzyme-treated SM adhesive(ESM), and the ESM grafted GMA (ESM-g-GMA) adhesive were prepared . The properties of these adhesives were characterized by rheological measurement, mechanical performance testing, Fourier transform infrared spectroscopy (FTIR), and thermogravistric analysis (TGA ). The results indicated that the apparent viscosity of the adhesives decreased due to the enzymatic treatment and the presence of GMA. The wet shear strength of the plywood panels bonded with ESM-g-GMA adhesive was significantly improved from 0.45 MPa to 1.05 MPa, which met the interior plywood requirement (≥0.7 MPa) of the China National Standard. This study also investigated the pot life of the ESM-g-GMA adhesive and the impact of hot pressing. The change in wet shear strength was not obvious within 24 h. The optimum hot press temperature and time were 150 oC and 6 min, respectively. FTIR showed that GMA was successfully grafted onto the ESM adhesive. TGA indicated that the peak degradation temperature of the ESM-g-GMA adhesive was higher than that of the SM adhesive due to the cross-linking reaction that created the macromolecular dense structure between the ESM adhesive and the GMA monomer. PDF
To increase the water resistance and reduce the viscosity of soybean meal (SM)-based non-formaldehyde wood adhesives, polyethyleneglycol diacrylate (PEGDA) used as crosslinker and viscosity reducer was introduced into the SM adhesive system. The apparent viscosity was evaluated by rheological measurements; gel content and water absorption of adhesives, the wet shear strength of plywood bonded with these modified adhesives were tested to evaluate their water resistance. In addition, the crosslink structures of modified adhesives were characterized by Fourier transform infrared (FTIR) spectroscopy and solid-state 13C NMR analysis. The results indicated that all of the SM adhesives were pseudoplastic fluids with the property of shear-thinning. The viscosity of modified SM adhesives effectively decreased by 35% compared with the addition of PEGDA, and the wet shear strength of their bonded plywood increased; the wet shear strength of plywood bonded with 4% PEGDA-modified SM adhesive increased 114.2% compared to SM adhesive. FTIR spectroscopy and solid-state 13C NMR analysis demonstrated that the crosslinking reaction of the PEGDA occurred successfully during the curing process of PEGDA modified SM adhesive, and no crosslinking reaction between the PEGDA and soy meal adhesive appeared to have occurred. Interpenetrating networks (IPNs) might be formed between the cured PEGDA and SM adhesive system. PDF
A combination of steam explosion (SE) and alkaline peroxide (AP) used to pretreat bamboo was investigated. Steam explosion at 224 °C for 4 min was applied to bamboo, and the pretreated bamboo was delignified by alkaline peroxide. Enzymatic hydrolysis was compared in the pretreated samples. Steam pretreatment led to remarkable hemicellulose solubilization (63.2%). Lignin solubilization (93.1%) was achieved by alkaline peroxide treatment of steam-pretreated bamboo at 80 °C for 1 h in 0.88% (v/v) H2O2, whereas only 33.4% of lignin was solubilized when using raw bamboo. Pretreatment methods resulted in a low degree of polymerization and increased hydrolysis of cellulose. A maximum glucose yield of 90.5% was achieved with a combined steam explosion and alkaline peroxide pretreatment. The surface structure of treated bamboo and the adsorption of enzyme on the substrate were characterized by X-ray photoelectron spectroscopy. Delignification decreased enzyme adsorption and increased enzymatic conversion. SEM analyses indicated that SE-AP pretreatment disrupted lignin networks and exposed crystalline cellulose in bamboo more effectively than SE or AP pretreatment alone. PDF
Kabir, M. M., del Pilar Castillo, M., Taherzadeh, M. J., and Sárvári Horváth, I. (2013). "Effect of the N-methylmorpholine-N-oxide (NMMO) pretreatment on anaerobic digestion of forest residues," BioRes. 8(4), 5409-5423.
Pretreatment of forest residues using N-methylmorpholine-N-oxide(NMMO or NMO) prior to anaerobic digestion was investigated, where the effects of particle size, NMMO concentration, and pretreatment time were the primary focus. The pretreatments were carried out on forest residues; with different particle sizes of 2, 4 and 8 mm, at 120 °C for 3, 7, and 15 h in two different modes of NMMO-treatment: dissolution by 85% NMMO and swelling without dissolution using 75% NMMO solution in water. The pretreatment process led to minor changes in the composition of the forest residues. The best improvement in methane yield of the forest residues was achieved by pretreatment using 85% NMMO for 15 h at 120 °C. This treatment resulted in 0.17 Nm3/kg VS methane yield, which corresponds to 83% of the expected theoretical yield of carbohydrates present in the material. Additionally, the accumulated methane yield and the rate of the methane production were highly affected by the amounts of remaining NMMO when it was not well separated during the washing and filtration steps after the treatment. The presence of concentrations even as low as 0.008% NMMO resulted in a decrease in the final methane yield by 45%, while the presence of 1% of this solvent in the digester completely terminated the anaerobic digestion process. PDF
The effects of refining history and recycling times of NSSC pulp as a representative of semi-chemical pulps were studied. The results indicated that NSSC behaved as would be expected for a chemical pulp in all aspects. In fact, increasing the recycling cycles decreased the apparent density, tensile index, burst index, tear index, water retention value (WRV), and increased the hornification. In the current research, 400 mL CSF was judged to be the most suitable treatment among the refining levels considered. In the case of virgin pulp 400 mL CSF yielded better results than 500 mL CSF in all aspects (apparent density, tensile index, burst index, tear index, WRV and hornification). Also, there was not much difference with 300 mL CSF in these properties. Generally, a refining history of 400 mL CSF gave rise to the least negative influence on different properties compared to 500 and 300 mL CSF in 1st, 2nd, and 3rd recycling cycles of NSSC. PDF
This study explored the effect of processing parameters on surface roughness as a result of aesthetic designs processed on walnut, chestnut, and beech wood edge-glued panels (EGPs) by CNC (computer numerical control) router. To accomplish this, the average roughness value (Ra) on an engraved surface in a Ying-Yang design treated on the material was measured. Using analysis of variance (ANOVA), the feed rate, spindle speed, step-over, and axial depth of cut factors; surface roughness factors; and the interactions between these factors were found to form significant differences at the level of 95%. At the end of the study, the Ra value was lower in walnut and beech EGPs (3.423 μm and 4.316 μm, respectively) and higher in chestnut EGPs (5.005 μm). PDF
The use of mineral fillers in cellulosic paper products can result in cost/energy savings and improvement of paper properties. However, the increase in filler addition levels is hampered by the negative impact of fillers on paper strength, poor filler retention, etc. As an attempt to improve the use of fillers in papermaking, filler modification with the combination of cationic starch and carboxymethyl cellulose was preliminarily explored in this mini-study. This concept was compared with filler modification with either cationic starch or carboxymethyl cellulose. The combination of cationic starch with carboxymethyl cellulose resulted in improved attachment of the starch to the filler, possibly suggesting the in-situ formation of polymer complexes with lower solubility than starch. With respect to filler retention, tensile strength, brightness, and opacity of the filled paper, the combined use of cationic starch and carboxymethyl cellulose resulted in a modified filler material with modestly better performance, in comparison to filler modification with either cationic starch or carboxymethyl cellulose. The combined use of a cationic polymer and an anionic polymer to modify fillers may provide an alternative approach to improving the use of mineral fillers in the paper industry. PDF
Biochars produced from thermochemical conversions of biomass were evaluated by temperature programmed oxidation (TPO). This technique, used to characterize carbon deposits on petroleum cracking catalysts, provides information on the oxidative stability of carbonaceous solids, where higher temperature reactivity indicates greater structural order, an important property for biochar applications. Differences between TPO profiles of biochars generated by fast pyrolysis of soy straw, barley straw, switchgrass, bamboo, and various woods demonstrated that the oxidative stabilities of the biochars are dependent on the starting biomass. Biochars from softwood and hardwood feedstocks were also processed by torrefaction and gasification to assess the impact of the thermoprocessing method on the TPO data. Results from these TPO analyses showed that the biochars produced under higher temperature conditions afford biochars that are more oxidation resistant. Biochars produced from pine wood (softwood) were consistently more resistant to oxidation compared to their hardwood counterparts. This exploratory study represents the first application of TPO to biochars. PDF
To better understand how moisture content (MC) affects the longitudinal compressive mechanical properties of bamboo, mechanical tests on both the macroscopic and cellular levels were performed on Moso bamboo (Phyllostachys pubescens Mazei ex H. de Lebaie) at different MCs. At the macroscopic level, the compressive modulus of elasticity (CMOE) was determined using a common mechanical tester, while the indentation modulus of elasticity (EIT) and the hardness (HIT) of the bamboo fiber cell walls were obtained using nanoindentation. The results showed that CMOE, EIT, and HIT were all negatively correlated with the change in MC below the fiber saturation point (FSP) with strong linear relationships. However, the CMOE was found to be more sensitive to a change in MC than was EIT, which indicated that the bamboo was more sensitive to MC at the macro level than at the cellular level, at least in terms of longitudinal compression stiffness. Moreover, EIT was found to be much less sensitive to a change in MC than was HIT, which may explain why the longitudinal compression strength of bamboo was much more sensitive to changes in MC than was the compression modulus of elasticity on the macro scale. PDF
Gui, X., Wang, G., Hu, M., and Yan, Y. (2013). "Combined fungal and mild acid pretreatment of Glycyrrhiza uralensis residue for enhancing enzymatic hydrolysis and oil production," BioRes. 8(4), 5485-5499.
The feasibility of the combination of fungal with mild acid pretreatments of Glycyrrhiza uralensis residue (GUR) for enzymatic hydrolysis and oil production was studied. Combined pretreatment with Phanerochaete chrysosporium and 2.5% sulfuric acid was shown to be more effective than the acid-only pretreatment. Subsequently, the residue obtained from acid hydrolysis was subjected to enzymatic hydrolysis to generate fermentable sugars for oil production by Chlorella protothecoides. The reducing sugar yield of enzyme hydrolysate from co-treated GUR was 1.08- to 1.71-fold higher than that obtained from acid-treated GUR under the same conditions. The highest cell dry and oil yield from co-treated GUR reached 4.16 and 1.66 g/L dry weight, respectively, values which were 2.1- and 3.32-fold higher than those using glucose as a carbon source. This study suggested that combined pretreatment with P. chrysosporium and 2.5% sulfuric acid is an effective strategy for enhancing enzymatic hydrolysis and microalgal oil production from GUR. PDF
Zhang, J., Wang, X., Zhang, S., Gao, Q., and Li, J. (2013). "Effects of melamine addition stage on the performance and curing behavior of melamine-urea-formaldehyde (MUF) resin," BioRes. 8(4), 5500-5514.
Three formaldehyde-based resins were prepared: urea-formaldehyde (UF) resin without melamine modifier (named UF0 resin) and melamine-urea-formaldehyde (MUF) resins with melamine modifier added at two different synthesis stages (named MUF1 resin and MUF2 resin). The effects of the melamine addition stage on the performance and curing behavior of MUF resin were studied. Three-ply plywood bonded by these adhesives was manufactured, and its bond strength and formaldehyde emissions were measured. The curing behavior and functional groups of the resins were measured by differential scanning calorimetry (DSC) and Fourier transform infrared spectroscopy (FT-IR). Their activation energies were calculated using the Kissinger equation and the Kissinger-Akahira-Sunose (KAS) method. The results showed that melamine addition and the addition stage had significant influences on the characteristics of resins. The plywood bonded by MUF1 resin showed the highest bond strength and the lowest formaldehyde emissions. The activation energies of UF0 resin, MUF1 resin, and MUF2 resin were significantly different; the values were 99.44 kJ/mol, 105.75 kJ/mol, and 150.65 kJ/mol, respectively. According to the FT-IR spectra, the amount of methylene and methylene-ether bonds in cured MUF2 resin was the lowest, which meant that the cross-linking degree of MUF2 resin was the lowest. PDF
Park, C.-Y., Choi, C. -H., Lee, J.-H., Kim, S., Park, K.-W., and Cho, J. H. (2013). "Evaluation of formaldehyde emissions and combustion behaviors of wood-based composites subjected to different surface finishing methods," BioRes. 8(4), 5515-5523.
To use wood-based panels as a final product, they must undergo surface finishing via various processes, such as low pressure laminate (LPL), polyvinyl chloride (PVC), coating paper (CP), direct coating (DC), or veneer overlay/UV coating (VO-UVC). Tests were conducted to look for any reduction of formaldehyde emissions and in combustion behaviors with the use of five different surface finishing methods. To determine formaldehyde emissions, the desiccator method was used according to the Korean Standard KS M 1998. The combustion behaviors of wood-based panels were investigated using a cone calorimeter. The formaldehyde emissions of VO-UVC were lower than those of the other methods. In the burning tests, the heat release rate (HRR) with DC was higher than that with the other methods. The mass loss rate (MLR) when the product with DC was burned was higher than that for the other finishing materials. PDF
Zygomycetes fungi are able to produce ethanol, and their biomass may hold a high market value, making them interesting microorganisms from a biorefinery perspective. In the present study, the inhibitor tolerance of the Zygomycetes fungus Rhizopus sp. was evaluated and compared with a flocculating strain of Saccharomyces cerevisiae. The inhibitors furfural, 5-hydroxymethylfurfural [HMF], acetic acid, and levulinic acid and the phenolic compounds catechol, guaiacol, and vanillin were applied in different combinations in a semi-synthetic medium. Glucose uptake and conversion of HMF in the presence of inhibitors were analyzed for the two organisms, and it appeared that the inhibitor resistances of Rhizopus sp. and S. cerevisiae were comparable. However, in the presence of catechol (0.165 g L-1), guaiacol (0.186 g L-1), and vanillin (0.30 g L-1), the glucose uptake by S. cerevisiae was only 3.5% of its uptake in a medium without inhibitors, while under equal conditions, Rhizopus sp. maintained 43% of its uninhibited glucose uptake. PDF
Cui, L., Yan, J., Yang, Y., Li, L., Quan, G., Ding, C., Chen, T., Fu, Q., and Chang, A. (2013). "Influence of biochar on microbial activities of heavy metals contaminated paddy fields," BioRes. 8(4), 5536-5548.
Biochar (BC) amendments might decrease the bioavailability of metals in soils that are contaminated with heavy metals. In general, soil microbial communities are sensitive to changes in soil property changes. Microbial communities were tested in a Cd- and Pb-polluted paddy field in southern China. BC was applied as a basal soil amendment before rice transplantation in 2009. The BC was applied at rates of 0, 10, 20, and 40 tons per hectare. Soil heavy metal fractions with sequential extraction procedure, soil microorganisms, and enzymes were monitored in 2011. The soil pH and soil organic carbon (SOC) were significantly increased by 2% to 5% and 16% to 51% under BC amendment, respectively. Compared to the non-BC treatment, the cadmium (Cd) and lead (Pb) acid-soluble fraction concentrations were significantly decreased by 15.3% to 26.7% and 18.2% to 30.9%. The Cd and Pb reducible fraction were decreased by 13.5% to 25.6% and 21.9% to 23.53%.The Cd and Pb oxidizable fraction by 15.4% to 69.2% and 22.7% to 29.3% with BC application, respectively. The populations of actinomycetes and fungi were increased by 19.0% to 38.5% and 3.7 to 9.3 times, respectively. Meanwhile, BC significantly increased the cellulose, urine enzyme, neutral phosphatase, and sucrase activities by 117.4% to 178.3%, 31.1% to 37.6%, 29.7% to 193.8%, and 36.5% to 328.6%, respectively. BC amendment offers a basic option to reduce Cd and Pb bioavailability and change the fractions. The BC also increases microorganism quantity and soil enzyme activity. PDF
Moisture content (MC) has an important effect on the performance of wood in service. In an attempt to rapidly and non-destructively acquire the MC of heat-treated wood, a radio frequency-type moisture meter was used to take the MC of 170, 185, and 200 °C heat-treated Manchurian ash and Mongolian pine wood samples as well as reference (conventional kiln-dried) samples. A linear regression analysis was applied to assess the relationship between the MC values obtained using the meter and those obtained using the oven-dry method by fitting the data points according to the least squares method. From the results of the high coefficients of determination of the regression equation, it was concluded that the meter could be effectively used to obtain the MC of heat-treated wood. Finally, to ensure the simple and reliable application of the meter, the meter correction factors corresponding to each species and heat treatment temperature were calculated and listed. PDF
Samariha, A., Khakifirooz, A., Nemati, M., Ravanbakhsh, F., Kiaei, M., and Saghafi, A. (2013). "Newsprint from NSSC bagasse pulp mixed with hardwood CMP pulp and bleached softwood kraft pulp," BioRes. 8(4), 5561-5569.
In this work, the possibility of using neutral sulfite semi-chemical (NSSC) bagasse pulp mixed with hardwood chemimechanical pulp (CMP) and bleached softwood kraft pulp (BSKP) was investigated with the aim of reducing hardwood and BSKP consumption. The bagasse NSSC pulp had a digester yield of about 73% and was unbleached. It was refined by a PFI mill to 400 mL CSF, but in the case of the hardwood CMP and imported long fiber pulp, the final refined freeness were selected to be 350 and 500 mL CSF. Handsheets were made (60 gm-2), and their strength indices and optical properties were measured. Results of this research on a laboratory scale indicated that using bagasse NSSC pulp mixed with hardwood CMP to make newsprint with acceptable quality is possible, and this process will also noticeably reduce the consumption of imported long fiber pulp and wood for producing the grades of paper usually made from CMP. PDF
Nurul Izzati, M. Z., Ainun, Z. M. A., Abdullah, L. C., Hazwani, H. A., Harun, J., and Jawaid, M. (2013). "Water absorbency and mechanical properties of kenaf paper blended via a disintegration technique," BioRes. 8(4), 5570-5580.
In this study, blended paper was prepared by blending synthetic polyethylene (PE) via a disintegration technique. The produced paper was targeted to resist water or moisture. Unbleached kenaf whole stem pulp was used as the main source of fibre in making the paper. The pulp was blended with two types of PE: low-branched (LB) and high-branched (HB) polymers. To study the effect of PE addition to the paper, the water absorbency and mechanical properties were characterized. The pulp to PE mixtures were prepared at ratios of 9:1, 8:2, 7:3, 6:4, and 5:5. Scanning electron microscopy (SEM) showed that the PE was melted between the fibre linkages. The Cobb test determined that the blended paper absorbed less than 20 g/m2 of water within 60 s. The best water contact angle successfully achieved was at 84°, which is almost hydrophobic. The mechanical properties, such as tensile strength and tear strength, were in the range of accepted standard requirements. The obtained results indicated that blending via a disintegration technique can be applied in the process of making water-resistant paper. The produced paper is suitable for the manufacturing of water-resistant corrugated packaging materials. PDF
Three kinds of wheat straw black liquor were extracted by alkaline solution at 25 °C, 100 °C, and 165 °C, and were precipitated by the stepwise addition of acid to pH 10.5, 9.0, and 2.0, respectively. The corresponding three lignin fractions were isolated. The characteristics of these lignin fractions were investigated, and their impacts on anti-oxidant properties were evaluated. The pH 10.5 fractions with low lignin content, low phenolic hydroxyl content, and high lignin molecular weight showed very poor radical scavenging ability. The pH 9.0 and 2.0 fractions with high phenolic hydroxyl contents exhibited excellent radical scavenging ability. The major portion of the degraded lignin was precipitated in the pH 2.0 fraction, resulting in a lower molecular weight and higher phenolic hydroxyl content as compared to the pH 10.5 and pH 9.0 fractions. The high extraction temperature degraded more lignin and generated more phenolic hydroxyl groups. Therefore, the lignin fractions extracted at 165 °C exhibited the best radical trapping potential as compared to the lignin extracted at 100 °C and 25 °C. The coefficients of DPPH· removal for the lignin fractions were ordered in sequence by phenolic hydroxyl content, methoxyl content, molecular weight, E+T content, and NO yield of lignin. The lignin fraction extracted at higher temperature and precipitated at lower pH had the best radical scavenging ability. PDF
In the present study, jatropha oil cake (JOC), a waste produced from processing jatropha seeds for biodiesel production, has been investigated for the removal of nickel (II) from aqueous solutions. Jatropha oil cake contains different functional groups that can participate in the metal ion complexation. Jatropha oil cake is used in its natural form (JOCN) as well as in its immobilized form (JOCB). Batch experiments were performed for adsorption of Ni (II) by JOCN and JOCB. Parameters affecting the adsorption, such as the effect of adsorbent dose, pH, the initial concentration of metal ion, agitation speed, and contact time, were studied for the maximum removal efficiency. Removal efficiency was found to be 62% and 63% for Ni (II) at pH 6.2 in its natural and immobilized forms, respectively. Maximum adsorption occurred within an hour for Ni (II) with JOCN and 90 min for JOCB. The equilibrium data was analyzed using Langmuir and Freundlich isotherms. PDF
Biomass catalytic fast pyrolysis is one of the most promising technologies for the production of renewable aromatics and olefins directly from solid biomass. In this study, catalytic pyrolysis experiments were carried out on biomass in a fluidized bed reactor using typical metal-loaded (Mg, K, Fe, Ga, and Ni) ZSM-5 zeolites as catalysts. The effects of catalysts on the product distribution and bio-oil components were investigated to determine the cheapest and most efficient metal-loaded catalyst. The results showed that bio-oil yields with metal-loaded catalysts (40 to 43.4 wt.%) were a little lower than that of pure ZSM-5 (46.4 wt.%). Metal-loaded catalysts produced more CO2 and CO than did pure ZSM-5. Fe/ZSM-5 produced the highest yield of CO2 (13.8 wt.%), as well as the highest yield of olefins (2.7 wt.%). Fe/ZSM-5 showed the same catalytic characteristics as Ga/ZSM-5 (aromatic hydrocarbon proportion in bio-oils of more than 80%), but it is much cheaper than Ga/ZSM-5. PDF
The pulp yield of orange tree wood was tested under various conditions including processing with soda-anthraquinone (soda-AQ), kraft-anthraquinone (kraft-AQ), or ethanol under different temperature, time, reagent concentration, and PFI laboratory beater beating regimes. Beating grade and stretch properties were studied, with a view to identifying the optimum operating conditions. Polynomial equations were derived that generally reproduced the dependent variables, with errors in most cases much less than 20%. Kraft-AQ pulping was the most efficient. The values of the tensile, burst, and tear indices obtained with kraft-AQ (78.04 Nm/g, 4.84 kN/g, and 2.97 mNm2/g, respectively), were in most cases higher than those found for soda-AQ and ethanol pulps. Using lower values of operational conditions than those required to maximize the studied paper properties (170 °C, 65 min, 13% active alkali, and 2700 number of PFI beating revolutions), it was possible to provide a more energy- and chemically-efficient process for industrial facilities. PDF
Following previous kinetic investigations of the acetylation of cotton linter pulp (Luo et al. 2013), a mathematical model was set up based on the mass and energy balances to simulate the batch acetylation process; a particular goal was to predict the temperature profile. The equations were discretized using a time-dependent finite difference method. The parameters for the model, including the kinetic parameters and heat transfer rate, were well estimated from the literature and our previous work. The model using the least-mean-square-error criterion optimizes the unknown parameters. The proposed model provides an accurate prediction of the process, including the temperature profile, peak temperature, and DS value under the peak temperature. The content of the catalyst, sulfuric acid, has a dramatic effect on the temperature profile. A slight increase in sulfuric acid content will lead to a faster dissolution process for the sulfated cellulose fibers, whereas the reaction rate of the sulfated fibers with acetic anhydride in the liquid phase is not affected. The optimized values of the activation energy are 11.0 and 7.6 kJ/mol for the dissolution processes with low and high sulfuric acid contents, respectively. PDF
Qi, J., Xie, J., Hse, C.-Y., and Shupe, T. F. (2013). "Analysis of Phyllostachys pubescens bamboo residues for liquefaction: Chemical components, infrared spectroscopy, and thermogravimetry," BioRes. 8(4), 5644-5654.
Residues of Phyllostachys pubescens bamboo obtained from central Louisiana, USA, were comprehensively investigated for use in liquefaction. The results showed that bamboo branches had the highest Klason lignin and ash content, about 26% and 2.75%, respectively. The epidermis layer sample had relatively higher carbohydrate content, while the wax layer sample had the highest hot water and ethanol-toluene extractives and starch content. The results indicated that the bamboo processing residues showed potential for different chemical feedstocks. No significant differences were found in the infrared spectroscopy (FTIR) spectra of the different samples, indicating that the chemical functional groups were the same, despite variation in chemical components between samples. Klason lignin isolated from the residues showed a higher maximum degradation rate temperature (501 °C) and wider degradation temperature range (200 to 550 °C) than the carbohydrates. PDF
Oil-impregnated insulation paper is widely used in power transformers, and the insulation properties of oil-impregnated insulation paper play an important role in the reliability of power equipment. The formation and dynamics of space charge can affect the performance of insulation material. However, methods to improve the space charge distribution in oil-impregnated insulation paper are rarely reported. In this paper, space charge behavior in oil-impregnated insulation paper has been investigated using the pulsed electro-acoustic (PEA) technique. A series of measurements was applied when the oil-impregnated insulation paper reinforced with different nano-TiO2 contents was subjected to various electric field strengths. The accumulation and decay of space charge are discussed, and the internal electric field strength distribution of oil-impregnated insulation paper is analyzed. The test results show that the space charge distribution is improved and the distortion rate of the internal electric field strength is reduced by adding nano-TiO2 to the oil-impregnated insulation paper. The results show that the proposed method offers a new way to improve the properties of oil-impregnated insulation paper. PDF
Guo, W., Song, S., Zhao, R., Ren, H., Jiang, Z., Wang, G., Sun, Z., Wang, X., Yang, F., Chen, H., Shi, S. Q., and Fei, B. (2013). "Tension performance of metal-plate connected joints of Chinese larch dimension lumber," BioRes. 8(4), 5666-5677.
Tension tests of metal-plate connected (MPC) joints for Chinese larch (Larix gmelinii (Rupr.) Rupr.) were conducted in four orientations. Load-deflection curves were obtained for each MPC jointed specimen. Ultimate tension load, translation stiffness, stiffness at large slip, and failure modes for each specimen were obtained. A Foschi 3-parameter model was found to fit the load-deflection curves very well. Wood grain, and MPC length and loading directions had significant effects on elastic deformation and stiffness at large slip of the MPC joints. Load parallel to the grain with MPC length parallel to load (AA) represented the highest elastic deformation, while load perpendicular to the grain and MPC parallel to load (AE) showed the lowest. Load perpendicular to grain with MPC length perpendicular to load (EE) presented the highest stiffness at large slip, AA the second, load parallel to grain-MPC length perpendicular to load (EA) the third, and AE the lowest. The translation stiffness and tension load showed similar trends in terms of the effect of test orientations. The ultimate tension load was reduced by 18.9% from AA to EA, 34.2% from AA to AE, and 36.8% from AA to EE. Multiple failure modes occurred at the MPC joint, including MPC shear failure, tooth withdrawal, and wood failure. PDF
Alpha cellulose was extracted from Bambusa rigida fibers by carrying out Soxhlet extraction and bleaching and alkali treatments with acidified sodium chlorite solution and sodium hydrate solution. Then, cellulose nanofibers were isolated from α-cellulose with the combination of (33 wt%) sulfuric acid and ultrasonic treatment. The nano-sized fibers were successfully isolated, and the average diameters were about 10 to 30 nm. FTIR showed that a majority of the hemicelluloses and lignin were removed from the raw fiber and that the chemical constituents of α-cellulose and cellulose nanofibers were similar. XRD showed that the obtained nano-fibers presented a cellulose I structure, and thus the crystallinity of cellulose nanofibers was significantly increased. TGA showed that the thermal stability of the cellulose nanofibers was significantly improved. The relative crystallinity and thermal degradation temperature of the cellulose nanofibers reached 61.21% and 315.2 °C, respectively. PDF
Hot water extraction of hemicelluloses from aspen wood chips of different sizes and wood meal was performed, and the extracted hemicelluloses were characterized. With decreasing wood chip size, the total sugars and total poly- and oligosaccharides extracted with hot water increased. The dissolution of hemicelluloses was mainly limited by diffusion in the fiber wall and mass transfer from fiber to fiber during hot water extraction of the wood chips. The extraction yield of high molecular weight hemicelluloses was less than that of low molecular weight hemicelluloses, and the reduction of wood chip size benefited the extraction of high-molecular weight hemicelluloses. Compared to the wood chips, the high molecular weight hemicelluloses extracted from wood meal had a higher extraction yield and an increased average molecular weight. PDF
Structural and mechanical aspects of the forming of paperboard have received attention in the literature; however, specific forming phenomena of the tray corner and rim area of paperboard packaging have not been researched widely. In light of the importance of the corner for packaging quality, and to enable improved process control of forming, this study considers the forming phenomena of the corner of a press-formed paperboard tray. Four different thicknesses of extrusion-coated paperboard were studied to research the effect of paperboard thickness and mould clearance on the final product of the press-forming process. Suitable mould clearance, i.e., the percentage of the mould cavity that is filled with paperboard, was found to be from 95% to 135% for the tested paperboard types. PDF
The aim of this study was to investigate the decay resistance of wood- polypropylene composites (WPCs) treated with nano-zinc oxide against the white rot fungus Trametes versicolor and the brown rot fungus Coniophora puteana. WPCs containing different loadings of nano-zinc oxide, namely 0, 1, 2, and 3 percent (by weight), were made. The composites were subsequently exposed to a decay test according to a modified ASTM D1413 standard. Nano-zinc oxide distribution in the composite was studied by scanning electron microscopy (SEM) combined with energy dispersive analysis of X-rays (EDAX). No clear evidence of nano-zinc oxide agglomeration at a loading of 3% (w/w) was obtained using SEM-EDAX. The results showed that nano-zinc oxide improved the decay resistance of the composite against the fungi. PDF
The effects of wollastonite nanofibers on the physical and mechanical properties of particleboard were studied. Nano-wollastonite (NW), with the size range of 30 to 110 nm, was applied at 5, 10, 15, and 20%, based on the dry weight of wood chips, and compared with control specimens. Two application methods of NW were used: surface application (SA) and internal application (IA). Density was kept constant at 0.68 g/cm3 for all treatments. Tests were carried out in accordance with ASTM D-1037 specifications. The obtained results showed that NW formed bonds between the wood chips and improved the physical and mechanical properties, both when applied internally and when applied superficially. However, formation of micro-cavities and decreased integration in the particleboard matrix caused by a reduction in wood chip content resulted in a decrease in the mechanical properties of IA-NW-treated specimens at higher NW consumption levels. It may be concluded that surface application of NW at a 1.5% consumption level can be recommended for use in particleboards. PDF
Low mole ratio urea-melamine-formaldehyde (UMF) resins synthesized with 2.5% and 5.0% melamine levels added at the beginning, middle, and end points of the first alkaline step of the typical urea-formaldehyde (UF) resin synthesis procedure were compared with typical UMF resins synthesized with melamine additions made at the final alkaline step. Various resin analysis, particleboard preparation, physical performance, and formaldehyde emission level tests were carried out. UMF resins synthesized with melamine additions at the beginning of the first alkaline step showed adequate storage lives of 2 to 3 weeks, and their particleboard bonding tests showed small but significant improvements in water soak test values, while formaldehyde content values were slightly higher in comparison with typical UMF resins. The particleboards showed adequate board strength and the formaldehyde contents were relatively low to qualify for the E1 Class of European Standards. UMF resins synthesized with melamine addition made at the middle and end of the first alkaline step were highly turbid and showed chemical structure differences and very short storage lives and the resin synthesis procedures were concluded to be of little practical value. PDF
Japanese pine sawyer beetle, pine shoot beetle, and Formosan subterranean termite were selected to investigate the inhibitory abilities of solid wood and wood-based composites (MDF and WPCs) made with Eucalyptus urograndis and Melaleuca leucadendra. The chemical components in the extractives of the two types of wood were also analyzed by GC-MS. The results indicated that the inhibitory ability can generally be listed in descending order as WPCs, MDF, and solid wood when made by the same wood filler. However, samples in each group made using Melaleuca leucadendra exhibited a higher inhibitory level than samples made using Eucalyptus urograndis. 2,3-dihydro-2,2-dimethyl-3,7-benzofurandiol, which was identified in the extractives of both woods (14.169% in Eucalyptus urograndis and 12.686% in Melaleuca leucadendra), was a significant factor for inhibition due to its high toxicity to insects. The chemical components with greatest potential for inhibition were stigmast-4-en-3-one (8.656%) in Eucalyptus urograndis andboth 3-demethyl-colchicine (2.642%) and squalene (1.649%) in Melaleuca leucadendra. Additionally, perlite-based MDF showed the best inhibitory ability, possibly because the alimentary of the insects are prone to injury by perlite. PVC-based WPCs had a greater inhibitory level than HDPE-based WPCs due to the presence of the Cl element in PVC, as well as the addition of calcium zinc stabilizer and inorganic filler. PDF
The catalytic conversion of lignocellulosic biomass to levulinic acid in ionic liquid, [EMIM][Cl] was conducted using a hybrid catalyst. The hybrid catalyst (1:1 ratio) with equal CrCl3 and HY zeolite weight ratios was synthesized using a wet impregnation method. Initially, optimization of cellulose as a model compound was carried out using two-level full factorial design (23) with two centre points. Under optimum process conditions, 46.0% of levulinic acid yield was produced from cellulose. Subsequently, utilization of lignocellulosic biomass demonstrated 15.5% and 15.0% of levulinic acid yield from empty fruit bunch (EFB) and kenaf, respectively, at the optimum conditions. Meanwhile, in the presence of ionic liquid under the same process conditions, 20.0% and 17.0% of levulinic acid were obtained for EFB and kenaf, respectively. The results indicated that ionic liquid could disrupt the covalent linkages between the biomass structures and dissolved the hollocellulose. This allowed the hollocellulose chains, accessible to the chemical transformation, to react and produce levulinic acid in presence of the hybrid catalyst. This study demonstrated that the combination of hybrid catalyst and ionic liquid has the potential to be applied for biomass conversion to levulinic acid under adequate process conditions. PDF
To achieve a desired ethanol concentration and maximize substrate concentration, the fed-batch simultaneous saccharification and fermentation (SSF) process was performed on steam-exploded corn stover using the yeast strain Saccharomyces cerevisiae Y5. The fed-batch SSF experiments were conducted with feed loading and scheduled feed time conditions that were optimized with response surface methodology (RSM). The overall ethanol yield (based on the raw material cellulose content) in 48 h was as high as 64.0%, which was achieved with a final substrate loading of 26%(w/w), enzyme loading of 7 FPU/g cellulose, and dry yeast loading weight of 2.0 g/L. No additional yeast cells or enzymes were added during solid substrate fermentation. PDF
In Central Europe the main species that are used for the production of sawn wood are spruce, pine, and European beech. After the sawing process, the sawn timber is technically dried to a certain moisture content by means of condensation drying. The water movement in the cellular structure, which is caused by the drying process, draws some of the extractives into solution. In the process of kiln drying, hot air evaporates the water and the dissolved extractives. Some of the water condenses on the floor and the walls of the kiln, while the rest is blown out with the steam. Therefore, condensate was taken from the bottom of the kiln as well as from the energy recovery system. A chemical analysis by means of purge-and-trap showed the presence of volatiles that could be classified as typical for the wood materials from which they originated under the conditions of high temperature and high moisture content. PDF
Unbleached kraft pulp fibers were modified with laccase and ferulic acid (FRC) to improve their physical strength properties in paper products. The optimal conditions of laccase-FRC modification were examined in terms of the physical properties of pulps. The effects of laccase-FRC modification on the carboxyl group content and surface lignin content of pulps were investigated. The surface morphologies of laccase-FRC-modified pulp fibers were observed by atomic force microscopy (AFM). The carboxyl group and surface lignin contents for laccase-FRC-modified pulps increased compared to the control pulp. AFM phase images showed that the laccase-FRC-modified fiber surfaces were covered with large granular substances from the products of FRC grafting and lignin polymerization/condensation reactions. The observed strength improvements of laccase-FRC-modified pulp could be attributed to the grafting of FRC onto the fibers, the higher carboxyl group content of the modified fibers, and the formation of covalent bonding between the fibers via radical coupling. PDF
Three tannin-based foam formulations differing in the type of surfactant added were tested during foaming via simultaneous monitoring of the variation in temperature, foam rising rate, internal foam pressure, and dielectric polarization, the latter being a direct measure of the setting and curing of a thermosetting foam. This monitoring is an effective descriptor of the process and possible characteristics of the foam being prepared and constitutes an invaluable tool for foam formulation. The addition of a surfactant was shown to have a major effect on foam dynamics by retarding the onset of cross-linking to a lesser or greater extent in relation to the peak of maximum temperature in self-blowing foams. Cationic surfactants, or non-ionic surfactants capable of transforming into cationic species under the acidic environmental conditions used for tannin-based foams, were found to retard cross-linking more markedly than did non-ionic surfactants. PDF
Binary bio-composites of acorn shell (AS) and low density polyethylene (LDPE) were prepared via a twin-screw extruding method. The mechanical properties of the composites decreased with increasing AS content, and all composites maintained similar tensile strength as expected based on the Nicolais-Narkis model, indicating weak adhesion between AS and LDPE. The effects of three compatibilizers, ethylene-acrylic acid (EAA), ethylene-vinyl acetate (EVA), and maleic anhydride grafted polyethylene (PE-g-MAH) on the composites were also studied. The results showed that the three compatibilizers improved the mechanical properties of composites at different levels, and the PE-g-MAH compatibilizing system showed the best mechanical strength, which was increased by about 80% from that of the control. Micro-morphologic investigation revealed a rough fractured surface, indicating that the addition of compatibilizers improved the interfacial bonding properties of the matrix materials LDPE matrix. Dynamic mechanical thermal analysis (DMA) further confirmed that the addition of compatibilizers significantly improved the compatibility of blending components and changed the properties of LDPE matrix materials. PDF
Zaaba, N. F., Ismail, H., and Jaafar, M. (2013). "Effect of peanut shell powder content on the properties of recycled polypropylene (RPP)/peanut shell powder (PSP) composites," BioRes. 8(4), 5826-5841.
Green composites are gradually replacing general plastics to achieve the aim of environment sustainability. In the present study, both compatibilized and uncompatibilized recycled polypropylene (RPP) and peanut shell powder (PSP) composites were prepared. The effect of various PSP loadings (0 to 40% by weight) on the processing, tensile properties, morphology, Fourier transform infrared (FTIR) analysis, and water uptake properties were examined. The results showed that the incorporation of PSP caused an increase in stabilization torque, tensile modulus, and water absorption, but lowered the tensile strength and elongation at break of the RPP/PSP composites. Compatibilized RPP/PSP composites with poly(ethylene-co-acrylic acid) (PEAA) significantly enhanced the tensile properties while decreasing the water absorption of RPP/PSP composites. FTIR analysis revealed a slight change in band positions and intensities, indicating a distinct interaction between the chains of polymers. SEM micrographs showed the interaction between PSP and the matrix. PDF
Gulsoy, S. K., Kustas, S., and Erenturk, S. (2013). "The effect of old corrugated container (OCC) pulp addition on the properties of paper made with virgin softwood kraft pulps," BioRes. 8(4), 5842-5849.
In this study, old corrugated container (OCC) pulp was added in different ratios (5%, 10%, 15%, 20%, and 25% w/w) to unbleached virgin pulps of both European black pine and Scots pine, and its effects on paper properties were investigated. As a control, OCC pulp-free handsheets were separately produced from European black pine and Scots pine pulps. The results indicated that the addition of OCC pulp decreased the strength properties, except for the tear index, of the handsheets. In addition, compared to the control handsheets, the paper containing the OCC pulp displayed higher air permeability. The results showed that up to 10% of the virgin softwood kraft pulp could be replaced with OCC pulp without bringing about considerable loss of strength. Also, this ratio of OCC addition could be suitable for production of wrapping papers. PDF
The influence of particle size and an alkaline pretreatment on the anaerobic digestion of corn stover was studied. Four particle sizes, 0.075 to 0.25, 0.25 to 1.0, 1.0 to 5.0, and 5.0 to 20.0 mm, were used. The highest and lowest methane yields were obtained from untreated corn stover at particle sizes of 0.25 to 1.0 and 5.0 to 20.0 mm, respectively. 4% NaOH and 2% Ca(OH)2 (combined alkaline pretreatment, CAP) were then used together to pretreat corn stover at these two particle sizes, compared with 6% NaOH pretreatment (single alkaline pretreatment, SAP). The cumulative methane yields from particle sizes 0.25 to 1.0 mm after CAP, 0.25 to 1.0 mm after SAP, 5.0 to 20.0 mm after CAP, and 5.0 to 20.0 mm after SAP were 286.9, 287.0, 268.7, and 272.6 mLg-1 VS, respectively. The particle size barely influenced the final cumulative methane yield of alkali-treated corn stover. Moreover, the cumulative methane yield of the corn stover after CAP was comparable with that of the corn stover after the SAP under the same conditions. These results provide us with a promising substitute of NaOH pretreatment for corn stover bioconversion in the future. PDF
Zhang, Z.-J., Chen, Y.-Z., Hu, H.-R., and Sang, Y.-Z. (2013). "The beatability-aiding effect of Aspergillus niger crude cellulase on bleached simao pine kraft pulp and its mechanism of action," BioRes. 8(4), 5861-5870.
Bleached simao pine kraft pulp was treated with Aspergillus niger crude cellulase produced by submerged fermentation using the pulp as the carbon source. The effects of the cellulase on the pulp beatability and mechanical properties were studied. Fourier transform infrared spectroscopy (FT-IR) was performed to study the effect of cellulase treatment on the cellulose crystallinity index. The fiber morphology difference before and after treatment was also revealed by atomic force microscope observation. Compared to the control pulp, the beating time of the cellulase-treated pulp with the dosage of 7 u/g could be reduced from 360 s to 260 s under the same beating degree of 48 °SR, which indicates a savings of about 28% beating energy consumption. The cellulase treatment had negative impacts on the pulp’s mechanical properties. The cellulase preferentially adsorbed on the fine surface. The cellulose amorphous region was easier to treat with cellulase than the crystalline region. Atomic force microscope images demonstrated that the primary wall of fibers was peeled off and the S1 layer of fibers came to the surface after the cellulase treatment. PDF
This study evaluated the properties of fluting paper made with a blend of unbleached bagasse soda pulp (340 mL CSF freeness) and OCC pulp (250 to 300 mL CSF freeness) of 0:100, 10:90, 30:70, 50:50, 70:30, and 90:10 ratios by weight, respectively. Some handsheets at 120 g/m2 basis weight were made. Strength characteristics such as tear index, tensile index, air resistance, double folds, burst index, and Concora medium test (CMT) were measured according to TAPPI and ISO standards and compared to each other. Inferior handsheet properties were observed when using 100% recycled fibers. Results further showed that addition of 10 to 30% bagasse pulp to OCC pulp did not significantly enhance the sheet strength of the product compared with the control sample (100% OCC pulp). However, it was found that addition of 70% or more of virgin pulp to the OCC pulp resulted in a substantial increase in the strength properties, except for the tear index. The modification of the fibers was visually evaluated by Scanning Electron Microscope (SEM). Overall, the results showed that flexible virgin bagasse fibers can be used as a lignocellulosic fiber for making fluting paper in combination with recycled OCC fibers. PDF
Zakaria, S., Ahmadzadeh, A., and Roslan, R. (2013). "Flow properties of novolak-type resin made from liquefaction of oil palm empty fruit bunch (EFB) fibres using sulfuric acid as a catalyst," BioRes. 8(4), 5884-5894.
Novolak-type resins were produced via liquefaction of oil palm empty fruit bunch (EFB) fibres with various liquefaction and resinification parameters such as temperature, time, catalyst concentration, and phenol-to-EFB ratios, and investigated in terms of flow properties (melt viscosity and melt flow rate) of the phenolated EFB (PEFB) and resinified PEFB (RPEFB). The results showed that the phenol/EFB ratio was the most effectual parameter in the variation of melt viscosity and melt flow rate (MFR) of PEFB. The melt flow rate of the PEFB was tremendously lower than that of the commercial novolak resin. The results showed that the activation energy for flow, which was obtained using the Arrhenius equation, increased when the liquefaction temperature increased. The results also demonstrated that the molten PEFB showed a shear thinning or pseudo-plastic behavior. PDF
A direct synthesis of methyl levulinate from the degradation of paper sludge in a methanol medium at moderate temperatures ≤ 230 °C) was performed using low-concentration sulfuric acid (≤ 0.05 mol/L) as the catalyst. Response surface methodology with a four-factor, five-level central composite rotatable design was employed to optimize the process conditions for maximized methyl levulinate production under the condition of controlling the dehydration of methanol to dimethyl ether. The yields of methyl levulinate and dimethyl ether as a function of the process variables were fitted to second-order polynomial models through application of multiple regression analyses. A good agreement between the experimental and modeled data was obtained. When the controlled yield of dimethyl ether was less than 20%, a maximum methyl levulinate yield of 54.8% was achieved, corresponding to 27.7% (w/w) overall yield for dry paper sludge. The findings indicated that paper sludge can act as a potential biomass material for upgrading and converting into high value-added chemicals. PDF
The wood pellet industry has been in a growing trend worldwide. The Southern U.S. has been proposed as a good location to further develop wood pellet industries geared toward the supply of international markets. This research looks into the current status of the wood pellet industry of the region in terms of consumption of biomass, installed capacity, and production levels of wood pellets. It assesses the known future developments for the region (Virginia, North Carolina, South Carolina, Georgia, and Florida). The study also includes an analysis of major ports within the region. Currently, companies within the region have a total production capacity of over 4.7 million tons of pellets, while the current production levels are estimated at 3.1 million tons. Research indicates that at least 20 facilities within the region will be opening their operations, and the expected capacity of the wood pellet industry will then be over 5 million tons of pellets per year. The biomass requirement for the production of these pellets was determined, and the current production level requires over 11 million tons of green biomass (55% moisture content). Future developments may require over 13 million tons, making the industry total over 24 million tons in coming years. PDF
Brodin, F. W., and Theliander, H. (2013). "High temperature TEMPO oxidation in a heterogeneous reaction system: An investigation of reaction kinetics, pulp properties, and disintegration behavior," BioRes. 8(4), 5925-5946.
TEMPO oxidation was performed on never-dried bleached softwood kraft pulp fibres to study the influence of reaction temperature and the dosage of sodium hypochlorite in the oxidation treatment. It was found that oxidation at a high temperature shortened oxidation time, but it also resulted in more extensive degradation of the pulp. Harsh reaction conditions (high temperature and high dosage of sodium hypochlorite) enabled the rapid disintegration of pulp fibres with a low energy demand. The freeze-dried disintegrated pulp fibres had a high absorption capacity of saline liquid, 40 to 80 g/g, and retained 9 to 14 g saline liquid/g material in a standard centrifuge retention test. Four different models were investigated to describe the kinetics of TEMPO oxidation of pulp fibres. However, none of the models could adequately describe all the mechanisms involved in this reaction system. The results showed that the diffusion of hypochlorite ions was sufficiently fast compared to the chemical reactions. In contrast, the concentration of the catalytic compounds, NaBr and TEMPO, both had a strong influence on the reaction rate. Results show that the reactions have different phases, possibly with different rate-determining steps. It remains to be determined which reaction steps correspond to the different phases. PDF
The possibility of using cellulose from kenaf as reinforcing fibres in lithium-conducting composite polymer electrolytes based on 49% poly(methyl methacrylate)-grafted natural rubber and LiCF3SO3 has been explored. Cellulose was extracted from kenaf bast fibres by a two-step chemical treatment, specifically an alkali treatment and a bleaching process. High-performance composite polymer electrolytes were prepared by solution casting with various compositions of cellulose (0-10 wt%). Scanning electron microscopy was used for morphological studies of the kenaf fibres at each stage of treatment. The morphology of the electrolytes showed a good dispersion of the cellulose fibres. Infrared spectroscopy showed significant interactions between Li+ ions from the salt and the C=O and C-O-C groups of methyl methacrylate. X-ray diffraction analysis showed that the crystallinity of the polymer host increased upon addition of cellulose and decreased upon addition of salt. Composite electrolytes with 4 wt% cellulose exhibited the best mechanical performance with 10.9 MPa and 995 MPa for tensile strength and Young’s modulus, respectively. The electrolyte films were analyzed by electrochemical impedance spectroscopy and the optimum value of ionic conductivity of SPE with cellulose was 5.3×10-7 Scm-1. The addition of cellulose involved a weak decrease of the conductivity, which might be due to interactions between cellulose, polymer, and LiCF3SO3. The incorporation of cellulose fibres in polymer electrolytes provides a high reinforcing effect at an acceptable level of ionic conductivity. PDF
Zheng, R., Chen, Z., Cai, C., Wang, X., Huang, Y., Xiao, B., and Sun, G. (2013). "Effect of biochars from rice husk, bran, and straw on heavy metal uptake by pot-grown wheat seedling in a historically contaminated soil," BioRes. 8(4), 5965-5982.
The effect of biochar amendment of a multi-element contaminated soil on the transfer and accumulation of Cd, Zn, Pb, and As in wheat was investigated in this study. Addition of biochars from rice residues (straw, husk, and bran) significantly decreased shoot Cd, Zn, and Pb concentrations by up to 71%, 37%, and 60%, respectively, but increased As by up to 199%. Biochar additions decreased the NH4NO3-extractable concentrations of Cd, Zn, and Pb in soil by 23 to 81%, 29 to 94%, and 31 to 92%, respectively, especially straw-char treatment, though biochar treatment increased the concentration of As by 64 to 2650%. A decrease in biochar particle size generally favored the immobilization of Cd, Zn, and Pb in soil and reductions in their accumulation in wheat shoot, but this was reversed for As. Increases of up to 21%, 70%, 59%, and 40% in shoot biomass, root length, and shoot P and K levels, respectively, of wheat seedlings were caused by biochar amendments. Biochar has the potential to reduce accumulations of Cd, Zn, and Pb in wheat shoot and improve its growth. PDF
Microcrack behaviors in black and red heartwoods of Cryptomeria japonica were compared in this study. Black and red heartwoods have extremely different green moisture contents but similar wood structure. Small heartwood samples were prepared from these two types of green wood. Moisture contents of black and red heartwood were 201.5% and 51.3%, respectively. The samples were dried at 50 °C in a controlled-environment chamber with a relative humidity below 5%. The propagation of microcracks was continuously observed using a confocal laser scanning microscope while the samples dried. The electrical resistivity of the surface was also measured to assess surface moisture content. Results showed that the transformation of the microcracks was similar between black and red heartwoods. However, the appearance of microcracks in the black heartwood was delayed, whereas the microcracks appeared in red heartwood immediately after drying. These suggested that in-situ observation is essential for distinguishing when microcracks emerged. It was also suggested the green moisture content of heartwood has a major effect on the occurrence of microcracks. Drying conditions must be adjusted to account for the moisture content of green heartwood, even for specimens of the same species that have the same anatomical structure. PDF
Mou, H.-Y., Li, B., Heikkilä, E., Iamazaki, E., Zhan, H.-Y., and Fardim, P. (2013). "Low consistency refining of eucalyptus pulp: Effects on surface chemistry and interaction with FWAs," BioRes. 8(4), 5995-6013.
The surface chemistry of eucalyptus pulp fibers prior to and after low-consistency (LC) refining was studied using a state-of-the art laboratory refining device and advanced surface analysis techniques. It was found that LC refining could generate fines and fibrillation and change the surface chemical composition of fiber surfaces. Both of these two effects can facilitate the adsorption of fluorescent whitening agents (FWAs) by the combination of increased specific surface area, electrostatic forces, and hydrophobic interactions, thus compensating for the loss of optical properties resulting from LC refining. The mechanical hydraulic force generated by the high refining energy disturbed the FWA retention. Therefore, high refining energy could improve the adsorption of FWAs when they are added after refining, but for better performance, the refining energy should be controlled and lowered. In addition, small amounts of calcium salt added after refining can also ameliorate the adsorption of FWAs. PDF
Transformation of the hemicellulose fraction in an environmentally benign manner to deliver high value-added chemicals is critical for the integrated utilization of biomass. Amongst all the chemicals derived from hemicellulose, furfural (produced by hydrolysis of xylan into xylose and successive dehydration of the latter) is a promising option. In this manuscript, a catalytic approach for converting xylan and xylose into furfural co-catalyzed by choline chloride-citric acid·H2O, a deep eutectic solvent (DES) synthesized from biorenewable building blocks, and trivalent metal chloride was developed. Choline chloride-citric acid·H2O acted as both reaction medium and Brønsted acid catalyst. Both monophasic route and biphasic route (with methyl isobutyl ketoneas extractant for in situ extraction of furfural) were proposed. The highest furfural yields obtained from xylose and xylan in monophasic approach were 59.3% and 54.2%, respectively, at 140 °C, and these values increased to 73.1% and 68.6% when biphasic system was applied for the reaction. Moreover, in biphasic system, choline chloride-citric acid and metal chloride could be recycled and reused for 5 runs with stable catalytic ability. PDF
Magnetic chitosan composite microparticles (MCCPs) were successfully prepared using a simple one-step co-precipitation method and characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), and vibrating sample magnetometer (VSM). The experimental results showed that the particles possessed a honeycomb-like porous structure and had super-paramagnetic properties, with a saturation magnetization of about 33.3 emu/g. Congo red (CR), an anionic azo dye, was used to investigate the adsorption properties of the MCCPs. The adsorption kinetics data and isotherms produced from these experiments indicated that CR adsorption onto the MCCPs was best fitted with a pseudo-second-order kinetic equation and was well described by the Langmuir model. Thermodynamic parameters such as the changes in Gibbs free energy (ΔG0), enthalpy (ΔH0), and entropy (ΔS0) were also estimated; the results revealed that the adsorption process was spontaneous and endothermic. The regeneration studies demonstrated that the MCCPs can be used as a reusable adsorbent for CR adsorption from aqueous solution. The molecular similarity between chitosan and cellulose suggests that the present results might serve as a model of what might be achieved with a cationic derivative of cellulose. PDF
The wood industry continues to strive to reduce production costs and increase productivity to remain competitive. Knowledge of the effect of wood cutting parameters on power consumption could increase energy efficiency, reducing operating costs and increasing profitability. Measuring power consumption also provides information about other variables, such as tool edge wear, occurrence of catastrophic failures, and other parameters that affect the quality of the sawn boards and the momentary efficiency of the breakdown process. In this work, power consumption during sawing of Pinus sylvestris L. using a double arbor circular saw was investigated. Both climb-sawing and counter-sawing were considered. The experiments were carried out under normal production circumstances in two Swedish sawmills. The relationship between cutting parameters and theoretical power consumption was investigated. The experimental power consumption increased by 11 to 35% during an 8-h shift, mainly due to an increase in the tooth radius. Additionally, this study showed that climb-sawing consumed more power than counter-sawing. PDF
Green vein is one of the most severe defects that affect wild cherry (Prunus avium L.). It consists of green streaks that alter the typical color and uniformity of the cherry wood, causing considerable value losses. A colorimetric analysis was performed on wild cherry clones using the CIE L*a*b* system, and the influences of environmental and genetic factors on green vein as well as the effects of the presence of green vein on the physical properties of the wood were investigated. Discriminant analysis shows that the color parameter that best discriminated green vein were low values of L* and a*. The cloning effect was the most important, but the environment also played an important role in the development of green vein. Finally, the presence of green vein was found to mainly affect the longitudinal shrinkage of wood and, to a lesser extent, wood density. These same features are typical of tension wood, to which green vein was strictly linked, as confirmed by some preliminary anatomical observations. PDF
In this study, four species of wood-rot fungi—Piptoporus betulinus, Fomes fomentarius, Irpex lacteus, and Coriolus versicolor—were compared regarding their ability to degrade the wood of white birch and used to assess the degradation mechanisms. Chemical analyses were conducted following the Chinese national standard methods and included Fourier transform infrared spectroscopy (FTIR). The wood samples were inoculated with the four wood-rot fungi for a predetermined duration in the wood-decaying test. In the wood weight loss test, both F. fomentarius and P. betulinus showed the greatest reduction, but through different mechanisms: F. fomentarius mainly decomposed lignin, whereas P. betulinus mainly acted on cellulose. F. fomentarius, I. lacteus, and C. versicolor exhibited a shift at 3417 cm-1 related to O-H stretching in hydroxyl groups, along with decreased absorption at 3410, 3406, and 3405 cm-1, most likely due to the degradation of the related functional groups of lignin side chains. The wood decayed by P. betulinus displayed a change in the relative position of cellulose-associated bands at 1161 and 898 cm-1. F. fomentarius can be considered a potential agent for the biopulping of white birch because of its high ability to degrade lignin, high holocellulose content, low content of 1% NaOH, and ethanol-benzene extractives. PDF
Cationic dry strength agents (DSAs) are commonly used for paper strengthening. However, before they are applied, another chemical called an anionic trash catcher (ATC) is often used to pretreat pulp to neutralize the negative dissolved and colloidal substances (DCS), increasing the effectiveness of the subsequently added cationic DSA. However, in many cases, the negativity of the fibers is also neutralized by the ATC. Under such circumstances, it remains unclear to what degree the effectiveness of the DSA will be affected. In this paper, a deinked pulp was first pre-treated with a polyamine ATC; then, the effectiveness of two subsequently-added DSAs, anionic polyacrylamide (APAM) and cationic polyacrylamide (CPAM), were compared. Results showed that when the ATC was used alone, it deteriorated paper formation, resulting in a decrease of paper strength. When the DSAs were used alone, the CPAM was effective but the APAM was not. However, when the ATC was used to pretreat the pulp, the effectiveness of the CPAM clearly decreased, while that of the APAM clearly increased. The reason for this could be that the adsorption of APAM onto fibers was promoted by the pretreatment of ATC, possibly through the formation of an ATC and APAM polyelectrolyte complex. PDF
The wet strength of handsheets subjected to dipping treatment by solutions such as glyoxal with Zn(NO3)2 as a catalyst, chitosan, and the crosslinking system of glyoxal and chitosan is studied in this paper. The crosslinking system achieved better wet strength performance than glyoxal or chitosan alone and slightly better than the sum of glyoxal and chitosan in the case of a curing temperature between 90 and 130 oC. However, handsheets treated by this crosslinking system became more brittle, which was shown by the reduction of folding endurance of the handsheets with increasing wet strength. The capillary rise and contact angle of the treated handsheets showed certain relations to their wet strength when the above solutions were used to improve the wet strength of the handsheets. The physical changes of the treated handsheets can provide evidence to explain the mechanism of wet strength development. PDF
A simple electroless Ni-Cu-P plating process for preparing an EMI-shielding and corrosion-resistant wood-based composite has been developed. The effects of solution pH value on the metal deposition, surface resistivity, chemical composition, anti-corrosion properties, and crystal structure of the coatings were studied. The coatings were characterized using X-ray photoelectron spectroscopy, X-ray diffraction, and scanning electron microscopy. When the solution pH was increased from 8.5 to 10.0, the metal deposition increased and the surface resistivity decreased. Chemical composition indicated that the nickel deposition increased, whereas the opposite effect was obtained on copper and phosphorus elements with a pH increase from 9.0 to 10.0, and the crystal structure of the Ni-Cu-P coatings changed from an amorphous state to a microcrystalline one. Tafel curves of the Ni-Cu-P coatings prepared at pH 9.0 or 9.5 showed that they had excellent anti-corrosion properties in a 3.5 wt% NaCl solution. The morphology of the coating containing 69.86% Ni - 7.65% Cu - 22.49% P is superior to that with 75.99% Ni - 6.60% Cu - 17.41% P after corrosion tests. The plated birch veneers exhibited electromagnetic shielding effectiveness higher than 58 dB in frequencies ranging from 9 KHz to 1.5 GHz, and the coating firmly adhered to the wood surface. PDF
A novel cationic amphiphilic lignin derivative with high surface activity was prepared from kraft lignin via the introduction of dehydroabietyl groups as lipophilic groups and diethylenetriamine groups as hydrophilic groups by the Mannich and ketone-amine condensation reactions. Solubility, surface tension, hydrophilic-lipophilic balance (HLB) values, foamability, and zeta potential were used to evaluate the basic physico-chemical properties of the cationic amphiphilic lignin derivative. The experiments show that the solubility of the cationic amphiphilic lignin derivative is 2.10 wt%, the critical micelle concentration is 5.0 g·L-1, the surface tension is 29.85 mN·m-1 at a concentration of 5.0 g·L-1, the HLB value is 12, and the foam volume is 11.1 mL initially and 8.0 mL after standing for 5 min in an aqueous solution at pH 2.0. PDF
Gironès, J., Espinach, F. X., Pellicer, N., Tresserras, J., Alcalà, M., and Mutjé, P. (2013). "High-performance-tensile-strength alpha-grass reinforced starch-based fully biodegradable composites," BioRes. 8(4), 6121-6135.
Though there has been a great deal of work concerning the development of natural fibers in reinforced starch-based composites, there is still more to be done. In general, cellulose fibers have lower strength than glass fibers; however, their specific strength is not far from that of fiberglass. In this work, alpha-fibers were obtained from alpha-grass through a mild cooking process. The fibers were used to reinforce a starch-based biopolymer. Composites including 5 to 35% (w/w) alpha-grass fibers in their formulation were prepared, tested, and subsequently compared with those of wood- and fiberglass-reinforced polypropylene (PP). The term “high-performance” refers to the tensile strength of the studied composites and is mainly due to a good interphase, a good dispersion of the fibers inside the matrix, and a good aspect ratio. The tensile strength of the composites showed a linear evolution for fiber contents up to 35% (w/w). The strain at break of the composites decreased with the fiber content and showed the stiffening effects of the reinforcement. The prepared composites showed high mechanical properties, even approaching those of glass fiber reinforced composites. PDF
Abdul Rahman, N. H., Abdul Rahman, N. A., Abd Aziz, S., and Hassan, M. A. (2013). "Production of ligninolytic enzymes by newly isolated bacteria from palm oil plantation soils," BioRes. 8(4), 6136-6150.
Three aerobic lignin-degrading bacterial strains were isolated from palm oil plantation soils. The bacterial isolates were screened using a selective nutrient medium of minimum salt media (MSM), with kraft lignin as lignin substrate and methylene blue as the ligninolytic dye indicator. The newly isolated bacterial strains SHC1, SHC2, and SHC3 were found to have the potential to tolerate high concentrations of kraft lignin and produced all three main ligninolytic enzymes (lignin peroxidase, manganese peroxidase, and laccase); these strains may therefore be useful in the degradation of lignin in oil palm empty fruit bunch biomass. The production of ligninolytic enzymes was carried out by means of submerged fermentation for 7 days using 2 mm of oil palm empty fruit bunch (OPEFB) fiber as a substrate. These bacterial isolates were characterized using biochemical tests from Biolog and identified using 16S rRNA gene sequencing analysis, which identified the strains SHC1, SHC2, and SHC3 as Bacillus sp., Ochrobactrum sp., and Leucobacter sp., respectively with 99% sequence similarity. Bacillus sp. SHC1 produced the highest manganese peroxidase (MnP) of 2313.4 U/L on the third day and the highest lignin peroxidase (LiP) of 209.30 U/L on the fifth day of fermentation. The optimum pH and temperature for the production of ligninolytic enzymes by Bacillus sp. SHC1 were pH 8 and 30 °C. PDF
In this study, oil palm empty fruit bunch (OPEFB) was treated with sodium hydroxide at room temperature and produced pulps with acceptable quality suitable for the making of commercial serviettes. The cold soda pulping of OPEFB was performed using various NaOH concentrations (1, 3, 5, 7, and 10%) for 24 hours using a liquor/OPEFB ratio of 8/1. The treated pulps were refined in 4 stages under atmospheric conditions by means of a Sprout Bauer disk refiner. The refined pulps were then screened and evaluated for their physical characteristics. The main pulp properties obtained were related to the caustic concentrations; higher caustic concentrations gave better properties. The measured pulp characteristics were: freeness 550-750 mL, sheet density 0.18-0.34 g/cm3, tear index 4.2-5.8 mN*m2/g, tensile index 3-20 N*m/g, and burst index 1.3-2.5 kPa*m2/g. In most cases the refining had little impact on pulp properties. The resulting cold soda OPEFB pulp treated with 3% caustic charge or higher showed good quality for serviette making. PDF
A simple, green method was developed for the synthesis of silver nanoparticles (AgNPs) by using Dialdehyde Chitosan (D-CTS) as the reducing and stabilizing agent. D-CTS was prepared from the oxidation of chitosan by sodium periodate, and its degree of oxidation was determined by 1H-NMR and elemental analysis. The synthesized AgNPs were characterized by UV-Vis spectroscopy, dynamic light scattering (DLS), Fourier-transform infrared spectroscopy (FT-IR), X-ray diffraction (XRD), and scanning electron microscopy (SEM). The morphology and size distribution of the AgNPs were found to vary with the dialdehyde content of D-CTS and the pH value of the reaction solution. FT-IR spectra revealed that the aldehyde groups and the amino groups were the major agents that stabilized the AgNPs. XRD results indicated the presence of nano-silver having a face-centered cubic structure. SEM results showed that nano-silver particles of 30 to 40 nm in size were homogeneously dispersed in the solution. The possible mechanism of D-CTS on the reduction and stabilization of AgNPs may be due to the formation of four-coordinate complexes. The synthesized AgNPs remained stable for more than three months. PDF
Preprocessing of biomass at or near the growing site has considerable advantages over transporting to distant fermentation refineries equipped to process cellulosic material. The alkali-cellulase (Alkcell) process converts biomass to glucose using materials and methods that can be implemented at or near a growing site. This study has shown that the Alkcell process can be configured to run continuously. The use of carriers to contain the biomass allows continuous movement along a treatment train starting with alkali pretreatment and ending with glucose release. Conditions for pretreatment with NaOH, washing, and pH adjustment have been determined. Immersion of the carriers in a cellulase bath at optimal temperature and duration follows. The carriers are then submerged in a large volume of buffer at pH and temperature that allows release of glucose. Finally, the residual solids are returned to the start of the process to be mixed with fresh biomass and the treatment cycle is repeated. The glucose solution can be concentrated locally to reduce volume and enhance transportation savings. The local operation can be done at farms or near regional centers prior to being transported to distant existing conventional fermentation facilities. PDF
Wang, X., Li, D., Li, W., Peng, J., Xia, H., Zhang, L., Guo, S., and Chen, G. (2013). "Optimization of mesoporous activated carbon from coconut shells by chemical activation with phosphoric acid," BioRes. 8(4), 6184-6195.
Mesoporous activated carbons were prepared from coconut shells by the method of chemical activation with H3PO4. Effects of main influence factors on the yield and adsorption properties of activated carbon were studied via orthogonal experiments. Experimental results under the optimum conditions were as follows: the yield of the activated carbon was 36.90%; methylene blue adsorption was 21.5 mL/0.1 g; and the iodine number was 889.36 mg/g. The surface area of the activated carbon prepared was 891 m2/g, as determined by the BET method. Horvath-Kawazoe equations (H-K) and density functional theory (DFT) were introduced to analyze the porous structures of the activated carbon. It was shown that the activated carbon was mesoporous, with a total pore volume of 0.7233 mL/g, a micropore volume of 37.06%, a mesopore volume of 62.85%, and a macropore volume of 0.07%. Scanning electron microscopy (SEM) and transmission electron microscopy (TEM) studies demonstrated the results of the pore structure analysis. PDF
Pyrolysis-gas chromatography/mass spectrometry (Py-GC/MS) was employed to investigate the primary pyrolysis product distribution of the pyrolysis of wood-plastic composites (WPCs) and the mutual effects of poplar wood (PW) and high-density polyethylene (HDPE). The PW, HDPE, and WPCs were pyrolysed at 475, 550, and 625 °C. The effect of temperature on the WPC pyrolysis products was examined. The comparison of the degradation composition results for HDPE, PW, and WPCs indicated that thermal degradation of WPCs comprised individual poplar wood and HDPE pyrolytic decompositions, and the pyrolytic products of PW and HDPE did not react with each other. The experimental results demonstrate that the pyrolytic product distribution of HDPE changed apparently in the presence of PW during pyrolysis. The PW decomposed at lower temperature during pyrolysis provided radicals, enhancing the scission of polymer chains to obtain more light paraffins. Further, the proposed pathway for the evolution of the main volatile organic products was probed. This study provides insights into the fundamental mechanisms of WPC pyrolysis and a basis for developing more descriptive models of WPC pyrolysis. PDF
This study investigated the effects of various solvents on cypress liquefaction in the range of 180 to 300 °C. The solid residues and bio-oils obtained from cypress liquefaction were characterized to investigate the mechanism of the liquefaction process. Results obtained using FT-IR, sugar analysis, and elemental analysis showed that the solvent could affect both the formation of various compounds in the bio-oil and the product distribution during the cypress liquefaction process. Considering the bio-oil yield, the solvent efficiency in cypress liquefaction was as follows: water > methanol > ethanol. The decomposition velocities of cellulose, hemicelluloses, and lignin were different in the solvents, and hemicellulose decomposition preceded cellulose and lignin in all solvents. Water had the most pronounced effect on the higher heating value (HHV) of residues among the three tested solvents; the highest HHV was 26.3 MJ/Kg. This study suggests that characterization of products provides a promising approach for investigating the mechanism of solvent effects on biomass liquefaction. PDF
The present paper aims to determine values of the modulus of elasticity (MOE) and modulus of rupture (MOR) of particleboards made from specially prepared particles from willow (Salix viminalis L.) and black locust (Robinia pseudoacacia L.) to enable formulation of an orthotropic material model for use in computer numerical simulations (FEM; finite element method). The mean densities of the panels were 600 and 660 kg·m-3 for the willow and black locust, respectively. The MOE was used to test entire particleboards as well as their individual layers. The willow and black locust particleboards were compared with commercially available particleboards that met the requirements of the EN 312 standard. The modulus of rupture (MOR) of the particleboards was also determined according to the requirements of the EN 312 standard. The commercial particleboards showed the effects of different manufacturing directions, which resulted in changes in properties. No influence from manufacturing direction was found for the laboratory-made experimental panels. The impact of the thickness of the face layer of the specimens on MOE was also investigated. These tests indicated that the 2.1-mm sample showed no detectable distortive impact from the core layer. The tests confirmed the impact of manufacturing direction on the MOE of the commercial panels, which moreover was higher for the face layer. The highest MOE was found for the commercial panels, although the experimental panels met the requirements of the EN 312 standard, excluding the black locust at a mean density of 600 kg·m-3. PDF
Aluminum oxide nanoparticles were used as nanofillers in urea-formaldehyde (UF) resin and prepared for medium density fiberboards (MDF). The nanofillers composed weight percentage of the UF resin. The thermal and viscoelastic properties were studied using differential scanning calorimetry and dynamic mechanical analysis. The DH value of the UF resin showed an increase with increasing nanoparticle concentration. The core temperature during hot pressing increased with the addition of nanofillers. The formaldehyde emissions from MDF decreased with an increase in the concentration of nanofillers. The internal bonding strength and the modulus of rupture of boards were improved significantly after nanoparticle loading. PDF
Effects of UV-light irradiation and water spray on the mechanical strength and surface characteristics of untreated and pretreated Scots pine sapwood samples were studied. The specimens were treated with parsley seed oil, pomegranate seed oil, linseed seed oil, nigella seed oil, canola oil, sesame seed oil, and soybean oil. The compositional changes and surface properties of the weathered samples were characterized by Fourier transform infrared (FTIR-ATR) spectroscopy and color and surface roughness measurements. The results showed that all vegetable oils provided lower color changes than the control group after 600 h of exposure in a weathering test cycle. The least color change was found on the Scots pine surface pretreated with pomegranate seed oil. The vegetable oil treatment retarded the surface lignin degradation during weathering, indicating that the surface roughness values of pine wood treated with vegetable oils decreased with irradiation over time compared with those of control samples. The effect of artificial weathering on mechanical strength was determined with a compression strength test. It was observed that the compression strength values of Scots pine samples treated with vegetable oils was higher than that of untreated samples after 600 h of weathering exposure. PDF
Zhou, X., Yu, Y., Lin, Q., and Chen, L. (2013). "Effects of maleic anhydride-grafted polypropylene (MAPP) on the physico-mechanical properties and rheological behavior of bamboo powder-polypropylene foamed composites," BioRes. 8(4), 6263-6279.
To improve the interfacial compatibility between bamboo powder and polypropylene (PP), the effects of maleic anhydride-grafted polypropylene (MAPP) on the physico-mechanical properties and rheological behavior of 33 wt% bamboo powder/PP foamed composites were investigated. The results showed that the mechanical properties, water resistance, and surface wettability of MAPP-treated composites improved significantly, and the optimum content of MAPP was 9%. The density of 9% MAPP-treated composite was 0.845 g/cm3 and its specific bending and tensile and notched impact strengths increased by 22.9%, 29.6%, and 49.0%, respectively, and the water absorption decreased from 8.80% to 1.92%, compared to the untreated composite. The frequency sweep results indicated that both the modulus and complex viscosity of the 9% MAPP-treated composite reached minimum values, and the slope of the lgG'-lgf curve for the treated composite increased by 15.9% compared with that of the untreated analogue. ESEM results indicated that the MAPP-treated composite had better bamboo powder dispersion and better interfacial compatibility. FTIR and XPS analyses confirmed the esterification between anhydride groups of MAPP and hydroxyl groups of bamboo powder. XRD studies showed the degree of crystallinity for the MAPP-treated composite increased to 26.52%, compared to 21.05% for the untreated composite. PDF
The objective of this study was to quantify the influence of zinc oxide nanoparticles (nano-ZnO) on the water repellency and dimensional stability of beech wood. Beech wood blocks were treated with a nano-ZnO solution at four treatment levels (0, 10,000, 20,000, and 40,000 ppm) using a modified dip method. Also, a thermal treatment was performed at 60 and 120 °C. After conditioning the samples, water absorption, volumetric swelling, water repellency effectiveness, and anti-shrink/anti-swell efficiency were determined within 24 h of soaking time. The results indicated that the nano-ZnO used for wood modification greatly improved dimensional stability and reduced the hygroscopicity of the wood. In addition, the Fourier-transform infrared spectroscopy (FTIR) analysis suggested a strong interaction between the nano-ZnO and the chemical components of wood. The heat treatment effectively improved the effects of nano-ZnO. PDF
Thermal properties of wood and modified wood-based materials are important parameters that influence the manufacturing process and final industrial utilization. The aim of this work was to investigate three main thermal properties (thermal conductivity, thermal diffusivity, and specific heat capacity) of ammonia-treated compressed beech wood (Lignamon material) and natural beech wood (Fagus sylvatica).These properties were measured based on the quasi-stationary method developed at the Department of Wood Science at the Technical University in Zvolen. The influence of increased density (caused by ammonium treatment and compression) of four different types of Lignamon material on the thermal properties was discovered, and the results were compared with those from untreated beech wood. The results confirmed a dependency on the density of the material. With increasing Lignamon compression extent (increasing density value), the thermal conductivity increased and the thermal diffusivity decreased. The maximum value of thermal conductivity reached (0.26 W.m-1.K-1 at 1070 kg.m-3) in the case of Lignamon 6k and (0.26 W.m-1.K-1 at 950 kg.m-3) in the case of Lignamon 7n. PDF
This paper reports on the total deformation and loading force after plasticizing beech wood by microwave heating. There have been few studies devoted to the examination of microwave heating for plasticizing of beech wood. Therefore, a procedure was developed to verify the use of microwave heating for the purpose of plasticizing. Total deformation and loading force were investigated on beech samples immediately after plasticizing by microwave heating. The samples were loaded with pressure applied parallel to the grain. Measured results served the purpose of quantifying total deformation. The investigated factors (wood moisture and plasticizing time) had significant influences on the loading force and total deformation of beech wood plasticized by microwave heating. Increasing initial wood moisture increased total deformation. Increasing plasticizing time decreased the total deformation of wood because of a larger loss of wood moisture. Loading force had contrary behavior: increasing wood moisture decreased the loading force, and increasing plasticizing time increased the loading force. PDF
High-yield pulps (HYP, including BCTMP and APMP) have been increasingly used in various paper grades due to their unique properties. However, higher bulk at a fixed tensile strength is desirable for most HYP applications. This study explored the possibility of changing the bulk-tensile relationship of an aspen PRC-APMP pulp by adding fines from a well-refined HYP into a high freeness HYP (backbone pulp). The effect of backbone pulp freeness on the property-freeness relationship of the fines-reinforced pulps was also examined. The results indicate that to reach a target freeness, adding fines from a well-refined pulp (refined by a PFI mill at 20,000 revolutions) to a high-freeness pulp can help achieve a higher bulk and light scattering while maintaining a similar tensile strength, which is desirable in most of the HYP applications. To reach the same tensile index at a range of 20 to 24 Nm/g, the bulk of APMP550-fines (produced by fines and a pulp at 550 mL freeness) was 12 to 17% higher than that of the control pulp. The higher the freeness of the backbone pulp, the higher was the bulk and light scattering coefficient of fines-reinforced pulp when the fines-reinforced pulps were compared at the same freeness. PDF
Liu, Q., Huo, X., Yan, X., and Lucia, L. A. (2013). "Physical and chemical properties of effluent from the pre-conditioning refiner chemical alkaline peroxide mechanical pulp (P-RC APMP) process," BioRes. 8(4), 6323-6329.
The properties of P-RC APMP effluent, including relative density, Baume degree, viscosity, surface tension, specific heat capacity, boiling point rise (BPR), and elemental contents of the effluent, were studied. Results indicated that relative density, viscosity, Baume degree, and solids content all displayed a direct proportional correlation; however, there was an inverse linear relationship between Baume degree and temperature. Viscosity rose sharply when the solids content was more than 40%. Surface tension gradually decreased with the rise of solids content. However, when the solids content was over 35%, it increased with an increase in solids content. Specific heat capacity was closely related to the solids content, but it was reduced with an increase in solids content. BPR was proportional to effluent solids content, especially when the solids content exceeded 30% with an uptrend in BPR. PDF
Surface acetylated nanocrystalline cellulose (NCC) was prepared from cotton fiber by a single-step method under mild conditions using anhydrous phosphoric acid as the solvent. The absorbance peak of O-H was reduced, and the absorbance peaks of C=O and CH3 appeared in the Fourier transform infrared (FTIR) spectrum of the acetylated NCC with respect to that of the unmodified NCC. The roughly estimated degree of substitution was a little greater than 1.5 by FTIR analyses, implying that most of the free hydroxyl groups on the NCC surface were acetylated at 40 °C for 3 h. The carbons of the acetyl groups were clearly identified in the 13C cross polarization-magic angle spinning (CP-MAS) nuclear magnetic resonance (NMR) spectrum. The zeta potential was reduced from -32.12 mV to -20.57 mV after acetylation. Transmission electron microscope (TEM) and field-emission scanning electron microscope (FESEM) images showed that they were thread-like nano-crystals with a diameter less than 5 nm. Crystal structure analysis using X-ray diffraction (XRD) demonstrated that the acetylated NCC had the typical CelluloseⅡstructure. The PLA film reinforced with 3 wt% acetylated NCC content exhibited the highest tensile strength, which was increased by 117% compared to the control. SEM observation demonstrated good interfacial interaction between the acetylated NCC and the matrix. PDF
Vaithanomsat, P., Sangnam, A., Boonpratuang, T., Choeyklin, R., Promkiam-on, P., Chuntranuluck, S., and Kreetachat, T. (2013). "Wood degradation and optimized laccase production by resupinate white-rot fungi in northern Thailand," BioRes. 8(4), 6342-6360.
One hundred and thirty samples of resupinate white-rot fungi were collected from natural sites in Northern Thailand during the dry season (October-December) as a bioresource for lignin-degrading enzymes (laccase (Lac), lignin peroxidase (LiP), and manganese peroxidase (MnP)). All 130 isolated fungal strains grew well in potato dextrose broth and produced lignin-degrading enzymes at different levels after 7 days of incubation. The selected resupinate fungi, RCK783S, produced maximum Lac at 4,218 U/L, whereas MnP and LiP activities were detected at relatively low levels in all selected fungal strains. The RCK783S was further identified as a new record of Fibrodontia sp. in Thailand. Response surface methodology (RSM) was applied to evaluate the effect of medium composition, i.e., peptone, glycerol, L-asparagine, and CuSO4, on Lac production by Fibrodontia sp. RCK783S. The experiments showed optimum concentrations of peptone, glycerol, L-asparagine, and CuSO4 at 0.625, 15.00, 2.188, and 0.003 g/L, respectively, to produce the highest Lac concentration of 6,086.01 U/L, a 1.44-fold increase from that in the original medium. In addition, the degradation of Eucalyptus camaldulensis was investigated during the solid-state cultivation of Fibrodontia sp. RCK783S. The results showed that lignin was degraded, with lignin loss being 18% after 30 days, coinciding with the highest released Lac activity. PDF
Two particulate amphoteric larch tannin (CLT) products (CTD and CTB) were prepared by cross-linking reactions, and their acid dyes removal abilities were investigated. The effects of several parameters such as pH, contact time, and particle doses were tested, and the acid dyes removal behaviors of both types of particles were compared. The removal of azo acid dyes on CTD and CTB was pH-dependent, and the maximum removal of ≥90.7% was reached for Acid Black 10 B and 52.6% for Acid Red 14 in aqueous solution at pH 5.0. The effect of particle dosages on the removal of Acid Black 10 B and Acid Red 14 was important for two modified CLT particles. An excessive amount of modified CLT particles increased the chromaticity of water samples and caused the decline of dyes removal. Zeta (ζ) potential data revealed that the main mechanism of removal of the acid dyes on the CTD and CTB particles was charge neutralization. PDF
Chemical modification of natural fibres has been carried out using different methods for such purposes as reinforcement in polymer matrices and heavy metals adsorption. In this work, palm fibres were modified by zirconium oxychloride in situ. The palm fibres that had been chemically modified were compared to those in nature using fibres that passed through 20 and 40 mesh screens to evaluate the influence of particle size on modification. Palm fibres were modified with ZrO2.nH2O nanoparticles through the use of zirconium oxychloride in an acidic medium in the presence of palm fibres using ammonium solution (1:3) as the precipitating agent. Scanning electron microscopy (SEM), X-ray diffraction (XRD), infrared spectrophotometry (FTIR), and atomic emission spectrometry with inductively coupled plasma (ICP-AES) were used to characterize the hybrid materials. Results indicated that the particle size of the palm fibres influenced in the modification, because the fibres with smaller particle size had a greater deposition of inorganic material. The ICP technique revealed an increase of 21% nanoparticles ZrO2.nH2O deposited on fibres (40 mesh) when compared to fibres (20 mesh). The diameter of nanoparticles ZrO2.nH2O deposited on fibres was about 50 to 220 nm, as observed by SEM. PDF
This work investigated the ability of biopretreatment with different white-rot fungi to improve the medium-temperature pyrolysis of biomass. It was found that biopretreatment can significantly increase the production of phenols and glucopyranoside up to 2.82 and 2.94 fold, respectively. Biopretreatment can also decrease the content of carbon dioxide, propanol, and propanone, making the pyrolysis more efficient and product-oriented. Moreover, distinct bio-deconstruction mechanisms can result in different pyrolysis products. By deconstructing cellulose and modifying lignin with a minimum of demethoxyation, white-rot fungus Irpex lacteus CD2 can improve the production of acetaldehyde (up to 6.72%) and methoxyl substitutes such as dimethoxyphenyl (up to 21.59 folds). By decomposing carbohydrates, carbonxyl, and methoxyl groups, white-rot fungi Pleurotus ostreatus BP2 and Echinodontium taxodii 2538 can increase the production of D-allose (up to 3.09%) and formic acid (up to 6.98%), while decreasing the methoxyl substitutes such as 2-methoxy-4-vinylphenol (up to 70.08%). PDF
Cao, S., Ma, X., Luo, X., Huang, F., Huang, L., and Chen, L. (2013). "Experimental determination and empirical modeling of oxalate formation during oxygen delignification of wheat straw kraft pulp," BioRes. 8(4), 6395-6408.
The formation of oxalate during oxygen delignification causes a number of operational problems in pulp and paper mills. In this work, the oxygen delignification of wheat straw pulp was carried out under various conditions and the concentration of resulting oxalate in the effluent was determined. The experimental results show that the amount of oxalate in the effluent was closely related to the reaction conditions, specifically reaction temperature, oxygen pressure, and alkali charge. Raising reaction temperature and/or oxygen pressure could promoted oxalate formation. The oxalate concentration increased linearly with the consumption of alkali but logarithmically with reduction of kappa number. An empirical model for describing the oxalate formation in the oxygen delignification of wheat straw pulp was generated with a reasonably high correlation coefficient (R2=0.909), which can provide useful guidance for control of oxalate formation during oxygen delignification through adjustment of process parameters. PDF
Talc was incorporated as filler alongside rattan powder in polypropylene (PP) matrix to produce a hybrid composite. 20 phr of rattan powder was used for all samples. Talc filler loadings were varied from 0 to 10 phr. The composite was manufactured using a Polydrive Thermo Haake internal mixer, which provided processing characteristics for the composite. Peak and stabilization torques gradually increased with increasing talc filler loading. Tensile properties of the hybrid composites showed an increase in tensile modulus and a decline in elongation at break with increasing talc loading. The tensile strength was enhanced with the addition of talc up to a loading of 4 phr and then decreased with further talc filler loading. A water absorption test was carried out, whereby the water uptake of the hybrid composites was reduced with higher talc filler loading. Thermal degradation of the composites was analyzed by studying thermogravimetric analysis (TGA) thermograms and derivative thermogravimetry (DTG) curves, which showed improvement in the thermal stability of the composite with higher talc content. The morphological studies carried out on tensile-fractured surfaces of the hybrid composites explained the enhancement and deterioration of tensile properties with regard to different filler loadings. PDF
In this work, a xylanase-producing strain, Streptomyces griseorubens LH-3, was cultured, and the crude xylanase was prepared. Analysis of its enzymatic properties revealed that the crude xylanase possessed good thermal stability at temperatures below 60 °C, exhibited a wide pH range from 4.0 to 9.0, and was cellulase-free. This crude enzyme was used to treat eucalyptus kraft pulp, and the release of chromophores was the highest at the dosage of 20 IU g-1 dry pulp. Compared with the untreated group, biobleaching of eucalyptus kraft pulp with this enzyme increased the brightness of the pulp by 12.9% and reduced the Kappa number by 27.4%. Biobleaching of eucalyptus kraft pulp with this enzyme obtained the same final pulp brightness compared with that of the control; however, hydrogen peroxide consumption was reduced by 17% and the yield and viscosity of the pulp was increased by 1.47% and 1.53%, respectively. This crude xylanase has promising potential for industrial applications. PDF
Yu, X., and Gu, Z. (2013). "Optimization of nutrition constituents for feruloyl oligosaccharides production by a new isolate of Aureobasidium pullulans 2012 under fermentation on wheat bran," BioRes. 8(4), 6434-6447.
One-step fermentation of wheat bran (WB) by Aureobasidium pullulans 2012 to produce ferulic oligosaccharides (FOs) was developed. As the WB concentration was increased, the xylanase activity and yield of FOs increased; the optimum concentration of WB was 50 to 60 g/L, which enhanced xylanase synthesis and the preparation of FOs. A moderate amount of xylan and peptone promoted xylanase synthesis and FO production. The addition of metal ions and surface active agents suppressed the yield of FOs. The optimum medium composition for FO preparation was 10 g/L xylan and 1 g/L peptone added to 60 g/L WB solution. Under these conditions, an FO yield of 774 nmol/L was achieved. According to observations by scanning electron microscopy, the internal structure of WB was obviously disrupted after fermentation. This process featured one-step fermentation of WB without further hydrolyzing, which greatly decreased the raw material cost and thus facilitated its practical application. PDF
The purpose of this study was to determine the dimensional stability of oriented strand boards (OSBs) with the core layer made of fine wood chips when the boards were exposed to air of variable relative humidity (30%, 65%, and 85%). The share of fine wood chips, intended for the particleboard core layer or originating from comminution of unrefined particleboards, accounted for 50% or 100% of the core layer mass. This study revealed much greater changes in the length of the board's shorter axis, regardless of the type of fine wood chips in the core layer. These changes increased with an increasing share of this type of chips in the core layer. More pronounced changes in thickness were observed for particleboards containing 50% of the fine chips. The research also showed that the relative changes in linear dimensions were slightly smaller in OSBs containing 50% of wood chips from the comminution of unrefined particleboards than in the boards with a core layer made from wood chips designed for this purpose. PDF
Mercerized fibers were prepared from native cotton fabrics via NaOH solution treatment at different concentrations. Mercerization led to transformation of the crystal structure of cotton fibers from cellulose I to II when the NaOH concentration was greater than 10 wt%. In addition, the cotton fibers were converted into a swollen and rough state after mercerization treatment. The results of Fourier transform infrared spectrometry and wide-angle X-ray diffraction indicated that the cellulose molecular structure changed (e.g. the degree of disorder of O-H stretching vibration increased, while the crystallinity index decreased) in the process of mercerization. Thermogravimetric analysis determined that the cellulose II fibers were more thermally stable than the cellulose I fibers. The mechanical properties of cellulose fiber-reinforced polyethylene oxide (PEO) composites showed that both original and mercerized cotton fibers enhanced the tensile strength of the PEO matrix. These properties directly contributed to the advantages of mercerized textile products (e.g. higher luster, holds more dye, more effectively absorbs perspiration, and tougher under different washing conditions). PDF
This study investigated optical and strength properties of light-weight coated (LWC) printing paper. Two different pigments, namely nanoclay and precipitated calcium carbonate (PCC) with rhombohedral particle shape, were used with acrylic styrene latex to coat base paper using a blade method. Strength properties such as: tensile, burst, and tear indices, stiffness and optical properties including brightness, yellowness, and opacity were measured. Surface topography was studied using atomic force microscopy (AFM). Comparison between the coated paper and the control sample demonstrated that surface of the paper coated with nanoclay was more uniform than the paper coated with PCC. Although there were no significant differences in terms of the strength of these paper samples, burst and tear strength were enhanced by up to 10 and 16% in some or all treatments, respectively. There was a slight increase in paper opacity with PCC because it has a narrower particle size distribution in comparison with that of nanoclay. Yellowness of the papers treated with nanoclay was degraded about 20% as compared to the control sample, while some small differences were also noticed in brightness and opacity of the papers. PDF
Bark is one of the most under-utilized types of lignocellulosic biomass in the forest industry. In this study, bark fast pyrolysis was optimized for phenols yield using response surface methodology (RSM), considering the pyrolysis temperature, gas flow rate, and biomass particle size. The bio-oil generated under optimal conditions was then characterized by gas chromatography-mass spectrometry (GC-MS), ultimate analysis, and several physical methods. A regression equation was estimated based on the statistical analysis. It was found that the optimal conditions for phenols yield were 485 °C (pyrolysis reaction temperature), 28 L/min (gas flow rate), and 0.35 mm (biomass particle size), giving an experimental phenols yield of 13.2 wt%. The bio-oil obtained in optimum conditions met ASTM standard D7544-12 and contained up to 30.42% phenols. This renewable, phenol-rich bio-oil may be a good feedstock for phenolic-based chemicals, such as phenolic resin and phenoplast. PDF
Effects of heat treatment on some physical properties of poplar and plane wood specimens were investigated. The main aim was to compare effects of heat on some physical properties of low-density poplar wood and high-density oriental plane wood. Heat treatment was conducted at temperatures of 150 and 200 °C for 3 h in the presence of air at atmospheric pressure. After the heat treatment, the mass loss; oven-dried density; tangential, radial, and volumetric swelling; fiber saturation point; and moisture content were determined. Regression analyses between mass loss and volumetric swelling were performed. The findings were analyzed statistically with ANOVA and the T-test. The results showed that heat treatment at 200 °C influenced the physical properties of both poplar wood and plane tree wood. In addition, the heat treatment had a little greater effect on the swelling and fiber saturation point of poplar wood than it did on the properties of plane wood. PDF
This study investigates the relative ability of natural bamboo fiber used in textile manufacturing to resist attack by bacteria and fungi. These tendencies were determined with the dynamic test method for evaluating antibacterial activity and were compared with the bacterial and fungal resistance of other textile fibers, such as cotton, jute, flax, ramie, and regenerated bamboo fiber. The bacteria studied were Escherichia coli (8099) and Staphylococcus aureus (ATCC 6538), and the fungal species was Candida albicans (ATCC 10231). The relationships between the bacteriostatic ability of natural bamboo fiber and its physical state, hygroscopicity, and extractives were tested to explore the possible influencing factors. The results show that natural bamboo fiber has no natural antibacterial properties, as compared with natural cotton bacteriostatic rates against the bacteria were all zero. The physical state did not impact the natural resistance of natural bamboo fiber to the bacteria and the fungus. The resistance of the plant fiber may be related to its hygroscopicity, and some extraction methods could improve the ability of natural bamboo to resist microorganisms. PDF
A novel superabsorbent was prepared by utilizing carboxymethyl starch and carboxymethyl cellulose biocomposites as a grafting backbone. The scheme of the CMS-CMC double backbone structure was speculated. It was proposed that the superabsorbent possesses a three-dimensional network with an interpenetrating structure. The response surface methodology was used to optimize the parameters. Interactions among the most influential variables, i.e., the dosage of CMC, the acrylic acid to acrylamide mass ratio, and the neutralization degree of acrylic acid were estimated. A mathematical model was developed, which fit the experimental results well for all of the response variables. The optimal conditions included 28.8 % of CMC dosage, a 1.6 mass ratio of acrylic acid to acrylamide, and 73.4 % of neutralization degree of acrylic acid to achieve 815.2 g/g of water absorbency. PDF
Chowdhury, Z. Z., Abd Hamid, S. B., Das, R., Hasan, M. R., Zain, S. M., Khalid, K., and Uddin, M. N. (2013). "Preparation of carbonaceous adsorbents from lignocellulosic biomass and their use in removal of contaminants from aqueous solution," BioRes. 8(4), 6523-6555.
The feasibility of using lignocellulosic biomass as a source for preparing carbon adsorbents has received rigorous attention over the last few decades. Many studies have discussed its great potential as a renewable feedstock for preparation of carbonaceous adsorbent materials. This review paper provides an overview of the different types of carbonization techniques that so far have been applied to convert lignocellulosic biomass to carbon adsorbents. The effects of various process parameters on the conventional pyrolysis process are reviewed. The paper focuses on the mechanism for the formation of carbons, its wide variety of applications for waste effluents, and the regeneration techniques so far adopted by researchers. Low-cost carbons derived from lignocellulosic biomass have demonstrated excellent capabilities for the removal of organic and inorganic contaminants, including some pharmaceutical compounds, from the waste aqueous stream. PDF
Cellulose and some cellulose derivatives can play vital roles in the enhancement of the performance of absorbent products. Cellulose itself, in the form of cellulosic fibers or nano-fibers, can provide structure, bulk, water-holding capacity, and channeling of fluids over a wide dimensional range. Likewise, cellulose derivatives such as carboxymethylcellulose (CMC) have been widely studied as components in superabsorbent polymer (SAP) formulations. The present review focuses on strategies and mechanisms in which inclusion of cellulose – in its various forms – can enhance either the capacity or the rate of aqueous fluid absorption in various potential applications. PDF
This review article presents a state-of-the-art survey on timber-concrete composite (TCC) bridges. It starts with a presentation of a sample of relevant TCC bridges, offering a global perspective on the use of this type of bridge. The number of TCC bridges has clearly increased in the past few years, and some of the reasons for this trend are explored. Next, an extensive literature review is presented regarding the most significant technological innovations and recent developments in the application of TCC structures to bridge construction. Firstly, the engineering specificities and the advantages of TCC bridge structural systems are enumerated. Afterwards, the importance of proper mechanical connection for optimal performance of TCC structures is explained, and a thorough description of the connection systems suitable for bridge construction is provided. Some research into the structural behavior of TCC bridges under service conditions is then presented and discussed. Finally, possible areas of future research regarding the development of TCC bridges are suggested. PDF