Our peer-reviewed sister journal: Lignocellulose (no author payment)
BioResources, Volume 5, Issue 1
NOTE: Each current issue of BioResources continues to build as new articles are approved.
Our ancestors knew a great deal about wood. They had to in order to do well in life. Wood has played a dominant role in human infrastructure for many generations, and for most of that time woodcraft has depended on the decentralized knowledge passed down among families and guilds. This editorial, while celebrating the knowledge, skills, and insights of the woodworkers of past generations, also calls for a renewed attention to wood’s unique character, including characteristics that today are too often classified as “defects.” We may need to take lessons from generations past to truly derive the best value from wood resources. PDF
Production of ethanol from lignocellulosic feed-stocks is of growing interest worldwide in recent years. However, we are currently still facing significant technical challenges to make it economically feasible on an industrial scale. Genetically modified lignocellulosic biomass has provided a potential alternative to address such challenges. Some studies have shown that genetically modified lignocellulosic biomass can increase its yield, decreasing its enzymatic hydrolysis cost and altering its composition and structure for ethanol production. Moreover, the modified lignocellulosic biomass also makes it possible to simplify the ethanol production procedures from lignocellulosic feed-stocks. PDF
The use of traditional inorganic fillers and pigments for both filling and coating applications in papermaking may have certain limitations in such aspects as recyclability and combustibility. Novel renewable organic fillers and pigments derived from natural resources can possibly be completely recyclable, combustible, biodegradable, and environmentally friendly, and they can potentially be used as substitutes for inorganic fillers and pigments to improve the recyclability and other properties of the paper products. Although there are still challenges lying ahead, the strategic significance of the use of renewable organic fillers and pigments for the sustainable development of papermaking industry is an indisputable and demonstrable fact. PDF
Two fungi (unidentified) were isolated from soil and marine environ-ments. These isolates were used for bioremediation of pulp and paper mill effluent at the laboratory scale. The treatment resulted in the reduction of color, lignin, and COD of the effluent in the order of 78.6%, 79.0%, and 89.4% in 21 days. A major part of reductions in these parameters occurred within 5 days of the treatment, which was also characterized by a steep decline in the pH of the effluent. The enzyme activity of these fungi was also tested, and the clearance zone was obtained in the plate assay. PDF
Knot rejects obtained from pulp screening after sulphite pulping are difficult to dewater, which makes landfilling expensive and burning inefficient. The rejects were found to contain up to 50% cellulose, which is very susceptible to enzymatic hydrolysis to glucose. Knot rejects were hydrolyzed at 20% consistency in a laboratory peg mixer with cellulase enzyme. The thick slurry was liquefied within the first hour of mixing and resulted in a glucose concentration of over 100 g/L after 24 hours of reaction. This solution was fermented by yeast to give an ethanol concentration of over 5%. The laboratory results were confirmed at pilot scale with a mortar mixer (high consistency) or stirred tank reactor (medium consistency) at the 400 L and 6000 L scales, respectively. It was found that washing the knots with ammonia resulted in increased glucose conversion. Enzyme costs could be lowered by separating the enzyme from the hydrolyzed sugars by membrane ultrafiltration and recycling the enzyme to the subsequent batch of substrate. The combination of high-consistency hydrolysis and enzyme recycling minimizes capital investment, energy requirements, and enzyme costs, which are significant factors in the overall economic viability of cellulose conversion to ethanol. PDF
In this study, the use of bagasse fiber (BF) and unbleached bagasse pulp (BP) in a cement matrix, as a raw material, to produce lightweight construction materials is reported. The bagasse was used as partial replacement of cement at different levels: 0% (control cement), 1%, 2% 3%, and 4% by weight. The average size of bagasse fibers was less than 2 mm. Although a reduction in the physical and mechanical strength was observed, the incorporation of either fiber or pulp increased the water of consistency and setting time. A composite containing 4% of bagasse fibers can be used for lightweight concrete. FT-IR spectra showed that the BF or BP adversely affect the rate of calcium silicate hydrate (CSH) formation by decreasing its promotion. PDF
White birch was stored in the form of bundles, wood chips, and loose slash for a period of one year to examine the changes in biomass fuel properties. The samples were collected at regular quarterly intervals to measure moisture content, CNS content, ash content, and calorific value. Data loggers were also placed into the stored woody biomass to measure the temperature change inside the piles. After the first quarter of the storage period and continuing into the next three months of storage, the moisture content showed the most significant change. The moisture content of the biomass bundles increased from 29 % to above 80 % (db). The moisture content of the pile of wood chips covered with a tarp decreased from 51% to 26% and showed a continuous decline in moisture content to the end of storage period to an average range of 16.5% (db). However, the moisture content of uncovered wood chip pile was observed to continuously increase throughout the storage period, resulting in more than double in magnitude from 59% to 160% (db). The dry matter loss was higher in wood chip piles (8~27%) than in bundles (~3%). Among the other properties, there was slightly higher loss of calorific value in wood chips (~1.6%) as compared to bundles (~0.7%) at the end of one year. PDF
Sahin Kol, H., Ozbay, G., Köse, L., and Kurt, S. (2010). "Effects of some impregnation chemicals on combusion characteristics of laminated veneer lumber (LVL) produced with oak and poplar veneers," BioRes. 5(1), 70-80.
The objective of this research was to investigate the effects of impregnation chemicals on the combustion properties of 3-ply laminated veneer lumber (LVL) made of Oak (Quercus petraea subsp. İberica) and Poplar (Populus tremula L.). For this purpose, oak wood was used as the outer ply and poplar used for the core ply in LVL. Borax (BX), boric acid (BA), borax+boric acid (BX+BA), and di-ammonium phosphate (DAP) were used as impregnation chemicals, and urea formaldehyde (UF), phenol formaldehyde (PF), and melamine-urea-formaldehyde (MUF) adhesives as bonding agent were used to produce LVLs. The vacuum – pressure method was used for the impregnation process. The combustion test was performed according to the procedure defined in the ASTM–E 69 standards, and during the test the mass reduction, temperature, and released gas (CO, O2) were determined for each 30 seconds. As a result, di-ammonium phosphate was found to be the most successful fire retardant chemical in LVL with MUF adhesive. LVL produced from a combination of oak and poplar veneers with MUF adhesive and impregnated with DAP can be recommended to be used as a fire resistant building material where required. PDF
Chaetomium erraticum was capable of producing all the three components of a cellulase enzyme system including exoglucanase, endoglucanases, and b-glucosidase extracellularly. However, the cultivation conditions and the medium composition markedly affected the ability of microorganism to synthesize various enzymes. Exoglucanase was highest under static conditions, while endoglucanase and b-glucosidase were maximized under shake conditions. Among the various defined substrates, CMC proved to be the best inducer for exoglucanase under static conditions and b-glucosidase under shake conditions. MCC induced maximum endoglucanase under shake conditions. The biosynthesis of all three components of cellulases was repressed with different concentrations of glucose, puromycin, actinomycin, and actidione, while the supplementation of exogenous cyclic-AMP was fully capable of releasing the catabolite repression for production of all three components. PDF
Trametes gallica (T. gallica) is a high producer of lignin-degrading enzymes including laccases, lignin peroxidases (LiPs), manganese-dependent peroxidases (MnPs), and hemicellulases (Hcels). The enzyme activities could peak at an early stage of fermentation. The activities of laccases and LiPs were high in high-nitrogen, low–carbon, and high inorganic salt media, while the activities of MnPs, and Hcels were the high in low-nitrogen, high–carbon, and high inorganic salt medium. It was found that T. gallica caused 34.4% mass losses after 20 days, 46.7% after 30 days, and 70.1% after 60 days, and at the same time T. gallica was able to degrade lignin at an early stage of solid fermentation. Based on these results, T. gallica may be a strain candidate for biopulping in the paper industry. PDF
The thin layer drying of pine forest residues consisting of bark, needles, leaves, and chips was experimentally conducted at air temperatures of 40, 50, 60, 70, and 80oC. Physical and chemical properties of fractionated forest residues were determined to evaluate its fuel properties. The experimental data obtained from thin layer drying study were fitted with Lewis, Page, and Henderson and Pabis equations to evaluate the drying behavior of the forest residues. Among the three drying models, the Henderson and Pabis model fitted well with the experimental drying data at the tested temperatures (40, 50, 60, 70, 80oC), achieving R2 values of0.992, 0.994, 0.997, 0.989, and 0.983, respectively. The drying constant k for the forest residues was increased with increase in drying air temperature and was correlated in the form of a second order regression equation. The thin layer drying data developed from this study will be useful for designing low temperature dryers for forest residues. PDF
Starch microcellular foams (SMCF) containing pores in the micron size range may be prepared by pore-preserving drying processes, developing highly porous, high specific surface area materials useful for applications such as opacifying pigments or as adsorbent materials. The objective of this research was to understand how the exchange of water with ethanol, used as a pore preserving step, affected the dimensional properties of the starch material during and after processing. SMCF were prepared from molded aquagels of cooked corn starch that were subjected to ethanol exchanges with different time intervals (6, 12, or 48 hrs) and number of exchanges (1, 2, or 3) and then air dried. To study the transformation of water-swollen starch into precipitated starch foam in ethanol, the volume of the starch material was measured in the wet state after each exchange and after final air drying. As water is replaced by ethanol, the starch material contracts, with the greatest contraction during the first ethanol exchange. The amount of contraction during air drying decreased with decreased starch water content just before air drying, presumably due to less pore collapse of the stiffer cell walls on drying. Interestingly, the minimum density of 0.37 g/cc SMCF was for the 12 hour exchange time, not the longest exchange time. Evidence of a skin-core morphology included SEM images as well as dimensional instability data on dried samples. The results indicate that SMCF of low density with fewer tendencies to deform during drying does not necessarily require extremely long exchange times. PDF
This study aims to understand the mechanism of bio-oil gasification and the influence of operating parameters on the properties of the gas products. Firstly, the pyrolysis/gasification of bio-oil was performed using a thermogravimetric analyzer (TGA). The evaporation of gas products from bio-oil were measured on-line with coupled Fourier Transform Infrared Spectroscopy (FTIR). The main gas products were CO, CO2, CH4, H2O, and light hydrocarbons, etc. Organics mainly evolved out at lower temperature (100-200°C), while the cracking of heavy hydrocarbon components took place at higher temperature (>200°C). Simultaneously, the gasification behavior of bio-oil was investigated in a fixed bed gasification reactor under different temperature and residence time. The gas product evolving was checked using micro-gas chromatography. It was observed that the yield of CO and H2 increased with increasing gasification temperature above 600°C, and the maximum value was obtained at 800°C. Prolonging the residence time was not favorable for the upgrading of syngas quality. PDF
Lu, X., Zhang, Y., Yu, Y., and Ji, J. (2010). "Deacidification and esterification of waste cooking oil: Comparison of the coupled process with stand-alone catalytic esterification and extraction processes," BioRes. 5(1), 147-158
The free fatty acids in waste oil with high acid value were removed and transformed into fatty acid methyl esters by the extraction-reaction coupled process. The de-acidification efficiency and esterification conversion in the extraction-reaction coupled process were studied and compared with those in the stand-alone extraction process and the esterification process, respectively. Compared with cross-current batch extraction, the de-acidification efficiency of the extraction-reaction coupled process was equivalent to that of seven equilibrium stages in the conditions of the oil/methanol mass ratio of 1:1 at 60 oC. Compared with the esterification process, the esterification conversion of the coupled process was 90.3%, which is much larger than 46% in the esterification process at the reaction time of 32 minutes. Based on these findings, it is suggested that the extraction-reaction coupled process is a very effective and promising method for biodiesel production from oils having high acid value. PDF
Mixed hardwood chips were treated with lignin-degrading fungi to study the effect of fungal pretreatment on bleaching characteristics of kraft pulp. Pretreated wood chips were subjected to reduced active alkali doses in comparison to untreated chips. Comparable results were obtained for pretreated chips with reduced alkali dose as was obtained with higher dose of alkali in case of untreated chips. Fungal treatment made the process more energy-efficient, and 4.8% less chlorine was consumed in comparison to the control process. Pretreatment with Ceriporiopsis subvermispora was responsible for reduction of 4.7% in lignin contents, 14.3% permanganate number, and overall reduction of 15.5 kg/T of Cl2 consumption. The pollution load in terms of COD and BOD at the CD stage was reduced by 32.6% and 41.5% respectively, whereas 12% reduction in AOX compounds was observed in effluent of pretreated pulp. PDF
Valto, P., Knuutinen, J., Alén, R., Rantalankila, M., Lehmonen, J., Grönroos, A., and Houni, J. (2010). "Analysis of resin and fatty acids enriched in papermaking process waters," BioRes. 5(1), 172-186.
The applicability of a special pilot-scale installation (Short Circulation Device) was studied for demonstrating the enrichment of selected resin and fatty acids in process waters when increasing water reuse during the manufacture of paper. The traditional gas chromatography with flame ionization detection (GC-FID), turbidity, and online sample enrichment (solid phase extraction, SPE) for atmospheric pressure chemical ionization-mass spectrometry (APCI-MS) measurements were used for the analysis of the resin and fatty acids. The data from all the measurements with unbleached thermomechanical pulp (TMP) process waters were in a good agreement, and correlation coefficients (R2) > 0.9 were obtained in each case. Rapid information about the levels of wood extractives in papermaking process waters is of great importance, and it offers a suitable way to predict oncoming pitch problems. It was concluded that the routine control of the extractives level in papermaking process waters is possible by all these methods. PDF
Three methods for improved deresination of sulphite pulps were evaluated, namely, alkaline washing, enzyme treatment, and pulp fractionation. Alkaline washing appears to come at a high cost, because caustic is expensive and affects cellulose chain length, as indicated by lower viscosity of the pulps. Thus this is not a viable option for pulps that are sensitive to changes in viscosity. Enzyme treatment did not completely degrade the glycerides under the mill conditions used. Fibre fractionation studies showed that the fines fractions contained 8 to 13 times more residual lipophilic extractives than the whole pulps. Removing this fraction, which represents only a small percentage of the whole pulp, could reduce by about a half the amount of lipophilic extractives in the remaining pulp. Thus pulp fractionation appears to be a viable option to achieve further deresination of sulphite pulps. PDF
Chelation of unbleached and oxygen bleached hardwood and softwood kraft pulps with EDTA was studied. The main focus was on the desorption of magnesium, manganese, and iron due to their impact in TCF-bleaching. Desorption of other metal ions present were also studied in order to get an over-all estimation of the metal ion concentrations and their desorption during chelation. By using the concept of side reaction coefficients, an estimation of the chelating strength of EDTA at different pH can be made. Metal ion concentrations were determined by DCP-AES and ICP-MS techniques. Mn, Zn, and Cd were the metal ions that could almost completely be chelated with EDTA. Most of the metal ions were found to be desorbed from the pulps at low pH values by ion exchange with hydrogen ions. With EDTA chelation 50 to 70% of the iron was desorbed. By EDTA chelation the highest Mg/Mn concentration ratios were obtained in the pH range 4 to 6. For oxygen-bleached softwood pulp the ratio was over 7000. Our study showed that both unbleached and bleached pulps can quite successfully be chelated by EDTA. PDF
Granholm, K., Harju, L., and Ivaska, A. (2010). "Desorption of metal ions from kraft pulps. Part 2. Chelation of kraft pulps with different complexing agents and with EDTA in a reducing environment," BioRes. 5(1), 227-243.
Desorption of metal ions from oxygen-bleached hardwood and softwood kraft pulps by different chelation treatments were studied. The main focus was on desorption of manganese, iron, and magnesium ions, but also on desorption of some other common metal ions. The metal ion concentrations were determined by the DCP-AES and ICP-MS techniques. Acid treatments with nitric and oxalic acids removed manganese and magnesium very effectively and partially iron as well. Some potential complexing agents such as triethanolamine (TEA), citric acid, oxalic acid, and formic acid were also tested. By using the concept of side reaction coefficients, a comparison of the chelating strengths between different chelating agents can be made. TEA is a strong chelant for iron and did remove part of iron at pH 10. The effect of chemical reduction simultaneously with EDTA was studied by using sodium borohydride, sodium dithionite, and sodium bisulfite as reducing agents. The reducing environment improved desorption of manganese but did not improve removal of iron. The measured redox potentials indicated that the reducing effect with the used agents was not enough to convert iron(III) to iron(II). The effect of the reducing agents was decreased by their decomposition during the chelation experiment. PDF
Chun, D. T. W., Foulk, J. A., and McAlister, D. D. III. (2010). "Antibacterial properties and drying effects of flax denim and antibacterial properties of nonwoven flax fabric," BioRes. 5(1), 244-258.
A modification of “AATCC Test Method 100-1999” was used for assaying for bacteriostatic/antibacterial properties of denim containing various flax concentrations. Since no direct evidence that increasing the flax content of fabric imparted the fabric with increased bacteriostatic properties was found against the control bacteria, Staphylococcus aureus and Klebsiella pneumoniae, other possible explanations for the long held presumption that flax fabric exhibited antibacterial properties was sought. Because the appearance of having antibacterial or bacteriostatic properties might be imitated if the flax content would decrease the time fabric would be moist enough for bacterial growth, the effect of drying was evaluated. When flax fabric was saturated and the moisture lost during incubation was measured, there was no improved drying associated with increased flax content. When untreated nonwoven flax was evaluated as possibly containing more ‘antibacterial’ or bacteriostatic components than scoured nonwoven flax material, the population densities increased. This increase suggests that the unscoured nonwoven flax contain compo-nents that support bacterial growth to the extent that bacteriostatic or antibacterial components, if any, are overwhelmed by the components that support bacterial growth. In tests involving the control bacteria, Staphylococcus aureus and Klebsiella pneumoniae, increasing the flax content of flax fabric did not demonstrate increased antibacterial properties. PDF
Chalamcherla, V. L., Singaracharya, M. A., and Lakshmi M., V. (2010). "Amino acids profile of the lignocellulosic feed treated with cellulase-free lignolytic mutants of Pleurotus ostreatus," BioRes. 5(1), 259-267.
Defining and quantifying amino acid requirements will become an important consideration in the next generation of feeding schemes for dairy cattle beyond the current emphasis on identification of limiting amino acids. In this context different amino acid profiles of untreated, urea treated, fungal treated, and urea plus fungal treated lignocellulosic feed by both P. ostreatus wild and its two cellulase-minus/ less lignolytic mutants were analyzed. Cellulase-free mutant strains were obtained after 20 minutes of exposure to UV light and 0.4 seconds to X-rays. A UV mutant of P. ostreatus (POM1) exhibited better performance than the X-ray mutant (POM2) in terms of production of less cellulolytic and more lignolytic enzymes. Urea treatment of straw enhanced the total amino acid content by less than a factor of two, while the fungal treatment improved it by 13-14 times. Fungal treatment of urea-treated straw improved the total amino acid content by a factor of 15, indicating the importance of urea in the straw. Further, the fungal treatment of urea-treated straw enhanced the quantity of amino acids such as glutamine, glycine, aspergine, etc. by 15-20 times. The quantity of limiting amino acids such as methionine, lysine, and histidine was also enhanced by 8 to 10 times through the fungal treatment. Maximum amounts of all the amino acids were found in urea plus fungal (POM1) treated paddy straw than in only fungal treated and only urea treated paddy straws. PDF
In this study, two local strains of Penicillium chrysogenum named EGEK458 and EGEK469 were selected for enhancement of Penicillin G (PenG) production under solid state fermentation (SSF) conditions. These two strains were selected among seven strains according to their fermentation yields for PenG production during previous tests under submerged fermentation conditions. Sugar beet pulp, an agro-industrial residue of the sugar industry, was used as an inert support for the first time in PenG production under SSF. In order to enhance the production of PenG, two points of moisture level and three concentration values of nutrients (impregnated in solid support), which are the key parameters in production of PenG, were compared. As the yields from solid and submerged fermentation were compared, 570U/g of PenG – almost 15 times higher quantities of its production vs. submerged conditions – were obtained under SSF conditions in 50 hours by the strain EGEK458. The conditions for the enhanced production of PenG were 65% moisture content with a four-fold concentrated nutrients impregnated solid support. PDF
To enhance the bleaching efficiency, the activator of tetra acetyl ethylene diamine (TAED) was used in conventional H2O2 bleaching. The H2O2/TAED bleaching system can accelerate the reaction rate and shorten bleaching time at relative low temperature, which can reduce the production cost. In this research, the process with hydrogen peroxide activated by TAED bleaching of Populus nigra chemi-thermo mechanical pulp was optimized. Suitable bleaching conditions were confirmed as follows: pulp consistency 10%, bleaching temperature 70oC, bleaching time 60 min when the charge of H2O2 was 4%, NaOH charge 2%, and molar ratio of TAED to H2O2 0.3. The pulp brightness gain reached 23.6% ISO with the optimized bleaching conditions. FTIR analysis indicated that the H2O2/TAED bleaching system can decrease carbonyl group further than that of conventional H2O2 bleaching, which contributed to the higher bleaching efficiency and final brightness. The H2O2/TAED bleaching had stronger oxidation ability on lignin than that of H2O2 bleaching. PDF
Alfa, also knows as Stipa tenacissimaI or “halfa”, is grown in North Africa and south Spain. Due to its short fiber length, paper made from alfa pulp retains bulk and takes block letters well. In this study alfa was evaluated for bleached pulp production. Two cellulose pulps with different chemical compositions were pulped by a conventional kraft process. One sample was taken from the original alfa material and another from alfa that had been pretreated by diluted acid. The pulp produced from the pretreated alfa was bleached by the elemental-chlorine-free sequences DEPD and DEDP. The yield, Kappa number, brightness, and α- cellulose content of bleached and unbleached pulps were evaluated. The results showed that during the chemical pulping process, treated alfa cooked more easily than the original alfa. The treated alfa pulp also showed very good bleaching, reaching a brightness level of 94.8% ISO with a yield of 93.6% at an α-cellulose content 96.8(%) with a DEDP bleaching sequence, compared to 83.2% ISO brightness level, 92.8% yield, and 95.1% α-cellulose content for bleached pulp with a DEPD bleaching sequence. Therefore, this alfa material could be considered as a worthwhile choice for cellulosic fiber supply. PDF
Electrically conductive paper was prepared via in-situ chemical oxidative polymerization of pyrrole by using ferric chloride as an oxidant and p-toluenesulfonic acid (PTSA) as a dopant. The deposition of polypyrrole (PPy) on the fiber surface was verified by ATR-FTIR and SEM analyses. Pyrrole concentration had a significant effect on the surface resistivity of conductive paper, especially when the pyrrole concentration was less than 1.8 g·L-1. The conductivity of the PPy-coated paper could be controlled by adjusting pyrrole concentration. The threshold concen-tration of pyrrole was 1.2 g·L-1 when the molar ratio of dopant to pyrrole was 2:1. Very little polymerization reaction in solution occurred when pyrrole concentration was less than 2.5 g·L-1. The pyrrole concentration should reach a higher value to prepare a relatively stable conductive paper with lower resistivity. The XPS results showed that the amount of the PPy coating increased, while the doping level first decreased then increased with the increase of pyrrole concentration. The SEM-EDXA results showed that there was no difference in the amount of PPy coated between the outer surface and the internal wall, but the doping level of the outer surface was higher than that of the internal wall. PDF
Composites of flour from different lignocellulosic sources with high-density polyethylene were prepared, and their water absorption and flexural properties were studied. Flour samples from loblolly pine, hybrid Euro-American poplar, and wheat straw were mixed with the polymer at 35 wt % lignocellulosics content and either zero or 2% compatibilizer. Water absorption tests were carried out on injection-molded specimens for temperatures of 30, 45, 60, and 75°C. Results indicated a significant difference among different lignocellulosic types, of which wheat straw composites exhibited the highest and the pine composites showed the lowest water absorption values. The composites with 2% MAPE showed lower water absorption compare to the composites without MAPE. This indicates that the compatibilizer plays an important role to repel the water molecules. For all four temperature conditions, rising temperature increased water absorption significantly. Composites with poplar had the highest flexural strength and modulus. Adding compatibilizer to the composites boosted the flexural properties by improving the adhesion between natural filler and the polymer matrix. PDF
Hamdan, S., Talib, Z. A., Rahman, M. R., Ahmed, A. S., and Islam, M. S. (2010). "Dynamic Young's modulus measurement of treated and post-treated tropical wood polymer composites (WPC)," BioRes. 5(1), 324-342.
By means of dynamic mechanical thermal analysis (DMTA), selected tropical wood species, namely Eugenia spp., Artocarpus rigidus, Artocarpus elesticus, Koompassia malaccensis, and Xylopia spp. have been characterized. The woods were treated with sodium metaperiodate to convert them into wood polymer composites (WPC). After two weeks the WPC were chemically treated with phenyl hydrazine to convert them into secondary wood polymer composites, also called post-treated WPC (PTWPC). The chemical treatment and post-treatment are successful in improving the mechanical properties of the final product. The storage modulus (E’) was measured using dynamic mechanical thermal analysis (DMTA), and the dynamic Young’s modulus (Ed) was calculated using free-free vibrational testing. The results reveal that the elastic properties i.e. stiffness (Ed) and storage modulus (E’) of the composite were dependent on the type of wood species. The E’ of WPC and PTWPC were much higher than raw wood, whereas the glass transition temperatures (Tg) of WPC and PTWPC were much lower than those of raw wood. Free-free vibration testing provided rapid information about the quality of the composite material, such as the stiffness (Ed) of the PTWPC compared to the respective WPC and raw woods. The WPC and PTWPC were characterized using Fourier transform infrared (FTIR) spectroscopy and scanning electron microscopy (SEM). FTIR analysis indicated the absorption band of raw wood at 1635 cm-1 due to carbonyl stretching, whereas WPC and PTWPC showed increased absorption bands near 1718 cm-1 and 1604 cm-1, respectively. PDF
Atar, M., Keskin, H., Peker, H., Ustündağ, A., Togay, A., and Candan, Z. (2010). "Impacts of different joint angles and adhesives on diagonal tension perfrmances of box-type furniture," BioRes. 5(1), 343-355.
The goal of this study was to determine the effects of different joint angles and adhesives on diagonal tension performances of the box-type furniture made from solid wood and medium density fiberboard (MDF). After drilling joints of 75º, 78º, 81º, 84º, and 87º degrees on Oriental beech, European oak, Scotch pine, and MDF samples, a diagonal tensile test was applied on corners glued with polyvinyl acetate (PVAc) and polyurethane (D-VTKA = Desmodur-Vinyl Trieketonol Acetate) according to ASTM D 1037 standard. With reference to the obtained results, the highest tensile strength was obtained in European oak with PVAc glue and joint angle of 84º, while the lowest value was obtained in MDF with D-VTKA glue and joint angle of 75º. Considering the interaction of wood, adhesive, and joint angle, the highest tensile strength was obtained in European oak with joint angle of 81º and D-VTKA glue (1.089 N.mm-2), whereas the lowest tensile strength was determined in MDF with joint angle of 75º and PVAc glue (0.163 N.mm-2). Therefore, PVAc as glue and 81º as joint angle could be suggested to obtain some advantageous on the dovetail joint process for box-type furniture made from both solid wood and MDF. PDF
Extraction of hemicelluloses from wood prior to pulping is being pursued to generate more value-added products, while still producing high quality pulp from the pre-extracted wood. For a better understanding of the factors limiting selective extraction, enzymatic hydrolysis in combination with size exclusion chromatography (SEC) was applied to milled wood and hydrothermally treated wood. Complete dissolution was achieved in a lithium chloride/dimethylacetamide solvent system after mild ball-milling of a Southern Hardwood Mixture (SHM), of SHM extracted using auto-hydrolysis, and of enzyme-treated SHM. SEC tests showed that severe degradation of wood polymers occurred after a milling time of 3 hours. The SEC data also confirmed the presence of lignin-carbohydrate complexes. Based on the results, it is suggested that linkages between lignin and polysaccharides may play an important role in limiting extraction of hemicelluloses. PDF
Chand, N., Bajpai, S. K., Joshi, R., and Mary, G. (2010). "Thermomechanical behavior of sisal fibers grafted with poly(acrylamide-co-N-vinyl-2-pyrrolidone) and loaded with silver ions or silver nanoparticles," BioRes. 5(1), 372-388.
The graft copolymerization of acrylamide, N-vinyl-2-pyrralidone and N, N’-methylene-bis-acrylamide was carried out to modify the sisal fiber to improve its mechanical and thermal stability. The grafting of poly-(acrylamide-co-N-vinyl-2-pyrrolidone) on sisal fiber surfaces facilitated the loading of Ag(I) ions and Ag(0) nanoparticles. Surface microstructure of the surface modified sisal fiber confirmed the grafting of the copolymer. The XRD and FTIR graphs also showed changes on grafting and on Ag(I) ions and the loading of Ag(0) nanoparticles. It is evident from the DSC curves that the initial thermal stability was improved by delaying the hemicellulose decomposition on grafting and silver ion loading. PDF
Swapnavahini, K., Srinivas, T., Kumar, P. L., Kumari, M. S., and Lakshmi, T. (2010). "Feasibility study of anaerobic digestion of Ocimum sanctum leaf waste generated from Sanctum sanctorum," BioRes 5(1), 389-396.
The waste originated in temples is presently piled up at one place and then disposed off in water bodies or dumped on land to decay, leading to water and soil pollution. The present work aims to determine the biogas yield and nutrient reduction potential of Ocimum sanctum (basil) leaf waste obtained from temples. Laboratory scale digesters of 2.5 L capacity were used and fed with basil leaf waste, which was digested in a batch reactor for a retention period of 30 days at room temperature. Preliminary results indicate that the process is effective in reducing the pollution potential of the basil waste. The process removed up to 73% and 42% of total solids and BOD, respectively, along with biogas production. PDF
The isolation of cellulose from different lignocellulosic biomass sources such as corn cob, banana plant, cotton stalk, and cotton gin waste, was studied using a steam explosion technology as a pre-treatment process for different times followed by alkaline peroxide bleaching. The agricultural residues were steam-exploded at 220 ºC for 1-4 min for the corn cob, 2 and 4 min for the banana plant, 3-5 min for the cotton gin waste, and for 5 min for the cotton stalk. The steamed fibers were water extracted followed by alkali extraction and finally peroxide bleaching to yield cellulose with different degrees of crystallinity. The degree of polymerization of the cellulose fraction ranged from 167.4 to 1615.7. Longer residence time of the steam explosion led to an increase in cellulose crystallinity. The ten isolated cellulose samples were further characterized by SEM, FT-IR, and thermal analysis. Four lignin preparations were also obtained from steam-exploded corn cob, banana plant, cotton stalk, and cotton gin waste after alkali treatment. The SEM micrographs of the lignin showed different morphological structure for the different agricultural residues. The FT-IR and TGA analyses showed that the steam pre-treatment led to an extensive cleavage of ether bonds, condensation reactions, and some demethylation of aromatic methoxyl groups in the lignin structure. The thermal stabilities of the isolated lignins were different for different agricultural residues. PDF
The use of low-cost, locally available, highly efficient, and eco-friendly adsorbents has been investigated as an ideal alternative to the current expensive methods of removing dyes from wastewater. This study investigates the potential use of activated carbon prepared from the peel of Cucumis sativa fruit for the removal of methylene blue (MB) dye from simulated wastewater. The effects of different system variables, adsorbent dosage, initial dye concentration, pH, and contact time were investigated, and optimal experimental conditions were ascertained. The results showed that as the amount of the adsorbent increased, the percentage of dye removal increased accordingly. The optimum pH for dye adsorption was 6.0. Maximum dye was sequestered within 50 min of the start of each experiment. The adsorption of methylene blue followed the pseudo-second-order rate equation and fit the Langmuir, Freundlich, Dubinin-Radushekevich (D-R), and Tempkin equations well. Maximum removal of MB was obtained at pH 6 as 99.79% for adsorbent doses of 0.6 g/ 50 mL and 25 mg/L initial dye concentrations at room temperature. The maximum adsorption capacity obtained from the Langmuir equation was 46.73 mg g-1. The rate of adsorption was found to conform to pseudo-second-order kinetics with a good correlation (R2 > 0.9677) with intraparticle diffusion as one of the rate-determining steps. Activated carbon developed from the peel of Cucumis sativa fruit can be an attractive option for dye removal from wastewater. PDF
Batch adsorption studies were undertaken with the abundantly available waste biosorbent Tectona grandis L.f. leaf powder for removal of cadmium(II) from aqueous solutions. The adsorption experiments were performed under various conditions such as time, temperature, different initial Cd(II) concentrations, pH, adsorbent dosage, and adsorbent particle size. The data showed that in 30 minutes, 1 g of Tectona grandis L.f. could remove 86.73% of cadmium(II) from 50 mL aqueous solution containing 100 mg L-1 of Cd. The isothermal data fitted well to both Langmuir and Freundlich models for Cd(II) adsorption on Tectona grandis L.f. Using the Langmuir model equation, the monolayer sorption capacity of Tectona grandis L.f. was evaluated to be 29.94 mg g-1. The optimum pH value was found to be 5.5. The pseudo-first-order and pseudo-second-order kinetic models were used to describe the kinetic data. The dynamic data fitted well to the pseudo-second-order kinetic model. Cd(II) adsorption was only marginally affected in the temperature range of 30 to 50oC. An SEM of Cd(II) loaded powder showed formation of agglomerates. The FTIR of Cd(II) loaded powder showed negative shift in the wave numbers. PDF
We have developed a semi-empirical model to relate the tensile energy absorption (TEA) of paper sheets formed from high-consistency refined pulp to pulp properties, including water retention value (WRV), fibre length, and fibre curl. TEA is shown to be related to the normalized stretch (ratio of stretch to tensile strength) and the tensile strength of the pulp. Normalized stretch appears to be a function of fibre curl, whereas tensile strength for a given pulp is a function of the fibre length, fibre curl, and WRV. The manner in which these three pulp properties develop in a given refining operation determines the development of TEA. PDF
Talaeipour, M., Hemmasi, A. M., Kasmani, J. E., Mirshokraie, S. A., and Khademieslam, H. (2010). "Effects of fungal treatment on structural and chemical features of hornbeam chips," BioRes. 5(1), 477-487.
Structural and chemical changes were investigated in Hornbeam (Carpinus betulus) chips that had been exposed to Phanerochaete chrysosporium BKM-1767 fungus. Samples subjected to fungal treatments for durations of 1, 2, and 4 weeks were investigated and compared with a control sample not subjected to fungal treatment. Results of scanning electron microscopy indicated that fungal hyphae were present on the surfaces of all chips exposed to the fungus. In the samples treated for a 2 or 4-week period, these hyphae additionally penetrated into vessels and lumens through ray cells, softening and destroying the cell walls. FT-IR spectra indicated that fungal treatment modified the chemical structure of the wood. Furthermore, there was a remarkable decrease in the amount of lignin in woods exposed to fungus. Lignin decreases after 1, 2, and 4 weeks of treatment were 2.83%, 11.4%, and 18.56%, respectively. Measurement of fiber dimensions indicated that cell wall thicknesses decreased after treatment, but that the lumen width increased compared with the control sample. PDF
The effect of corn stover lignin structure alteration caused by white-rot fungi pretreatment on the pyrolysis kinetics was studied by FTIR and TG/DTA. Results showed that biopretreatment had a remarkable effect on lignin pyrolysis. Biopretreatment can decrease the activation energy and increase the pre-exponential factor in the initial stage of pyrolysis, which makes it possible to start the lignin pyrolysis at a relatively gentle condition and improve the availability of biomass pyrolysis as a renewable energy. Analysis by FTIR showed that white-rot fungi destroyed the aromatic skeletal carbons, which are the main ether and carbon linkages of lignin, converting lignin into compounds having relatively simple structures. The relationship between the pyrolysis characteristics and the structure alteration pretreated by white rot fungi showed that the deconstruction and depolymerization of recalcitrant linkages of lignin could accelerate the reaction and lignin pyrolysis with lower energy consumption. PDF
This paper reviews recent results in the field of chemical modification of wood with linear chain anhydrides. Though the main focus is on work performed by the author, this is described in the context of related progress in the field. The combined research has demonstrated the effectiveness of chemical modification applied to solid wood and wood raw material for composites production in overcoming the main disadvantages of wood. Wood samples and wood chips/strands have been chemically modified with a series of anhydrides at equivalent levels of modification, under identical conditions, and the question was to determine which is the primary factor controlling the biological durability, the degree of cell wall bulking by the bonded adduct, or the extent of hydroxyl substitution. The results have clearly indicated that the degree of cell wall bulking caused by the adduct, rather than the extent of hydroxyl substitution, is the primary factor controlling the biological durability and water vapour sorption. Despite the large difference in OH substitution level, reaction with different anhydrides results in the same level of protection against decay, marine borers and termites, and in the same level of water vapour sorption. These observations suggest that the mechanism of protection is not chemical/biochemical in origin, but relates to the bulking of the cell wall by the reacted adduct. PDF