BioResources, Volume 5, Issue 2
NOTE: Each current issue of BioResources continues to build as new articles are approved.
It is ironic to think that the venerable pulp and paper industry is now considering ways to degrade cellulose. This notion can be understood as a way that the industry can face a protracted downturn in profitability and ever-mounting socio-economic pressures to enhance the efficiency of biofuels production. Many approaches have been recently taken to deconstruct cellulosic biomass, but this Editorial explores one key that may start to explain the increasing momentum in the biofuels community – biotechnology. Two approaches appear to be possible as scientists search for an effective way to unzip cellulose to its key constituents through the use of biotechnology. On the one hand, there are efforts to re-engineer the chemical composition of the tree, rendering it more digestible by enzymes and decreasing the need for mechanical or chemical pretreatment. On the other hand, what we are learning about lignocellulose biosynthesis can be of potential help in designing more efficient systems to essentially reverse that process. PDF
Fibers and fillers are important raw materials for the preparation of paper products. Similar to fiber engineering, filler engineering for papermaking has become an active research area. There are similarities as well as differences between engineering involving each of these classes of materials. There are differences in such aspects as the nature of materials to be engineered, applicable engineering methods, and engineerablity of the material surfaces. The co-development of fiber engineering and filler engineering can potentially provide many benefits to the papermaking industry. For filler engineering, the relevant research topics broadly can include fibrous filler engineering, hollow/porous filler engineering, acid-stabilization of calcium carbonate fillers, surface encapsulation of naturally occurring polymers or their derivatives, preflocculation, precoagulation, cationic modification, filler/size hybrid formation, organic filler engineering, using combinations of different types of available fillers, multilayer deposition modification, modification with polymer latexes or dispersants, physical modification, mechanical modification, surface functionalization, fines-filler composite/hybrids or fiber-filler composite/ hybrid formation, in-situ polymerization modification, surface grafting, physical treatment in the presence of polymeric additives, filler precipitation, and core-shell composite filler engineering. PDF
In this study a rapid at-line ATP (adenosine triphosphate) analysis is applied in papermaking. This ATP analysis takes less than a minute, and the information can be utilized instantly to adapt the biocide program. The study shows the effect of different biocide strategies at paper mills. Comparison is made between oxidative and reductive biocides on the one hand, and on the other hand between continuous vs. batch additions of biocide. Continuous biocide addition keeps the microbial activity at a constant level. However, a long production period without a boil-out might result in accumulation of resistant bacteria, which cannot be eliminated without changing the biocide strategy. Batch addition of biocide creates a high temporary concentration of biocide in the process. This causes lower temporary microbial activity in the process, but between the doses the microbial activity may rise to an intolerable level. Batch addition causes chemical variation to the wet end of a paper machine more easily than continuous addition. This can affect the performance of papermaking chemicals and cause problems with retention, fixing, etc. Both biocide addition strategies can be used if they are monitored and optimized properly. Rapid ATP analysis is a suitable tool for both purposes. PDF
The “near neutral hemicellulose extraction process” involves extraction of hemicellulose using green liquor prior to kraft pulping. Ancillary unit operations include hydrolysis of the extracted carbohydrates using sulfuric acid, removal of extracted lignin, liquid-liquid extraction of acetic acid, liming followed by separation of gypsum, fermentation of C5 and C6 sugars, and upgrading the acetic acid and ethanol products by distillation. The process described here is a variant of the “near neutral hemicellulose extraction process” that uses the minimal amount of green liquor to maximize sugar production while still maintaining the strength quality of the final kraft pulp. Production rates vary between 2.4 to 6.6 million gallons per year of acetic acid and 1.0 and 5.6 million gallons per year of ethanol, depending upon the pulp production rate. The discounted cash flow rate of return for the process is a strong function of plant size, and the capital investment depends on the complexity of the process. For a 1,000 ton per day pulp mill, the production cost for ethanol was estimated to vary between $1.63 and $2.07/gallon, and for acetic acid between $1.98 and $2.75 per gallon depending upon the capital equipment requirements for the new process. To make the process economically attractive, for smaller mill sizes the processing must be simplified to facilitate reductions in capital cost. PDF
The objective of this research was to investigate the effects of some impregnation materials and varnishes on the thermal conductivity of oak wood. Ammonium sulfate, borax, boric acid, zinc chloride, diammonium phosphate, and sodium silicate as impregnation chemicals and polyurethane, cellulosic, synthetic, coloured varnishes and cellulosic, synthetic, industrial paints as finishes were used. The wood materials were impregnated by using the vacuum-pressure method. The thermal conductivity test was performed based on the ASTM C 1113-99 hot-wire method. Results showed that the impregnation chemicals increased the thermal conductivity. The highest values were obtained with boric acid and sodium silicate. In addition, the thermal conductivity of painted oak was higher than that of varnished oak. The lowest thermal conductivity of 0.1465 Kcal/mh°C was obtained with the oak control. The highest thermal conductivity of 0.1756 Kcal/mh°C was obtained when oak was painted with industrial paint and impregnated with boric acid. PDF
Near infrared (NIR) spectroscopy method was introduced to measure the lignin content in Acacia species. Acid-soluble lignin, Klason lignin, and total lignin contents from 78 wood meal samples of Acacia spp. trees grown in Guangxi province with different ages, height, and families were measured by wet chemistry. NIR spectra were also collected using a Bruker MPA spectrometer within 4000-12500cm-1 of wavenumbers using a standard sample cup and split into calibration and prediction sets. Equations were developed using partial least squares (PLS) regression and cross validation for multivariate calibration in this study. High coefficients of determination (R2) and low root mean square errors of cross-validation (RMSECV) were obtained for Klason lignin (R2=0.94, RMSECV=0.398), acid-soluble lignin (R2=0.87, RMSECV=0.144), and total lignin (R2=0.91, RMSECV=0.448) from wood meal. High correlation coefficients were found between laboratory and predicted values for Klason lignin, acid-soluble lignin, and total lignin contents, with R2 and RMSEP values ranging from 0.67 to 0.94, and 0.19 to 0.526, respectively. The study showed that NIR analysis can be reliably used to predict lignin content in Acacia spp. PDF
Water hyacinth (Eichhornia crassipes) biomass has been used for many years for the remediation of heavy metals. The present study successfully utilizes the dried powdered biomass of the aerial part (stem and leaves) of water hyacinth for biosorption of hexavalent chromium. The effect of various parameters (viz. pH, initial metal ion concentration and temperature) on the removal of Cr(VI) was studied by conducting only 15 sets of sorption runs using Box-Behnken Design (BBD). The pH had a negative and temperature and concentration had positive effects on uptake of chromium. The predicted results (obtained using an empirical linear polynomial model) were found to be in good agreement (R2 = 99.8%) with the experimental results. The predicted maximum removal of Cr(VI) (91.5181 mg/g) can be achieved at pH 2.0, initial metal ion concentration 300 mg/L, and temperature 40 °C. The sorption capacity of sorbent was also calculated using a Langmuir sorption isotherm model and was found to be 101 mg/g at 40 °C and pH 2.0. PDF
An analysis of the chemical composition and anatomical structure of banana pseudo-stem was carried out using Light Microscopy (LM), Scanning Electron Microscopy (SEM), and Confocal Laser Scanning Microscopy (CLSM). The chemical analysis indicated there is a high holocellulose content and low lignin content in banana pseudo-stem compared with some other non-wood fiber resources. These results demonstrate that the banana pseudo-stem has potential value for pulping. In addition, we report for the first time from using LM and CLSM that banana stems possess a structure involving helicoidal fibers separated by barrier films. PDF
This study was carried out to determine the changes of the surface color of Scots pine (Pinus sylvestris L.) and Oriental beech (Fagus orientalis Lipsky) woods after exterior conditioning. First, the samples were bleached with 25% NaOH and 17.5% H2O2. Afterwards, they were varnished with polyurethane and synthetic varnishes, and then they were exposed to exterior conditions for 12 months. Tests for color differences and metric chroma were done according to the ASTM D-2244 standard. It was deduced that exposure to exterior conditions causes color differences in samples, while bleaching with the given solution reduces that effects, and reverts the surface color to that of the natural control specimens. However, bleached specimens exposed to 12 months exterior conditioning had more discoloration than those of natural control samples. In conclusion, if the wood materials will be exposed to outdoors after bleaching, finishing process should be applied to surfaces in order to prevent further color change. PDF
Pandey, K. K., Hughes, M., and Vuorinen, T. (2010). "Dimensional stability, UV resistance, and static mechanical properties of Scots pine chemically modified with alkylene expoxides," BioRes. 5(2), 598-615.
Unprotected wood exposed outdoors suffers from photodegradation due to absorption of UV light by lignin and dimensional changes because of moisture absorption or desorption by free hydroxyl groups in wood constituents. Chemical modification of cell wall polymers is one of the effective methods of inducing dimensional stability and UV resistance in wood. In this work, etherification of Scots pine (Pinus sylvestris L.) was carried out with alkylene epoxides. Extracted blocks of Scots pine were modified with propylene oxide (PO) and butylene oxide (BO) between 30 and 75 oC for different durations and under varying alkaline conditions. Different weight percent gains (WPG) were obtained. WPG increased with temperature, reaction time, and NaOH concentration. The dimensional stability, mechanical properties, and UV resistance of chemically modified wood were evaluated. Etherified wood exhibited an improvement in dimensional stability, but the efficacy dropped with successive water-soaking, oven-drying cycles, indicating a loss of modifying chemical. After four soak-dry cycles, both modifications retained positive anti-swelling efficiency (ASE) values; however, at WPG values >30%, the PO modified material exhibited a reduction in ASE, indicating cell wall degradation. Both PO and BO modified wood exhibited a loss in static mechanical properties measured as modulus of elasticity and modulus of rupture, with the reduction being dependent upon the level of modification. Modification of wood with PO provided partial photo stability to wood polymers, whereas BO was more promising in improving dimensional stability. PDF
The chemical degradations of highly-purified cellotriose, cellotetraose, and cellopentaose in H2O2 and NaOH media were studied, respectively. The degradation products were analyzed by HPLC, FTIR, and GC-MS techniques. The results show that for the three oligosaccharides the main oxidative degradation products are 2, 3-dihydroxy-butanedioic acid, 2-keto-gluconic acid, glucopyranose, D-glucose, D-gluconic acid, and cellooligosaccharides with lower DP. A small amount of arabinose is formed during the oxidation of cellotriose. The main alkaline degradation products for the three oligomers include 3-deoxy-isosaccharinic acid-1,4-lactone and 3-deoxy-hexonic acid-1,4-lactone. Arabinose coumpounds are found to be an accidental degradation product of cellotriose. Finally, the possible formation mechanisms are proposed, including 2,3-dihydroxy-butanedioic acid, 2-keto-gluconic acid, D-gluconic acid, arabinose, 3-deoxy-isosaccharinic acid-1,4-lactone, and 3-deoxy-hexonic acid-1,4-lactone. The radical attack from H2O2 is probably at the glycosidic linkage, resulting in the formation of a series of degradation products. Degradations of cellooligosaccharides in alkaline solution are elucidated to follow an enediol anion reaction mechanism. PDF
Gilleran, C. T., Hernon, A. T., Murray, P. G., and Tuohy, M. G. (2010). "Induction of enzyme cocktails by low cost carbon sources for production of monosaccharide-rich syrups from plant materials," BioRes. 5(2), 634-649.
The production of cellulases, hemicellulases, and starch-degrading enzymes by the thermophilic aerobic fungus Talaromyces emersonii under liquid state culture on various food wastes was investigated. A comprehensive enzyme screening was conducted, which resulted in the identification of spent tea leaves as a potential substrate for hydrolytic enzyme production. The potent, polysaccharide-degrading enzyme-rich cocktail produced when tea leaves were utilised as sole carbon source was analysed at a protein and mRNA level and shown to exhibit high level production of key cellulose and hemicellulose degrading enzymes. As presented in this paper, the crude enzyme preparation produced after 120 h growth of Talaromyces emersonii on used tea leaves is capable of hydrolysing other lignocellulosic materials into their component monosaccharides, generating high value sugar syrups with a host of industrial applications including conversion to fuels and chemicals. PDF
The flexural properties of commercial bagasse-filled polyethylene (PE) and polypropylene (PP) composites were determined as a function of strain rate at room temperature. The applied strain rates were 1.5 ×10-4, 3.75×10-4, 7.5×10-4, and 1.5×10-3 s-1. The flexural modulus tended to increase linearly for the two types of composites with the logarithm of strain rate. The bending strength of polypropylene composite also behaved in a similar manner, but the polyethylene composite exhibited different behavior in which the MOR values of polyethylene composite didn’t alter appreciably as a function of strain rate. The flexural response of a polypropylene-based composite was found to exhibit higher dependency on strain rate than a polyethylene-based composite. Water absorption of both composites followed the kinetics of a Fickian diffusion process. Water absorption and dimensional instability of PE-based composites were lower than those of PP-based composites. The highest swelling took place in the thickness of the samples, followed by the width and length, respectively. PDF
Mulinari, D. R., Voorwald, H. J. C., Cioffi, M. O. H., Rocha, G. J., and Pinto Da Silva, M. L. C. (2010). "Surface modification of sugarcane bagasse cellulose and its effect on mechanical and water absorption properties of sugarcane bagasse cellulose/HDPE composites," BioRes. 5(2), 661-671.
Cellulose fibres from sugarcane bagasse were bleached and modified by zirconium oxychloride in order to improve the mechanical properties of composites with high density polyethylene (HDPE). The mechanical properties of the composites prepared from chemically modified cellulose fibres were found to increase compared to those of bleached fibres. Tensile strengths of the composites showed a decreasing trend with increasing filler content. However, the values for the chemically modified cellulose fibres/HDPE composites at all mixing ratios were found to be higher than that of neat HDPE. Results of water immersion tests showed that the water absorption affected the mechanical properties. The fracture surfaces of the composites were recorded using scanning electron microscopy (SEM). The SEM micrographs revealed that interfacial bonding between the modified filler and the matrix was significantly improved by the fibre modification. PDF
Sbiai, A., Maazouz, A., Fleury, E., Sautereau, H., and Kaddami, H. (2010). "Short date palm tree fibers / polyepoxy composites prepared using RTM process: Effect of TEMPO mediated oxidation of the fibers," BioRes. 5(2), 672-689.
Short date palm tree lignocellulosic fibers were used as a reinforcing phase in a polyepoxy thermoset commodity resin. Unmodified fibers as well as counterparts chemically oxidized using TEMPO catalyst mediation were used as fillers for composite materials prepared in a Resin Transfer Molding process. The preparation was facilitated in the case of the composites based on oxidized fibers. During the process, the front displacement of injected resin was more regular, more homogeneous, and faster in the case of oxidized fibers. The morphology, thermal and mechanical properties of the resultant composites were characterized by SEM, DSC, DMA, as well as three-point bending and Charpy impact tests. An elevated reinforcing capability of the oxidized fibers as compared to their unmodified counterparts was demonstrated, particularly by a high strain test in the glassy state. This confirmed the enhanced filler/matrix interface observed in such materials during the process and in the final composite as analyzed by SEM. No significant difference in reinforcing capability of the two kinds of filler was observed in the DMA analysis. PDF
Hosseini Hashemi, S. H., Latibari, A. J., Khademi-Eslam, H., and Alamuti, R. F. (2010). "Effect of boric acid treatment on decay resistance and mechanical properties of poplar wood," BioRes. 5(2), 690-698.
This study was performed to determine the effect of boric acid treatment upon the decay resistance and mechanical properties of poplar wood. Test specimens were prepared from poplar wood (Populus nigra L.) to meet ASTM D 143-94 and BS 838:1961 requirements. Samples were impregnated with boric acid solution (0.5, 1, and 2% w/w in distilled water) and by a long-term (21 days) dipping technique to reach complete saturation. Impregnated specimens were exposed to rainbow white-rot fungus (Trametes versicolor) for 14 weeks according to BS 838:1961 as applied by the kolle-flask method. The weight loss, compression strength parallel to the grain, and Brinell hardness were determined after impregnation and exposure to white-rot fungus. The highest weight loss (28.60%) was observed for untreated control samples and the lowest (0.63%) occurred in samples treated with 2% boric acid solution. The highest compression strength parallel to the grain was noted in samples treated with 0.5% boric acid and decayed (22.59 MPa) and the lowest compression strength parallel to the grain was recorded in untreated decayed samples (10.42 MPa). The highest Brinell hardness on tangential surface was observed in samples treated with 1% boric acid and decayed (1.32 KN) and the lowest was noted in untreated decayed samples (0.39 KN). The highest Brinell hardness on radial surface was observed in samples treated with 1% boric acid and decayed (1.07 KN) and the lowest was found in untreated decayed samples (0.35 KN). PDF
This paper presents the production of xylooligosaccharides from auto-hydrolysis liquors of wheat straw and sunflower stalk, as wells as the antioxidant activity of these autohydrolysis liquors. The autohydrolysis liquors (raw or refined by ultrafiltration) of both wastes were subjected to the action of two different endoxylanase to produce xylooligosaccharides with low degree of polymerization that are potentially useful as food additives. Trichoderma reseei xylanase led to the highest proportion of oligomers with degree of polymerization values in the range 1–3, while Aspergillus niger xylanase gave mainly oligomers with polymerization degree in the range 2-3. T reseei xylanase gave a higher increase in equivalent xylose concentration and produced more monosaccharide than A.niger xylanase. Membranes with a nominal MWCO 1 kDa did not reject antioxidant-related and other low molar mass compounds, and most of these compounds were recovered with monosaccharides in the permeate of the membrane. PDF
Polyaniline (PAn)-coated conductive paper was prepared by in-situ polymerization of aniline and a two-step process. XPS results confirmed that the bond between PAn and cellulose existed in the form of hydrogen bonding. The mild treatment did not result in the oxidation and degradation of cellulose. Decreased bonding strength of conductive paper was attributed to the coverage of hydroxyl groups on pulp fibers by PAn. For the PAn-coated paper about one in every three nitrogen atoms was doped with p-toluenesulfonic acid (PTSA). The quinoid imine nitrogens of the PAn molecular chain were preferentially doped. Pulp fibers seemed to be favorable for the doping of PAn with PTSA. The surface resistivity sharply decreased at least two orders of magnitude with a very small increase in the amount of PAn coated (from 3.6% to 4.2%). A continuous conductive network was formed and the surface resistivity was lowest when the amount of PAn coated reached 30.1%. The upper and lower threshold values were around 4% and 30%, respectively. SEM study showed that the shape of the PAn coated on pulp fibers was spherical with a diameter from 100 to 200 nm. PDF
In this work the annual plant called Luffa cylindrica (LC) has been characterized and used to prepare macroscopic lignocellulosic fibers and cellulosic nanoparticles, viz. microfibrillated cellulose (MFC) and whiskers, each of which can be used as a reinforcing phase in bionanocomposites. The morphological, chemical, and physical properties of LC fibers were first characterized. The contents of lignin, hemicellulose, and other constituents were determined, and scanning electron microscopy (SEM) observations were performed to investigate the surface morphology of the LC fibers. Sugars contents were determined by ionic chromatography, and it was shown that glucose was the main sugar present in the residue. MFC and whiskers were prepared after chemical treatments (NaOH and NaClO2), purifying cellulose by eliminating lignin and hemicellulose. Transmission electron microscopy (TEM) and SEM made it possible to determine the dimensions of LC whiskers and MFC. Tensile tests were carried out to investigate the mechanical properties of LF nanoparticles. PDF
Soni, S. K., Batra, N., Bansal, N., and Soni, R. (2010). "Bioconversion of sugarcane bagasse into second generation bioethanol after enzymatic hydrolysis with in-house produced cellulases from Aspergillus sp. S4B2F," BioRes. 5(2), 741-757.
An integrated approach was studied for in-house cellulase production, pretreatment, and enzymatic conversion of sugarcane bagasse into glucose followed by the production of second generation bioethanol. Solid state cultures of Aspergillus sp. S4B2F produced significant levels of cellulase complex on wheat bran, supplemented with 1% (w/w) soyabean meal, moistened with 1.5 parts of distilled water after 96 h of incubation at 30oC. The highest productivities of endoglucanase, exoglucanase, and β-glucosidase were 66, 60, and 26 IU/g of fermented dry bran, respectively. The enzyme components had a temperature and pH optima at 50oC and 4.0, respectively and revealed high thermostability at 50oC, retaining 66, 54, and 84% residual activities after 72 h. Pretreatment with 2% alkali in combination with steam was the most efficient pre-hydrolysis method for enzymatic bioconversion and fermentation of cellulosic residue of sugarcane bagasse, which produced the highest cellulose conversion (67%), with glucose and alcohol yields of 323 mg and 175 ml respectively per dry gram of bagasse. PDF
Rice straw fiberboard was made using 12 wt % urea-formaldehyde (UF) resin as binder and 1.0 wt % polymeric methylene diphenyl diisocyanate (pMDI) and 1.2 wt % wax emulsion as water retardants. The prepared fiberboards were heat-treated at 120, 150, 185, and 210°C in the presence of steam in a high-temperature dry kiln, respectively for 90 min. The effect of water retardants and heat treatment on the water resistant and some mechanical properties of the fiberboards were investigated. It was found that the water resistance of the rice straw fiberboard could not be improved by adding wax emulsion. The use of pMDI to the system significantly increased the interfacial strength and reduced 24-h thickness swelling (TS) compared to the boards with or without wax emulsion. After heat treatment, the TS was significantly decreased due to the decrease in the free reactive hydroxyl group content of rice straw fiber. Some mechanical properties of the fiberboards, such as the internal bonding strength, modulus of elasticity, and modulus of rapture were dramatically reduced with increasing temperature from 120°C to 210°C. PDF
Three hybrid systems were compared to a solvent-based low-VOC system. The goal of the project was to determine if the hybrid systems met the requirements of the kitchen cabinet and furniture industries. Adhesion of each system to the substrate was first evaluated, and significant differences were recorded. Subsequently, resistance to heat and moisture was evaluated using hot box and hot and cold check tests. These tests indicated that the experimental systems generally performed relatively well in terms of thermal resistance, but the appearance of those prepared from solvent-borne sealers and lacquers were less stable. The chemical resistance of these systems was also studied. The ability of the finish to withstand the effects of substances typically found in a kitchen was tested, as was their resistance to detergents and water. All the systems performed very well in vertical testing. Volatile organic compound emissions were finally measured after conditioning times of 3 and 21 days. These tests showed that the different systems behaved quite differently. The systems prepared with solvent-borne sealers and lacquers produced a high level of VOCs at the beginning of the test, with a rapid decrease thereafter, while the opposite was observed in systems based on water-borne sealers and lacquers. PDF
Zhang, Y., Cao, C.-Y., Hou, Q.-X., Feng, W.-Y., Xu, M., Su, Z.-H., Lin, Q.-Y., Zhuang, J.-F., and Lv, W.-J. (2010). "Using a membrane filtration process to concentrate the effluent from alkaline peroxide mechanical pulping plants," BioRes. 5(2), 780-795.
Using a multi-effect evaporation system to concentrate the effluent from alkaline peroxide mechanical pulping (APMP) plants is known to require a high energy consumption. In order to improve the situation, a polyethersulfone membrane was used to concentrate the effluent of APMP plants beforehand. An orthogonal experimental design was applied and a mathematical model was established to optimize the filtration parameters. An estimation of potential energy and water savings from this new concentration process was developed. The optimal filtration conditions obtained were: molecular weight cut-off at 10,000 Dalton, trans-membrane pressure at 3 bar, feed temperature at 50oC, cross-flow velocity at 420 rpm, and volume reduction factor at 0.93. The average permeate flux under these conditions was 45.31 l/m2.h. The total solids content was increased from 14.74 g/l in the feed to 95.04 g/l in the concentrate. The permeate had low total solid contents of 8.75 g/l, Chemical Oxygen Demand of 6696 mg/l, and Biochemical Oxygen Demand of 4383 mg/l. Such qualities would allow the permeate to be reused in the alkaline peroxide mechanical pulping process. With this new concentration process, about 4840.6 kwh energy can be saved and 23.3 m3 effluent discharge can be reduced for each ton of pulp produced. PDF
Recent studies on the ultrastructure and composition of the gelatinous layer (g-layer) in poplar have reported findings of xyloglucan. Using correlated fluorescence, scanning- and transmission electron micros-copy, we found evidence for xyloglucan present in and surrounding the g-layer, using the fucosylated xyloglucan specific CCRC-M1 antibody and the carbohydrate binding module FXG-14b. However, labeling of isolated gelatinous layer remained negative. PDF
The aim of this study was to evaluate the possibilities for chemical consumption reduction in P-P-Paa-P bleaching (P alkaline peroxide stage, Paa peracetic stage) of hot water treated straw and the effect of the wheat straw variability on the process. Papermaking fibre production from wheat straw using such a process could be implemented on a small scale if chemical consumption was low enough to eliminate the need for chemical recovery. The pulp properties obtained with this process are equal to or even superior to the properties of wheat straw soda pulp. The possibility of enhancing the first peroxide stage with oxygen and pressure was studied. The possibility for substitution of sodium hydroxide partially with sodium carbonate was also investigated. The objective was to achieve International Standardization Organization (ISO) brightness of 75%, with minimal sodium hydroxide consumption, whilst maintaining the pulp properties. The optimization of the peroxide bleaching is challenging if the final brightness target cannot be reduced. Results indicate that up to 25% of the sodium hydroxide could be substituted with sodium carbonate without losing brightness or affecting pulp properties. Another possibility is a mild alkali treatment between the hot water treatment and the bleaching sequence. PDF
The characteristics of enzymatic/mild acidolysis lignin (EMAL) isolated from moso bamboo were investigated using pyrolysis-gas chromatography/mass spectrometry (Py-GC/MS). Pyrolysis temperature as a factor on products was studied, and the pyrolysis mechanism was inferred with respect to the dominating products. Research results showed that pyrolysis products derived from EMAL pyrolysis were mainly heterocyclic (2,3-dihydrobenzofuran), phenols, esters, and a minor amount of acetic acid. Pyrolysis temperature had a distinct impact on yields of pyrolysis products. As pyrolysis temperature increased, the yield of 2,3-dihydrobenzofuran rapidly decreased; however, yields of phenols increased smoothly. It can be obtained that, at the low temperatures (250-400oC), pyrolysis products were mainly 2,3-dihydrobenzofuran, and the highest yield was 66.26% at 320oC; at the high temperatures (400-800oC), pyrolysis products were mainly phenols, and yields hit their highest level of 56.43% at 600 oC. A minor amount of acetic acid only emerged at 800°C. Knowledge of pyrolysis products releasing from EMAL and the pyrolysis mechanism could be basic and essential to the understanding of thermochemical conversion of EMAL to chemicals or high-grade energy. PDF
Prasad, A. G. D., and Abdullah, M. A. (2010). "Biosorption of Cr(VI) from synthetic wastewater using the fruit shell of gulhomar (Delonix regia): Application to electroplating wastewater," BioRes. 5(2), 838-853.
The biosorption of Cr(VI) from synthetic solutions and electroplating wastewater using the fruit shell of gulmohar has been investigated in a batch system. The effects of various parameters such as pH, contact time, adsorbent dosage, and initial concentration of Cr(VI) on the biosorption process were studied. The complete removal of Cr(VI) was observed at pH < 3.0. Studies indicated that both biosorption and bioreduction were involved in the removal of Cr(VI). The sorption equilibrium exhibited a better fit to the Langmuir isotherm than the Freundlich isotherm. The maximum biosorption capacity of fruit shell of gulmohar to remove Cr(VI) was 12.28 mg/g. A kinetic model of pseudo-second order provided a good description of the experimental data as compared to a pseudo-first order kinetic model. The sorption rate was found to be dependent on the initial concentration of Cr(VI) and biomaterials dosage. The study showed that the abundant and inexpensive fruit shell of gulmohar biosorbent has a potential application in the removal of Cr(VI) from electroplating wastewater and its conversion into less or non-toxic Cr (III). PDF
In this study rice husk reinforced polyethylene composites and their test specimens were manufactured using a single screw extruder and an injection molding machine, respectively. Raw rice husk was chemically treated with benzene diazonium salt in alkali, acidic, and neutral media, in order to improve in the mechanical properties. The mechanical properties of the composites prepared from alkaline media treated rice husk were found to increase substantially compared to those of acidic media, neutral media, and untreated ones. However, the values for the alkaline media treated rice husk-PE composites at all mixing ratios were found to be higher than those of treated acidic media, treated neutral media, and untreated rice husk composites respectively. The SEM micrographs reveal that interfacial bonding between the treated filler and the matrix has significantly improved, suggesting that better dispersion of the filler into the matrix was achieved upon treatment of rice husk. Based on filler loading, 35% filler reinforced composites had the optimum set of mechanical properties among all composites manufactured. PDF
Bleaching of soda-anthraquinone jute pulp by chlorine dioxide (ClO2) was studied to reach a target brightness of above 88% for the purpose of using less bleaching chemicals. The performance of either chlorine dioxide or peroxide in the final bleaching to boost brightness was also studied. The experimental results revealed that the final brightness depended on ClO2 charge in the Do and D1 stages. The brightness reversion was lower when the final stage brightening was done by peroxide. The use of Mg(OH)2 in the D1 and D2 stages improved the final brightness due to the formation of less chlorate and chlorite during the Mg(OH)2- based ClO2 brightening stages. The strength properties of pulp bleached by peroxide in the final stage was slightly better than that from ClO2 as the final ClO2 bleaching stage. PDF
Barros, D. P., Silva, V. L., Hämäläinen, H., and Colodette, J. L. (2010). "Effect of last stage bleaching with peracetic acid on brightness development and properties of eucalyptus pulp," BioRes. 5(2), 881-898.
Investigation of last stage bleaching with peracetic acid is the main subject of this paper. Proper conditions were established to apply peracetic acid as the last bleaching stage of the D(Ep)D/Paa, DHT(Ep)D/Paa, A/D(Ep)D/Paa, DHT/Q(PO)Paa and Z/ED/Paa sequences. In addition, the impact of last stage bleaching with Paa on pulp refinability and strength properties was determined. Peracetic acid was consumed relatively fast when applied as the last stage of ECF bleaching sequences. A reaction time of 120 min at 75 oC and pH 5.0 is seemingly adequate regardless of the Paa dose, in the range of 1-5 kg/odt pulp and bleaching sequence. The optimum dose of Paa depends upon the sequence under investigation. In general the Paa application as last bleaching stage caused slight decrease in pulp viscosity, kappa number and HexA content but had no significant effect on pulp reversion and L*a*b* coordinates. The refinability and bonding strength properties of the pulps bleached with the sequences DHT(Ep)DD and DHT(Ep)D/Paa were quite similar when the pH of the last bleaching stage of both sequences were near 5. These properties improved slightly when Paa bleaching pH was raised to 8.5. PDF
The influences of pulp type, content of acidic groups (i.e., sulfonic and carboxylic groups) in CTMP, kappa number (i.e., residual lignin content) of unbleached kraft pulp, and beating degree of bleached kraft pulp on the conductivity of polyaniline (PAn)-coated conductive paper were investigated. The amounts of PAn coated on chemical pulps were higher than those coated on high yield pulps, and the surface resistivities of conductive papers prepared from chemical pulps were lower than those prepared from high yield pulps. As the substrates for the production of PAn-coated conductive paper, bleached chemical pulps were better than unbleached chemical pulps. The conductivity had a significant positive linear correlation with the amount of PAn coated. The amount of PAn coated increased with increasing content of sulfonic groups in CTMP or decreasing kappa number of unbleached kraft pulp. We hypothesized that this might be associated with the ionizability of acidic groups and the inhibiting effect of lignin on aniline polymerization. The beating degree of pulp seemed to have an insignificant effect on the conductivity of PAn-coated conductive paper. As a whole, the interpretations of the influence of the chemical composition are based on proposed ideas and need to be confirmed by future experimental work. PDF
Bhattacharya, P., Hassan, E. B., Steele, P., Cooper, J., and Ingram, L. (2010). "Effect of acid catalysts and accelerated aging on the reaction of methanol with hydroxy-acetaldehyde in bio-oil," BioRes. 5(2), 908-919.
Bio-oil is a promising alternative source of energy produced from fast pyrolysis of biomass. Increasing the viscosity of bio-oil during storage is a major problem that can be controlled by the addition of methanol or other alcohols. This paper reports the results of our investigation of the reactions of short chain alcohols with aldehydes and acids in bio-oil. The reaction of methanol with hydroxyacetaldehyde (HA) to form the acetal was catalyzed by the addition of 7 x 10-4 M strong acids such as sulfuric, hydrochloric, p-toluene sulfonic acid, and methanesulfonic acid. HA formed 2,2-dimethoxyethanol (DME), and at 60 oC the equilibrium was reached in less than one hour. Smaller amounts of DME were formed in the absence of strong acid. HA, acetaldehyde, and propanal formed their corresponding acetals when reacted with methanol, ethanol, 1-propanol or 1-butanol. Esters of acetic acid and hydroxyacetic acid were observed from reactions with these same four alcohols. Other acetals and esters were observed by GC/MS analysis of the reaction products. The results from accelerated aging experiments at 90 oC suggest that the presence of methanol slows polymerization by formation of acetals and esters from low molecular weight aldehydes and organic acids. PDF
The continual expansion of urbanization and industrial activity has led to the accumulation of a large quantity of lignocellulosic residues throughout the world. In particular, large quantities of paper and bagasse are largely produced in Visakhapatnam. In this work we present the study of the degradability of these substrates with fungi. Three cultures of soil fungi were screened for their ability to degrade cellulose. Aspergillus flavus degraded the most, as shown by the highest CO2 release. Further, Aspergillus flavus was tested with the standard fungus Phanerochaete chrysosporium for cellulose degradation, which showed nearly equivalent potential. PDF
Mirahmadi, K., Kabir, M. M., Jeihanipour, A., Karimi, K., and Taherzadeh, M. J. (2010). "Alkaline pretreatment of spruce and birch to improve bioethannol and biogas production," BioRes. 5(2), 928-938.
Alkaline pretreatment with NaOH under mild operating conditions was used to improve ethanol and biogas production from softwood spruce and hardwood birch. The pretreatments were carried out at different temperatures between minus 15 and 100ºC with 7.0% w/w NaOH solution for 2 h. The pretreated materials were then enzymatically hydrolyzed and subsequently fermented to ethanol or anaerobically digested to biogas. In general, the pretreatment was more successful for both ethanol and biogas production from the hardwood birch than the softwood spruce. The pretreatment resulted in significant reduction of hemicellulose and the crystallinity of cellulose, which might be responsible for improved enzymatic hydrolyses of birch from 6.9% to 82.3% and spruce from 14.1% to 35.7%. These results were obtained with pretreatment at 100°C for birch and 5°C for spruce. Subsequently, the best ethanol yield obtained was 0.08 g/g of the spruce while pretreated at 100°C, and 0.17 g/g of the birch treated at 100°C. On the other hand, digestion of untreated birch and spruce resulted in methane yields of 250 and 30 l/kg VS of the wood species, respectively. The pretreatment of the wood species at the best conditions for enzymatic hydrolysis resulted in 83% and 74% improvement in methane production from birch and spruce. PDF
Khosravani, A., Latibari, A. J., Mirshokraei, S. A., Rahmanninia, M., and Nazhad, M. M. (2010). "Studying the effect of cationic starch-anionic nanosilica system on retention and drainage," BioRes. 5(2), 939-950.
Nanoparticles are widely used in the papermaking industry as retention/ drainage aids, usually in conjunction with a high mass cationic polyelectrolyte such as cationic starch. However, little convincing knowledge of their role and mechanism in the wet-end system is yet found. This work focused on the role of nanosilica on papermaking wet end system in response to some processing parameters (drainage, retention, and electrostatic force of the whole system). The observations indicated that the nanosilica performance is defined by interactions of nanosilica with the complex aqueous environment of wet end system. The interaction mechanism seems to rely on introduction of nanoparticles into a cationic starch-fines-fibers network, converting the fiber mat on the forming wire into a porous structure that is responsive to retention and drainage. PDF
The anatomical, chemical, and physico-mechanical properties of the fibres of C. pangorei were investigated in this study. The results indicate that the rind region that is split and used in mat making contains compactly arranged fibrovascular bundles and a discontinuous patch of fibrous sheath. The frequency and the R/T ratio of the bundles were high in the rind region and were indicative of fibre strength. Lignin and cellulose, the major cell wall substances, were localized with heterochromatic, fluorescent, and natural dyes. The holocellulose content was high (82.2 %), and the lignin content was comparatively low (13.28 %) as analyzed by the method of Doree. Very thick walled, thick walled, very thin walled, and thin walled fibres were characterized when fibres were macerated, and their derived values indicated a high Slenderness and Runkell ratio that is indicative of tear resistance. The tenacity and percentage elongation of the split culm strands was also high, and this implies high strength of the fibre strands. The fibre of this mat sedge thus has favorable characteristics to be potentially utilized in the mat and silkmat industry. Furthermore the plant’s annual harvesting period, biomass, and appropriate fibre characteristics makes this sedge very attractive as an alternative fibre source in the miscellaneous plant fibre industry. PDF
Jarusombuti, S., Ayrilmis, N., Bauchongkol, P., and Fueangvivat, V. (2010). "Surface characteristics and overlaying properties of MDF panels made from thermally treated rubberwood fibers," BioRes. 5(2), 968-978.
The objectives of this research were to investigate surface characteristics and overlaying properties of medium density fiberboard (MDF) panels, as affected by thermal treatment of the fibers. MDF panels were manufactured from untreated rubberwood fibers and fibers treated at three different temperatures (120, 150, or 180°C) for 15 or 30 min. Contact angle measurements were obtained by using a goniometer connected with a digital camera and computer system. Roughness measurements, average roughness (Ra), mean peak-to-valley height (Rz), and maximum roughness (Ry), were taken from the sanded samples along and across the sandmarks using a fine stylus tracing technique. With the increasing thermal treatment temperature and time of the fibers, surface roughness of the panels decreased, while their wettability and adhesive bonding strength decreased. Statistical analyses showed significant differences in the surface roughness, contact angle, and adhesive bonding strength of the panels following thermal treatment. Based on the findings obtained from this study, the contact angle and surface roughness parameters of the MDF panels made from thermally treated rubberwood fibers can provide a good information on their ability to bond. PDF
Phase transformations in microcrystalline cellulose (MCC) were studied following dissolution of 5, 10, and 20 wt. % MCC in the ionic liquid 1-butyl-3-methylimidazolium formate (BMIMFmO) and regeneration via water. BMIMFmO was found to be useful as a non-derivatizing solvent for cellulose without the need for any pre-treatment. Wide angle X-ray scattering indicated that a phase transformation from cellulose I to either a poorly crystalline form of cellulose I and/or cellulose II occurs during regeneration after dissolution in BMIMFmO. The dissolution time affected the resulting microstructure of the regenerated cellulose. Thermogravi-metric analysis showed that regeneration from the ionic liquid lowers the decomposition onset temperature and increases the char yield when compared with the as-received MCC. PDF
Corn stover and rice straw lignin samples received from ethanol pilot plants, along with softwood kraft lignin samples, were characterized using pyrolysis GC-MS, 13C CP/MAS NMR spectroscopy, and permanganate oxidation degradation. The lignins were then esterified using 1-methylimidazole as a catalyst in a pyridine-free reaction, and the thermal properties of the products were evaluated. Solid state NMR showed the rice straw lignin contained 18% residual polysaccharides. Pyrolysis GC-MS showed the softwood kraft, corn stover, and rice straw lignins to be G – type, H/G/S – type, and G/S – type, respectively. However, some discrepancy was apparent between the pyrolysis and permanganate oxidation studies as to the ratios of the monomeric make-up of the lignins. The kraft and rice straw lignins were determined to have high degrees of condensation, while the corn stover lignin was uncondensed. Little to no increase in solubility was noticed for corn stover or rice straw lignin esters in organic solvents. Glass transition temperatures (Tg) of the lignin derivatives were determined by a combination of differential scanning calorimetry, dynamic mechanical analysis, and parallel plate rheometry. PDF
Pereira, P. H. F., Voorwald, H. C. J., Cioffi, M. O. H., and Pinto Da Silva, M. L. C. (2010). "Preparation and characterization of cellulose/ hydrous niobium phosphate hybrid," BioRes. 5(2), 1010-1021.
In recent years, increasing attention has been directed to the use of renewable resources, particularly of sugarcane bagasse. Considering the abundant availability of such lignocellulosic materials, relatively few attempts have been made regarding their utilization. Studies about properties and morphology, heavy metal adsorption, and membranes preparation have been conduced by this research group in order to use these materials. In this paper, cellulose fibers obtained from sugarcane bagasse were bleached and modified by hydrous niobium phosphate. Hybrids (cellulose/NbOPO4.nH2O) were prepared from metallic niobium dissolved in a fluoridric/nitric (10:1) mixture, to which cellulose sugarcane bagasse was added. Afterwards a concentrated orthophosphoric acid (85mL, 85% w/w) was added to precipitate hydrous niobium phosphate particles. This material was characterized by X-ray diffraction (XRD), thermogravimetry (TG/DTG), and differential scanning calorimetry (DSC) analyses, as well as scanning electronic microscopy (SEM) coupled to an energy dispersive spectrophotometer (EDS). Morphological studies of bleached cellulose revealed different sizes and arrangement of cells, showing that NbOPO4.nH2O was present in the cellulose structure. Thermal stability of the hybrid was observed up to approximately 200°C, and the cellulose decomposed at 300°C. These data will help finding new uses for these materials. PDF
Malaysia, especially the Borneo Island state of Sarawak, has a large variety of tropical wood species. In this study, selected raw tropical wood species namely Artocarpus Elasticus, Artocarpus Rigidus, Xylopia spp., Koompassia Malaccensis, and Eugenia spp. were chemically treated with sodium metaperiodate to convert them into plasticized wood (PW). Manufactured plasticized wood samples were characterized using, Fourier transform infrared spectroscopy, scanning electron microscopy, and mechanical testing (modulus of elasticity (MOE), modulus of rupture (MOR), static Young’s modulus (Es), decay resistance, and water absorption). MOE and MOR were calculated using a three-point bending test. Es and decay resistance were calculated using the compression parallel to grain test and the natural laboratory decay test, respectively. The manufactured PW yielded higher MOE, MOR, and Es. PW had a lower water content compared to the untreated wood and had high resistance to decay exposure, with Eugenia spp. having the highest resistance compared to the others. PDF
Karaaslan, A. M., Tshabalala, M. A., and Buschle-Diller, G. (2010). "Wood hemicellulose/chitosan-based semi-interpenetrating network hydrogels: Mechanical, swelling and controlled drug release properties," BioRes. 5(2), 1036-1054.
The cell wall of most plant biomass from forest and agricultural resources consists of three major polymers, cellulose, hemicellulose, and lignin. Of these, hemicelluloses have gained increasing attention as sustainable raw materials. In this study, novel pH-sensitive semi-IPN hydrogels based on hemicelluloses and chitosan were prepared using glutaraldehyde as the crosslinking agent. The hemicellulose isolated from aspen was analyzed for sugar content by HPLC, and its molecular weight distribution was determined by high performance size exclusion chromatography. Results revealed that hemicellulose had a broad molecular weight distribution with a fair amount of polymeric units, together with xylose, arabinose, and glucose. The effects of hemicellulose content on mechanical properties and swelling behavior of hydrogels were investigated. The semi-IPNs hydrogel structure was confirmed by FT-IR, X-ray study, and the ninhydrin assay method. X-ray analysis showed that higher hemicellulose contents yielded higher crystallinity. Mechanical properties were mainly dependent on the crosslink density and average molecular weight between crosslinks. Swelling ratios increased with increasing hemicellulose content and were high at low pH values due to repulsion between similarly charged groups. In vitro release study of a model drug showed that these semi-IPN hydrogels could be used for controlled drug delivery into gastric fluid. PDF
The present study deals with the surface modification of Agave americana L. fiber through graft copolymerization of methyl methacrylate under pressure in the presence of ceric ammonium nitrate as redox initiator. The various reaction parameters such as reaction time, pressure, concentration of nitric acid, initiator, and monomer, etc. were optimized to have the maximum graft yield of 13.6%. The grafted fibers were then subjected to the evaluation of different physico-chemical properties such as swelling behavior, solubility, moisture absorption under different humidity levels, resistance to acids and bases, etc. It was observed that swelling behavior, solubility behavior, and moisture absorbance decreased with increase in grafting, whereas resistance to acids and bases increased with grafting. The fibers grafted under the optimized conditions were then characterized by Fourier transform infra-red spectroscopy, scanning electron microscopy, thermogravimetric analysis, and x-ray diffraction techniques. PDF
Istek, A.,. Aydemir, D., and Aksu, S. (2010). "The effect of decor paper and resin type on the physical, mechanical, and surface quality properties of particleboards coated with impregnated decor papers,"BioRes. 5(2), 1074-1083.
The objective of this study is to evaluate the effect of décor paper and resin type on physical properties, mechanic properties, and surface quality properties of particleboards coated with décor papers impregnated by using different resin. White oak, New wenge and common maple pattern decor papers impregnated with urea formaldehyde (UF), melamine formaldehyde (MF) and urea-melamine formaldehyde (UF+MF) were used as coating materials. Particleboard surface was laminated with these coating materials by hydraulic press. As a result, specimens coated with MF-impregnated papers showed better performance than those coated with UF and UF+MF-impregnated papers. Resin type and paper pattern affected the physical, mechanical (with exception of tension strength), and surface properties (especially cigarette burn and abrasion) of coated particleboards. Physical and mechanical properties of coated particleboard were significantly improved compared to non-laminated particleboards. It was found that paper pattern affected the surface properties, such as impact, scratch, and abrasion, resistance to staining and cigarette burn. However, it did not change the cracking and steaming properties of the coated samples. After the coating process, it was determined that cigarette burn, abrasion, impact, and scratch performances were among 1 to 3 grade, lp:10-35, Fp:210-340/100-150, and 2 to 5 grade, respectively. PDF
Coastal Bermuda grass (CBG) has been shown to have potential as a biomass feedstock for sugar production. In this study, the effectiveness of ozone pretreatment for CBG to improve the sugar recovery via enzyme hydrolysis was investigated. Raw CBG and autohydrolysis-treated CBG were pretreated with ozone at ozone consumption of 1.8 to 26.4 % (w/w) at room temperature. Lignin degradation and hemicellulose solubilization increased with increased ozone consumption. At 26.4% ozone consumption by weight on CBG the amount of lignin in the CBG was reduced by 34%. Autohydrolysis of CBG increased the reactivity of cellulose, hemicellulose, and lignin with ozone. The maximum total sugar recovery after enzymatic hydrolysis was 32% for a 14.0% consumption of ozone on raw CBG. For CBG samples pretreated with autohydrolysis followed by a 3.1% ozone consumption pretreatment the maximum total sugar recovery after enzyme hydrolysis was 40.1%. Autohydrolysis pretreatment followed by enzyme hydrolysis yielded a 36.4% sugar recovery, indicating that the application and benefits of ozone after autohydrolysis with the conditions studied herein are marginally better than autohydrolysis alone. PDF
Nechita, P., Dobrin, E., Ciolacu, F., and Bobu, E. (2010). "The biodegradability and mechanical strength of nutritive pots for vegetable planting based on lignocellulose composite materials," BioRes. 5(2), 1102-1113.
Considering the mild degradation strength and the fact that it may be an organic matter reserve for the soil, in the past years lignocellulosic materials have been used as fibrous raw materials in the manufacture of biodegradable nutritive pots for the seedling in vegetable containerized production. This paper analyses the behavior of the nutritive pots madefrom biodegradable composites for the vegetable seedling production process, focusing on their mechanical strength properties and biodegradability. It was found that the biodegradability of composite materials obtained from a mixture of secondary cellulosic fibers, peat, and additives, is strongly influenced by the presence or absence of the rhizosphere effect and the synergistic relations set in the culture substrate between the plant roots and microorganisms, which develop permanently the recycling and solubilization of mineral nutrients. The results showed that the presence in the substrate of some complex populations made by heterotrophic bacteria favors full degradation of the pulp and lignin contained in the substrate and pots composition. Therefore, unlike the reference sample (plant-free), cultivated versions exhibited an intense biodegradation on the account of rhizosphere effect. PDF
Cellulose hydrogels with quaternary ammonium (QA) groups were prepared via the etherification and cross-linking reaction. The structure of the functional hydrogels with QA groups was confirmed with FT-IR. Differential scanning calorimeter (DSC) analysis indicated that there was a large amount of free water in the hydrogels. The hydrogels showed salt-sensitivity behavior, and they also exhibited a strong antibacterial activity toward Escherichia coli. PDF
The durability of Scots pine heartwood has previously been shown to be affected by the industrial drying process of sawn lumber. The durability of heartwood from boards dried at temperatures between 20°C-110°C was studied by measuring the mass loss in a decay test with a brown rot fungus (Coniophora puteana), and the concentration of total phenolics was measured according to the Folin-Ciocalteu (FC) assay. The relation between mass loss and phenolics in dried heartwood showed a weaker negative correlation at lower levels of phenolics as compared to the strong relationship found in a study on heartwood from standing Scots pine trees. Mass loss in dried heartwood showed a weak negative correlation to density. Heating of extractives-rich green sawdust under moist conditions resulted in a reduction of phenolics with temperature up to 180 oC and with increasing time. The concentration of phenolics in heated, green sawdust was higher in extractives-rich pine heartwood than in heartwood with a normal extractives content. PDF
Carvalho, K. C. C., Mulinari, D. R., Voorwald, H. J. C., and Cioffi, M. O. H. (2010). "Chemical modification effect on the mechanical properties of HIPS/coconut fiber composites," BioRes. 5(2), 1143-1155.
Lignocellulosic fibers from green coconut fruit were treated with alkaline solution (NaOH 10%m/v) and then bleached with sodium chlorite (NaClO2) and acetic acid (CH3COOH). Alkali-treated and bleached fibers were mixed with high impact polystyrene (HIPS) and placed in an injector chamber in order to obtain specimens for tensile tests. Specimens of HIPS/alkali-treated and bleached coconut fiber composites were tested in tensile mode, and the fracture surfaces of the composites were analyzed by scanning electron microscopy. Untreated, alkali-treated, and bleached coconut fibers were analyzed by scanning electron microscopy and X-ray diffraction. Alkaline treatment was effective for removing the extractives and increasing the roughness of surfaces, while the bleaching treatment intensified the effect of alkaline treatment, while increasing the crystallinity index and surface energy of fibers. Results of tensile tests showed that the addition of 30% alkali-treated and bleached fibers reinforcing the HIPS matrix provided considerable changes in the mechanical properties of composites in comparison with the pure HIPS. On the other hand, chemical treatments were not totally effective for improving the adhesion between the fiber and matrix, as was observed in the analysis of the fracture surfaces of composites materials. PDF
Oxygen delignification can be considered to be the most important part of TCF and ECF bleaching sequences because it allows for cleaner production of pulp. During the process, oxygen gets one electron from lignin in the alkaline condition to form some active oxygen species (AOS), including a superoxide anion radical (O2-•), which is crucial for lignin degradation without damage of carbohydrates. The reaction of O2-• on cellulolytic enzymatic lignin (CEL) from Masson pine was studied. The change in active hydroxyl content after reaction with O2-• was investigated using 31P-NMR. After reaction, the aliphatic hydroxyl and uncondensed type phenol hydroxyl contents decreased, but the content of carboxylic group increased in Masson pine lignin. Through the analysis with HSQC-2D13C-H technology, β-O-4 linkages could be cleaved by O2-•, but β-β and β-5 linkages were observed to be more stable; benzaldehyde and cinnamic aldehyde structures could be oxidized to carboxylic acids by O2-•. Guaiacyl units in lignin were more easily degraded than p-hydroxybenzene units. PDF
Blomstedt, M., Asikainen, J., Lähdeniemi, A., Ylönen, T., Paltakari, J., and Hakala, T. K. (2010). "Effect of xylanase treatment on dewatering properties of birch kraft pulp," BioRes. 5(2), 1164-1177.
In this study it was shown that the enzymatic removal of xylan from ECF-bleached birch kraft pulp enhances the water removal from the pulp, especially in the late stages of pulp drying. The effect of xylanase treatments on dewatering was clarified by using a moving belt former (MBF), a press simulator (MTS), and an IR-drying equipment, to simulate and to measure dewatering properties on wire, press and drying sections of a paper machine. The xylanase treatment slightly increased the pulp freeness indicating improved pulp drainage properties. At the moving belt former, however, no significant changes that would indicate enhanced dewatering in forming were observed. The xylanase treatments slightly enhanced the dewatering in wet pressing and furthermore, at the thermal drying the xylanase treatment had a positive effect on the dry solid content (DSC) development, and time to reach the 95% dry solids content was reduced by up to 15%. This was also confirmed by the decrease in the fiber saturation point (FSP) values and the amount of bulk water. Our results indicate that the xylanase treatment affected the water-binding xylan in the fiber cell wall, yielding enhanced dewatering properties, without deteriorating the pulp and paper properties. PDF
Self-assembled multilayers were fabricated from lignosulfonate (LS) and poly(diallyldimethylammonium chloride) (PDAC), and the adsorption and desorption behaviors of LS on the LS/PDAC multilayers under different pH conditions were intensively investigated. Results showed that the adsorption and desorption behaviors were controlled by electrostatic attraction, hydrophobic interaction, and changes in the microstructure, which depended on solution pH. Lignosulfonates exist as colloids in solutions at low pH because of a hydrophobic interactions, and the LS colloids adsorbed on the PDAC layer because of electrostatic attraction. LS colloids started to disassociate at pH 3.5, resulting in an abrupt rise of the adsorption rate, a sharp decrease of the adsorbed amount, and a steep reduction in the surface roughness. Desorption behaviors of LS multilayers were related to the pH values of both LS dipping solution for self-assembly and the immersing solution for post-preparation treatment. Desorption of LS could be induced by a weakening of electrostatic attraction or hydrophobic interaction. A significant desorption occurred only when LS colloids dissociated in the multilayers. LS colloids were harder to dissociate in the multilayers than in the solutions because of electrostatic attraction between LS and PDAC. PDF
Bagasse from early species of Saccharum officinerum-Co 89003 has 71.36% useful, long, and thick-walled fibers with good slenderness ratio, but the rigidity coefficient is less than that of Eucalyptus tereticornis and Leucaena leucocephala. The kink index and kink per mm length are lower in bagasse fiber than E. terticornis, which gives rise to fewer weak points in the fiber. Low alcohol–benzene soluble substances in bagasse induce less pitch problems and favor more homogeneity in the paper. Lignin content in bagasse is comparable to Eucalyptus globulus and Leucaena leucocephala, but α-cellulose, and pentosans are slightly lower. A higher proportion of carbon content compared to hydrogen and oxygen increases the energy value of bagasse. It produces 42.2% pulp yield of kappa number 28.2 at optimum cooking conditions, such as active alkali 12% (as Na2O), temperature 150oC, and time (at temperature) 60 min. An addition of 0.1% anthraquinone at the optimum condition improves pulp yield by 2.6% and mitigates kappa number by 3.9 units. PDF
Wheat straw was used to produce medium-density fiberboard (MDF). The chemical and physical characteristics of fractionated size-reduced wheat straw were investigated. The pH, pH-buffering capacity, ash, and silicon content increased as wheat straw particle size decreased. Ash of the finest straw, <0.2 mm, had high ash (15%) and silicon (18%) contents. The outer and inner parts of size-reduced straw were analyzed using scanning electron microscopy (SEM). The SEM micrographs revealed a complex ultrastructure containing a notable portion of thin-walled cells approximately 1 µm thick. Pressurized defibration of size-reduced wheat straw produced lignocellulosic fibers nearly 1.0 mm long combined with approximately 24% of small particles and dust. The high water uptake of straw-based MDF was significantly reduced using melamine-modified urea-formaldehyde (UF) resin and removing wheat straw particles and dust by screening. UF resin was added at levels of 12.5%, 13.1%, and 14%. In terms of water resistance, 12-mm-thick straw MDF displayed thickness swelling below 10%, acceptable according to the EN 622-5 MDF standards. It was concluded that manufacturing wheat straw MDF entails straw size reduction (hammer-milling), removing small particles and dust, and adding melamine-modified UF resin to attain necessary MDF quality standards. PDF
Jacobs, A., Botha, A., Reddy, J., and Van Zyl, W. H. (2010). "Sunflower press cake as a substrate for eicosapentaenoic acid production by representatives of the genus Mortierella," BioRes. 5(2), 1232-1243.
Long chain omega-3 fatty acids such as eicosapentaenoic acid (EPA) are essential for the regulation of critical biological functions in humans and other mammals. EPA production via solid state fermentation of sunflower press cake was investigated using eight fungal strains representing the genus Mortierella. During this study the effect of supplementing the sunflower press cake substrate with 10% (w/w) linseed oil was studied with regard to the supplement’s impact on EPA production and the polyunsaturated fatty acid profile of the fermented substrate. The addition of the linseed oil improved the EPA yield of most strains, leading to a reduction in the average arachidonic acid:EPA ratio from 50.68 to 3.66. The ratio of polyunsaturated to saturated fatty acids was increased significantly (t=5.75, p=0.05) by the addition of linseed oil, with higher desaturation levels among the 20-carbon fatty acids. The strains that produced the highest levels of EPA on sunflower press cake supplemented with linseed oil were Mortierella alpina Mo 46 and Mortierella basiparvispora Mo 88, which produced 6.4 mg and 5.8 mg EPA per g of sunflower press cake, respectively. PDF
Heavy metal’s release without treatment poses a significant threat to the environment. Heavy metals are non-biodegradable and persistent. In the present study the ash of water hyacinth (Eichhornia crassipes), was used to remove six metals from aqueous solutions through biosorption. Results of batch and column experiments showed excellent adsorption capacity. Removal of lead, chromium, zinc, cadmium, copper, and nickel was 29.83, 1.263, 1.575, 3.323, 2.984 and 1.978 µgg-1, respectively. The biosorptive capacity was maximum with pH >8.00. Desorption in µgg-1 of ash for lead, chromium, zinc, cadmium, copper, and nickel was 18.10, 9.99, 11.99, 27.54, 21.09, and 3.71 respectively. Adsorption/desorption of these metals from ash showed the potential of this technology for recovery of metals for further usages. Hydrogen adsorption was also studied with a Sievert-type apparatus. Hydrogen adsorption experiments showed significant storage capacity of water hyacinth ash. PDF
Acacia hybrid (Acacia mangium x auriculiformis), a wood species of low dimensional stability which is used almost exclusively for pulp, paper, or as firewood, was heat treated in nitrogen at 210-230 ºC for 2 to 6 hours. The changes in color and anti-swelling efficiency (ASE) of wood after heat treatment were determined for the different heat treatment conditions. The results show that heat treatment mainly resulted in the darkening of wood tissues, and heat-treated wood had better dimensional stability than those of the control samples. Chemical modifications of wood components were determined by FT-IR analysis. Spectra indicated that the hydroxyl group content was reduced by increased treatment intensity. This result coincides with the increase in dimensional stability of heat-treated wood. Heat treatment of acacia hybrid wood shows an interesting potential to improve the quality and value for solid wood products from plantation-grown wood species. PDF
This study investigates effects of six kenaf cultivars named Cubano, Niger, Cubano 2032, 9277, 7551, and 7566 and three harvesting time stages on the properties of pulp and handsheet paper made from kenaf. Six cultivars of an Iranian kenaf (Hibiscus Cannabinus L.), were planted on 19 May 2007, and harvested after 85, 105, and 135 days. It was understood that with the increase of plant age, fiber yield increased. Maximum yield at each of three harvesting time stages was related to Niger. Consequently, if a high fiber yield is sought, Niger can be recommended, but for a paper with high strength properties, Cubano 2032 is strongly suggested. This cultivar produces a paper with significant burst, tear, breaking length and fold endurance even though its yield was somewhat lower than that of Niger at short harvesting times. Moreover, at second harvesting time stage, maximum strength properties of handsheets such as burst, tear, and breaking length, were seen in Cubano, though the fiber yield of this cultivar was a bit lower than Niger, but still more than Cubano 2032. We showed that a minor positive change in the handsheet properties could be achieved through harvesting kenaf at the third stage as compared to the first and second stages. PDF
In order to study the thermal decomposition characteristics of hemicellulose, a highly efficient procedure was carried out to extract hemicellulose from corn stalk. Several different sugar units were observed by 13C NMR spectra to show the presence and species of hemicellulose. Following isolation of the hemicellulose, experimental research on its thermal behavior were carried out with a thermogravimetric analyzer under inert atmosphere at heating rates ranging from 10 to 50°C/min, and the kinetic parameters were calculated by the Kissinger and Ozawa methods, respectively. It was found that the thermal degradation of hemicellulose mainly occurred in the temperature range 180-340°C with a final residue yield of 24% at 700°C. An increase of the heating rate could slightly increase both the temperatures at which the peak weight loss rate was observed and the maximum value of weight loss rate. The activation energy (E) and the pre-exponential factor (lnA) obtained by the Kissinger and Ozawa methods were 213.3kJ mol-1, 211.6kJ mol-1 and 46.2min-1, 45.9min-1, respectively. Even though the data showed little difference, the fitting degree of the Ozawa method was better than that of the Kissinger method. The experimental results and kinetic parameters may provide useful data for effective design and improvement of thermochemical conversion units. PDF
In order to prepare nanoparticles, corn cobs were treated with sodium hydroxide in the range 0-6 mole/litre (0-24% of sodium hydroxide on oven dry basis) at 165 oC for 1.5 h at a liquor to solid ratio of 4.5:1. The sample obtained at the optimised condition (4.5 mole/litre) was washed with deionised water, disintegrated, and filtered through 80 mesh screens. Powder thus obtained was delignified by acidified sodium chlorite and dried in a vacuum oven to constant weight. Dried powder was further separated by 270 mesh screens. An average particle size approximately equal to 22 nm was observed by Transmission Electron Microscopy (TEM). Its crystallinity was determined by XRD analysis. The aggregated particle size was observed in the micron range by Scanning Electron Microscopy (SEM). PDF
The fast growing aquatic weed water hyacinth, which is available almost year-round in the tropics and subtropics, was utilized as the chief source of cellulose for production of fuel ethanol via enzymatic hydrolysis and fermentation. Fungal cellulases produced on-site by utilizing acid-alkali pretreated water hyacinth as the substrate were used as the crude enzyme source for hydrolysis of identically pretreated biomass. Four different modes of enzymatic hydrolysis and fermentation were trialed in the present study for optimization of the yield of ethanol. Two common yeasts viz., Saccharomyces cerevisiae and Pachysolen tannophilus, were used for fermentation of hexose and pentose sugars in the hydrolysate. Significant enhancement of concentration (8.3 g/L) and yield (0.21 g/g) of ethanol was obtained through a prefermentation hydrolysis-simultaneous saccharification and fermentation (PH-SSF) process, over the other three processes viz., separate hydrolysis and fermentation (SHF), simultaneous saccharification and fermentation (SSF), and single batch bioconversion (SBB) by utilizing fungal culture broth with and without filtration as crude enzyme source. PDF
The pulp and paper industry has started applying new, ecologically sound technology (biotechnology) in its manufacturing processes. Many interesting enzymatic applications have been proposed. Implemented technologies tend to change the existing industrial process as little as possible. Enzymes have great potentials in solving many problems associated with the use of recycled fiber, especially related to deinking, drainability, hornification, refining, and stickies. Based on the promising results of mill-scale trials, several mills in the world have started using enzymes for deinking. The potentials of cellulase enzymes have also been demonstrated for reducing the energy requirement in pulp refining, improving the machine runnability and stickies control when using recycled fiber. They have the important benefits in that they can be considered a “green” product. They are natural occurring compounds with little adverse impact on the environment. This paper deals with the importance of recycling of paper, problems associated with the recycling, and potentials of enzymes in solving these problems. A few case studies have also been included. PDF