BioResources, Volume 3, Issue 4
NOTE: Each current issue of BioResources continues to build as new articles are approved.
Sustainability considerations for product and energy production in a future US economy can be met with lignocellulosic biomass. The age of petroleum as the key resource to meet the US economy requirements is rapidly dwindling, given the limited resources of petroleum, the growing global population, and concurrent detrimental effects on environmental safety. The use of natural and renewable feedstocks such as trees and switchgrass is becoming more attractive; indeed, lignocellulosic biomass is becoming a logical alternative to petroleum in light of looming oil shortages, increases in oil prices, and environmental sustainability considerations. This editorial aims at providing a broad overview of the consider-ations for replacing the US petroleum economy with one based on lignocellulosic biomass. PDF
The fatigue behavior of the wood fiber cell wall under mechanical treatment in refining was simulated dynamically using a finite element method. The effect of the amplitude and frequency of impacts on the mechanical breakdown of the fiber wall structure was examined. The proposed model of the fiber cell wall was constructed from elementary microfibrils in various orientations embedded in isotropic lignin. The fatigue of the cell wall was simulated under normal refiner mechanical pulping conditions. A cyclic load was applied on the model fiber through a hemispherical grit proposed to be applied on the surface on refiner segments. Changes in the elastic modulus of the cell wall were analyzed to determine the potential for cell wall breakdown. An increase in the amplitude of applied forces and frequency of impacts was found to have a significant influence on the reduction of the elastic modulus of the wall structure. A high frequency of impacts increased the stiffness of the cell wall, but resulted in faster reduction of the elastic modulus. At a lower amplitude of impacts, efficient breakdown of the cell wall using grits was achieved with a high frequency of impacts or a high rotational speed of refiners. PDF
Zanini, S., Canevali, C., Orlandi, M., Tolppa, E.-L., Zoia, L., Riccardi, C., and Morazzoni, F. (2008). "Radical formation on CTMP fibers by argon plasma treatments and related lignin chemical changes," BioRes. 3(4), 995-1009.
The changes at molecular level induced by cold argon plasma treat-ments on fibers obtained from chemi-thermo-mechanical pulp (CTMP) fibers were investigated. The radicals formed on CTMP fibers after treatments were identified and quantified by Electron Paramagnetic Resonance (EPR) spectroscopy. The plasma conditions which maximize the formation of radicals on fibers were assessed: after treatment with 0.4 mbar Ar pressure and 75 W radiofrequency power, phenoxy radicals triple their concentration in only 60 s and reach a value 4 times higher than that reported for laccase-catalyzed lignin oxidation. It was found that in plasma-treated fibers, the formation of radicals competes with their coupling. This latter result leads to cross-linkages of the lignin mono-meric units and formation of new intermonomeric C-C and C-O bonds, for the first time assigned to specific molecular interactions through Heteronuclear Single Quantum Coherence (2D-HSQC) spectroscopy and Nuclear Magnetic Resonance spectroscopy of carbon (13C-NMR). These results were confirmed by Nuclear Magnetic Resonance spectros-copy of phosphorous (31P-NMR). The lack of evidences of inter-fiber bond interactions, deduced from Gel Permeation Chromatography (GPC) data, suggests the possible application of plasma treatments for the production of wood fiber-based composites. PDF
Kalia, S., Sharma, S., Bhardwaj, B., Kaith, B. S.., and Singha, A. S. (2008). "Potential use of graft copolymers of mercerized flax as filler in polystyrene composite materials,"BioRes. 3(4), 1010-1019.
Graft copolymerization of binary vinyl monomers onto mercerized flax fiber was carried out for the enhancement of mechanical properties of polystyrene composites. Binary vinyl monomer mixture of AA+AN has been found to show maximum grafting (33.55%) onto mercerized flax. Graft copolymers thus synthesized were characterized with FT-IR spectroscopy, SEM, and TGA techniques. Mercerized flax (MF) showed maximum thermal stability in comparison to graft copolymers. It has been found that polystyrene composites reinforced with graft copolymers showed improvement in mechanical properties such as wear resistance, compressive strength, and tensile strength. PDF
Millati, R., Karimi, K., Edebo, L., Niklasson, C., and Taherzadeh, M. J. (2008). "Ethanol production from xylose and wood hydrolyzate by Mucor indicus at different aeration rates," BioRes. 3(4), 1020-1029.
The fungus Mucor indicus is able to produce ethanol from xylose as well as dilute-acid lignocellulosic hydrolyzates. The fungus completely assimilated 10 g/L xylose as the sole carbon and energy source within 32 to 65 h at an aeration rate of 0.1 to 1.0 vvm. The highest ethanol yield was 0.16 g/g at 0.1 vvm. Xylitol was formed intermediately with a maximum yield of 0.22 g/g at 0.5 vvm, but disappeared towards the end of experiments. During cultivation in a mixture of xylose and glucose, the fungus did not assimilate xylose as long as glucose was present in the medium. The anaerobic cultivation of the fungus in the hydrolyzate containing 20% xylose and 80% hexoses resulted in no assimilation of xylose but complete consumption of the hexoses in less than 15 h. The ethanol yield was 0.44 g/g. However, the xylose in the hydrolyzate was consumed when the media was aerated at 0.067 to 0.333 vvm. The best ethanol yield was 0.44 g/g at 0.067 vvm. The results of this study suggest that M. indicus hydrolyzate can be first fermented anaerobically for hexose assimilation and subsequently continued under oxygen-limited conditions for xylose fermentation. PDF
Specific and strong cellulose-binding characteristics were utilized for promoting retention of additives in contaminated papermaking systems. Cellulose-binding domain (CBD) of cellulase derived from Trichoderma viride was separated by digestion with papain, and then introduced into anionic polyacrylamide (A-PAM) through a condensation reaction using water-soluble carbodiimide. The CBD-modified A-PAM (CBD-A-PAM) showed good retention on pulp fibers, resulting in high tensile strength paper sheets. The effect remained almost unchanged in the presence of model interfering substances such as ligninsulfonate and Ca2+ ions, whereas commercial cationic paper-strengthening polymer became ineffective. The cellulose-binding force of CBD was quantitatively determined by atomic force microscopy (AFM) in the liquid state. Histidine-tagged CBD protein was obtained using Escherichia coli via an expression of CBD derived from Cellulomonas fimi, and immobilized on a gold-coated AFM probe. A strong attractive force was detected only at a CBD/cellulose interface, even when Ca2+ ions were present in high concentration. Direct estimation of CBD affinity for cellulose substrate by AFM would provide significant information on the interfacial interactions useful for the functional design of papermaking additives. PDF
Barbosa, E. S., Perrone, D., Amaral Vendramini, A. L., and Ferriera Leite, S. G. (2008). "Vanillin production by Phanerochaete chrysosporium grown on green coconut agro-industrial husk in solid state fermentation," BioRes. 3(4), 1042-1050.
Agro-industrial residues have become an important source for the production of chemical compounds using biological pathways, contributing to preservation of the environment and making the overall process economically supportable. Vanillin is a very important aromatic compound for the food, beverage, and pharmaceutical industries. The aim of the present study was to evaluate the vanillin production by solid-state fermentation on green coconut residue using the basidiomycete Phanerochaete chrysosporium. Solid-state fermentation was carried on a support of green coconut husk treated in two different ways: sun-dried and mechanical-pressed. A Plackett-Burman experimental design was used to screen the compounds of liquid medium culture of the vanillin production. Nineteen variables were studied to optimize the culture conditions, and eleven of them were significant. The screening improved the production of vanillin from 44.4 mg/g of support to 52.5 mg/g of support in 24 hours of fermentation. Sun-dried coconut husk was found to be superior to mechanical-pressed coconut husk for production of vanillin. HPLC was used for the quantification of vanillin aroma. PDF
The effects of alkali treatment on the thermal degradation and weathering properties of bamboo strips were investigated in this work. Dried bamboo strips with average dimensions of 100 x 15 x (1.1-1.5) mm were mercerized with caustic soda solution (10%, 15%, 20%, and 25%) (w/v) at ambient temperature, maintaining a liquor-to-solids ratio of 15:1. All types of bamboo specimens were subjected to thermogravimetric anal-ysis and accelerated weathering by water immersion and further char-acterized by flexural property measurements. Water absorption and dimensional changes were recorded at 100% humidity, room temperature, and atmospheric pressure. The results showed that the treated bamboo strips had a higher deterioration in flexural properties compared to the untreated ones. Thermogravimetric analysis of all the samples indicated better thermal properties of alkali-treated samples. The highest activation energy was observed with a 15% alkali-treated bamboo sample. PDF
The production of microporous carbon foams from renewable starch microcellular foam-fiber (SMCF-Fiber) composites is described. Carbon foams are used in applications such as thermal insulation, battery electrodes, filters, fuel cells, and medical devices. SMCF-Fiber composites were created from an aquagel. The water in the aquagel was exchanged with ethanol and then dried and carbonized. Higher amylose content starches and fiber contents of up to 4% improved the processability of the foam. The SMCF structure revealed agglomerates of swollen starch granules connected by a web of starch with pores in the 50-200 nanometer range. Heating the SMCF-fiber in a nitrogen atmosphere to temperatures between 350-700˚C produced carbon foams with a three-dimensional closed cell foam structure with cell diameters around 50 microns and pore walls around 1-3 microns. The stress versus strain compression data for carbonized samples displayed a linear elastic region and a plateau indicative of brittle crushing, typical of an elastic-brittle foam. The carbon foam products from these renewable precursors are promising carbon structures with moderate strength and low density. PDF
Kovur, S. K., Schenzel, K. C., Grimm, E., and Diepenbrock, W. (2008). "Characterization of refined hemp fibers using NIR FT Raman micro spectroscopy and environmental scanning electron microscopy,"BioRes. 3(4), 1081-1091.
The research was focused on the separation of single hemp (Cannabis sativa L.) fibre cells with low fineness from mechanically extracted fibre bundles of high fineness. The fiber bundles were treated with enzymes, namely panzym, pectinase, hemicellulase, and cellulase, along with a combination of panzym and ultrasonic treatments. Changes in the fiber structure were followed at molecular and microscopic levels by means of NIR FT Raman spectroscopy and Environmental Scanning Electron Microscopy (ESEM). Buffer-panzym treatments of hemp fibers had a prominent effect in loosening of the fiber cells. The best of refining was achieved when the fiber bundles were treated with buffer-panzym solution in combination with ultrasonic treatment. PDF
The capacity for removal of heavy metals from liquid streams by formation of complexes with lignins oxidized by acid treatment was studied. Lignins were obtained from different sources: sulfuric acid pre-treated cane bagasse, soda pulping bagasse, eucalypt Kraft lignin, and commercial Kraft lignin. These lignins were characterized using different techniques to determine Klason lignin, carbohydrates, total acids, ashes, and their main functional groups: phenolic-OH, carbonyls, etc. The studied lignins were determined spectroscopically using FTIR. In order to increase the metal adsorption capacity, lignins were oxidized at 100°C during 2 h, using aqueous solutions of H2O2 in distilled water solvent and HCl catalyst. Some lignin adsorption isotherms were constructed before and after the oxidation process to define Cd(II) ion removal capacity. PDF
A theoretical method for prediction of cutting edge recession during milling wood and wood-based products, due to the presence of hard mineral contamination, High Temperature Tribochemical Reactions (HTTR), and frictional wearing, based on 3D random distribution of contaminant particles is presented and positively verified based on the example of three experiments from the literature, showing good correlation between the predicted and observed cutting edge recession. PDF
The purpose of this study is to develop an analytical method to quantify the nitrogen present at the surface of paper by using X-ray photo-electronic spectroscopy (XPS). A sample of softwood thermomechanical pulp (TMP) was treated with a cationic starch containing primary amines, while another one was treated with a cationic polymer containing quaternary amines. We also grafted monomers containing a quaternary amine to the fiber. Sheets were prepared and analyzed by XPS. The technique used allowed us to identify the type of amine and to give a semi-quantitative evaluation. PDF
Environmental pollution has a harmful action on bioresources, including agricultural crops. It is generated through many industrial activities such as mining, coal burning, chemical technology, cement production, pulp and paper industry, etc. The toxicity of different industrial wastes and heavy metals excess was evaluated using crop plant assays (germination and hydroponics seedlings growth tests). Experimental data regarding the germination process of wheat (from two cultivars) and rye seeds in the presence of industrial wastes (thermal power station ash, effluents from a pre-bleaching stage performed on a Kraft cellulose – chlorinated lignin products or chlorolignin), along with use of an excess of some heavy metals (Zn and Cu) are presented here. Relative seed germination, relative root elongation, and germination index (a factor of relative seed germination and relative root elongation) were determined. Relative root elongation and germination index were more sensitive indicators of toxicity than seed germination. The toxic effects were also evaluated in hydroponics experiments, the sensitivity of three crop plant species, namely Triticum aestivum L. (wheat), Secale cereale (rye), and Zea mays (corn) being compared. Physiological aspects, evidenced both by visual observation and biometric measurements (mean root, aerial part and plant length), as well as the cellulose and lignin content were examined. PDF
The present work concerns the experimental evaluation of hazelnut shells as a low cost natural biosorbent. Adsorption of the direct azo dye Congo Red was performed within a concentrations range of 50-5000 mg/L. Hazelnut shells were employed as organic support for Phanerochaete chrysosporium cultures to study the best cultural medium composition for the MnP production. The capability of Phanerochaete chrysosporium to take macronutrients as carbon and nitrogen from hazelnut shells was demonstrated. Cultures of Phanerochaete chrysosporium were carried out with hazelnut shells coming from Congo Red adsorption tests, showing that 43% of the adsorbed dye was degraded. PDF
Mellouk, H., Khezami, L., Rezzoug, S.-A., and Capart, R. (2008). "Total valorisation of red cedar (Thuja Plicata) sawmills wastes. Isolation of extractives and production of activated carbon from solid residue," BioRes. 3(4), 1156-1172.
Experiments were performed to evaluate a recent extraction process called the instantaneous controlled pressure drop process (briefly: DIC process: “Détente Instantanée Contrôlée”) for extracting some volatile compounds from red cedar wood. This process involves subjecting red cedar chips for a short time (30 s to 5 min) under a steam pressure (1 to 6 bars or from 100 to 165 °C). This first step is followed by a flash decompression toward vacuum (up to 50 mbar). This transition induces a fast evaporation of water and volatile compounds and a cooling effect. The effects of two processing parameters (steam pressure and heating time) on the total extraction yield and on yield of four volatile compounds were evaluated by response surface methodology. The results indicated that the processing pressure is the predominant parameter for global extraction yield of oil (E.O= Extracted Oil) and for yield of the four compounds investigated in this study. The processing time is also a significant parameter but less than processing pressure. Moreover, activated carbon produced from DIC-treated residue revealed larger pore sizes compared to untreated samples. PDF
Fabrication of polymer composites reinforced with lignocellulosic materials has increased considerably during the last few years. This work reports the synthesis of natural fiber reinforced phenol-formaldehyde (PF) resin matrix based polymer composite using a compression molding technique. Initially the PF resin was prepared by varying the concentration of formaldehyde with a fixed weight of phenol. Polymeric resin of different P: F ratios were subjected for optimization of their mechanical properties. The sample ratio of 1:1.5 (P: F) was found to possess maximum mechanical strength. Then reinforcing of this optimized resin was done by taking different ratios of Hibiscus Sabdariffa (HS) fiber in short form (3mm) to prepare green polymer composites. Polymer composite materials thus prepared were subjected to evaluation of their mechanical properties such as tensile strength, compressive strength, flexural strength, and wear resistance, etc. Optimum mechanical properties were obtained with a fibre loading of 30%.Thermal (TGA/DTA/DTG) and morphological studies (SEM) of the polymeric resin, and composites thus synthesized have also been studied. The results obtained suggest that thesefiberscan be a superior candidate for the reinforcement of high performance polymer composites. PDF
Polystyrene sulfonic acid (PSS), lignosulfonic acid (LS) sodium salts, and carboxymethylcellulose (CMC) were used as doping/dispersing agents in the chemical polymerization of polypyrrole (Ppy). Conductivity measure-ments performed on dry Ppy pellets showed a sharp increase in conductivity when adding the anionic polymers to the polymerization liquor. For a polyanion/pyrrole weight ratio ranging between 0.1 and 0.6, the highest conductivity was given by PpyCMC (82 S/m) and PpyPSS (80 S/m), followed by PpyLS (6 S/m). On the other hand, for a polyanion/pyrrole ratio higher than 0.6, the conductivity of PpyPSS systems sharply decreased, and for polyanion/pyrrole ratios higher than 1, the highest conductivity was given by PpyCMC (~10 S/m), followed by PpyLS (~7 S/m) and PpyPSS (~5 S/m). Zeta-potential measurements showed that the surface charge of Ppy was strongly affected by the polyanion type and amount. Cationic Ppy particles were obtained in the presence of the two polymers bearing strongly acidic moieties (PSS and LS). Anionic PpyPSS colloids were obtained at the highest PSS/Py ratio, after the degradation of the conducting properties. When using a weakly acidic dopant (CMC), PpyCMC colloids had a negative charge for all of the tested conditions. PDF
The present study investigates the economical production of bacterial cellulose (BC) byGluconacetobacter subsp. Xylinus (ATCC 10245) in 250 ml Erlenmeyer flasks cultivated under static conditions. The fermentation media used contained food industrial by-product liquors, such as black strap molasses solution and corn steep liquor (CSL), which represents some of the most economical carbon and nitrogen sources. However, because of the presence of undesirable components in molasses (such as coloring substances, heavy metals, and other compounds) that may act as inhibitors, and in order to eliminate them, crude molasses has been treated with an acid, as an attempt to increase BC productivity. The amount of BC produced using these carbon and nitrogen sources was determined and compared to that produced using previously reported fermentation media. The characterizations of the bacterial cellulose (BC) pellicles obtained using either conventional or by-product media were studied by thermal and spectral techniques and compared to those of plant-derived cellulose such as cotton linter, viscose pulp, and microcrystalline cellulose. PDF
Fibre flexibility is often anticipated to play a role in fibre flocculation phenomena. In this study, 3 thermomechanical pulps (TMPs) were sampled along a post-refining line. The only fibre morphological property that varied was fibre flexibility. These TMP samples were then tested for fibre flocculation and sheet formation tendency. The measurements clearly showed that fibre flocculation decreased and sheet formation uniformity increased with increasing fibre flexibility. The beneficial effect of fibre flexibility was larger at high consistency. These results support the elastic energy storage theory within flocs, which states that the more rigid the fibre, the stronger the flocs. Papermakers may take advantage of the beneficial effect of fibre flexibility on sheet formation through a careful tuning of post-refining. PDF
Unmodified and modified rice husk powder filled PVC composites were prepared having different amounts of rice husk powder. Mechanical, thermal, and electrical properties of these composites were determined. The tensile strength of rice husk powder PVC composites having 0, 10, 20, 30, and 40 weight percent of rice husk powder was found to be 33.9, 19.4, 18.1, 14.6, and 9.5 MPa, respectively. Adding of maleic anhydride- modified rice husk powder improved the tensile strength of rice husk powder PVC composites. Flexural strength and flexural modulus of composites increased on treatment of rice husk powder due to the improved bonding between rice husk powder and PVC matrix. Arc-resistance of rice husk powder PVC composites was not affected on increasing loading of the powder. Volume resistivity and surface resistivity decreased with increasing loading due to the presence of impurities and water molecules. Vicat softening temperature increased with rice husk powder loading. Addition of rice husk increased the melting temperature of the composite matrix as compared to pure PVC. PDF
Manure, an animal waste product with many negative economic and environmental issues, can today be converted using anaerobic digestion technology into a number of commercial products ranging from fertilizer, compost, animal bedding, and plant bedding. A number of new uses are now being explored such as bioenergy (both electrical and biofuel) and a lignocellulose-rich potential feedstock for engineered biocomposite products for building materials. This paper explores the engineering potential of using anaerobically digested bovine biomass (ADBF) as a feedstock material for biocomposite building materials. Our evaluation generally indicated that making dry-formed fiberboard using up to a 50/50% mixture of wood fiber and ADBF-fiber compared favorably with some commercial requirements for wood-based medium-density fiberboard and particleboard. PDF
This paper explores the physical and economic potential to substitute anaerobically digested bovine biofiber (ADBF) for wood in the making of particleboard. Laboratory tests indicated that replacement of one-half the wood in particleboard with ADBF produced panels that compared favorably to the requirements for commercial particleboard performance (specified by ANSI Standard A208.1–1999). The economic question hinges on the opportunity costs of alternative uses for ADBF. The current use is primarily animal bedding, and prices appear to be greater than those paid by particleboard plants for sawdust and planer shavings but less than for chips. ADBF is most similar in size to, thus most likely to be substitutable for, sawdust and shavings. At current bedding values, use for particleboard appears a less favorable alternative. However, this could be overcome by large-volume, long-term contractual arrangements that provide a secure long-term outlet for excess ADBF fiber that may otherwise not have value. For a particleboard operation, the opportunity for fiber diversification and the incorporation of post-industrial waste in the process offer strategic advantages. PDF
Chemical and thermal stability of rice husks against alkali treatment with 2 to 8% w/v NaOH are presented and discussed in this paper. The thermal stability of the rice husks was examined by using a thermal gravimetric analysis instrument. Chemical stability was evaluated by examining the organic components of rice husks using proximate analysis. The results indicated that the proportion of lignin and hemicellulose in rice husks treated with NaOH ranging from 4 to 8% decreased significantly by 96% and 74%, respectively. The thermal stability and final degradation temperatures of the alkali-treated rice husks were also lowered by 24-26°C due to degradation of hemicellulose and lignin during alkali treatment. Absence of the onset degradation zones in the alkali-treated rice husks was a further indication that hemicellulose and other volatile substances degraded during alkali treatment. This leads to a conclusion that alkali treatment of rice husks with more than 4% NaOH causes a substantial chemical degradation of rice husks, which subsequently decreases their thermal stability. PDF
Solár, R., Mamoň, M., Dibdiaková, J., Reinprecht, L, Pánek, M., and Hudec, J. (2008). "Effect of biotic and abiotic pretreatments of hornbeam wood on its properties interesting from viewpoint of pulping in alkaline media. Part 1: Physical Properties," BioRes. 3(4), 1278-1290.
A series of comparable specimens of hornbeam wood were submitted to pretreatments by white-rot fungi, by alkali alone, or by alkali and oxidizing agents. The pretreatments caused weight loss of wood and modified its physical properties and chemical composition. All pretreat-ments reduced markedly axial permeability of the test specimens in the wet state (w > FSP). The chemical pretreatments of the test specimens, however, increased the rate of diffusion in the direction parallel to the grain. All pretreatments made the kinetics of wood/water interactions in the initial phase much higher, especially when white-rot fungi were used. The chemical pretreatments caused extreme swelling of wood, and on the other hand, drying of the pretreated specimens to their initial moisture content resulted in extremely deep reduction of their dimen-sions. An increased rate of wood/water interactions, high uptake of water, and higher diffusion coefficients of wood pretreated by alkali may positively influence the pulping processes. PDF
Solár, R., Kačík, F., Reinprecht, L, Laurová, M., Geffertová, J., and Dibdiaková, J. (2008). "Effect of biotic and abiotic pretreatments of hornbeam wood on its properties interesting from viewpoint of pulping in alkaline media. Part 2: Chemical alterations," BioRes. 3(4), 1291-1302.
A series of comparable specimens of hornbeam wood were submitted to fungal and chemical pretreatments. Two strains of erosive white-rot fungi (P. chrysosporium and T. versicolor) and a lignin-selective fungus C. subvermispora were used. Chemical pretreatments were carried out with diluted sodium hydroxide, or sodium hydroxide and then by hydrogen peroxide, or per-acetic acid. Both biotic and abiotic pre-treatments modified the chemical composition of wood and were accompanied by its weight loss. The applied fungi apparently delignified the specimens, however at the expense of cellulose, especially when the erosive strains of fungi were used. The chemical pretreatments caused deep deacetyl-ation, and milder delignification of wood and did not cause an apparent loss of cellulose. Biotic pretreatments of hornbeam wood, despite their marked delignification effect, led to unexpected increase in the contents of residual lignin in the resulting kraft pulps. On the other hand, pulping of the chemically pre-treated chips yielded pulps with low contents of residual lignin and much higher brightness. PDF
Three commercial silicone emulsions with different functional groups i.e., quat-silicone micro-emulsion (<40 nm particle size), amino-silicone macro-emulsion (110 nm), and silicone macro-emulsion with alkyl-modified side groups (740 nm) were used to protect wood samples against fungal decay. The addition of the emulsions to an agar growth medium revealed that all three silicone formulations inhibited the growth of Coniophora puteana and Trametes versicolor compared to the controls without silicone. Wood mini-blocks of pine sapwood and beech wood were treated with 2%, 5%, 10%, and 15% concentration of silicone emulsions and tested for their resistance against basidiomycete decay. Quat-silicone and amino-silicone emulsions at higher concentrations imparted resistance of wood to both types of basidiomycetes, while the alkyl-modified silicone formulation did not enhance the resistance. In a soft rot test according to ENV 807, wood treated with an amino-sililcone emulsion showed the lowest weight loss and loss of dynamic MOE. Quat-silicone micro-emulsion had a lower effect, while the alkyl-modified silicone emulsion did not cause reduction in weight and strength loss compared to the untreated controls. The increased resistance against soft rot might be attributed to a lag in fungal colonization rather than to a sustained effect of protection. PDF
Polymer adsorption on cellulose nanofibrils and the effect on nanofibril water binding capacity were studied using cellulose nanofibril films together with quartz crystal microbalance with dissipation (QCM-D) and surface plasmon resonance (SPR). The experiments were performed in the immersed state, and special attention was paid to the effect of polymer properties on the water content and viscoelastic properties of the polymer/fibril layer. The dry mass of the adsorbed polymers was determined using SPR. The type of the adsorbed polymer strongly affected the water content and viscoelastic properties of the nanofibril film. The adsorption of a highly charged flocculating polymer, PDADMAC, caused dehydration of the film, which was also detected as nanofibril film stiffening. The adsorption of xyloglucan introduced a dispersing effect to the nanofibril film, which was detected as a loosening and softening of the nanofibril/polymer layer. A dispersing effect was also achieved with carboxymethyl cellulose (CMC), but CMC did not adsorb irreversibly on the nanofibril surfaces. In addition to the nanofibril film studies, the effect of polymer adsorption on cellulose nanofibril suspension aggregation was demonstrated using confocal laser scanning microscopy (CLSM). Xyloglucan was shown to open the nanofibril aggregate structures and act as a dispersing agent, whereas the other polymers studied did not have as significant an effect on aggregation. PDF
Switchgrass varieties grown under various environments were investigated by dispersive and Fourier Transform Near-Infrared (NIR) spectrometers. The collected NIR spectra were analyzed using multivariate approaches. More specifically, principal component analysis (PCA) and projection to latent structures (PLS) regression techniques were employed to classify and predict characteristics of the switchgrass samples. The multivariate results were compared to reflectance indices that are commonly used to study the physiological performance of plants. From near infrared spectra, discrimination between the two growth locations was successfully achieved by PCA. Separation based on the ecotype and the rate of fertilizer applied to the field was also possible by the multivariable analysis of the spectral data. For the classification/ discrimination of the switchgrass samples, the near infrared spectra collected by the dispersive and the Fourier Transform spectrometers provided similar results. From the two near infrared data sets robust models were developed to predict non-structural carbohydrates content and the rate of nitrogen applied to the field. However, the spectra collected by the dispersive spectrometer resulted in more accurate models for these samples. PDF
Stoutenburg, R. M., Perrotta, J. A., Amidon, T. E., and Nakas, J. P. (2008). "Ethanol production from a membrane purified hemicellulosic hydrolysate drived from sugar maple by Pichia stipitis NRRL Y-7124," BioRes. 3(4), 1349-1358.
In an effort to devise inexpensive and sustainable production of ethanol fuel, experiments were conducted to establish conditions for Pichia stipitis NRRL Y-7124 to ferment a membrane treated wood hydrolysate derived from sugar maple to produce ethanol. The degree of aeration required to effectively utilize xylose, produce ethanol, and minimize xylitol formation as well as the optimal hydrolysate concentration were the conditions examined. P. stipitis produced the highest concentrations of ethanol in shake flasks at 150 rpm (14.3 g/L in 71 h), and 50% hydrolysate maximized ethanol yield (12.4 g/L in 51.5 h). In the 50% hydrolysate cultures, P. stipitis produced ethanol at a rate of 0.24 g/L×h with a yield of 0.41 g ethanol/g wood-derived carbohydrate. PDF
Dissolving pulps are the raw materials of cellulose derivatives and of many other cellulosic products. Jute is a very good source of cellulose and worthy of consideration for the production of dissolving pulp. In this investigation jute fiber, jute cuttings, and jute caddis were used as raw materials to prepare dissolving pulp by a formic acid process. A very high bleached pulp yield (49 to 59%) was obtained in this process. The alpha-cellulose content was 93 to 98%, with a high pulp viscosity. Also a good brightness (81 to 87%) was achieved in totally chlorine free bleaching. Jute fiber showed the best and jute caddis showed lowest performance in producing dissolving pulp via the formic acid process. R18-R10 values were much lower than for conventional dissolving pulp. PDF
The chemical modification of lignin through hydroxymethylation and epoxidation is a way to develop new application fields and improvement of lignin performances. In this paper the influence of reaction conditions was studied using different samples of unmodified and modified lignins from annual plants (Wheat straw and Sarkanda grass). The progress of reactions was monitored by evaluating the epoxy index. The resulting products were characterized by FTIR-spectra, UV-Vis spectroscopy, and thermogravimetry analysis. The products obtained were tested to be used in composite formulation for wood applications. PDF
Microbial enzymes such as xylanases enable new technologies for industrial processes. Xylanases (xylanolytic enzyme) hydrolyze complex polysaccharides like xylan. Research during the past few decades has been dedicated to enhanced production, purification, and characterization of microbial xylanase. But for commercial applications detailed knowledge of regulatory mechanisms governing enzyme production and functioning should be required. Since application of xylanase in the commercial sector is widening, an understanding of its nature and properties for efficient and effective usage becomes crucial. Study of synergistic action of multiple forms and mechanism of action of xylanase makes it possible to use it for bio-bleaching of kraft pulp and for desizing and bio-scouring of fabrics. Results revealed that enzymatic treatment leads to the enhancement in various physical properties of the fabric and paper. This review will be helpful in determining the factors affecting xylanase production and its potential industrial applications in textile, paper, pulp, and other industries. PDF
Cellulose has a complex, multi-level supermolecular architecture. This natural polymer is built from superfine fibrils having diameters in the nano scale, and each such nanofibril contains ordered nanocrystallites and low-ordered nano-domains. In this review, the nano-structure of cellulose and its influence on various properties of the polymer is discussed. In particular, the ability of nano-scale crystallites to undergo lateral co-crystallization and aggregation, as well as to undergo phase transformation through dissolution, alkalization, and chemical modification of cellulose has been the subject of investigation. The recent investigations pave the way for development of highly reactive cellulosic materials. Methods for preparation nanofibrillated cellulose and free nano-particles are described. Some application areas of the nanostruc-tured and nano-cellulose are discussed. PDF
Aqueous dispersions of lignocellulosic materials are used in such fields as papermaking, pharmaceuticals, and preparation of cellulose-based composites. The present review article considers published literature dealing with the ability of cellulosic particle dispersions (fiber, fines, nanorods, etc.) to either remain well dispersed or to agglomerate in response to changes in the composition of the supporting electrolyte solution. In many respects, the colloidal stability and coagulation of lignocellulosics can be understood in terms of well-known concepts, including effects due to osmotic pressure arising from overlapping electrostatic double layers at the charged surfaces. Details of the morphology and surface properties of lignocellulosic materials give rise to a variety of colloidal behaviors that make them unique. Adjustments in aqueous conditions, including the pH, salt ions (type and valence), polymers (charged or uncharged), and surfactants can be used to control the dispersion stability of cellulose, lignin, or wood-extractive materials to serve a variety of applications. PDF