NC State
  • Editorialpp 2288-2290Wang, X., and Sun, R. (2011). "Self-assembled lignocellulose micelles: A new generation of value-added functional nanostructures," BioRes. 6(3), 2288-2290.AbstractPDF
    Lignocellulose-based self-assembled micelles have emerged as a new generation of value-added functional nanostructures that show promise to address issues concerning the depletion of non-renewable resources; also these materials may contribute to the growing enthusiasm of utilizing biomass resources. Lignocellulose micelles can be conveniently prepared by self-assembly of amphiphilic lignocellulose derivatives in aqueous solution. They show great potential for applications in disparate fields, e.g. drug delivery, bioimaging diagnosis, sensing, nanoreacting, and so on. However, as a new research topic, a lot of research work would be needed to find out the critical structural factors that correlate with the formation, stability, morphology, and flexibility of lignocellulose micelles.
  • Researchpp 2291-2308Hemmasi, A. H., Khademi-Eslam, H., Pourabbasi, S., Ghasemi, I., and Talaiepour, M. (2011). "Cell morphology and physico-mechanical properties of HDPE/EVA/rice hull hybrid foamed composites," BioRes. 6(3), 2291-2308.AbstractPDF
    In this research, the cell morphology and physico-mechanical properties of HDPE/EVA/Rice hull hybrid foamed composites were investigated. For this aim, composites were prepared via melt mixing and then foamed using a compression molding method. Mechanical properties such as tensile strength, tensile and flexural modulus, and density were measured. Morphology of the samples was also evaluated by scanning electron microscopy (SEM). Results indicated that the tensile strength, tensile and flexural modulus, and density increased with the increase of rice hull content. However, with addition of blowing agent content and EVA content, mechanical properties and density of foamed composites decreased. Rice hull fibers acted as nucleating agents that substantially reduced cell size and increased cell density. In addition, EVA played an important role in foaming process by increasing the melt viscosity of the polymer matrix, in a way that samples with higher content of EVA have the highest cell density and the lowest cell size.
  • Researchpp 2309-2322Jawaid, M., and Abdul Khalil, H. P. S. (2011). "Effect of layering pattern on the dynamic mechanical properties and thermal degradation of oil palm-jute fibers reinforced epoxy hybrid composite," BioRes. 6(3), 2309-2322.AbstractPDF
    Dynamic mechanical and thermal analysis of oil palm empty fruit bunches (EFB)/jute fiber reinforced epoxy hybrid composites were carried out. The effect of layering pattern on dynamic mechanical properties (storage modulus (E’), loss modulus (E”), and tan δ) was investigated as a function of temperature. The storage modulus (E’) was found to be decreased with temperature in all cases, and hybrid composites had almost the same values of E’ at glass transition temperature (Tg). The tan δ peak height was minimum for jute composites and maximum for epoxy matrix. Layering pattern affected the dynamic mechanical properties of hybrid composites. Cole-Cole analysis was carried out to understand the phase behaviour of the composite samples. Thermogravimetric analysis (TGA) results indicated an increase in thermal stability of pure EFB composite with the incorporation of jute fibers. The overall results showed that hybridization with jute fibers enhanced the dynamic mechanical and thermal properties.
  • Researchpp 2323-2339Xie, Y., Hill, C. A. S., Sun, D., Jalaludin, Z., Wang, Q., and Mai, C. (2011). "Effects of dynamic aging (hydrolysis and condensation) behaviour of organofunctional silanes in the aqeous solution on their penetrability into the cells walls of wood," BioRes. 6(3), 2323-2339.AbstractPDF
    The hydrolysis and condensation (aging) dynamics of aqueous solutions of (3-glycidyloxypropyl)trimethoxysilane (GPS), vinyltrimethoxysilane (VTS), and (3-aminopropyl)trimethoxysilane (APS) and their penetrability into the cell walls of European spruce (Picea abies) wood were studied to investigate the feasibility of using silanes as a cell wall modifying agent for wood and other lignocellulosic materials. The size distribution of silane particles in aqueous solution was determined using a dynamic light scattering apparatus and increased with the aging time, but at different rates depending on the silane monomer. With increasing aging time, the treated wood exhibited decreased cell wall bulking (swelling), and the water vapour sorption behaviour was less affected by treatments when compared with unmodified wood; SEM-EDX analysis revealed that there was a reduced amount of silane in the cell walls with increased aging time. These findings demonstrate the reduced accessibility of silane to cell walls following aging.
  • Researchpp 2340-2355Orblin, E., and Fardim, P. (2011). "Interactions between cationic polyelectrolyte and pulp fines," BioRes. 6(3), 2340-2355.AbstractPDF
    Papermaking pulps are a mixture of fibres, fibre fragments, and small cells (parenchyma or ray cells), usually called pulp fines. The interactions between pulp fines and a cationic copolymer of acrylamide and acryloxyethyltrimethyl ammonium chloride were investigated based on solid-liquid isotherms prepared under different turbulence, and subsequent advanced surface characterization using X-ray photoelectron spectroscopy (XPS) and time-of-flight secondary ion mass spectrometry (ToF-SIMS). The surface charge and surface area of pulp fine substrates were measured by methylene blue sorption-XPS analysis and nitrogen adsorption combined with mercury porosimetry, respectively. The driving force behind polyelectrolyte adsorption was the amount of the surface anionic charge, whereas surface area appeared to be of less importance. Based on a comparison of solid-liquid and XPS sorption isotherms, different polyelectrolyte conformations were suggested, depending on the types of fines: A flatter conformation and partial cell-wall penetration of polyelectrolytes on kraft fines from freshly prepared pulp, and a more free conformation with extended loops and tails on lignocellulosic fines from recycled pulp. Additionally, ToF-SIMS imaging proved that recycled pulp fines contained residual de-inking chemicals (primarily palmitic acid salts) that possibly hinder the electrostatic interactions with polyelectrolytes.
  • Researchpp 2356-2365Nenkova, S., Velev, P., Dragnevska, M., Nikolova, D., and Dimitrov, K. (2011). "Lignocellulose nanocomposite containing copper sulfide," BioRes. 6(3), 2356-2365.AbstractPDF
    Copper sulfide-containing lignocellulose nanocomposites with improved electroconductivity were obtained. Two methods for preparing the copper sulfide lignocellulose nanocomposites were developed. An optimization of the parameters for obtaining of the nanocomposites with respect to obtaining improved electroconductivity, economy, and lower quantities and concentration of copper and sulfur ions in waste waters was conducted. The mechanisms and schemes of delaying and subsequent connection of copper sulfides in the lignocellulosic matrix were investigated. The modification with a system of 2 components: cupric sulfate pentahydrate (CuSO4. 5H2O) and sodium thiosulfate pentahydrate (Na2S2O3.5H2O) for wood fibers is preferred. Optimal parameters were established for the process: 40 % of the reduction system; hydromodule M=1:6; and ratio of cupric sulfate pentahydrate:sodium thiosulfate pentahydrate = 1:2. The coordinative connection of copper ions with oxygen atoms of cellulose OH groups and aromatic nucleus in lignin macromolecule was observed.
  • Researchpp 2366-2374Wang, Q., Chen, K., Liu, S., Li, J., and Xu, J. (2011). "Kinetics of bagasse delignification by using high-boiling solvent," BioRes. 6(3), 2366-2374.AbstractPDF
    Kinetic modeling of lignin removal under conditions of high-boiling solvent (HBS, i.e. 1,4-butanediol) auto-catalyzed pulping of bagasse has been studied. The experimental data were collected based on the absorption of dissolved lignin in black liquor at a wavelength of 320 nm, which can eliminate the interferences arising from furfural (F) and 5-hydroxymethyl furfural (HMF) generated during pulping. The results indicated that the delignification process consists of two distinct phases. The initial phase, involving a very fast reaction, is followed by a rather slow second phase. The delignification equation was determined as: D=87.71×C0.8982× (1-e-1.757t) ×100%, which is valid within an HBS concentration range of 50% to 80% and can be used for predict the lignin removal from bagasse by HBS pulping.
  • Researchpp 2375-2385Li, W., Wu, L., Di, C., Liu, C., and Sun, R. (2011). "DMAP-catalyzed phthalylation of cellulose with with phthalic anhydride in [bmim]Cl," BioRes. 6(3), 2375-2385.AbstractPDF
    It has been generally accepted that some ionic liquids are good media for homogeneous functionalization of cellulose. However, phthalylated cellulosic derivatives prepared in ionic liquids without any catalyst have lower DS as compared to the acetylated ones. In order to prepare the phthalylated cellulosic derivatives with higher DS, chemical modification of sugarcane bagasse cellulose with phthalic anhydride using ionic liquid 1-butyl-3-methylimidazolium chloride ([bmim]Cl) as a solvent and 4-dimethylaminopyridine (DMAP) as a catalyst has been examined. The results indicated that DMAP could enhance the reaction efficiency. The native cellulose and cellulose phthalates were characterized by FT-IR, solid-state CP/MAS 13C NMR, and thermogravimetric analysis. The results from FT-IR and solid-state CP/MAS 13C NMR analyses indicated that the phthalylation between cellulose and phthalic anhydride was successfully achieved. In addition, it was found that the thermal stability of the cellulose phthalates decreased upon chemical modification.
  • Researchpp 2386-2398Tammelin, T., Harlin, A., Vehviläinen, M., Nousiainen, P., and Kolppo, K. (2011). "Method to prepare smooth and even cellulose-lignophenol films," BioRes. 6(3), 2386-2398.AbstractPDF
    Dissolved cellulose was contacted with dissolved linear or slightly branched lignophenol polymers in alkaline solution, and films were formed through precipitation. Lignophenol is a polymeric lignin derivative isolated from wood meal, and due to its size and chemical structure, it is expected to a better model for natural lignin compared to the previously exploited small lignin model molecules. Smooth and even of cellulose-lignophenol films were achieved, and the interactions between cellulose and lignophenol were tentatively detected. The formed film structures had the crystalline form of cellulose II, and they did not contain any fibril-like material. Although the amount of hemicelluloses was negligible, it seems that the lignin modelling lignophenol tended to positively interact with cellulose.
  • Researchpp 2399-2410Chen, H., Chen, K., Yang, R., Yang, F., and Gao, W. (2011). "Use of aluminum trihydrate filler to improve the strength properties of cellulosic paper exposed to high temperature treatment," BioRes. 6(3), 2399-2410.AbstractPDF
    Cellulosic paper is thermolabile and its strength properties tend to decrease under high temperature conditions. In this work, the effects of aluminum trihydrate filler on the tensile and burst strength of paper prepared from bleached wood pulps were investigated. The use of aluminum trihydrate maintained the tensile and burst strength of paper sheet dried at 200 °C for 4 hours. Thermogravimetric analysis and differential scanning calorimetry gave the evidence that the maintainance of strength after drying associated with the use of aluminum trihydrate filler is possibly due to the increase in degradation temperature and heat absorption of cellulosic paper. The results regarding Fourier Transform Infrared spectroscopy, and the () and crystallinity index of fibers indicated the alleviated degradation of fibers when aluminum trihydrate was incorporated into the paper matrix.
  • Researchpp 2411-2424Najafi, A., and Khademi-Eslam, H. (2011). "Lignocellulosic filler/recycled HDPE composites: Effect of filler type of physical and flexural properties," BioRes. 6(3), 2411-2424.AbstractPDF
    The aim of the research was to study the potential of lignocellulosic fillers such as flour of rice hull, wood saw dust, sanding flour from Medium Density Fiberboard (MDF), and sawdust from particleboard as reinforcement for recycled high density polyethylene. Natural filler HDPE composites were made from recycled HDPE and lignocellulosic fillers at 60% by weight filler loadings using a dry blend/hot press method. In all compounds 3 per hundred compound (phc) Maleic Anhydride Polyethylene (MAPE) was used. Nominal density and dimensions of the panels were 1g/cm3 and 35×35×1 cm. Physical properties of panels including short and long-term of water absorption and thickness swelling and mechanical properties, including flexural modulus, flexural strength, strain at yield, and energy to yield point were studied. Composites containing sanding flour from MDF showed higher short-term values of water absorption and thickness swelling. For the long term, such as maximum values of water absorption and thickness swelling and diffusion coefficient, composites including wood sawdust showed higher values, and composites contain rice hulls exhibited the lowest values. In addition, composites made from sanding flour from MDF showed high value of the swelling rate parameter. Water absorption behavior of studied composites followed Fick's model. The flexural properties of composites were investigated with reference to the effect of filler type. Composites containing sanding flour from MDF and particleboard sawdust exhibited better flexural properties than others and composites containing wood sawdust showed the lowest values.
  • Researchpp 2425-2434Wang, Y., Lindström, M. E., and Henriksson, G. (2011). "Mild alkaline treatment activates spruce wood for enzymatic processing: A possible stage in bio-refinery processes," BioRes. 6(3), 2425-2434.AbstractPDF
    The structure of wood is so compact that enzymes are too large to penetrate into the structure and thereby attack the wood components for modifications that can be valuable for various purposes. Here we present a pretreatment method based on traditional kraft pulping, which opens the wood structure, so that enzymes are able to attack the wood components. To study this kind of chemical pretreatment, spruce wood samples were treated at similar conditions used in kraft cooking at varying intensities (H-factors). To verify if the structure was “opened” for enzymes, the pretreated wood samples were incubated with a cellulolytic culture filtrate, and the released reducing sugar concentration after the enzymatic hydrolysis was measured. The results indicated that un-pretreated wood fibers could not be attacked by the enzymes, but already relatively mild pretreatment was sufficient for letting the culture filtrate attack wood polysaccharides, and more intensive treatments opened the structure further. The mildest treatments did not cause any significant yield losses of lignin (Klason lignin). Some galactogluco-mannans were however lost during the pretreatments. The mechanisms behind the effect and the technical significance of the method are discussed.
  • Researchpp 2435-2447Chen, X., Qian, X., and An, X. (2011). "Using calcium carbonate whiskers as papermaking filler," BioRes. 6(3), 2435-2447.AbstractPDF
    Whiskers, having large length/diameter ratio, are fiber-shaped single crystals. The technical possibility of using calcium carbonate whiskers as papermaking filler to replace conventional powder-like calcium carbonate was investigated. The results showed that it may be feasible to use calcium carbonate whisker as papermaking filler. Compared with conventional precipitated calcium carbonate, calcium carbonate whisker had higher retention efficiency. The use of calcium carbonate whisker also favorably affected the strength properties of paper sheets. A model was proposed to suggest the mechanism for paper strength improvement. The whiskers filled in paper sheets could increase the friction between fibers, thus increasing bonding strength. Moreover, the strength properties of paper were further improved because calcium carbonate whiskers were partly embedded in pulp fiber walls.
  • Researchpp 2448-2459Sanchez, R. A., and Espósito, B. P. (2011). "Preparation of sugarcane bagasse modified with the thiophosphoryl function and its capacity for cadmium adsorption," BioRes. 6(3), 2448-2459.AbstractPDF
    Sugarcane bagasse (SCB) is an important by-product from the sucro-alcohol industry in Brazil, and it is a convenient raw material for new applications. In this study, SCB was modified with thiophosphoryl chloride in order to attach the P=S chelating moiety to the fibers, aiming at the production of a new material (SCB-F) with increased cadmium adsorption capacity. The SCB-F was characterized by elemental analysis, infrared spectrometry, thermogravimetry coupled to mass spectrometry, and acid-base titration. Adsorption isotherms for Cd(II) revealed a maximum adsorption capacity (qmax) of 74 mg/g, over 60 times higher than that of unmodified SCB. SCB-F thus represents a potentially interesting product for the decontamination of water bodies or effluents polluted with heavy metals.
  • Researchpp 2460-2470Xu, X., Shang, S., Song, Z., Cui, S., Wang, H., and Wang, D. (2011). "Preparation and characterization of rosin-based waterborne polyurethane from maleopimaric acid polyester polyol," BioRes. 6(3), 2460-2470.AbstractPDF
    Maleopimaric acid (MPA) can be used for polymer materials as a rosin derivative. In this study, rosin-based waterborne polyurethane (RWPU) was prepared with different content of maleopimaric acid polyester polyol (MAPP), which was synthesized from MPA. The properties of RWPU were studied by Fourier transform infrared spectroscopy (FT-IR), thermogravimetric analysis (TGA), and differential scanning calorimetry (DSC). Other properties including tensile strength, elongation at break, and water absorption were also determined. The onset decomposition temperature of RWPU with 30 wt% MAPP is improved from 170°C to 237°C, compared to the pure WPU. The tensile strength of the derivative was increased from 7.24 MPa to 23.24 MPa as well relative to the default polyurethane. The water absorption decreased significantly from 78.6% to 14.7%.
  • Researchpp 2471-2482Pereira, P. H. F., Voorwald, H. C. J., Cioffi, M. O. H., Mulinari, D. R., Da Luz, S. M., and Da Silva, M. L. C. P. (2011). "Sugarcane bagasse pulping and bleaching: Thermal and chemical characterization," BioRes. 6(3), 2471-2482.AbstractPDF
    Cellulose fibers were isolated from sugarcane bagasse in three stages. Initially sugarcane bagasse was subjected to a pre-treatment process with hydrolyzed acid to eliminate hemicellulose. Whole cellulosic fibers thus obtained were then subjected to a two-stage delignification process and finally to a bleaching process. The chemical structure of the resulting cellulose fibers was studied by Fourier Transform Infrared (FTIR) spectroscopy. Scanning Electron Microscopy (SEM) and X-ray diffraction (XRD) were used to analyze the effects of hydrolysis, delignification, and bleaching on the structure of the fibers. Two different thermal analysis techniques were used to study the bleaching cellulose fibers. These techniques confirmed that cellulose fibers were isolated from sugarcane bagasse. A future goal is to use these fibers as reinforcement elements in composites, organic-inorganic hybrid, and membranes for nanofiltration.
  • Researchpp 2483-2491Jafari-Petroudy, S. R., Resalati, H., and Rezayati-Charani, P. (2011). "Newsprint from soda bagasse pulp in admixture with hardwood CMP pulp," BioRes. 6(3), 2483-2491.AbstractPDF
    Based on global research and experiences producing newsprint from bagasse, the possibility of using bagasse chemical pulp in the furnish of local mill-made mixed hardwood CMP pulp was studied at laboratory scale, for making newsprint. Bagasse soda chemical pulp at digester yield of about 47% was bleached to about 60% brightness by single stage hydrogen peroxide. The effects of using up to 30% bagasse chemical pulp in a blend with hardwood CMP pulp, with or without softwood kraft pulp, were studied. The results showed that superior hand sheet properties could be achieved by using bagasse chemical pulp; in comparison with main mill pulp furnish (83% hardwood CMP pulp and 17% imported long fiber pulp). In other words, by using bagasse chemical pulp in a blend with local mill made hardwood CMP pulp, acceptable newsprint could be made with considerable reduction in the consumptions of hardwood species and softwood reinforcing kraft pulp.
  • Researchpp 2492-2503El Mansouri, N.-E., Yuan, Q., and Huang, F. (2011). "Synthesis and characterization of kraft lignin-based epoxy resins," BioRes. 6(3), 2492-2503.AbstractPDF
    Epoxidization is an interesting way to develop a new application of lignin and therefore to improve its application potential. In this work, kraft lignin-based epoxy resins were obtained by the epoxidization reaction, using the kraft lignin recovered directly from pulping liquor and modified by a methylolation reaction. The methylolated lignins were obtained by the reaction of original kraft lignin with formaldehyde and glyoxal, which is a less volatile and less toxic aldehyde. 1H-NMR spectroscopy showed that methylolated kraft lignin has more hydroxymethyl groups than glyoxalated kraft lignin. For the epoxidization reaction we studied the influence of the lignin:NaOH (w/w) ratio, temperature, and time of the reaction on the properties of the prepared epoxidized lignins. The structures of lignin-based epoxy resins were followed by epoxy index test and FTIR spectroscopy. Optimal conditions were obtained for lignin-based epoxy resin produced at lignin/NaOH = 1/3 at 70 ºC for 3h. Thermogravimetry analysis (TGA) revealed that the epoxidization enhances the thermal stability of lignins and may allow a wider temperature range for applications with lignin epoxy-PF blends.
  • Researchpp 2504-2521Yildiz, S., Yildiz, U. C., and Tomak, E. D. (2011). "The effects of natural weathering on the properties of heat-treated alder wood," BioRes. 6(3), 2504-2521.AbstractPDF
    The objective of this study was to investigate the effect of natural weathering in ground contact on biological resistance, modulus of rupture, and color stability of heat-treated alder wood. Chemical composition of weathered wood was also studied by FTIR-ATR spectra. Wood stakes were heated at 150, 180, and 200°C for periods of 2, 6, and 10 hours, and the stakes were subsequently exposed to natural weathering and decay in a field area located in the north of Turkey for 3 years. The decay index of heat-treated stakes was lower than that of the controls. The weight loss prevention ratio had an increasing tendency with increasing treatment temperature and length of time. Depending on the treatment parameters, heat treatment reduced the modulus of rupture by up to 50%; however decay caused by soil micro-organisms gave rise to a greater loss of modulus of rupture than heat. Weathering processes caused remarkable color changes in the samples. FTIR-ATR spectra showed significant deformations and degradations in wood components, especially in the hemicelluloses of heat-treated samples. Degradation of hemicelluloses increased with an increase in heat temperature and exposure time.
  • Researchpp 2522-2538Saleem, N., and Bhatti, H. N. (2011). "Adsorptive removal and recovery of U(VI) by citrus waste biomass," BioRes. 6(3), 2522-2538.AbstractPDF
    Adsorption and recovery of hexavalent uranium from dilute aqueous solutions by low cost citrus waste biomass was investigated by performing adsorption-desorption studies. Different samples of citrus waste biomasses were screened for removal of U(VI) from aqueous solutions. The results indicated that the biosorption capacity was strongly affected by the solution pH, biosorbent dose, contact time, and initial uranium concentration. Uranium binding by the test biomass was rapid, achieving >79% sorption efficiency within 15 min, and the equilibrium was established in 60 min. Optimum biosorption capacity (qe) was observed at pH 4.0, biosorbent dose 0.1 % (w/v), initial uranium concentration of 100 mg/L. The kinetic data fitted well to a pseudo-second-order rate equation (R2=0.980). The adsorption process conformed to a Langmuir adsorption isotherm model. Gibbs free energy (ΔGo) and enthalpy change (ΔHo) indicated that reaction was spontaneous and exothermic in nature at the studied temperatures. FT-IR studies showed the involvement of carbonyl, carboxyl, and amide groups in the biosorption process. Treatment of biomass with different reagents affected its biosorption capacity, and maximum removal (70.63%) was recorded with polyethyleneimine (PEI) treated biomass. EDTA had the best effects as an eluent, showing 94.7% desorption capacity.
  • Researchpp 2539-2550Guo, Z., Wang, S., Xu, G., and Cai, G. (2011). "Upgrading of bio-oil molecular distillation fraction with solid acid catalyst," BioRes. 6(3), 2539-2550.AbstractPDF
    Molecular distillation technology has been adopted to obtain a bio-oil fraction rich in carboxylic acids and ketones. This unique bio-oil fraction was then upgraded with a La-promoted solid acid catalyst. Three washing pretreatments were used to prepare catalysts A, B, and C, with the intention of reducing the amounts of residual sulfuric acid. Model reactions were used to estimate their catalytic activities and the residual amounts of sulfuric acid. Catalyst B, with washing after calcination, displayed higher catalytic activity (80.83%) and lower residual amount of sulfuric acid (50 μmol/g). The catalysts were characterized by techniques such as BET, XRD, and SEM to explain the differences in their catalytic activities. The optimum catalyst B was used in the upgrading of the bio-oil molecular distillation fraction. After upgrading, the corrosivity of the bio-oil fraction declined and its storage stability was improved. The carboxylic acid content in the upgraded bio-oil fraction decreased from 18.39% to 2.70%, while the ester content increased from 0.72% to 31.17%. The conversion of corrosive carboxylic acids to neutral esters reduced the corrosivity of the bio-oil fraction. Moreover, the ketones with unsaturated carbon-carbon double bonds (such as 2-cyclopenten-1-one, 3-methyl-2-cyclopenten-1-one, etc.) were converted into saturated compounds, which improved the stability of the bio-oil fraction.
  • Researchpp 2551-2567Gonzalez, R., Treasure, T., Phillips, R., Jameel, H., and Saloni, D. (2011). "Economics of cellulosic ethanol production: Green liquor pretreatment for softwood and hardwood, greenfield and repurpose scenarios," BioRes. 6(3), 2551-2567.AbstractPDF
    Green liquor pretreatment, a technology presently used worldwide in hundreds of kraft pulp mills, is proposed in this work as a potential pretreatment pathway for the efficient conversion of lignocellulosic biomass into ethanol. Mixed southern hardwood, eucalyptus, and loblolly pine were evaluated through process simulations in two investment scenarios: a greenfield mill scenario and a repurposing scenario, using existing kraft pulp mill assets for cellulosic ethanol production. Several advantages come with this concept: i) proven technology (both process and equipment), ii) chemical and energy recovery in place, iii) existing fiber supply chain, and iv) experienced labor force around the mill. Ethanol yields through enzymatic hydrolysis of pretreated fibers were highest in natural mixed hardwood and eucalyptus (280-285 liters of ethanol per dry ton of biomass) and lowest in loblolly pine (273 liters per dry ton of biomass). Natural hardwood and eucalyptus in the repurposing scenario form the most profitable combinations with an IRR of about 19%, mainly due to low capital expenditure (CAPEX) (per liter of ethanol), low enzyme costs, and higher ethanol yield (compared to loblolly pine). Production cost (in the repurposing scenario) was estimated at $2.51 per gallon of ethanol (or $0.66 per liter), cash cost at $2.14 gallon-1 (or $0.57 per liter), and CAPEX at $3.15 gallon-1 (or $0.83 per liter). Repurposing existing closed mills creates a potential alternative to ramp up in the task of producing alternative lignocellulosic biofuels.
  • Researchpp 2568-2580Yang, G., Lucia, L. A., Chen, J., Cao, X., and Liu, Y. (2011). "Effects of enzyme pretreatment on the beatability of fast-growing poplar APMP pulp," BioRes. 6(3), 2568-2580.AbstractPDF
    Effects of enzyme pretreatment on the properties of fast-growing poplar APMP pulp were evaluated. Compared with the unpretreated pulp, the beatabilities of the pulp that had been pretreated by enzymes were improved significantly, such as a decrease of Canadian Standard Freeness (CSF) in the range of 25 mL to 55 mL, a decrease of PFI mill revolutions from 1000r to 5500r, and a decrease of beating energy consumption from 12.5% to 22.0%. The values of brightness, breaking length, tearing index, bursting index, and folding number of the pulp pretreated by cellulase were improved by 1.2%ISO, 23.7%, 14.8%, 14.6%, and 50% respectively, while that of the pulp pretreated by xylanase were respectively improved by 2.1%ISO, 16.8%, 8.8%, 8.9%, and 25%. The optimal enzyme dosages were 25 IU•g-1 and 25IU•g-1 for cellulase and xylanase, respectively. Fibre quality analysis results showed that the fibre length of pretreated pulp increased partly, fibre width and fines content decreased, fibres torsion increased, and fibre bonding got stronger. X-ray diffractometer analysis indicated that the degree of crystallinity of fibres increased after the enzyme pretreatment.
  • Researchpp 2581-2591Javed, M. A., and Germgård, U. (2011). "The reactivity of prehydrolyzed softwood kraft pulps after prolonged cooking followed by chlorite delignification," BioRes. 6(3), 2581-2591.AbstractPDF
    In a laboratory study high-quality spruce chips were prehydrolyzed to remove hemicelluloses and then kraft cooked to different kappa numbers by varying the cooking time. Each pulp sample was then chlorite delignified to selectively remove the remaining lignin. The reactivities of the pulp samples before and after chlorite delignification were determined by Fock’s test, which is supposed to measure the pulp’s reactivity in the conventional viscose process. A number of analyses were carried out to determine which parameters affected pulp reactivity, as, for example: intrinsic viscosity, kappa number, pulp yield, carbohydrate composition, levelling-off degree of polymerization (LODP), and alkali solubility. The results of the study showed that the pulp reactivity increased with decreasing kappa number, and the highest reactivity was obtained after total lignin removal using chlorite delignification. It was also found that the carbohydrate composition had no influence on the pulp reactivity, but lower intrinsic viscosity either obtained by prolonged cooking or chlorite delignification correlated with higher pulp reactivity. Finally, lower alkali solubility, i.e. higher R18, reduced the reactivity.
  • Researchpp 2592-2604Liu, H.-M., Xie, X.-A., Feng, B., and Sun, R.-C. (2011). "Effect of catalysts on 5-lump distribution of constalk liquefaction in sub-critical ethanol," BioRes. 6(3), 2592-2604.AbstractPDF
    Liquefaction of cornstalk in sub-critical solution of ethanol without and with catalysts (K2CO3, Na2CO3 and ZnCl2) was performed in a stainless steel reactor (1 L) at temperatures of 200 to 300 oC. The cornstalk and the products of decomposition were divided into five lumps (gas, organic dissolved, heavy oil, volatile organic compounds, and residue). The effects of reaction temperature and the catalyst amount on the five lump yields were studied. The bio-oils produced with and without catalysts were characterized by GC/MS. Results showed that an increment in the temperature and the addition of catalysts had a synergetic effect on the lumps yield as compared to the non-catalytic experiments, and different catalytic procedures had an important effect on the lump yields and compounds of the bio-oils. The addition of the catalyst enhanced the gas yield and the total conversion rate. A high temperature, lower amount of Na2CO3, moderate amount of K2CO3, and a high amount of ZnCl2 were propitious to enhance the heavy oil. The formation of volatile organic compounds with the presence of ZnCl2 and K2CO3 was less than that in non-catalytic experiments at the higher temperatures. However, a higher conversion temperature had a negative impact on the bio-oils yield from liquefaction of cornstalk with and without catalysts.
  • Researchpp 2605-2618Cui, L., Li, L., Zhang, A., Pan, G., Bao, D., and Chang, A. (2011). "Biochar amendment greatly reduces rice Cd uptake in a contaminated paddy soil: A two-year field experiment," BioRes. 6(3), 2605-2618.AbstractPDF
    A field experiment was conducted on the effect of biochar (BC) amendment on Cd uptake by rice (Oryza sativa L.) in a contaminated paddy in 2009 and 2010. BC was applied as a basal soil amendment before rice transplantation in 2009 at rates of 0, 10, 20, 40t ha-1, and rice yield and Cd uptake were monitored in both 2009 and 2010. The BC amendment significantly increased soil pH by 0.15-0.33 units in 2009 and 0.24-0.38 units in 2010, and decreased CaCl2 extracted Cd in soil by 32.0%-52.5% in 2009 and 5.5%-43.4% in 2010, respectively. Under BC amendment at 10, 20, 40 t ha-1, rice grain Cd concentration was observed to be reduced by 16.8%, 37.1%, and 45.0% in 2009 and by 42.7%, 39.9%, and 61.9% in 2010, while the total plant Cd uptake was found to decrease by 28.1%, 45.7%, and 54.2% in 2009 and by 14.4%, 35.9%, and 45.9% in 2010, respectively. Such effect of BC amendment on reducing Cd plant uptake has profound implications among those using bioresources for field application. Finally, BC amendment in combination with low Cd cultivars may offer a basic option to reduce Cd levels in rice as well as to reduce greenhouse gas emissions in rice agriculture in contaminated paddies.
  • Researchpp 2619-2631Dai, L., Dai, H., Yuan, Y., Sun, X., and Zhu, Z. (2011). "Effects of TEMPO oxidation system on kinetic constants of cotton fibers," BioRes. 6(3), 2619-2631.AbstractPDF
    The kinetics of the TEMPO-mediated oxidation of cotton fibers were studied. It was revealed that the oxidation reaction of the cotton fibers by TEMPO/NaBr/NaClO system can be approximately described as two pseudo-first-order reaction kinetics that are based on the cellulose microstructure, namely the kinetic processes of the primary wall and the secondary wall. In the concentration range used in this study, the rate constant k was directly proportional to the concentration of TEMPO. As to NaBr, the rate constant was proportional to the concentration in a relatively lower range, while it tended to level off at higher concentration, but the oxidation reaction rate increased with concentration when the concentration was above 1.0 mmol/g. The pH value had a great impact on the oxidation rate; the optimum pH was controlled from 10 to 11. The effect of temperature on the rate constant could be well described by the Arrhenius equation, and the apparent activation energy measured was about 56.66kJ/mol. The X-ray diffraction pattern, which indicates the crystallinity of cotton fibers, was nearly constant during the oxidation.
  • Researchpp 2632-2646Abdolahian Sohi, A. M., Khademi-Eslam, H., Hemmasi, A. H., Roohnia, M., and Talaiepour, M. (2011). "Nondestructive detection of the effect of drilling on acoustic performance of wood," BioRes. 6(3), 2632-2646.AbstractPDF
    The aim of this paper is to determine the effect of hole diameter (LR Direction) on acoustic performance indicators such as acoustic coefficient and acoustic conversion efficiency of wooden beams using flexural vibration of a free-free bar test.The drilling from 0 to 8 millimetres diameter was made exactly at the middle of the bar, on the node of the second mode of vibration. The results revealed that holes of diameter from 0 to 8 millimeters didn’t cause any sever change on acoustic coefficient and acoustic conversion efficiency when the beam was impacted on both radial and tangential surfaces. Nevertheless, these acoustic properties changed a bit when the beam was impacted on the tangential surface. Thus, the changes of the acoustic coefficient and acoustic conversion efficiency for both radial and tangential impacts were not significant, even with an 8 mm hole. Therefore, hole diameter not only didn’t cause any severe effect on acoustic coefficient and acoustic conversion efficiency but also somewhat increased their values. So, a hole having a relatively small diameter may cause improved acoustical performance of a wooden beam.
  • Researchpp 2647-2662El Mansouri, N.-E., Yuan, Q., and Huang, F. (2011). "Characterization of alkaline lignins for use in phenol-formaldehyde and epoxy resins," BioRes. 6(3), 2647-2662.AbstractPDF
    Besides polyurethanes and polyesters, phenolic and epoxy resins are the most prominent applications for technical lignins in thermosetting materials. To evaluate the potential application of lignin raw materials in phenol formaldehyde and epoxy resins, three types of alkaline lignins were characterized in terms of their structures and thermal properties. The lignin samples analyzed were kraft lignin (LIG-1), soda–rice straw lignin (LIG-2), and soda-wheat straw lignin (LIG-3). FTIR and 1H-NMR methods were used to determine their structure. Gel permeation chromatography (GPC) was used to determine the molecular weight distribution (MWD). Differential scanning calorimetry (DSC) was used to measure the glass transition temperature (Tg), and thermogravimetric analysis (TGA) to determine the thermal stability of lignin samples. Results showed that kraft lignin (LIG-1) has moderate hydroxyl-group content, is rich in G-type units, and has good thermal stability. These properties make it more suitable for direct use in phenol formaldehyde resins, and it is therefore a good raw material for this purpose. The alkaline soda-rice straw lignin (LIG-2) with a high hydroxyl-group content and excellent thermal stability is most suited to preparing lignin-based epoxy resins.
  • Researchpp 2663-2675Shahriarinour, M., Ramanan, R. N., Abdul Wahab, M. N., Mohamad, R., Mustafa, S., and Ariff, A. B. (2011). "Improved cellulase production by Aspergillus terreus using oil palm empty fruit bunch fiber as substrate in a stirred tank bioreactor through optimization of the fermentation conditions," Biores. 6(3), 2663-2675.AbstractPDF
    Response surface methodology (RSM) was performed to evaluate the effects of dissolved oxygen tension (DOT) and initial pH on the production of carboxymethyl cellulase (CMCase), filter-paper hydrolase (FPase), and β-glucosidase by Aspergillus terreus in a 2 L stirred tank bioreactor. Delignifiedoil palm empty fruit bunch (OPEFB) fibre was used as the main substrate under submerged fermentation. Growth of A. terreus and the production of three main components of cellulase were optimized by central composite design (CCD) design. Statistical analysis of results showed that the individual terms of these two variables (DOT and pH) had significant effects on growth and the production of all components of cellulase. Maximum growth (13.07 g/L) and cellulase activity (CMCase = 50.33 U/mL, FPase = 2.29 U/mL and β-glucosidase = 15.98 U/ml) were obtained when the DOT and initial culture pH were set at 55% and 5.5, respectively. A high proportion of β-glucosidase to FPase (8:1) in cellulase of A. terreus could be beneficial for efficient hydrolysis of cellulosic materials. The use of OPEFB as a main substrate would reduce the cost of fermentation for the production of cellulase.
  • Researchpp 2676-2689Espinoza, O., Buehlmann, U., Bumgardner, M., and Smith, B. (2011). "Assessing changes in the U.S. hardwood sawmill industry with a focus on markets and distribution," BioRes. 6(3), 2676-2689.AbstractPDF
    The U.S. hardwood sawmilling industry has experienced significant changes over the past decade. A slowing housing industry, competition from imported products, higher transportation costs, and high stumpage prices have changed the business of manufacturing and marketing hardwood lumber. Also, hardwood lumber buyers are changing their business practices by shortening lead times, requiring a more customized product, and buying smaller lumber quantities to cut costs and increase operational flexibility. A survey of hardwood lumber manufacturers was conducted in the fall of 2009 to assess changes and adaptations within the industry. Among respondents, average hardwood lumber sales decreased by 13.2 percent during the study's focus period from 2004 to 2008. Respondents also identified a change in customer demand with smaller, more frequent orders becoming more common. Moreover, the species mix shifted, with red oak losing considerable market share. Intermediaries, such as hardwood lumber distributors, were able to capture more of the industry's business. Respondents identified the slowing housing market and high energy costs as major factors affecting their businesses. While the survey's responses reflected the extremely challenging economic conditions, industry participants are aggressively adapting their businesses and pursuing new opportunities with the understanding that markets will eventually recover.
  • Researchpp 2690-2702Li, Y., and He, B. (2011). "Characterization of ink pigment penetration and distribution related to surface topography of paper using confocal laser scanning microscopy," BioRes. 6(3), 2690-2702.AbstractPDF
    The penetration of ink into paper affects the final appearance of printing and the amount of ink usage. In this work, UV-curing fluorescent rose ink was used to investigate the penetration and distribution of the ink pigments as well as their correlation with the surface topography of paper. The ink penetration and distribution were characterized with Confocal Laser Scanning Microscopy (CLSM), whereas the microstructure of the paper surface was observed using Atomic Force Microscopy (AFM). The AFM results showed that the surface of the paper coated with kaolin layer was the smoothest among the samples. Also the pore size of the calcium carbonate coating layer was smaller than that of the kaolin coating layer. Meanwhile, the pore size distribution of the calcium carbonate coating layer appeared to be relatively narrow, compared with other samples. The results of CLSM images indicated that the depth, size, and arrangement of pores affected the penetration depth and distribution of ink pigment on coated paper. The large pores led to deeper penetration of ink pigments, and uniform ink absorption occurred when the pore distribution was uniform. The UV-curing ink pigments not only set on the surface of the uncoated paper, but also they penetrated into the paper interior and adhered to the fiber surface.
  • Researchpp 2703-2710Rivilli, P. L., Yranzo, G. I., and Pérez, J. D. (2011). "Stepwise isothermal fast pyrolysis (SIFP) of biomass. Part 1. SIFP of pine sawdust," BioRes.6(3), 2703-2710.AbstractPDF
    Pyrolysis of pine wood sawdust was carried out using stepwise isothermal fast pyrolysis (SIFP), focusing on the search of reaction conditions to obtain chemicals in good yields from biomass. SIFP consists of successive isothermal fast pyrolysis reactions, where solid products obtained in the previous isothermal fast pyrolysis become the substrate of the subsequent reaction at a higher temperature. This article reports results obtained by SIFP of pine sawdust between 200 and 600°C using 100°C intervals under vacuum (0.2 mm), using nitrogen as carrier gas. Both sets of reactions made it possible to obtain most of the compounds that have been previously described in conventional fast pyrolysis experiments; however this system produces a smaller number of chemical compounds in each isothermal FP, making it easier to obtain determined chemicals with industrial or research value. Maximum yield of liquid products occurred at 300°C, giving around 30% of bio-oil, which contained mainly phenols and furan derivatives. Liquid-Liquid extraction led to a rich mixture of phenol derivatives. Results showed that SIFP is an interesting technique to obtain enriched fractions of products derived from biomass pyrolysis.
  • Researchpp 2711-2718Ghafarzade Mollabashi, O., Saraeian, A. R., and Resalati, H. (2011). "The effect of surfactants application on soda pulping of wheat straw," BioRes. 6(3), 2711-2718.AbstractPDF
    This paper details the effects of two non-ionic surfactants, ELA-7 and PEG 1500, on the soda pulping of wheat straw. The results showed that application of either surfactant improved the pulp yield and decreased the screen rejects. The increase in pulp yield at similar kappa number may be due to higher selectivity of delignification affected by surfactant, which can act as a co-solvent. Addition of ELA-7 to cooking liquor didn’t have significant effect on paper properties. But a significant effect was observed with PEG 1500. In fact, it caused a decrease in burst and tensile index but increased the tear index, probably because of a debonding effect of the surfactant. In addition, application of both surfactants improved brightness for both unbleached and bleached pulp samples.
  • Researchpp 2719-2731Teoh, Y. P., Don, M. M., and Ujang, S. (2011). "Media selection for mycelia growth, antifungal activity against wood-degrading fungi, and GC-MS study by Pycnoporus sanguineus," BioRes. 6(3), 2719-2731.AbstractPDF
    Wood-decaying fungi present a serious threat to items made from rubberwood (Hevea brasiliensis). Though conventional chemical control has been a successful method for preserving wood against stain and decay fungi growth, the effects of these chemicals are of concern because they create problems for the environment and public health. Pycnoporus sanguineus (P. sanguineus), is a white-rot fungus that invades wood during its growth, storage, or use, causing decay or other property changes. It was considered in this work as a potential source of bioactive compounds and investigated for its natural antifungal activity using a minimum inhibitory concentration assay against wood-degrading fungi. It was found that media consisting of 10.0 g/L malt extract, yeast extract, dextrose, and maltose, respectively at pH 4.7±0.2 provided the highest biomass production by P. sanguineus. Results showed that the antifungal properties of methanol and water extract of P. sanguineus mycelia and supernatant ranged from MIC values of 0.1 to 5.0 µg/µL. 4H-Pyran-4-one,2,3-dihydro-3,5-dihydroxy-6-methyl- (DDMP) was found to be the major component in the extract of this fungus, based on analysis using gas chromatography - mass spectrometry.
  • Researchpp 2732-2743Singh, J., Mishra, N. S., Uma, Banerjee, S., and Sharma, Y. C. (2011). "Comparative studies of physical characteristics of raw and modified sawdust for their use as adsorbents for removal of acid dye," BioRes. 6(3), 2732-2743.AbstractPDF
    The present paper aims to investigate the physical characteristics of sawdust relative to its use as an adsorbent for removal of an acid dye (Orange G) from aqueous solutions. The raw sawdust was sieved to have a uniform size and was activated by sulphuric acid by refluxing the content at 60 oC for 4 h. Surface morphology and surface functional groups of both raw and modified sawdust samples were investigated by Scanning Electron Microscope (SEM), Energy Dispersive X-ray Analysis (EDX), Fourier Transformation Infrared (FTIR), and elemental analysis. All these analyses displayed significant change in the structure of the sawdust. The data obtained from batch adsorption experiments for the removal of the selected dye confirmed that adsorption characteristics of the modified sawdust were better than those of raw sawdust.
  • Researchpp 2744-2756Lin, Y.-S., and Lee, W.-C. (2011). "Simultaneous saccharification and fermentation of alkali-pretreated cogongrass for bioethanol production," BioRes. 6(3), 2744-2756.AbstractPDF
    Simultaneous saccharification and fermentation (SSF) of alkaline pretreated cogongrass to ethanol was optimized using the commercial cellulase Accellerase 1500 and Ethanol Red dry yeast. Cogongrass was pretreated with 10% (wt) NaOH at room temperature for 24 hours, resulting in an increase in the cellulose percentage from 38.5% to 60.5%. Each SSF of alkali-pretreated cogongrass was carried out with 1 g/L of dry yeast loading at pH 5.0 under 150 rpm shaking. Response surface methodology (RSM) based on a three-level three-factor Box-Behnken design was employed to optimize the key variables within the following ranges: cellulase concentration per unit gram water-insoluble cellulose (WIS) (0.15-0.25 mL/g-WIS), substrate concentration (5-15 % WIS, w/w), and temperature (35-45°C) for the SSF process. The response surface model arrived at the optimum SSF conditions: cellulase concentration of 0.255 ml/g-WIS, temperature at 37.5°C, and substrate concentration of 7.28% WIS for obtaining 80.3 % ethanol yield in 72 h. The optimal conditions were verified experimentally with an average absolute relative deviation of 3.01 %. Also, the SSF was scaled up to a 5-L rotary drum reactor filled with 1 kg of substrate under the optimal conditions, and an ethanol yield of 76.2% was obtained.
  • Researchpp 2757-2762Yapici, F., Ozcifci, A., Esen, R., and Kurt, S. (2011). "The effect of grain angle and species on thermal conductivity of some selected wood species," BioRes. 6(3), 2757-2762.AbstractPDF
    In this study the thermal conductivity of different wood materials was determined. For this purpose, Scots pine (Pinus sylvestris L.), Uludag fir (Abies Bornmülleriana Matff), Oriental beech (Fagus orientalis L), Oak (Quercus robur L.), and Chestnut of Anatolia (Castanea sativa Mill.) woods were used. In the test, the thermal conductivity of the woods was measured according to procedure of ASTM C 1113-99 standards. The lowest thermal conductivity was obtained in the perpendicular direction of Scots pine samples as 0.156 Kcal/mh°C. The highest thermal conductivity was obtained from perpendicular direction of samples in Oriental beech as 0.331 Kcal/mh°C.
  • Researchpp 2763-2775Saloni, D. E., Lemaster, R., and Jackson, S. (2011). "Control system evaluation and implementation for the abrasive machining process on wood," BioRes. 6(3), 2763-2775.AbstractPDF
    Continuous process improvement and automation have proven to be powerful tools for the wood processing industries in order to obtain better final product quality and thus increase profits. Abrasive machining represents an important and relevant process in the manufacturing and processing of wood products, which also implies high cost of materials and labor; therefore, special attention to this process is necessary. The objective of this work was to evaluate and demonstrate a process control system for use in the abrasive machining of wood and wood-based products. A control system was created on LabView® to integrate the monitoring process and the actions required, depending on the abrasive machining process conditions. The system acquires information from the optical sensor to detect loading and activate the cleaning system. The system continuously monitors the condition of the abrasive belt (tool wear) by using an acoustic emission sensor and alerts the operator of the status of the belt (green, yellow, and red lights indicating satisfactory, medium, and poor belt condition). The system also incorporates an additional safety device, which helps prevent permanent damage to the belt, equipment, or workpiece by alerting the operator when an excessive temperature has been reached. The process control system proved that automation permits enhancement in the consistency of the belt cleaning technique by the elimination of the human errors. Furthermore, this improvement also affects the cost by extending the life of the belt, which reduces setup time, belt cost, operation cost, as well as others.
  • Researchpp 2776-2789Feng, Y., Liu, H.-Q., Sun, R.-C., and Jiang, J.-X. (2011). "Enzymatic hydrolysis of cellulose from steam-pretreated Lespedeza stalk (Lespedeza crytobotrya) with four Trichoderma cellulases," BioRes 6(3), 2776-2789.AbstractPDF
    The hydrolytic potential of cellulases produced by Trichoderma viride, Trichoderma pseudokoningii, Trichoderma koningii, and Trichoderma reesei with addition of exogenous β-glucosidase was evaluated on cellulose of steam-pretreated Lespedeza. The T. viride enzyme achieved the highest glucose conversion (90.09%), while T. pseudokoningii cellulase achieved the highest ratio of cellobiose to glucose (4.94%) at the end of hydrolysis. Enzymatic adsorption on the substrate was evaluated on filter paper activity and β-glucosidase activity in the corresponding digest with the obtained T. cellulases. T. viride cellulase possessed an efficient adsorption-desorption on the substrate and reached the highest FPA difference (0.72 U/mL) among enzyme activities, indicating to its excellent hydrolysis capability. However, β-glucosidase in T. viride cellulase system showed close bonding on the substrate, suggesting that efficiencies of adsorption-desorption on the cellulose are different between the entire cellulase system and β-glucosidase. T. viride cellulase, with active endogenous β-glucosidase (1.60 U/mL), has compatible synergism with the additional exogenous β-glucosidase.
  • Researchpp 2790-2804Yuan, G., Dai, H., Ye, C., Zhang, Y., and Wang, Z. (2011). "Adsorption of Ca(II) from aqueous solution onto cellulosic fibers and its impact on the papermaking process," BioRes. 6(3), 2790-2804.AbstractPDF
    Calcium(II) is one of the most common metal ions in papermaking systems. However, the effect of Ca2+ on papermaking processes has not drawn much attention. The adsorption of Ca2+ from aqueous solutions onto bleached Eucalyptus globulus kraft pulp fibers was investigated. Thermodynamic results indicate that the adsorption of Ca2+ onto bleached E. globulus kraft pulp fibers was exothermic, reversible, and spontaneous. The equilibrium data followed Langmuir isotherms. The adsorption basically agrees with the ionic reaction model between carboxyl groups of fibers and Ca2+ in which the molar ratio of carboxyl to Ca2+ is close to 2:1. The binding capacity with carboxyl groups is so strong that the anionic charge of the adsorption sites in fibers can be screened, leading to decreased performance of cationic polyacrylamide for retention and drainage, Alkyl Ketene Dimer (AKD) for sizing, and cationic starch for dry strengthThe precipitation effect of Ca2+ with three kinds of dissolved and colloidal substances (sodium rosinate, sodium stearate, sodium oxalate) also was investigated. The results showed that deposits formed by Ca2+ and dissolved and colloidal substances, which could adsorb to the surfaces of fibers, would affect drainage and retention abilities of cationic polyacrylamide.
  • Researchpp 2805-2817(2011). "The effects of the force loading direction on bending strength and modulus of elasticity in laminated veneer lumber (LVL)," BioRes. 6(3), 2805-2817.AbstractPDF
    This study was aimed at determining the effects of the force loading direction on bending strength (MOR) and modulus of elasticity (MOE) in laminated wooden materials obtained in different compositions from cut veneers of Oriental beech and Lombardy poplar with thicknesses of 4 mm and 5 mm. A total of 180 experimental specimens were prepared for determining the MOR and MOE values in parallel and perpendicular directions to the glue line. The study involved a total of 6 air-dried density layer organizations of solid Oriental beech and Lombardy popular in 4 different laminate compositions and in the same dimensions, aimed at control. Polyvinyl Acetate (PVAc) and Polyurethane (PU) were used as the adhesive type in laminations with PVAc5-PU5-PVAc4-PU4. The specimens were subjected to bending strength and modulus of elasticity experiments in parallel and perpendicular directions to the glue line in accordance with the TS EN 310 standards. As a result of the statistical analysis of the data obtained at the end of the experiments, it was determined that in the laminated materials, the force loading direction in parallel or perpendicular to the glue line affected the MOR and MOE results. The best result in the laminated materials was found to be approximately 10% higher for MOR and MOE in a parallel direction to the PU4 glue line compared to the perpendicular direction.
  • Researchpp 2818-2835Ioelovich, M., and Morag, E. (2011). "Effect of cellulose structure on enzymatic hydrolysis," BioRes. 6(3), 2818-2835.AbstractPDF
    Enzymatic hydrolysis of non-dried and dried cellulose samples having various particles size, degree of polymerization, porosity, crystalline polymorph, and content of non-crystalline domains has been studied. Regression analysis was carried out to determine contribution of various structural features of cellulose samples to their hydrolysability. It was found that particle size, degree of polymerization, and crystalline polymorph had a negligible influence on the conversion degree of cellulose into glucose under the effect of the cellulolytic enzyme. Such characteristics as the pores volume had a fair impact on the conversion degree of cellulose. Drying of the wet samples caused decreasing of the hydrolysability of cellulose due to irreversible collapse of the pores volume. The content of non-crystalline domains (Ax) in cellulose had the highest effect on the rate of enzymatic hydrolysis and average conversion degree (αa) of cellulose into glucose. A linear dependence αa = f(Ax) was established both for dried and non-dried cellulose samples.
  • Researchpp 2836-2850Kuutti, L., Haavisto, S., Hyvärinen, S., Mikkonen, H., Koski, R., Peltonen, S., Suortti, T., and Kyllönen, H. (2011). "Properties and flocculation efficiency of cationized biopolymers and their applicability in papermaking and in conditioning of pulp and paper sludge," BioRes. 6(3), 2836-2850.AbstractPDF
    Safe biodegradable “green” alternatives with minimal environmental and health risks have received widespread research interest. Thirty different kinds of bio-based flocculants (modified starches, modified celluloses, native chitosan, and lignin-based flocculant) were pre-tested using a simple jar test for the examination of the applicability of new organic flocculants in papermaking and in conditioning of waste activated sludge from the pulp and paper industry. Three starch-based and two cellulose-based polymers were chosen for further flocculation and filtrations tests. Key optimization parameters for the polymer were identified as the increasing of molecular weight and nitrogen content. The starch-based polymer had the best performance in both applications, but in neither of the cases did it function as well as the commercial polyacrylamide-based polymers. The importance of the molecular weight came up in the experiments. The developed starch-based polymer was cationic and had the charge density used in industry. On the other hand, although cationic flocculants are the most used in sludge conditioning, also anionic and non-ionic polymers are needed, depending on the characteristics of the sludge to be flocculated. Overall action of the tailored polymers was also studied in order to predict their potential as papermaking retention and dewatering aids.
  • Researchpp 2851-2860Mancera, C., El Mansouri, N-E., Vilaseca, F., Ferrando, F., and Salvado, J. (2011). "The effect of lignin as a natural adhesive on the physico-mechanical properties of Vitis vinifera fiberboards," BioRes. 6(3), 2851-2860.AbstractPDF
    Lignin was used as a natural adhesive to manufacture Vitis vinifera fiberboards. The fiberboards were produced at laboratory scale by adding powdered lignin to material that had previously been steam-exploded under optimized pretreatment and pressing conditions. The kraft lignin used was washed several times with an acidic solution to eliminate any contaminants and low molecular weight compounds. This research studied the effects of amounts of lignin ranging from 5% to 20% on the properties of Vitis vinifera fiberboards. The fiberboard properties evaluated were density, water resistance in terms of thickness swelling, water absorption, and the mechanical properties in terms of modulus of rupture, modulus of elasticity, and internal bond. Results showed that fiberboards made from Vitis vinifera without lignin addition had weaker mechanical properties. However, the fiberboards obtained using acid-washed kraft lignin as a natural adhesive had good mechanical and water resistance properties that fully satisfied the relevant standard specifications.
  • Researchpp 2861-2873Irshad, M., Asgher, M., Sheikh, M. A., and Nawaz, H. (2011). "Purification and characterization of laccase produced by Schyzophylum commune IBL-06 in solid state culture of banana stalks," BioRes. 6(3), 2861-2873.AbstractPDF
    Shyzophyllum commune IBL-06 produced 367 IU/mL of laccase in solid state bioprocess of banana stalk under optimum physical and nutritional parameters. The optimum SSF conditions were рH 4.5; temperature, 35°C; inoculum size, 3mL (106-108 mL-1); moisture content, 60%; C:N ratio in the medium, 15:1 (glucose and ammonium nitrate as additional carbon and nitrogen sources, respectively), ABTS (1mM), 1 mL, and CuSO4 (1mM), 1mL. Laccase was purified 3.95-fold with specific activity of 158 U/mg by ammonium sulfate precipitation, followed by gel filtration chromatography using Sephadex G-100 column. Molecular weight of the laccase was 63 KDa on SDS-PAGE. Purified laccase had an optimum рH of 6.0 and was stable in the рH range from 6 to 7. The optimum temperature was 40 °C, and it displayed considerable stability within the range 30 to 35 °C with 24 h incubation. Km and Vmax were 0.025 mM and 80 mM/min, respectively, using ABTS as a substrate. Copper sulfate increased the activity of purified laccase when used at low concentration, but silver nitrate exerted the strongest inhibition.
  • Researchpp 2874-2884Fang, R., Cheng, X.-S., and Lin, W.-S. (2011). "Preparation and application of dimer acid/lignin graft copolymer," BioRes. 6(3), 2874-2884.AbstractPDF
    Dimer acid (DA) was grafted onto lignin (EHL) to form a graft copolymer DA-g-EHL. The selection of the reaction type and the optimization of the reaction conditions for the grafting reaction were conducted through orthogonal and single factor experiments. FT-IR and thermal analysis were used to characterize the graft product. It was found that, compared with free radical grafting, DA can be grafted onto EHL more effectively by ester condensation with strongly acidic cation exchange resin as a catalyst. Under optimum reaction conditions, the increase of acid value and the yield of graft copolymer can reach about 9.3% and 83%, respectively. The application of DA-g-EHL in preparing modified phenolic aldehyde amine curing agent (PAA) was studied. Results showed that the flexibility of the epoxy resin cured by DA-g-EHL modified PAA is significant higher than that of the resin cured by EHL modified PAA. The graft of DA onto EHL may reduce the rigidity of EHL and the chain stiffness of the PAA modified by EHL.
  • Researchpp 2885-2895Ćilerdžić, J., Stajić, M., Vukojević, J., Duletić-Laušević, S., and Knežević, A. (2011). "Potential of Trametes hirsuta to produce ligninolytic enzymes during degradation of agricultural residues," BioRes. 6(3), 2885-2895.AbstractPDF
    Trametes hirsuta is an efficient lignin-degrading species due to its ability to produce laccase and Mn-dependent peroxidase. Agricultural residues represent prospective substrates for the bioconversion into fungal biomass and lignocellulolytic enzymes, but also they could be potential environmental pollutants. Evaluation of the potential of T. hirsuta to produce ligninolytic enzymes during solid-state fermentation of selected plant raw materials was the goal of the study. The highest level of laccase activity (3827.0 ± 219.0 U/L) was noted in mandarin orange peels medium, while wheat straw and glucose-enriched mandarin orange peels media were the optimum for Mn-dependent peroxidase (1971.5 ± 23.0 U/L) and versatile peroxidase (1173.0 ± 100.0 U/L), respectively. Levels of veratryl alcohol oxidation in the presence of H2O2 were similar to those in its absence during fermentation of all selected agricultural residues, and the highest values were obtained in glucose-enriched mandarin orange peels medium. The obtained results demonstrated the potential of T. hirsuta to produce ligninolytic enzymes and mineralize various plant wastes to low-molecular weight compounds that could be further used in food, feed, and other industries.
  • Researchpp 2896-2911Cao, X.-F., Yuan, T., Sun, S., and Sun, R.-C. (2011). "Isolation and characterization of soluble polysaccharides from Calamagrostis angustifolia Kom," BioRes. 6(3), 2896-2911.AbstractPDF
    Sequential treatments of dewaxed Calamagrostis angustifolia Kom with water (60 ºC and 90 ºC), 70% ethanol, and 70% ethanol containing 0.2%, 1.0%, 2.0%, 4.0%, and 8.0% NaOH at a solid to liquid ratio of 1:25 (g/mL) at 80 ºC for 3 h yielded 36.2% soluble polysaccharides of the dry dewaxed material. The eight polysaccharide fractions obtained were comparatively studied by sugar analysis, GPC, FT-IR, 1H and 13C-NMR, and 2D-NMR (HSQC) spectroscopy. The results showed that the water-soluble polysaccharides might contain noticeable amounts of β-D-glucan, as well as some and galactoarabinoxylan. 70% ethanol-soluble polysaccharide was mainly arabinogalactan. The five alkali-soluble hemicelluloses were mainly galactoarabinoxylans. The Ara/Xyl and Ara/Gal values of H5-H8 fractions decreased with the increment of NaOH concentration from 1.0% to 8.0%. Meanwhile, the molecular weights had a declining trend from ~60,000 to ~40,000 g/mol. The smaller sized and more branched polysaccharides ed in the early stages under milder conditions, and the larger molecular sized and more linear hemicelluloses tended to be isolated under more highly alkaline conditions.
  • Researchpp 2912-2931Pánek, M., and Reinprecht, L. (2011). "Bacillus subtilis for improving spruce wood impregnability," BioRes. 6(3), 2912-2931.AbstractPDF
    Impregnation of spruce and other conifers is very difficult due to aspiration of pits in tracheids. In this experiment, freshly cut and instantly debarked Norway spruce logs were pre-treated with the bacterium Bacillus subtilis at their ponding for 1, 3, 6 and 9 weeks under laboratory conditions at 30 °C or under outdoor conditions during the summer at 5 to 35 °C. Significant increases of the permeability and the impregnability of spruce sapwood were observed already after 3 weeks of its ponding due to bacterial attack and opening of pits in tracheids. Applied bio-treatments did not have a significant influence on selected mechanical properties of spruce wood. This method could be effectively used for poles and other round products from spruce or other conifers before their impregnation with preservatives or modification substances. However, its use for squared spruce timbers is not convenient because tracheids in the bacterially treated heartwood zone remained unchanged.
  • Researchpp 2932-2940Khanam, Z., Adam, F., Singh, O., and Ahmad, J. (2011). "A novel acylated flavonoidic glycoside from the wood of cultivated Acacia nilotica (L.) Willd. Ex. Delile.," BioRes. 6(3), 2932-2940.AbstractPDF
    Acacia is a fast-growing plant that has high potential in commercial plantations in tropical areas. It is already being grown as a plantation crop for building and industrial raw materials, as well as for reforestation of difficult sites. Extensive cultivation of this promising tree would enrich the natural resources besides being useful for industrial raw material, waste land management, and afforestation. In addition, Acacia exhibits extensive medicinal values. In view of the medicinal importance of Acacia nilotica and the therapeutic utility of flavonoids, an attempt has been made to isolate novel flavonoids from the wood of cultivated A. nilotica. The extraction of crude ethanol extract from the A. nilotica wood was followed by fractionation with chloroform, ethyl acetate, and methanol in increasing order of polarity of the solvent. The mixed ethyl acetate and methanol extract afforded three pure compounds through column chromtomatography and fractional crystallization. Among the isolated phenolic compounds, a new acylated flavonoidic glycoside, tricin-4′-O-β-(6′′-hydroxycinnamic)-glucoside (1) was isolated from the wood of A. nilotica together with two known compounds, gallic acid and apigenin. Their structures were established by chemical evidence, spectroscopic techniques (FT-IR, 1H-NMR, 13C-NMR, HSQC, HMBC, and ESI-MS), and by comparison with already existing spectroscopic data. The yield of novel tricin glucoside showed that it make up to 0.0786% of mixed ethyl acetate and acetone extract.
  • Researchpp 2941-2953Xin, T.-T., Yuan, T., Xiao, S., and He, J. (2011). "Synthesis of cellulose-graft-poly(methyl methacrylate) via homogeneous ATRP," BioRes. 6(3), 2941-2953.AbstractPDF
    Cellulose-graft-poly(methylmethacrylate) (cellulose-g-PMMA) copolymers were prepared by homogeneous atom transfer radical polymerization (ATRP) under mild conditions, in an attempt to develop an efficient way to modify the surface of cellulose. A cellulose macro-initiator was successfully synthesized by direct homogeneous acylation of cellulose with 2-bromopropionyl bromide in a room temperature ionic liquid (RTIL), 1-allyl-3-methylimidazolium chloride ([AMIM]Cl). Copolymers were obtained via ATRP of methyl methacrylate (MMA) with CuBr/penta-methyldiethylenetriamine (PMDETA) as catalyst and N,N-dimethyl-formamide (DMF) as solvent without homopolymer byproduct. The grafting copolymers were characterized by 1H-NMR, 13C-NMR, and FTIR. The grafted PMMA chain was obtained by the hydrolysis of the cellulose backbone and analyzed by GPC and TGA measurements. In addition, the assemblies or aggregates formed by cellulose-g-PMMA copolymers were studied by means of TEM and AFM. The results indicated that the graft polymerization occurred from the cellulose backbone and the obtained copolymers had grafted polymer chains with well-controlled molecular weight and polydispersity; the cellulose graft copolymer in solution could aggregate and self-assemble into sphere-like structures.
  • Researchpp 2954-2976Gonzalez, R., Phillips, R., Saloni, D., Jameel, H., Abt, R., Pirraglia, A., and Wright, J. (2011). "Biomass to energy in the southern United States: Supply chain and delivered cost," BioRes. 6(3), 2954-2976.AbstractPDF
    Supply chain and delivered cost models for seven feedstocks (loblolly pine, Eucalyptus, natural hardwood, switchgrass, Miscanthus, sweet sorghum, and corn stover) were built, simulating a supply of 453,597 dry tons per year to a biorefinery. Delivered cost of forest-based feedstocks ranged from $69 to $71 per dry ton. On the other hand, delivered cost of agricultural biomass ranged from $77.60 to $102.50 per dry ton. The total production area required for fast growing feedstocks was estimated as between 22,500 to 27,000 hectares, while the total production area for feedstocks with lower biomass productivity ranged from 101,200 to 202,300 hectares (corn stover and natural hardwood, respectively). Lower delivered cost per ton of carbohydrate and million BTU were found for loblolly pine, Eucalyptus, and natural hardwood. In addition, agricultural biomass had higher delivered costs for carbohydrate and energy value.
  • Researchpp 2977-2989Kemppainen, K., Körkkö, M., and Niinimäki, J. (2011). "Fractional pulping of toner and pigment-based inkjet ink printed papers - Ink and dirt behavior," BioRes. 6(3), 2977-2989.AbstractPDF
    Large visible dirt specks and microscopic ink particles are released from the surface of recycled paper when pulping toner and pigment-based inkjet ink printed papers. The applicability of pulp fractionation during laboratory scale pulping was investigated without chemicals to prevent the redeposition of small ink particles to fibers, and furthermore to break down the large toner fragments. Reference pulping was performed without fractionation stages, and the two pulping procedures were compared in terms of bound ink and dirt speck content. The results show that while the microscopic ink particles redeposit to the fibers at the very beginning of conventional pulping, the redeposition can be minimized by removing the detached ink particles from the vicinity of the fibers as soon as they have been detached. Thus, it is recommended to remove the ink from the pulp before a substantial defiberization level is achieved. In addition, the dirt specks broke down more efficiently in fractional pulping than in reference pulping at the same pulping consistency.
  • Researchpp 2990-3003Xu, J., Wang, Z., Sharma-Shivappa, R. R., and Cheng, J. J. (2011). "Enzymatic hydrolysis of switchgrass and coastal Bermuda grass pretreated using different chemical methods," BioRes. 6(3), 2990-3003.AbstractPDF
    To investigate the effects of biomass feedstock and pretreatment method on the enzyme requirement during hydrolysis, swichgrass and coastal Bermuda grass pretreated using H2SO4, NaOH, and Ca(OH)2 at the optimal conditions were subjected to enzymatic hydrolysis using two enzyme combinations: NS 50013 + NS 50010 and Cellic CTec + Cellic HTec. The enzyme loadings were optimized, and correlations between feedstock property, pretreatment strategy, and enzyme usage were evaluated. The results show that pretreatment methods resulting in greater lignin contents in the pretreated biomass were generally associated with higher enzyme requirements. More sugars could be recovered from alkaline-pretreated biomass during enzymatic hydrolysis due to the better carbohydrate preservation achieved at mild pretreatment temperatures. The cellulase enzyme, Cellic CTec, was more efficient in catalyzing the hydrolysis of coastal Bermuda grass, a feedstock more digestible than the pretreated swichgrass, following pretreatment with NaOH or Ca(OH)2.
  • Researchpp 3004-3018Kowaluk, G., Fuczek, D., Beer, P., and Grzeskiewicz, M. (2011). "Influence of the raw materials and production parameters on chosen standard properties for furniture panels of biocomposites from fibrous chips," BioRes. 6(3), 3004-3018.AbstractPDF
    The particleboards with different density from specially prepared particles from black locust and willow were prepared. The standard mechanical parameters of the panels were investigated, as well as the corner wall connections with eccentric connecting fitting element or confirmat strength. The screw withdrawal resistance and hinge bearing were also measured for investigated panels. The results, compared to the strength of commercial particleboards, show that excluding panels from black locust with low density, the rest of the panels can be successfully used for furniture production purposes.
  • Researchpp 3019-3033Danish, M., Hashim, R., Ibrahim, M. N. M., Rafatullah, M., Ahmad, T., and Sulaiman, O. (2011). "Characterization of Acacia mangium wood based activated carbons prepared in the presence of basic activating agents," BioRes. 6(3), 3019-3033.AbstractPDF
    The aim of this study was to observe the effects of alkaline activating agents on the characteristics, composition, and surface morphology of the designed activated carbons. Activated carbons were prepared by pyrolysis of Acacia mangium wood in the presence of two basic activating agents (calcium oxide and potassium hydroxide). The extent of impregnation ratio of precursor to activating agents was fixed at 2:1(w/w). Prior to pyrolysis, 24 hours soaking was conducted at 348 K. Activation was carried out in a stainless steel capped graphite crucible at 773 K for 2 hours in the absence of purge gas. The burn-off percentage was found to be 70.27±0.93% for CaO activated carbon (COAC) and 73.30±0.20% for KOH activated carbon (PHAC). The activating agents had a strong influence on the surface functional groups as well as elemental composition of these activated carbons. Characterization of the activated carbon obtained was performed with field emission scanning electron microscopy (FESEM), energy dispersive X-ray spectroscopy (EDX), Fourier transform infrared spectroscopy (FTIR), thermogravimetric analysis (TGA), and nitrogen adsorption as Brunauer, Emmett and Teller (BET) and Dubinin-Radushkevich (DR) isotherms.
  • Researchpp 3034-3043Wang, Q., Chen, K., Li, J., Yang, G., Liu, S., and Xu, J. (2011). "The solubility of lignin from bagasse in a 1,4-butanediol/water system," BioRes. 6(3), 3034-3043.AbstractPDF
    The solubility of lignin from bagasse in mixed solution was investigated and explained by the solubility parameter (). To explore the lignin solubility, enzymatic hydrolysis/mild acidolysis lignin (EMAL) isolated from bagasse was used as the starting material to prepare lignin solution by ultrasonic treatment. The lignin content in solution was determined by UV-vis spectroscopy at a wavelength of 280 nm. The results showed that 240 minutes of ultrasonic treatment was needed to achieve lignin dissolution equilibrium in the 1,4-butanediol/water mixture. Maximum lignin solubility (14.6 g/L) occurred at a concentration of 80% (v/v). The δ-value of lignin (14.0 (cal/cm3)1/2) was calculated based on the atomic and functional groups present in the phenylpropane unit. The δ-values of the 1,4-butanediol/water showed a decrease from 22.31 to 11.09 (cal/cm3)1/2 as the concentration of 1,4-butanediol increased. The maximum lignin solubility predicted by the δ-value should occur at a concentration of 80% (v/v), which agreed with the experimental result.
  • Researchpp 3044-3054Zhang, Y., Cao, C.-Y., Feng, W.-Y., Xue, G.-X., and Xu, M. (2011). "Performance of a pilot-scale membrane process for the concentration of effluent from alkaline peroxide mechanical pulping plants," BioRes. 6(3), 3044-3054.AbstractPDF
    A pilot-scale membrane process for the concentration of effluent from an alkaline peroxide mechanical pulping (APMP) plant was investigated. Specifically, the cross-flow velocity and volume reduction were optimized again for a higher flux and a lower system energy consumption. A mathematical model was established to obtain the optimal parameters. Estimates were obtained of the expected savings in energy and water. The obtained optimal concentration conditions were: molecular weight cut-off at 10,000 Dalton, trans-membrane pressure at 3 bar, feed temperature at 50 oC, cross-flow velocity at 2 m/s, and volume reduction at 0.9. The average permeate flux under these conditions was 43.21 l/m2.h. The total solids content was increased from 25.47 g/L in the feed to 128.36 g/L in the concentrate. The permeate had low total solids content of 11.03 g/L, Chemical Oxygen Demand of 9180 mg/l, and Biochemical Oxygen Demand of 5870 mg/L. Such qualities would allow the permeate to be reused in the APMP process after a light biochemical treatment. With this new membrane concentration process, about 1402 kWh energy can be saved and 22 m3 effluent discharge can be reduced for each ton of pulp produced.
  • Researchpp 3055-3065Kord, B. (2011). "Evaluation on the effect of wood flour and coupling agent content on the hygroscopic thickness swelling rate of polypropylene composites," BioRes. 6(3), 3055-3065.AbstractPDF
    The effect of wood flour and coupling agent content on the hygroscopic thickness swelling rate of polypropylene composites was investigated in this study. To meet this objective, the wood flour was compounded with polypropylene and coupling agent in an internal mixer; then the samples were fabricated by injection molding. The concentration was varied from 40 to 60% for wood flour and from 0 to 4% for coupling agent. A swelling model developed by Shi and Gardner (2006) was used to study the thickness swelling process of polypropylene/wood flour composites, from which the parameter KSR can be used to quantify the swelling rate. The results indicated that the swelling model provided a good prediction of the hygroscopic thickness swelling process of polypropylene-wood flour composites immersed in water. The minimum thickness swelling values were observed in composites made of 40% wood flour and 4% of PP-g-MA. Thickness swelling of the composite increased with immersion time, reaching a certain value at saturation point, after which the composites water content remained constant. Also, a good linear relationship was fit between KSR and coupling agent contents. When the coupling agent content increased, KSR linearly decreased. The maximum tensile modulus was achieved with 60% wood flour and 4% of PP-g-MA. The SEM revealed a positive effect of coupling agent on interfacial bonding between sawdust flour and polymer matrix.
  • Researchpp 3066-3079Xi, E.-H., and Zhao, G.-J. (2011). "Research on differentiated xylem cells based on fractal dimension," BioRes. 6(3), 3066-3079.AbstractPDF
    characteristics of differentiated xylem cells of the fast-growing 76’during the active phase by the method of differential box-counting fractal dimension. The fractal characteristics of differentiated xylem cells as well as the relationship between fractal dimension and tissues proportion were considered. Results showed that the fractal dimensions of cross sections were larger than those of tangential sections. Fractal dimension of cross sections had a remarkable negative correlation with the ratio of vessel element, significant positive correlations with the proportion of wood fiber and the proportion of parenchyma. The correlation of fractal dimension with wood fiber proportion was more significant than that with parenchyma proportion. The results were also verified by replacement of the tissues in the cross section. It was observed that fractal characteristics of the wood microstructure were very much related to the proportions of different tissues of the xylem cells.
  • Researchpp 3080-3086Mirski, R., and Dziurka, D. (2011). "Applicability of strand subsitution in the core of OSB," BioRes. 6(3), 3080-3086.AbstractPDF
    Strand substitution was evaluated for the core of OSB with chips produced by grinding of recycled particleboards and wood waste. All the boards manufactured under laboratory conditions having a share of small chips in the core had high mechanical parameters, thus meeting the requirements of the standard for OSB/3. No significant effect was found of the applied modification of the core on bending strength or modulus of elasticity (MOE) determined for the longer axis. In turn, such properties as modulus of rupture (MOR) and MOE, determined for the shorter axis, as well as internal bond (IB) were rapidly reduced. In the case of boards containing 100% recycled chips in the core, a reduction was found in values of MOR, MOE, and IB by 45%, 30%, and 45%, respectively. In turn, the application of small chips, which previously had not been resinated, makes it possible to manufacture boards with internal bond lower by only 30%, even at the 100% substitution. Application of recycled chips produced by grinding of the P2 type particleboard did not make it possible to manufacture boards meeting the requirements of the standard after the boiling test, irrespective of the amount of small chips added to the core. Boards containing in their core small chips, which previously had not been resinated, had much better properties in this respect, since only in case of 100% substitution the manufactured boards exhibited internal bond after the boiling test lower than the requirements of the standard EN 300.
  • Researchpp 3087-3095Wang, Y., Chen, K., Mo, L., and Hu, H. (2011). "A cationic polyacrylamide dispersion synthesis by dispersion polymerization in aqueous solution," BioRes. 6(3), 3087-3095.AbstractPDF
    A cationic polyacrylamide (CPAM) dispersion, the copolymer of acrylamide (AM) and acryloyloxyethyltrimethyl ammonium chloride (DAC), has been synthesized through dispersion polymerization in aqueous ammonium sulfate ((NH4)2SO4) solution. The polymerization was initiated by tert-butyl hydroperoxide (TBHP) and ferrisulfas (FeSO4) using poly(dimethyl diallyl ammonium chloride) (PDMDAAC) as the stabilizer. At the optimal reaction conditions, the relative molecular weight of the CPAM dispersion was 4.2×106, its charge density was 2.2 mmol·g-1, its average particle size was 6.01 μm, and its stability and dissolvability were both excellent. The CPAM dispersion was characterized using Fourier-transform infrared (FTIR) spectroscopy, nuclear magnetic resonance (NMR) spectroscopy, and differential scanning calorimeter (DSC). Results indicated that the copolymerization was successful.
  • Researchpp 3096-3114Gullón, P., Salazar, N., González Muñoz, M. J., Gueimonde, M., Ruas-Madiedo, P., de los Reyes-Gavilán, C. G., and Parajó, J. C. (2011). "Assessment on the fermentability of xylooligosaccharides from rice husks," Biores. 6(3), 3096-3114.AbstractPDF
    Rice husks were subjected to processing with hot, compressed water under selected conditions to cause the partial breakdown of xylan into soluble products (mainly xylooligosaccharides, XOS). The reaction media were subjected to membrane processing, endoxylanase treatment and ion exchange to obtain purified XOS concentrates. Human fecal slurry cultures with XOS were carried out to assess their bifidogenic activity to stimulate the production of Short Chain Fatty Acids (SCFA) and lactic acid. Results were compared with data obtained in similar cultures containing the prebiotic inulin and the non-prebiotic glucose. The experimental results confirmed the ability of XOS concentrates to act as fermentable carbohydrates for the human colonic microbiota, producing a rapid decrease of pH, comparable to that promoted by glucose and more pronounced than that occurring with inulin. XOS having different DP were degraded at different rates. The experimental results confirmed the ability of rice husk’s XOS concentrates for supporting the growth of bifidobacteria and for acting as carbon sources, leading mainly to the generation of acetic and lactic acids.
  • Researchpp 3115-3131Chaochanchaikul, K., Rosarpitak, V., and Sombatsompop, N. (2011). "Structural and thermal stabilizations of PVC and wood/PVC composites by metal stearates and organotin," BioRes. 6(3), 3115-3131.AbstractPDF
    Structural and thermal stabilizations of poly(vinyl chloride) (PVC) and wood/PVC (WPVC) composites were studied using lead stearate (PbSt2), calcium/zinc complex (Ca/Zn) stabilizers, and methyl tin mercaptide (MT). Thermal and structural stabilities of PVC and WPVC composites were assessed using FTIR spectrometer, thermogravimetric analysis (TGA) and UV-Vis spectrophotometry. The results indicated that the additions of thermal stabilizers into PVC and WPVC composites could promote the thermal stabilities under both un-aged and thermally aged conditions. The presence of wood particles resulted in increases in polyene and carbonyl sequences during processing and decreases in the decomposition temperature (Td). The presence of wood was found to accelerate the thermal degradation in PVC, and suppressed the efficiencies of the thermal stabilizers used. By increasing the stabilizer dosage, the thermal degradations of PVC and WPVC were moderated. Under thermally aged condition at 177oC, the additions of thermal stabilizer could decrease the increase in yellowness index (YI) and discoloration at different ageing times. In this work, MT was found to be the most suitable and promising stabilizer for PVC and WPVC composites, considering the polyene and carbonyl contents, Td, the shift of derivative thermogravimetric (DTG) curves, and changes in YI value and visual color.
  • Researchpp 3132-3141Morrison, D., van Dyk, J. S., and Pletschke, B. I. (2011). "The effect of alcohols, lignin and phenolic compounds on the enzyme activity of Clostridium cellulovorans XynA," BioRes. 6(3), 3132-3141.AbstractPDF
    In the production of biofuel from lignocellulose biomass, particularly in the case of consolidated bioprocessing where the saccharification and fermentation steps take place within the same bioreactor, many compounds may be present that could affect the enzymes within such a bioreactor. This study examined the effect of ethanol, butanol, propanol, lignin, r-coumaric acid, and gallic acid on the activity of XynA from C. cellulovorans. XynA from C. cellulovorans was purified, and the effects of various compounds on enzyme activity were assayed using the dinitrosalicylic acid method. In this study, it was found that XynA was very tolerant to ethanol and only lost 25% of activity even at high concentrations of ethanol. In the presence of lignin, XynA was inhibited at very low levels and retained ~85% of its activity. The highest degree of inhibition of XynA was experienced in the presence of r-coumaric acid (38%) and gallic acid (47%). The results indicate that the most problematic compounds within the bioreactor are likely to be soluble lignin degradation products resulting from pretreatment steps. Therefore, the removal of these compounds prior to saccharification should result in increased productivity within a bioreactor. This study indicates that XynA may be a suitable hemicellulase for use in bioethanol production, as it has very high tolerance for ethanol inhibition.
  • Researchpp 3142-3154Ravindran, C., Varatharajan, G. R., and Karthikeyan, A. (2011). "Role of alkaline-tolerant fungal cellulases in release of total antioxidants from agro-wastes under solid state fermentation," BioRes. 6(3), 3142-3154.AbstractPDF
    The alkaline-tolerant marine-derived fungus Chaetomium globosum was tested for the production of enhanced levels of cellulases and free phenolics under highly alkaline conditions using agro wastes (cotton seed, sugar cane bagasse) as substrates under solid state fermentation (SSF) processes. In both the agro wastes used, an increase in cellulases (β-endoglucanase, β-Glucosidase, and β-exoglucanase) production was observed with increase in pH. This enhanced carbohydrate-hydrolyzing enzymes (β-endoglucanase, β-Glucosidase and β-exoglucanase) and thereby enriched the total phenolic release from agro-wastes under SSF conditions of higher pH. A linear correlation was observed between released total phenolic contents of agro-wastes and total antioxidant property. The increased antioxidant activity on free radical scavenging was also observed with the increase in pH. Thus, the present study makes it possible to produce nutraceutical ingredients cost-effectively from agricultural wastes.
  • Researchpp 3155-3165Acharya, S. K., Mishra, P., and Mehar, S. K. (2011). "Effect of surface treatment on the mechanical properties of bagasse fiber reinforced polymer composite," BioRes. 6(3), 3155-3165.AbstractPDF
    Bagasse is a by-product of the sugarcane milling process, and it also is an important fuel resource for that industry. In this study an attempt has been made to utilize this by-product to prepare a composite using epoxy resin. The fibers surface was modified by alkali treatment with 5% NaOH solution for 0, 2, 4 and 6 hrs. The effect of fiber surface modification on the mechanical properties such as flexural strength of the composites was investigated with the fibers as received from the milling process. It was found that alkali-treated bagasse/epoxy composites significantly improved the flexural strength of the composite. An SEM investigation also indicated that the surface modifications improved the fiber–matrix interaction.
  • Researchpp 3166-3177Sönmez, A., Budakçı, M., and Pelit, H. (2011). "The effect of the moisture content of wood on the layer performance of water-borne varnishes," BioRes. 6(3), 3166-3177.AbstractPDF
    The test panels obtained from Scots pine (Pinus sylvestris L.) and Eastern beech (Fagus orientalis L.) were initially adjusted to have 8%, 10%, and 12% moisture content in this study. One-component semi-matte and two-component water borne varnishes were applied on the surfaces in order to investigate the effect of the type and the moisture content of the wood on the hardness and the gloss values as well as the adhesion strength of the varnishes. The hardness of the test samples was evaluated based on the standard ANS/ISO1522, the gloss based on TS.4318 EN ISO 2813, and the adhesive strength based on ASTM D-4541. The results indicated that variations in the moisture content of the wood material adversely affected the layer performance of water-borne varnishes and that the best performance was obtained for the wood with moisture contents of 8% and 10%.
  • Researchpp 3078-3187Ayrilmis, N. (2011). "Effect of fire retardants on surface roughness and wettability of wood plastic composite panels," BioRes. 6(3), 3178-3187.AbstractPDF
    Surface roughness and wettability of flat-pressed wood plastic composites (WPCs) incorporated with various fire retardants (FRs) (5, 10, or 15% by weight (wt)) at 50 wt-% content of the wood flour (WF) were investigated. The most common FRs, zinc borate (ZB), magnesium hydroxide (MH), and ammonium polyphosphate (APP), were used in the experiments. The WPC panels were made from dry-blended wood flour (WF), fire retardant (FR) powder, and polypropylene (PP) powder with maleic anhydride-grafted PP (2 wt-%) formulations using a conventional flat-pressing process under laboratory conditions. The contact angle measurements were obtained by using a goniometer connected with a digital camera and computer system. Three roughness measurements, average roughness (Ra), mean peak-to-valley height (Rz), and maximum roughness (Ry), were taken from the WPC panel surface using a fine stylus tracing technique. It was found that the surface smoothness of the WPC panels decreased with increasing content of the FR powder while the wettability increased. The control WPC panel without the FR had the smoothest surface, followed by the WPC panels containing the MH, ZB, and APP, respectively.
  • Researchpp 3188-3198Cheng, F., and Hu, Y. (2011). "Reliability analysis of timber structure design of poplar lumber with nondestructive testing methods," BioRes. 6(3), 3188-3198.AbstractPDF
    The safety of timber structure design based on the predicted Modulus of Rupture (MOR) of poplar lumber with nondestructive methods is presented in this paper. Dynamic(MOE) of poplar lumber was measured with three different nondestructive methods, and static MOE and MOR were obtained by a static bending test. The regression relationship between various MOE and MOR was evaluated to predict MOR with various MOE. Then timber construction design was conducted on poplar lumber based on measured and predicted MOR. Furthermore, reliability of timber structure design was analyzed with advanced first-order second-moment method. Results indicated that mean values of predicted MOR were slightly greater than those of measured MOR, but Coefficient of Variation (COV) of them were less than those of measured MOR. The reliability index of timber structure design based on predicted MOR, varying from 2.404 to 2.574, was less than that on measured MOR as 2.831.
  • Researchpp 3199-3209Tajdini, A., Tavakkoli, A., Jahan Latibari, A., Roohnia, M., and Tayeb, S. A. H. M. (2011). "Application of simultaneous equations model to estimate particleboard demand and supply," BioRes. 6(3), 3199-3209.AbstractPDF
    Dynamic supply and demand equations for particleboard using a three-stage squares simulation (3SLS) were estimated. Empirical data included annual observations over the period of 1976 to 2006. The stationary character of the data was checked by applying the Augmented Dickey-Fuller (ADF) Test. The results revealed that in the demand function, variables such as particleboard price, the gross national product (GNP) in the previous year (lagged quantity), and the MDF price were significant at 0.05%. In the supply function, variables such as the price of medium density fiberboard (MDF), demand for particleboard in the previous year, the product/raw material price ratio in the previous year, and particleboard imports in the previous year were shown to be significant at 0.05%. Also price, income, and cross elasticities of demand for particleboard were calculated as -0.65, 0.32, and 1.63, respectively, indicating that this commodity is a necessary and normal good and MDF is a substitute for it.
  • Researchpp 3210-3230Huang, H.-J., and Ramaswamy, S. (2011). "Thermodynamic analysis of black liquor steam gasification," BioRes. 6(3), 3210-3230.AbstractPDF
    Pulp and paper mills represent a major platform for the use of abundant, renewable forest-based biomass as raw material. The pulping processes produce a large amount of black liquor solids, which is currently burnt in a conventional Tomlinson recovery boiler for recovery of energy and inorganic chemicals. This combustion technology can recover chemicals with good efficiency, and steam and power can be produced for the mills. However, Black Liquor Gasification (BLG) can be used to substitute for the combustion process for potential higher energy efficiency, lower greenhouse gas emissions, and more safety. With BLG technology, current pulp and paper mills can be extended into future biorefineries. In this work, a thermodynamic equilibrium model using Gibbs free energy minimization approach and the software FactSage are utilized to analyze the thermodynamic equilibrium constraints of the complex multiple phase reactions and the effects of different operating conditions during black liquor gasification. The modeling results can help better understand the black liquor gasification process and be useful in process modeling and analysis of the future BLG-based biorefinery.
  • Researchpp 3231-3241Eugenio, M. E., Hernández, M., Moya, R., Martín-Sampedro, R., Villar, J. C., and Arias, M. E. (2011). "Evaluation of a new laccase produced by Streptomyces ipomoea on biobleaching and ageing of kraft pulps," BioRes. 6(3), 3231-3241.AbstractPDF
    The aim of this work is to prove the suitability of a new alkaline and halo-tolerant bacterial laccase (SilA) produced by Streptomyces ipomoea CECT 3341 to enhance the conventional chemical bleaching process of an industrial eucalyptus kraft pulp. The laccase used for this study was a recombinant laccase obtained from cultures of E. coli BL21 (DE3) grown in LB liquid medium. The biobleaching experiment was carried out on Eucalyptus globulus kraft pulps using the above mentioned laccase and acetosyringone as natural mediator. Then, an alkaline extraction and further hydrogen peroxide steps were applied to evaluate the efficiency of the laccase-mediator system as a pretreatment in the bleaching sequences. Biobleached pulps showed a kappa number decrease and a brightness increase without decreasing the viscosity values significantly. Also, a reduction in the consumption of hydrogen peroxide was observed when the enzymatic treatment was applied to the pulp. CIE L*a*b* and CIE L*C* color coordinates measured in pulps demonstrated that among all treatments applied to pulps, the laccase-acetosyringone system presented the best optical properties even after an accelerated ageing process. Finally, it is also remarkable that during this treatment 64% of the laccase activity remained unaltered.
  • Researchpp 3242-3251Klasson, K. T., Uchimiya, M., Lima, I. M., and Boihem, Jr., L. L. (2011). "Feasibility of removing furfurals from sugar solutions using activated biochars made from agricultural residues," BioRes. 6(3), 3242-3251.AbstractPDF
    Lignocellulosic feedstocks are often prepared for ethanol fermentation by treatment with a dilute mineral acid catalyst that hydrolyzes the hemicellulose and possibly cellulose into soluble carbohydrates. The acid-catalyzed reaction scheme is sequential, whereby the released monosaccharides are further degraded to furans and other chemicals that are inhibitory to the subsequent fermentation step. This work tests the use of agricultural residues (e.g., plant waste) as starting materials for making activated biochars to adsorb these degradation products. Results show that both furfural and hydroxymethylfurfural (HMF) are adsorbed by phosphoric acid-activated and steam-activated biochars prepared from residues collected from cotton and linen production. Best results were obtained with steam-activated biochars. The activated biochars adsorbed about 14% (by weight) of the furfurals at an equilibrium concentration of 0.5 g/L, and by adding 2.5% of char to a sugar solution, with either furfural or HMF (at 1 g/L), 99% of the furans were removed.
  • Researchpp 3252-3259Guo, H., Ma, A., Zhao, G., Yun, J., Liu, X., Zhang, H., and Zhuang, G. (2011). "Effects of farnesol on Penicillium decumbens's morphology and cellulase production," BioRes. 6(3), 3252-3259.AbstractPDF
    It is possible to improve cellulase production by controlling fungal morphology. Farnesol, the first quorum-sensing molecule found in eukaryotic organisms, is reported to influence the morphology of fungi. In this work, farnesol was investigated for its effect on morphology and cellulase production of Penicillium decumbens. Scanning electron microscopy (SEM) revealed that farnesol promoted the growth of hyphae, making possible and facilitating a higher yield of cellulase secretion. Enhanced interaction with the substrate in fermentation led to greater cellulase production. These findings are associated with the subsequent cellulase production of the fungus. Compared with a control medium, exogenously added 1 mM farnesol resulted in 1.32-fold increase in maximal filter paper activity with no significant change in the activity per unit of protein. These results provide a novel way to improve the cellulase production, promoting the commercial application of cellulase.
  • Researchpp 3260-3271Viet Cao, X., Ismail, H., Rashid, A. A., Takeichi, T., and Vo-Huu, T. (2011). "Mechanical properties and water absorption of kenaf powder filled recycled high density polyethylene/natural rubber biocomposites using MAPE as a compatibilizer," BioRes. 6(3), 3260-3271.AbstractPDF
    The performance of kenaf powder (KP) filled recycled high density polyethylene (rHDPE) /natural rubber (NR) blends with and without a compatibilizer, were investigated. The composites with different filler loading (0 to 40 phr) were prepared with a Haake internal mixer. Increasing the KP loading in rHDPE/NR/KP biocomposites reduced the tensile strength and the elongation at break but increased the stabilization torque and the tensile modulus. The addition of MAPE as a compatibilizer increased the tensile strength, elongation at break, and modulus of the composites. This might be attributed to the enhanced adhesion between the filler and polymer matrix, as evidenced from the morphology, using scanning electron microscopy. The incorporation of compatibilizer also reduced the water absorption of the composites.
  • Researchpp 3272-3288Kilulya, K. F., Msagati, T. A. M., Mamba, B. B., Ngila, J. C., and Bush, T. (2011). "Imidazolium ionic liquids as dissolving solvents for chemical-grade cellulose in the determination of fatty acids using gas chromatography-mass spectrometry," BioRes. 6(3), 3272-3288.AbstractPDF
    A quick, simple, and environmentally friendly sample preparation method for fatty acids analysis from chemical-grade cellulose was developed employing imidazolium based ionic liquids as solvents. A variety of imidazolium based ionic liquids were screened for their ability to dissolve chemical cellulose at different temperatures. Dissolution of chemical cellulose was observed to be dependent on the ionic liquids’ anions as well as temperature. The effect of ionic liquids on chemical cellulose was examined using FT-IR and TGA techniques, which showed no difference between the original and the regenerated cellulose except for the percentage mass residues in TGA profile which was high for regenerated cellulose, 15% compared to 8% of the original at 600 °C. Fatty acids extracted from cellulose were found to be predominant in the samples from different bleaching stages, with high levels in the oxygen delignification and low levels were observed in hypochlorite bleached samples. The number and levels of the identified fatty acids were observed to decrease with the bleaching sequence. The recoveries obtained using this method ranged from 90 - 107%.
  • Researchpp 3289-3299Hosseinihashemi, S. K., Modirzare, M., Safdari, V., and Kord, B. (2011). "Decay resistance, hardness, water absorption, and thickness swelling of a bagasse fiber/plastic composite," BioRes. 6(3), 3289-3299.AbstractPDF
    The decay resistance, hardness, water absorption, and thickness swelling of a bagasse fiber/polypropylene composite were evaluated. Brown- (Coniophora puteana) and white-rot (Trametes versicolor) fungal treatments were applied for 8, 12, and 16 weeks according to BS 838:1961 with the kolle-flask method. The brown- and white-rotted, and control composite samples were immersed in distilled water at 2 h and 24 h to measure the water absorption and thickness swelling of samples according to the ASTM D 570-98 requirements. Results indicated that the both lowest (3.2%) and the highest (7.2%) weight loss were observed in the white-rotted composite samples for 8 and 16 weeks fungal exposure times, respectively. The highest hardness (77.6 Shore D) was noted in the control composite samples, and the lowest hardness (65.5 Shore D) was recorded in the white-rotted composite samples. The highest water absorption (10.5%) was observed in the brown-rotted composite samples for 8 weeks fungal exposure time and after 24 h immersion in distilled water, and the lowest (3.8%) was noted in the control composite samples after 2 h immersion in distilled water. The highest thickness swelling (6.3%) was observed in the control composite samples after 24 h immersion in distilled water, and the lowest thickness swelling (1.9%) was found in the white-rotted composite samples for 16 weeks fungal exposure time and after 2 h immersion in distilled water.
  • Researchpp 3300-3312Chen, X., Shen, W., Kou, S., and Liu, H. (2011). "GC-MS study of the removal of dissolved and colloidal substances in recycled papermaking by flocculation with nano-size TiO2 colloids," BioRes. 6(3), 3300-3312.AbstractPDF
    In the papermaking process, the removal and control of dissolved and colloidal substances (DCS) is a key issue for reducing the usage of fresh water. Nano-size TiO2 is an excellent capturing and flocculating agent for DCS due to its large surface area and positive charge. The composition of dissolved and colloidal substances in a system and the removal of these substances by flocculation with nano-size TiO2 colloids were determined by gas chromatography and mass spectrometry (GC-MS). The samples were obtained from non-deinked pulp (non-DIP), deinked pulp (DIP), and whitewater. The research results indicated that the removal efficiencies of the DCS, which are associated with the molecular structures, were sequenced from large to small as follows: resin acids and sterols, benzene derivatives containing carboxyl, fatty acids, and the phthalic acid esters. Then, the mechanism of flocculation removal of DCS was considered. With hydrogen bonding between the surface hydroxyl (Ti4+-OH) and the functional groups containing oxygen, the nano-size TiO2 particles can capture dissolved substances (DS), and bridge colloidal substances (CS) and complexes to induce agglomerate flocculation. The flocculating removal efficiencies were influenced by the functional groups and alkyls of the DCS. Greater numbers and polarities of functional groups produced higher removal efficiencies. Long alkyl chains shield functional groups, thereby inhibiting the formation of hydrogen bonding, which results in a decrease in removal efficiencies.
  • Researchpp 3313-3323Samariha, A., and Khakifirooz, A. (2011). "Application of NSSC pulping to sugarcane bagasse," BioRes. 6(3), 3313-3323.AbstractPDF
    The NSSC pulping process was investigated to produce pulp from bagasse for corrugating board manufacture. The chemical contents including cellulose, lignin, ash, and extractives soluble in alcohol-acetone measured 55.75, 20.5, 1.85, and 3.25, respectively. The average fiber length, fiber diameter, lumen width, and cell wall thickness of bagasse were 1.59 mm, 20.96, 9.72, and 5.64 μm, respectively. The optimum conditions, with a yield of 74.95%, were achieved using 20 percent chemicals on the basis of sodium oxide, cooking temperature of 170 °C, and cooking time of 30 minutes. Pulp was refined to freeness 345 and 433 mL CSF according to Canadian standards. 127 g m-2 handsheets from both pulps were made and strength properties measured. Statistical analysis of results indicated that paper derived from freeness 345 and 433 mL CSF had better strength properties in all indices in comparison with NSSC pulp from hardwoods produced at Mazandaran Pulp and Paper factory, Iran.
  • Researchpp 3324-3338Mahajan, G., and Sud, D. (2011). "Kinetics and equilibrium studies of Cr(VI) metal ion remediation by Arachis hypogea shells: A green approach," BioRes. 6(3), 3324-3338.AbstractPDF
    Arachis hypogea shells (ground nut shells), a lignocellulosic waste biomass, was evaluated for sequestering of Cr(VI) from synthetic wastewater. Arachis hypogea shells (AHS) were used in three different forms, viz. natural (AHSN), immobilized in the form of beads (AHSB), and in the form of activated carbon (AHSC). Batch experiments were performed for the removal of hexavalent chromium. Effects of pH adsorbent dose, initial metal ion concentration, stirring speed, and contact time were investigated. The removal of metal ions was dependent on the physico-chemical characteristics of the adsorbent, adsorbate concentration, and other studied process parameters. Maximum metal removal for Cr(VI) was observed at pH 2.0. The experimental data were analyzed based on Freundlich and Langmuir adsorption isotherms. Kinetic studies indicated that the adsorption of metal ions followed a pseudo-second-order equation.
  • Researchpp 3339-3351Wang, W., Zhao, Z., Gao, Z., and Guo, M. (2011). "Whey protein-based water-resistant and environmentally safe adhesives for plywood," BioRes. 6(3), 3339-3351.AbstractPDF
    Whey protein is a renewable and environmentally safe biomaterial, a by-product of cheese production. It can be utilized for non-food applications for value-added products. The substances glyoxal (GO), glutaraldehyde (GA), polymeric methylene biphenyl diisocyanate (p-MDI), urea-formaldehyde (UF) resin, and phenol-formaldehyde oligomer (PFO) that contain reactive groups were applied together with whey protein as modifier in order to increase crosslinking density and molecular weight for improving the bond strength and water resistance of whey protein. A water-resistant and environmentally safe whey protein-based wood adhesive for plywood was developed by evaluating the effects of these modifiers on the bond strength, bond durability, and free formaldehyde emission of the resulting plywood panels. Results of FTIR and SEM analyses and bond evaluation indicated that GO, GA, and p-MDI were not suitable to modify whey proteins due to their high reactivity with whey proteins, causing phase separation. UF resin was not a good modifier for whey proteins because of either its poor water-resistance or higher emission of hazardous formaldehyde. Whey protein adhesives modified with PFO had a dry shear bond strength of 1.98 MPa and a 28h-boiling-dry-boiling wet shear strength of 1.73 MPa, which were both much higher than the required values for structural use according to standard JIS K6806-2003, while its formaldehyde emission was 0.067mg/L, much lower than the required value for green plywood according to standard JIS A5908.
  • Researchpp 3352-3362Hein, P. R. G., and Brancheriau, L. (2011). "Radial variation of microfibril angle and wood density and their relationships in 14-year-old Eucalyptus urophylla S. T. Blake wood," BioRes. 6(3), 3352-3362.AbstractPDF
    The orientation of cellulose microfibrils in the cell wall along the stem axis has major effects on stiffness and longitudinal shrinkage and is of key importance in wood quality. The aim of this study was to investigate the radial variability of MFA and wood density (ρ) and their relationships in Eucalyptus urophylla wood. Three MFA values were estimated by X-ray diffraction at three points of each one of the 175 tangential sections, and the basic density was measured. A decrease of microfibril angles from pith to bark can be observed in most samples; however, some radial strips presented different patterns of variation. For basic density, a linear significant increase from pith to bark was confirmed. There was no significant correlation between microfibril angle and density. The relationships among the three MFA estimated on tangential sections of wood were strong. The “curvature effect” due to the growth rings had a negligible effect on the three measurements of tangential sections cut near to the pith. This study showed that a single T value measurement by X-ray diffraction, preferably at the centre of the tangential section, is precisely sufficient to estimate the mean MFA of Eucalyptus urophylla wood.
  • Researchpp 3363-3375Olivella, M. À., Jové, P., Şen, A., Pereira, H., Villaescusa, I., and Fiol, N. (2011). "Sorption performance of Quercus cerris cork with polycyclic aromatic hydrocarbons and toxicity testing," BioRes. 6(3), 3363-3375.AbstractPDF
    Quercus cerris is an important oak species extended in large areas of Eastern Europe and Minor Asia that has a thick bark which is not utilized at all. The sorption performance of cork from Quercus cerris bark with four polycyclic aromatic hydrocarbons (PAHs) (acenaphthene, fluorene, phenanthrene, and anthracene) was investigated. Quercus cerris cork was characterized for elemental analysis, acidic groups, and summative chemical composition, and the results were compared with Quercus suber cork. A Microtox® test was carried out to test for the release of any toxic compounds into the solution. All isotherms fit the Freundlich model and displayed linear n values. Quercus cerris exhibited a high efficiency for sorption of PAHs for the studied concentrations (5 to 50 µg/L) with 80-96% removal, while the desorption isotherms showed a very low release of the adsorbed PAHs (<2%). In relation to Quercus suber cork, KF values of Quercus cerris cork are about three times lower. The quantity of Quercus cerris cork required to reduce water pollution by PAHs was estimated to be less than twice the quantity of other adsorbents such as aspen wood and leonardite. Toxicity tests indicated that non-toxic compounds were released into the solution by the Quercus cerris and Quercus suber cork samples. Overall the results indicate the potential use of Quercus cerris cork and of Quercus suber cork as effective and economical biosorbents for the treatment of PAH-contaminated waters.
  • Researchpp 3376-3395Neto, V. O. S., Oliveira, A. G., Teixeira, R. N. P., Silva, M. A. A., Freire, P. T. C., Keukeleire, D. D., and Nascimento, R. F. (2011). "Use of coconut bagasse as alternative adsorbent for separation of copper(II) ions from aqueous solutions: Isotherms, kinetics, and thermodynamic studies," BioRes. 6(3), 3376-3395.AbstractPDF
    The use of coconut bagasse as an adsorbent for the treatment of Cu(II) ions from aqueous solutions has been investigated. The adsorbent was characterized by infrared spectroscopy, including zeta potential and pH effects. To assess the possibility of removing Cu(II) from aqueous solutions by this sorbent the effects of contact time, initial metal ion concentration, and temperature were studied at pH 5.5. Kinetic studies showed that the amount adsorbed increased with initial Cu(II) concentration, and the equilibrium was established in 120 min. The kinetic data were analyzed using a pseudo second-order equation. Adsorption equilibrium data were investigated using the Langmiur, Freundlich, D–R, Temkin and Halsey isotherm models. The adsorption of Cu(II) on the coconut bagasse was endothermic (DH◦ 86.2 kJ/mol), resulting in an increase in entropy (DS◦ 339 J/mol/K) and a decrease in Gibbs free energy (DG -16.34 to -22.44 kJ/mol) in the temperature range of 301-313 K. A reduction in adsorption capacity with an increase in heat of adsorption revealed an ion exchange mechanism for Cu(II) adsorption.
  • Researchpp 3396-3409Wu, W.-B., Jing, Y., Gong, M.-R., Zhou, X.-F., and Dai, H.-Q. (2011). "Preparation and properties of magnetic cellulose fiber composites," BioRes. 6(3), 3396-3409.AbstractPDF
    Magnetic cellulose fiber composites were prepared by a “vacuum-lumen-loading” method with polyethylenimine (PEI) as retention aid. The composites thus formed preserved the inherent properties of the cellulose fiber and gained the magnetically responsive properties of nanoparticles. Magnetic paper was further made from the composites. These materials were characterized by X-ray diffraction, transmission electron microscopy, scanning electron microscopy, a vibrating sample magnetometer, and paper testers. There was a large amount of magnetic nanoparticles deposited on the exterior, in the pores, and especially in the lumen of fibers. Lumen loading of nanoparticles is favored by pulp beating, silica shell modification of magnetite, vacuum conditioning, and usage of PEI. The physical strength of paper was reduced to a certain extent because of unavoidable deposition of nanoparticles on the exterior of fibers, which could block the formation of hydrogen bonding between fibers. Our results show that both the cellulose fiber composites and the resulting paper possessed good superparamagnetism with tiny remnant magnetization and coercivity. These materials will allow the investigation of new concepts in paper making and packaging, security paper, and information storage.
  • Researchpp 3410-3423Chen, Y., Qian, X., and An, X. (2011). "Preparation and characterization of conductive paper via in situ polymerization of 3,4-ethylenedioxythiophene," BioRes. 6(3), 3410-3423.AbstractPDF
    Conductive paper was prepared via in situ chemical oxidative polymerization of 3,4-ethylenedioxythiophene (EDOT) in pulp suspension by using iron(III) p-toluenesulfonate (Fe(OTs)3) as both an oxidant and a dopant source. The deposition of poly(3,4-ethylenedioxythiophene) (PEDOT) on the pulp fiber surface was verified and characterized by ATR-FTIR and SEM analyses. The factors affecting the conductivity of the PEDOT-coated paper were investigated, and the preparation conditions of the conductive paper with a low resistivity and excellent environmental stability was obtained. The optimum reaction temperature and time were 60 °C and 4 h, respectively. The molar ratio of EDOT to Fe(OTs)3 of 1:1 was optimal when considering both cost and performance factors. The conductivity of the PEDOT-coated paper could be controlled by adjusting EDOT concentration. The threshold concentration of EDOT was about 3 g·L-1, and a volume resistivity as low as 5.9103 Ω·cm could be achieved, which reached the conductivity range of an electrical conductor. The environmental stability of the PEDOT-coated conductive paper was very good due to the much higher oxidation potential of PEDOT.
  • Researchpp 3424-3439Tsoi, W.-Y. I., Kan, C.-W., and Yuan, C.-W. M. (2011). "Using ageing effect for hydrophobic modification of cotton fabric with atmospheric pressure plasma," BioRes. 6(3), 3424-3439.AbstractPDF
    A hydrophobic modification of cotton fabric was demonstrated with atmospheric pressure plasma treatment with oxygen as the reactive gas. Oxygen plasma was determined to be capable of inducing hydrophobic modification of cotton fabric surface by utilizing the ageing effect. Upon ageing, the surface polarity was reversed and hydrophobic aliphatic hydrocarbons were formed, which was confirmed by Fourier Transform Infrared Spectroscopy. Surface hydrophobicity was quantified by the wetting area measurement. Wetted area of plasma-modified cotton was found to be strongly dependent on plasma-induced surface structures and the chemical composition on the fiber surface. Scanning electron microscopy revealed that physical morphological alteration was also a crucial factor that contributed to surface hydrophobicity. This work seeks to determine a controlled hydrophobic modification of textile materials through optimization of plasma process based on the Orthogonal Array Testing Strategy (OATS). Optimum process conditions were determined based on reduction of wetted area of plasma-modified cotton fabrics. Finally, hydrophobicity of plasma-modified cotton fabric was compared with conventional water repellency treatment.
  • Researchpp 3440-3451Zhong, W., Yu, H., Song, L., and Zhang, X. (2011). "Combined pretreatment with white-rot fungus and alkali at near room-temperature for improving saccharificaiton of corn stalks," BioRes. 6(3), 3440-3451.AbstractPDF
    Although biological pretreatment has the advantages of being environmentally friendly and having low-energy consumption, it usually requires a relatively long incubation time. In this study, a novel combined pretreatment with white-rot fungus and alkali at near room-temperature for saccharification of corn stalks was investigated to speed up the biological process. Biological pretreatment with Irpex lacteus or Echinodontium taxodii can improve enzymatic hydrolysis of corn stalk greatly, but the process requires a long time (60 days) to achieve a satisfactory sugar yield. The combination processes with the fungi were compared with the sole pretreatments. The results showed that the time of the biological process could be shortened to 15 days when the bio-treatment with I. lacteus was combined with alkali pretreatment. The efficiency of alkali pretreatment can be also enhanced significantly by biological treatment. 271.1mg/g of final glucose yield was obtained for the combination pretreatment, which was an improvement of 50.4% and 28.3% in comparison with the sole alkali pretreatment at the same and optimum reaction time, respectively. In conclusion, the combination of biological pretreatment with alkali processes not only speeded up the biological process, but also improved the sugar yield in comparison to the sole pretreatment and is favorable for the development of biological pretreatment.
  • Researchpp 3452-3468Buyukkileci, A. O., Tari, C., and Fernandez-Lahore, M. (2011). "Enhanced production of exo-polygalacturonase from agro-based products by Aspergillus sojae," BioRes. 6(3), 3452-3468.AbstractPDF
    Aspergillus sojae has been previously shown to produce exo-polygalacturonase (exo-PG) in synthetic media, where the potential of the organism to utilize agricultural substrates was not considered so far. In this study, the utilization of agro-based products was taken into account in the enhanced production of exo-PG using an A. sojae mutant by applying statistical design methods. Complex sources (orange peel, wheat bran, and corn meal), simple sugar sources (glucose, maltrin, and sugar beet syrup), and two phosphate salts were screened using D-optimal design method. Orange peel yielded the highest exo-PG activity with all simple sugars and phosphate sources. According to the results of response surface methodology (RSM), the optimum concentrations of orange peel, sugar beet syrup, and (NH4)2SO4 were found to be 10, 60, and 8 g L-1, respectively. The exo-PG activity under these conditions was 145.4 U m L-1 in shake flask cultures. In bioreactor studies enzyme production was induced at low pH values; thus highest production was obtained under uncontrolled pH conditions, in which the pH dropped to 2.0 in 72 h. As a result high exo-PG could be produced by an A. sojae mutant using a cost-effective medium containing agro-industrial substrates. Another important advantageous outcome was the low optimal pH, which is especially desired in industrial fermentations prone to contamination problems. In fact this highlights the easy adaptation of this fermentation to industrial scales.
  • Researchpp 3469-3480Liu, W., Yuan, Z., Mao, C., Hou, X., and Li, K. (2011). "Removal of hemicelluloses by NaOH pre-extraction from aspen chips prior to mechanical pulping," BioRes. 6(3), 3469-3480.AbstractPDF
    chips prior to mechanical pulping, which would offer new feedstocks for the production of chemicals and fuels. The aim of this study was to evaluate pre-extraction to maximize pre-extraction yield, while minimizing negative impacts on wood chips. The effects of three independent process variables (NaOH charge, pre-extraction temperature, and time) on three dependent variables (pre-extraction yield, xylan extraction yield, and cellulose content based on original wood) were studied using a Box-Behnken experimental design. The mathematical models were obtained and validated well. It was found that NaOH charge, time, interaction between NaOH charge and time, and interaction between temperature and time have significant effects on xylan extraction yield. The xylan extraction yield was 22.55%; i.e., about 37.3 kg of xylan could be extracted from one ton of oven-dried aspen chips under the conditions of 5.68% NaOH charge, 100 °C, and 35 min.
  • Researchpp 3481-3492Ferraz, J. M., Del Menezzi, C. H. S., Teixeira, D. E., and Martins, S. A. (2011). "Effects of treatment of coir fiber and cement/fiber ratio on properties of cement-bonded composites," BioRes. 6(3), 3481-3492.AbstractPDF
    This study investigated the effects of different treatments of coir fibers (Cocos nucifera L.), and cement:coir ratio on physical and mechanical properties of cement-bonded composites. Three treatments: adding 4% of CaCl2, immersion in hot water at 80°C for 90 minutes, and immersion in NaOH aqueous solution at 5% for 72 hours and two cement:fiber ratios (3:1 and 4:1) were chosen for manufacturing 24 panels. After 28 days of setting, characterization was made through static bending (MOE, MOR), parallel compression (COMP), internal bonding (IB), thickness swelling (TS), and water absorption (WA) (2 and 24 hours of water immersion) tests. Treating coir fibers with hot water provided an improvement in the panel’s properties. This treatment had better results in MOE and COMP. Panels produced with CaCl2 addition were resistant as well; however coir fibers treated with NaOH produced cement/coir composites with unsatisfactory physical and mechanical properties.
  • Researchpp 3493-3504Wang, L., Sun, L., and Li, J. (2011). "Electroless copper plating of Fraxinus mandshurica veneer using glyoxylic acid as reducing agent," BioRes. 6(3), 3493-3504.AbstractPDF
    Copper coating was deposited on Fraxinus mandshurica veneers for preparing EMI shielding composite by electroless plating using glyoxylic acid as reducing agent in the solution. XPS and SEM were used to analyze the activation process. It was found that a continuous chitosan membrane was loaded on the wood surface. XPS results showed that Pd(II) ions were ed on a chitosan membrane on the wood surface through an N-Pd σ coordination bond. After reduction, part of Pd(II) absorbed formed very little Pd(0) particles on the chitosan-treated wood surface. The activated wood veneers were immersed into a plating bath in which copper film was successfully initiated. The coatings were characterized by SEM-EDS, XPS, and XRD. The metal deposition, surface , and electromagnetic shielding effectiveness were measured. The morphology of the coating was uniform, compact, and continuous. The wood grains were preserved on the plated wood veneer, which had a copper-like color and sheen. EDS, XPS, and XRD results indicated that the coating consisted of Cu0 with crystalline structure. The surface resistivity and copper deposition reached 175.14 mΩ·cm-2 and 21.66 g/m2 when the veneer was pretreated with 0.8 % chitosan for 8 min and plated for 30 min at 55 oC. The plated veneers exhibited good electromagnetic shielding effectiveness of over 60 dB in frequency ranging from10 MHz to 1.5 GHz.
  • Researchpp 3505-3514Du, Y., Wang, Y., Peng, G., Su, Z., Xu, M., Feng, W., Zhang, S., Ding, Y., Zhao, D., and Liu, P. (2011). "Reducing COD and BOD, as well as producing triacylglycerol by LDS5 grown in CTMP effluent," BioRes. 6(3), 3505-3514.AbstractPDF
    Both the energy shortage and pollution tend to slow down economic development and affect our daily lives. Some microorganisms not only can digest pollutants, but also can convert pollutant metabolites to triacylglycerol (TAG) that can be used to produce biodiesel. Here, we present results showing that the bacterium strain LDS5, a mutant of Rhodococcus sp. RHA1 (RHA1) generated in our lab, could grow well in chemithermomechanical pulping (CTMP) effluent, a type of paper mill wastewater, reduce chemical oxygen demand (CODCr) and biochemical oxygen demand (BOD5) significantly, and produce TAG. Our data suggest that this strain has the potential to be used in paper mill wastewater treatment as well as in the development of biodiesel using biomass from paper mills.
  • Reviewpp 3515-3525Hu, L., Pan, H., Zhou, Y., and Zhang, M. (2011). "Methods to improve lignin's reactivity as a phenol substitute and as replacement for other phenolic compounds: A brief review," BioRes. 6(3), 3515-3525.AbstractPDF
    Lignin is readily available as a by-product from the pulp and paper industry. It is considered to be a promising substitute for phenol in phenol-formaldehyde (PF) resin synthesis, given the increasing concerns of the shortage of fossil resources and the environmental impact from petroleum-based products. One hurdle that prevents the commercial utilization of lignin is its low reactivity due to its chemical structure. Many efforts have been made to improve its reactivity by modification and/or depolymerization of lignin molecules. Methylolation and phenolation are the two most studied modification approaches aimed at introducing reactive functional groups to lignin molecules. Modified lignin from these two methods could partially replace phenol in PF resin synthesis. Demethylation of lignin could effectively increase the reactivity of lignin by forming catechol moieties in the lignin macromolecule. Other methods, including reduction, oxidation, and hydrolysis, have also been studied to improve the reactivity of lignin as well as to produce phenolic compounds from lignin. Most current methods of lignin modification are not economically attractive. One can expect that efforts will be continued, aimed at improving the utilization of lignin for value-added products.
  • Reviewpp 3526-3546Kumar, P., Negi, Y. S., and Singh, S. P. (2011). "Filler loading in the lumen or/and cell wall of fibers - A literature review," BioRes. 6(3), 3526-3546.AbstractPDF
    A review of the literature reveals potential advantages that papermakers can achieve by placing minerals in the lumens or cell walls of fibers before the pulp is formed into paper. Loading of filler into the fiber lumen by mechanical deposition or within the cell wall by in-situ precipitation has been reported to generally result in a moderate reduction in light scattering coefficient and increased strength properties of laboratory handsheets, as well as in paper manufactured with pilot plant equipment, when compared to conventional addition of filler. However, there are some exceptions to this general observation, where the fiber loading is reported to decrease the tensile strength of paper. Some related effects can be achieved by either precipitating mineral onto fiber surfaces or co-flocculating mineral particles with cellulosic fines. Challenges remain with respect to the implementation of fiber-loading concepts at a commercial scale. Also, there is a need for further research aimed at establishing high-end applications in which it may be an advantage to load cellulosic fiber cell walls or lumens with minerals or other substances.
  • Reviewpp 3547-3568Vishtal, A., and Kraslawski, A. (2011). "Challenges in industrial applications of technical lignins, BioRes. 6(3), 3547-3568.AbstractPDF
    The primary aim of modern biorefineries is the efficient conversion of lignocellulosic materials into valuable products. Sugars and oils can be converted into valuable chemicals, but processing of lignin is still a challenge. A vast amount of lignin is incinerated to produce process steam and energy, and only a very small part is used for the production of value-added products. Technical lignins are isolated as by-streams in lignocellulosic refineries, e.g., as kraft, soda, organosolv, and hydrolysis lignins, as well as lignosulphonates. They have a modified structure and contain impurities that are dependent on the processing method. The structure and the composition of technical lignins restrict their subsequent applications. This paper reviews limiting factors in utilization of technical lignins. Four major classes of problems are identified, and approaches to overcoming these problems are suggested.
  • Reviewpp 3569-3584Li, B., Li, H., Zha, Q., Bandekar, R., Alsaggaf, A., and Ni, Y. (2011). "Review: Effects of wood quality and refining process on TMP pulp and paper quality," BioRes. 6(3), 3569-3584.AbstractPDF
    For the thermomechanical pulping (TMP) process both wood chip quality and the refining process have important effects on the resulting pulp and paper quality. Properties of wood raw material give a framework for final pulp properties. During TMP refining the specific energy consumption and refining intensity strongly impact fibre and pulp qualities. Increasing specific energy consumption benefits the development of fibres and improves their properties. However, high intensity refining tends to shorten the fibres and produces more fines content when compared with low intensity refining. This review focuses on the influence of key variables of chip qualities and the refining process on TMP pulp and paper qualities.
  • Reviewpp 3585-3620Sasso, C., Beneventi, D., Zeno, E., Chaussy, D., Petit-Conil, M., and Belgacem, N. (2011). "Polypyrrole and polypyrrole/wood-derived materials conducting composites: A review," BioRes. 6(3), 3585-3620.AbstractPDF
    Wood and cellulose derivatives, in both fibrous and water-soluble macromolecular form, are emerging as outstanding candidates for organic electronics applications due to their large-scale availability, low cost, and easy processability. Paper and wood fibre-based derivatives are considered to be materials of choice as supports for communication world-wide. The interest in producing inexpensive and universally available conducting polymer/cellulose fibres substrates resides in the possibility of creating new materials that can be used for a broad range of advanced applications. For instance, PPy/cellulose fibres composites can be used for the preparation of energy storage devices thanks to the conjugation of the high specific area of cellulose fibres and the electrochemical properties of PPy. Other possible applications of such composites are in the area of the antistatic materials, sensors, electromagnetic interference shielding materials, smart packaging, and tissues. Concerning the woody polymers, some of them (i.e. cellulose derivatives) also exhibit biocompatibility, as well as film-forming properties and transparency. In combination with the electrical properties of PPy, these features make PPy/macromolecular cellulose composites suitable for applications as displays, lighting, and photovoltaics. Due to their chemical structure, macromolecular wood derivatives have been proposed with success as enhancing conductivity additives in Py polymerisation. The aim of the present review is to provide an overview of PPy chemistry and of the most relevant advances attained in the production of PPy/wood derived materials conducting composites.