Our peer-reviewed sister journal: Lignocellulose
BioResources, Volume 8, Issue 3
NOTE: Each current issue of BioResources continues to build as new articles are approved.
The concept of dry surface treatment for paper coating applications has been available for more than ten years. Different from conventional coating methods such as extrusion coating and suspension coating, dry surface treatment involves a combined process of non-contact deposition of coating materials and surface smoothening of the coated paper. Pronounced features of this concept include avoidance of the need for paper drying and elimination of various negative consequences related to rewetting of the paper with water, etc. However, to date the concept has not been commercialized. Some significant challenges remain. Commercializable technologies for production of size-controllable coating particles and their electrostatic deposition onto paper are the key. Reconsidering this interesting concept may at a minimum shed light on the technological advancement in the area of pulp and paper. PDF
Wheat straw pulp can be considered to be one of most important raw materials for specialty and functional paper products. Bleaching sequences involving laccase and xylanase were applied to bleach wheat straw pulp. The bleached pulp properties after a sequence of xylanase (X), laccase (L), and extraction (E), i.e. XLE, were compared with those of LE and LEX sequences. It was found that the XLE bleaching sequence was the most suitable sequence for laccase and xylanase synergetic biobleaching. The bleaching results of OXLEQP and OQP beaching sequences (where O stands of an oxygen stage, Q indicates a chelation stage, and P means peroxide) were compared. For a specific target brightness level of over 80% ISO, XL pretreatment was found to save 28.6% of the H2O2 requirement and increase the viscosity by 6.7% compared with the OQP bleaching sequence. It was also found that synergetic biobleaching could decrease the consumption of refining energy. There were no detectable adsorbable organic halides found in the biobleaching effluents. PDF
Budakçı, M., İlçe, A. C., Gürleyen, T., and Utar, M. (2013). "Determination of the surface roughness of heat-treated wood materials planed by the cutters of a horizontal milling machine," BioRes. 8(3), 3189-3199.
The aim of the present study was to determine the surface roughness of heat-treated Scots pine (Pinus sylvestris L.), Eastern beech (Fagus orientalis L.), Uludağ fir (Abies bornmülleriana Mattf.), and sessile oak (Quercus petraea L.) wood material samples following planing by the cutters of a horizontal milling machine. The samples that were heat-treated at 140 ºC or 160 ºC for 3, 5, or 7 hours were then processed by star blades or razor blades, which are the most frequently used blade types in a milling machine. The surface roughness of the samples was determined by a touch (spined) scan device (TIME TR200), as indicated by the ISO 4287 principle. The results of the study indicate that heat treatment decreases the surface roughness value of the wood material and a significant difference in surface roughness cannot be detected between planing using the razor blade or the star blade. PDF
Li, H.-L., Wang, S.-Y., Wang, W.-J., Ren, J.-L., Peng, F., Sun, R.-C., and Liang, L. (2013). "One-step heterogeneous catalytic process for the dehydration of xylan into furfural," BioRes. 8(3), 3200-3211.
Xylan, the major component of hemicellulose in hardwoods and various grasses, has great potential for bio-refinery applications such as the production of energy and high value-added chemicals. A convenient and environment-friendly catalytic process for the conversion of xylan into furfural in ultrapure water using chromium-loaded perovskite-type oxides as the solid catalyst has been investigated. The crystalline and morphologies of the catalysts were studied by X-ray diffraction analysis (XRD) and scanning electron microscope analysis (SEM), and the reactions were optimized by varying different parameters. It was found that LaCo0.8Cu0.2O3 modified with 1.5wt% chromium had the highest catalytic activity in the transformation of xylan to furfural at a temperature of 433 K in a 1:600 weight ratio of xylan to hyperpure water for 10 h; the corresponding yield was 21.2% for furfural. Furthermore, a possible mechanism for the dehydration of xylan to furfural using Cr-LaCo0.8Cu0.2O3 as a catalyst is proposed. PDF
Specific Edge Load (SEL) and Specific Energy Consumption (SEC) are nowadays the most popular parameters for defining the intensity of pulp refining. As a result, these factors are widely used in industrial practice. The purpose of this research was to determine limitations connected with use of these parameters during bleached kraft pulp refining. Performed tests showed that, despite keeping the SEL and SEC at constant level, changes of pulp refiner consistency always modified the character of the refining process. Obtained results showed that neither SEL nor SEC are fully reliable parameters to describe and to control the refining process. PDF
Reixach, R., Franco-Marquès, E., El Mansouri, N.-E., de Cartagena, F. R., Arbat, G., Espinach, F. X., and Mutjé, P. (2013). "Micromechanics of mechanical, thermomechanical, and chemi-thermomechanical pulp from orange tree pruning as polypropylene reinforcement: A comparative study," BioRes. 8(3), 3231-3246.
This work explores the use of mechanical (MP), thermomechanical (TMP), and chemi-thermomechanical (CTMP) pulps from orange tree pruning fibers (OPF) as reinforcing elements of polypropylene (PP) composites. Due to the nature of the natural fibers, the use of a coupling agent is needed to attain a good interface and to prevent fiber slippage from the matrix. The main objective of the present work was to investigate the orientation factor, the interfacial shear strength, and the intrinsic strength of the OPF. Coupled and non-coupled composites were formulated and tested, optimizing the coupling agent content with the objective of maximizing the tensile strength of the composites. Hirsch and Kelly-Tyson models and the Bowyer-Bader methodology were used to compute the micromechanic properties. The contribution of subcritical, supercritical fibers, and matrix were also calculated. PDF
Xu, Y., Fan, L., Wang, X., Yong, Q., and Yu, S.-Y. (2013). "Simultaneous separation and quantification of linear xylo- and cello-oligosaccharides mixtures in lignocellulosics processing products on high-performance anion-exchange chromatography with pulsed amperometric detection," BioRes. 8(3), 3247-3259.
A simple one-step method was developed for rapid separation and quantification of the linear xylo-oligosaccharides (XOS) and cello-oligosaccharides (COS) mixtures by using high-performance anion-exchange chromatography coupled with pulsed amperometric detection (HPAEC-PAD). By exploiting small ion-exchange behavioral differences of various oligosaccharide components on the CarboPac PA200 column, a two-stage binary gradient elution program of NaOAc-NaOH solution was established. Subsequently, nine linear oligomers were separated simultaneously and readily within 30 min, in the order of: xylobiose, cellobiose, xylotriose, xylotetraose, cellotriose, xylopentaose, cellotetraose, xylohexaose, and cellopentaose. The method was applied successfully in the analysis and determination of different lignocellulosics processing products. The system provides a convenient and powerful analytical tool for technical research and development on polysaccharide components bioconversion in lignocellulosic biomass processing. PDF
The effect of filler modification using methacrylic acid (MAA) on polypropylene (PP)/cocoa pod husk (CPH) composites was studied. The performances of unmodified and modified PP/CPH composites were analyzed for torque development, tensile properties, and thermal properties. The presence of MAA increased the stabilization torque of the PP/CPH composites. The tensile strength and modulus of the modified PP/CPH composites were improved compared to unmodified PP/CPH composites, but the elongation at break was reduced. The crystallinity and thermal stability of the PP/CPH composites increased after modification with MAA. All the composite property changes were due to the improvement in filler-matrix adhesion and this was confirmed by scanning electron microscopy (SEM). PDF
Bio-fibers have been used for some time to reinforce thermoplastic composites; such structures are being used in a variety of commercial applications. In this study, wood fiber and flax fiber were used to reinforce high-density polyethylene (HDPE) formed by extrusion. The flexural, tensile, and impact resistance properties of the resulting flax fiber/wood fiber/HDPE (F/W/HDPE) composites were measured and modeled as a function of the volume fraction of flax ﬁber. Finally, the correctness of the modified model was verified. Based on the measurement data, the volume fraction of flax ﬁber was shown to play an important role in determining the mechanical properties of these composites. With increasing flax fiber volume fraction, the flexural strength, tensile strength, tensile modulus of elasticity, and impact resistance of the composites generally increased. However, the flexural modulus decreased. Based on the rule of mixtures (ROM) model, two coefficients were introduced and a new curve-fitting model was established based on measurements of macrostructure. Compared with the traditional ROM model, the new model developed in the present study could describe the flexural strength, tensile modulus, and impact strength of F/W/HDPE composites more accurately. PDF
Loofah sponge was activated by thermochemical esterification between the carboxyl groups of citric acid and hydroxyl groups of cellulose to introduce free carboxyl groups, which were further reacted with lipase amino groups with 1-ethyl-3-(3-dimethylaminopropyl) carbodiimide (EDC) as the condensing reagent. This resulted in loofah sponge–immobilized lipase. Under the optimized immobilization conditions, the highest activity of immobilized lipase per gram of dry carrier was found to be 45.8 U/g. The immobilized lipase exhibited maximum activity at 40 °C, pH 8.0, while the optimal temperature and pH for the free lipase were 37 oC and 7.5, respectively. The immobilized lipase showed better thermal stability, storage stability, and reusability than free lipase. PDF
Copper-ethanolamine-based wood preservatives are still the most important solutions for protecting wood in ground applications in Europe. Wood in the ground is exposed to a variety of organisms that can act synergistically. In order to simulate these conditions in the laboratory, Scots pine (Pinus sylvestris) specimens impregnated with copper-ethanolamine preservative of three different concentrations (cCu = 0.125%, 0.25%, and 0.5%) were exposed to three different soils according to procedure ENV 807, for periods between 12 and 32 weeks. After the relevant period of exposure, samples were isolated, and their mass loss, bending strength, and modulus of elasticity were determined. In the final step, the remaining copper in the samples was determined. The results showed that, in spite of significant copper leaching, the tested copper-ethanolamine-treated wood exhibited good performance in ground applications. Furthermore, a good correlation was found between the mechanical properties and mass loss, regardless of the chemical treatment applied. PDF
Mandarin peels were investigated for the removal of copper ions from ethanol fuel. Infrared spectroscopy and thermogravimetric analysis were used for elucidating possible functional groups responsible for the adsorption of Cu(II) from ethanol. The influence of parameters such as the mass of the adsorbent, sample pH, stirring time, and initial copper(II) concentration was investigated using multivariate optimization strategies. The optimum conditions were a pH value of 7.0, a stirring time of 10.0 min, an initial copper(II) concentration of 6.0 mg L-1, and an adsorbent mass of 95.0 mg. The sorption data were fitted satisfactorily to the Langmuir and Freundlich isotherm models. The mandarin peel presented a maximum adsorption capacity of 2.71 mg g-1 and is low-cost, which makes it suitable for the removal of copper ions from ethanol fuel. PDF
Sabo, R., Jin, L., Stark, N., and Ibach, R. E. (2013). "Effect of environmental conditions on the mechanical properties and fungal degradation of polycaprolactone/microcrystalline cellulose/wood flour composites," BioRes. 8(3), 3322-3335.
Polycaprolactone (PCL) filled with microcrystalline cellulose (MCC), wood flour (WF), or both were characterized before and after exposure to various environmental conditions for 60 days. PCL/WF composites had the greatest tensile strength and modulus compared to neat PCL or PCL composites containing MCC. Electron microscopy indicated better adhesion between WF particles and PCL than between MCC particles and PCL. Neither wood flour nor MCC cellulose appeared to significantly affect the crystallinity of PCL. Environmental conditioning resulted in only minor deterioration of mechanical properties, although samples soaked in water had greater deterioration of mechanical properties than those in high humidity or freezing environments. After a modified 12-week soil block test, specimens made with wood flour lost weight and showed signs of decay after exposure to the brown-rot fungus Gloeophyllum trabeum. PDF
Unsaturated polyester (UPE) composites reinforced with natural fiber as non-structural materials have been used in engineering.In this study, three different types of coir-reinforced UPE consisting of coir non-woven needle mat (CNM), coir mesh (CM), and coir rope (CR) were produced , and the mechanical properties, such as flexural strength (FS), tensile strength (TS), and impact toughness (IT), were investigated. With the exception of FS, CR-reinforced UPE composites exhibited better mechanical properties, mainly due to good directionality of the coir fibers. Dynamic mechanical analysis (DMA) was also carried out to analyze the composite performances under wide temperature ranges. All the tests confirmed the beneficial effect of coir on the UPE matrix, noting that composites with higher toughness perform better in most applications. PDF
Xu, M., Xu, M., Dai, H., Wang, S., and Wu, W. (2013). "The impact of synthesis conditions on the structure and properties of di-(stearylamidoethyl) epoxypropyl ammonium chloride," BioRes. 8(3), 3347-3357.
Both alkylketene dimer (AKD) and alkenyl succinic anhydride (ASA) are widely used neutral papermaking sizing agents. However, AKD has the issue of sizing hysteresis, while ASA requires on-site emulsification. In addition, both reagents are readily hydrolyzed. Di-(stearylamidoethyl) epoxypropyl ammonium chloride (DSEAC) has been applied as a fabric softener, but it is a potential sizing agent which leads to good sizing without sizing hysteresis. It could be synthesized by a two-step process starting from stearic acid and diethylenetriamine. During the process, the stearamide structure obtained from the first step plays a key role in the second process as well as sizing. This paper focuses on the impact of the synthetic process of the first step on the structure and sizing properties of DSEAC. Single factor experimental results demonstrated that the optimal temperature should be 160 °C while the optimal reaction time should be less than 3.5 hours. Orthogonal analysis experiments indicated that the optimal synthetic process was maintaining 100 °C for 30 min, and then increasing the temperature to 160 °C for 3.5 hours. Dosages of the catalysis and antioxidant were 0.5% and 0.6% of stearic acid, respectively. PDF
The influence of chemical components of oil palm on properties of binderless particleboard were evaluated through a series of mechanical, physical, and chemical analyses in order to assess the self-bonding mechanism. Binderless particleboards were evaluated by relating the physical and mechanical properties to the chemical components. Results revealed that the addition of glucose and sucrose onto the board with and without extraction increased the modulus of rupture and internal bond strength. Glucose and sucrose also reduced the thickness swelling and water absorption of the board. The addition of starch onto the board enhanced the strength of the board, though sugar addition enhanced the board strength more than starch. Adding the sugar also lowered the xylose/ arabinose ratio, indicating that the boards consist of short-chain polymers with a large amount of branching with other monosaccharides. This implies that sugar content present in oil palm trunk plays a major role in the bonding of binderless boards. PDF
This paper reports on changes in temperature and moisture content after plasticizing beech wood by microwave heating. There is currently no known use of microwave heating for plasticizing wood. Therefore, a proper procedure was developed to verify the use of microwave heating for the purpose of plasticizing. Moisture content was monitored in beech test samples with dimensions of 25 × 25 × 400 mm and 40 × 40 × 600 mm, while temperature was investigated only on samples 25 × 25 × 400 mm. In all cases, the temperature was suitable for the wood bending process. Microwave heating is quite intense, therefore for this kind of heating, it is better to have higher moisture content in the appropriate power device and minimal plasticizing time. The biggest advantage of microwave heating is the short plasticizing time, a few minutes, while steaming requires tens of minutes or even hours. PDF
Black spruce (Picea mariana) wood chips were subjected to enzymatic pretreatments, using an enzyme formulation containing cellulolytic and hemicellulolytic enzymes, combined with light mechanical treatments including downsizing and/or compression/decompression. These pretreatments were followed by 3 stages of mechanical refining in a lab-scale disc refiner. Depending on the treatment, the overall energy savings obtained could be as high as 15%. Most of the savings were obtained during the first stage of refining. Pulps collected after this stage were imaged using TEM and SEM. Differences were observed between differing treatment types. The most significant differences were seen when macerated chips were compressed and allowed to decompress in enzyme solutions. Enzyme treatments are able to change the rupture pattern during refining, thus lowering the overall specific energy consumption (SEC) as evidenced by improved pulp freeness and direct energy measurements. Increasing enzyme penetration helps to improve the overall SEC savings and also improves the distribution of energy savings throughout the refining stages by moving initial fiber separation from the middle lamella into the secondary wall. PDF
Pulp and paper companies are seeking opportunities beyond the traditional production of market pulp. One interesting alternative is to expand their revenue streams by adding value to the wood residues that they generate. Considering that excess heat and electricity can be used for biomass pre-treatment and conversion, the aim of this work is to show how the integrated production of bio-oil or biochar would affect the operation of a 1.5M t/a kraft pulp mill in South America. Detailed balances with a focus on modern eucalyptus mills are then developed for this purpose. Since the attractiveness of increasing renewable energy is often influenced by energy policies or local market development for the new products, the target was not to determine the best investment decision. Nevertheless, an economic analysis was performed to observe the main variables affecting the viability of these technologies. The results showed that satisfactory internal rates of return can be achieved for multiple technologies depending on the price of electricity, torrefied pellets, or bio-oil. PDF
A copper coating was deposited on Fraxinus mandshurica veneers to create an EMI-shielding, wood-based material via a simple electroless copper plating process. The wood veneers were pretreated in a NaBH4 solution. The wood veneers treated with NaBH4 were immersed in a plating bath in which copper coating was successfully initiated. The coatings were characterized by SEM-EDS, XPS, and XRD. The metal deposition, surface resistivity, and the effectiveness of electromagnetic shielding were measured. The morphology of the coating was uniform, compact, and continuous. The grain of the wood was preserved on the plated wood veneer, which had a copper-like color. But the samples were less glossy compared to those from Pd activation. EDS, XPS, and XRD results indicated that the coating consisted of Cu0 with a crystalline structure. The surface resistivity and copper deposition were 0.399 Ω/cm2 and 31.98 g/m2 when the veneer was pretreated with a 3 g/L NaBH4 solution for 10 min and plated for 25 min at 60 °C. The plated veneers exhibited good electromagnetic shielding effectiveness of over 40 dB in frequencies ranging from 10 MHz to 1.5 GHz. PDF
Phragmites karka, a common wetland grass, was delignified by the soda pulping process, and all the operating parameters were optimized. The effects of both anthraquinone and surfactant on pulp yield and kappa number at optimum pulping conditions were also investigated. The pulp was beaten at different beating levels to optimize different mechanical strength properties. A detailed morphological study of soda-AQ pulp of P. karka was conducted by scanning electron microscopy. PDF
Hydroxypropyl methylcellulose (HPMC)–coated papers without plasticizer and plasticized with polyols were prepared, and the effects of coating weight, different plasticizers (glycerol (GLY), sorbitol (SOR), and polyethylene glycol (PEG)), and plasticizer contents (20% to 50%) on the physical and mechanical properties of the resulting biopolymer-coated papers were studied. Coating weight was the most important factor affecting mechanical properties. Conversely, increasing coating weight led to a decrease in gloss and to an increase in tensile strength (TS), elongation at break (%E), and tearing resistance of coated papers. The application of unplasticized HPMC coatings (3 g/m2) on paper reduced water vapor permeability (WVP) and water absorption capacity by 25% as compared with uncoated paper. All plasticizers significantly (p < 0.05) increased WVP and Cobb60 values of the films. With the exception of PEG, no effect was found with plasticizers on TS and %E of coated papers compared with those without plasticizer. HPMC-coated papers with PEG as a plasticizer showed significantly lower TS and higher %E and tearing resistance than the other plasticized films (p < 0.05). HPMC coating improved tensile properties and tearing resistance of paper and could be regarded as a reinforcement layer. PDF
The microwave liquefaction kinetics of corn stover in the presence of ethylene glycol (EG) using sulfuric acid as a catalyst was studied. The liquefaction apparent rate constant (k) was examined using a first-order reaction model. The k values of corn stover increased from 0.080 min-1 to 0.165 min-1, with the reaction temperature increasing from 120 °C to 180 °C. The k value of cellulose at 160 °C was close to that of corn stover, indicating that cellulose was involved in the rate-determining step in the microwave liquefaction. The microwave liquefaction rate of corn stover at 160 °C was seven times greater than that of conventional liquefaction with external heating. The apparent activation energy (Ea) was 22.6 kJ mol-1 and the frequency factor (A) was found to be 12.98×105 s-1. The decrease in apparent activation energy and the increase in the frequency factor as compared to conventional liquefaction kinetic parameters indicates a non-thermal effect of microwave in the liquefaction of corn stover, which explains the acceleration mechanism of liquefaction with microwaves. PDF
Santos, B. A. Q., Ntwampe, S. K. O., Doughari, J. H. and Muchatibaya, G. (2013). "Application of Citrus sinensis solid waste as a pseudo-catalyst for free cyanide conversion under alkaline conditions," BioRes. 8(3), 3461-3467.
In this study, Citrus sinensis (C. sinensis) solid waste was used to catalyze the conversion of free cyanide (F-CN) under alkaline conditions; conditions which represent most industrial wastewater containing F-CN. Acid hydrolysis of the solid waste increased the catalytic conversion of F-CN by 3.86 compared to the unhydrolysed solid waste. The conversion of F-CN using unhydrolysed and hydrolysed solid waste increased linearly with an increase in pH and temperature. The maximum catalytic conversion of a 100 mg F-CN/L solution containing 0.1% (w/v) of unhydrolysed and hydrolysed C. sinensis solid waste was 17.82% and 62.48%, respectively, at a pH of 12 and a temperature of 50 °C. The catalytic process was largely dependent on the availability of activated hydroxyl groups in the solid waste. As most wastewater contains heavy metals, it was determined that the presence of metallic species (Ni, Zn, and Cu) reduced the conversion of F-CN as the metallic ions attached to the hydroxyl groups. The observed reduction was 26.35% when 10 mg/L of heavy metals were present in the F-CN solution containing the hydrolysed solid waste at a pH of 12 and 40 °C. PDF
Birch and eucalyptus kraft pulps were treated with sulfite solutions in neutral conditions (pH 7) at 170 °C for 60 min and at 190 °C for 180 min. The pulps were analyzed for kappa number, viscosity, carbohydrate composition, and optical properties. Additionally, UV resonance Raman (UVRR) spectroscopy was applied to collect information on the contents of hexenuronic acid (HexA), lignin, and its phenolic hydroxyl groups. The sulfite treatments resulted in (i) depolymerization and partial dissolution of cellulose, (ii) partial dissolution of xylan and substantial decrease in its HexA content, and (iii) removal of the major part of lignin and increase in its phenolic hydroxyl group content. The extensive removal of HexA and depolymerization of cellulose by neutral sulfite were unexpected phenomena that have not been previously reported. According to their degree of polymerization (DP), the pulps were mainly in the form of microcrystalline cellulose after the more drastic treatments. PDF
In order to examine whether catalyst granular size was a factor for tar removal and syngas composition enhancement, three Ni/char catalysts with 90-100 mesh (Ni/SC), 50-60 mesh (Ni/MC), and 20-30 mesh (Ni/LC) size were prepared with a mechanical mixing method and tested in an updraft gasifier. Reforming parameters investigated were the reaction temperature (650-850 °C), the Ni loading (5-20% of the weight of char support), and the gas residence time (0.1-1.2 s). It was found that the catalyst granular size affected the diffusion of reactants, as well as of products. Ni/SC, Ni/MC, and Ni/LC removed more than 96.5% of the tars in syngas at 800 °C reforming temperature, 15 wt. % Ni loading, and 0.3 s gas residence time. Tar removal efficiencies increased with the decrease of Ni/char granular size, which can be attributed to the higher active surface area with the Ni/SC catalyst. As the catalyst granular size was increased, the H2 content in the syngas was increased and the CO content was significantly decreased. The total amount of combustible gases (H2, CO, and CH4) obtained in the syngas with Ni/MC was higher than with Ni/SC or Ni/LC. It was concluded that Ni/char, especially Ni/MC, can be considered as an effective and inexpensive catalyst for biomass gasification tar removal and syngas conditioning. PDF
Johakimu, J., and Andrew, J. (2013). "Hemicellulose extraction from South African Eucalyptus grandis using green liquor and its impact on kraft pulping efficiency and paper making properties," BioRes. 8(3), 3490-3504.
The feasibility of enhancing the efficiency of the kraft pulping operations while at the same time evolving the process into a biorefinery, and thus producing hemicelluloses together with paper products, was studied. Hardwood chips (Eucalyptus grandis) were pre-treatedwith green liquor prior to pulp production. At optimal pre-treatment conditions, the pH of the resulting extract was 7.8, the wood weight loss was 14%, and the hemicellulose extracted was almost 40 kg/ton of woodchips. In the subsequent kraft pulping, the resulting data revealed that the woodchips from which hemicellulose had been pre-extracted could be pulped much faster than woodchips pulped without hemicellulose extraction. As a result, to maintain the target kappa number, a 20% reduction in pulping chemicals was achievable. Hemicellulose pre-extraction led to a 10% reduction in black liquor solid contents. Moreover, the strength properties of the pulps produced with and without hemicellulose extraction were comparable. Industrial acceptance of this concept, however, still requires a more accurate understanding of the effect of specific mill operating conditions on mill energy balance. Careful economic assessment of the options for handling the calcium carbonate scale problem will also be required before the technology can be considered for implementation. PDF
Lignin-based anion exchangers (L-AE) were prepared by reacting lignin with epichlorohydrin and triethylamine in the presence of N,N-dimethylformamide and a catalyst. A multi-factor and multi-level orthogonal design of experiment was carried out in order to obtain the optimal conditions for the preparation of lignin-based anion exchangers. The optimized parameters including the dosages of catalysts, the amounts of triethylamine, graft reaction time, and the graft reaction temperature were defined. Data of nitrate removal and yield were used as performance indicators of the products prepared. The results indicated that the reaction temperature was the primary factor. The optimal synthesis reaction parameters were lignin:pyridine:triethylamine = 2 g:3 mL:12 mL. The optimal experimental temperature was 70 °C, and the reaction time was 7 h. The yield was 188.6% and the nitrate removal was 91.2%. Under some reaction conditions, the yields were found greater than 100%; this was due to the grafted mass from epoxidation with epichlorohydrin and quaternization (through the reaction of epoxide with triethylamine). PDF
Hydrotropic treatment is an attractive process that uses water-soluble and environmentally friendly chemicals. Currently, this method is practically unexploited on a large scale due to the long treatment times required. In this study, the hydrotropic process was modified by the addition of hydrogen peroxide, formic acid, or both. The modified treatments were more selective than the reference, and the pulps obtained using the modified treatments had lower lignin contents. After bleaching, the resultant pulps were comparable to dissolving pulps with respect to the content of hemicelluloses and viscosity. Cellulose solutions were successfully obtained in a 7% NaOH/12% urea aqueous solvent after pretreating the bleached pulp with a HCl/EtOH mixture. Hydrotropic lignin was recovered from the spent solution by precipitation in water. The lignin had very low contents of carbohydrates and sulphur. The preliminary results show that a hydrotropic process can be used for such biorefinery applications as fractionation of fibres, cellulose polymer, and lignin from birch wood. The green cellulose and lignin biopolymers can potentially be used for shaping biomaterials or production of bio-based chemicals. PDF
Su, L., Xing, Z., Wang, D., Xu, G., Ren, S., and Fang, G. (2013). "Mechanical properties research and structural characterization of alkali lignin/poly(vinyl alcohol) reaction films," BioRes. 8(3), 3532-3543.
With alkali lignin and PVA as the primary materials, glutaraldehyde as the cross-linker, and glycerin as the plasticizer, alkali lignin/PVA cross-linking reaction film was prepared by casting. The process conditions were evaluated one at a time for different variables. Mechanical properties of the composite film were tested. The performance of the reaction film was analysed by XRD, TG, SEM, and FT-IR. The results showed that when the mass ratio of alkali lignin/PVA was 1/5, glutaraldehyde content 1.67%, and glycerol content 7.1% (w/w) of the dry matter, respectively, the reaction film had satisfactory mechanical properties. Under the best conditions, the mechanical properties of the reaction film were better than that of pure PVA film. The thermal stability of the reaction film was higher than the stability of PVA film. Compared with pure PVA film, the crystallinity of the reaction film decreased a little. SEM images indicated that compatibility of alkali lignin and PVA was good. The FT-IR analysis showed that a cross-linking reaction occurred between alkali lignin and PVA(1788). But the aldol reaction between the lignin and PVA(1788) was weak. PDF
In order to improve the molecular weight and application of a lignin byproduct, the trimethyl quaternary ammonium salt of lignin-sodium alginate polyampholyte (QL-SA) was prepared with trimethyl quaternary ammonium salt of lignin (QL) and sodium alginate (SA), using the cross-linker glutaraldehyde. Its structure was analyzed by FTIR, SEM, and analysis of nitrogen and carboxylic contents. Results showed that QL and SA were grafted successfully. The nitrogen content was diminished from 4.21% to 3.69% and its carboxyl content increased from 2.66 mmol/g to 6.47 mmol/g. The product behaved as flocculant by electrostatic interactions and bridging actions. The effects of QL-SA on the flocculation performance of dyes were investigated with methylene blue and acid black ATT water as the representative dyes. The maximum decolorization rate of acid black ATT was 94.91% and methylene blue was 97.11% under the corresponding optimal conditions (5 g/L of the flocculant at pH 3, 30 °C, and 8 g/L at pH 8, 30 °C). The effect of QL-SA was found to be markedly superior to SA and QL on the whole. The QL-SA showed promise for practical applications. PDF
Teixeira, R. N. P., Neto, V. O. S., Oliveira, J. T., Oliveira, T. C., Melo, D. Q., Silva, M. A. A., and Nascimento, R. F. (2013). "Study on the use of roasted barley powder for adsorption of Cu2+ ions in batch experiments and in fixed-bed columns," BioRes. 8(3), 3556-3573.
The potential to remove Cu2+ ions from aqueous solutions through biosorption using roasted barley powder and alkalized barley was investigated in batch experiments and in fixed-bed columns. The influences of initial concentrations (40 to 600 mg/L) of the metal ion, the amount of adsorbent (0.01 to 0.25 g), the contact time (2 to 240 min), and the pH (1.0 to 5.5) were all studied. An isotherm model was applied to describe the equilibrium. The percentage of adsorption increased with increasing pH-values up to 5.5 and with dosage of adsorbent up to 0.1 g. The equilibrium adsorption capacities of Cu2+ after 3hours were 43.8 and 51.3 mg.g-1 for barley and alkalized barley, respectively. These values are higher when compared with the adsorption capacity of various adsorbents reported in literature. The adsorption data fit well to the Langmuir isotherm model, and the experimental results indicate that chemisorption onto the surface of the barley and alkalized barley is the major adsorption mechanism for binding Cu2+ ions for both sorbents. PDF
A new starch-based adhesive with high solid content, high binding force, and low viscosity was prepared via hydrolysis of cassava starch with α-amylase using glycerol as a plasticizer and Ammonium Zirconium Carbonate (AZC) as a crosslinker. The adhesive was applied to coated paper as a partial substitute for SBR latex. The effects of α-amylase, glycerol, AZC, and temperature on the starch adhesive and its performance in application were investigated. The prepared crosslinking cassava starch adhesive showed a significant effect when the starch slurry concentration was 50% (w/w), the dosages of glycerol and α-amylase were 15% and 0.075%, respectively, and the enzymolysis starch was crosslinked with 12% AZC at 50 oC. The modified starch improved the paper in terms of surface strength, gloss, whiteness, and smoothness when 20% SBR latex was substituted into the coating formulation. Statistical analysis indicated that the crosslinking temperature and AZC had significant effects on the performance of the paper, while glycerin and α-amylase had little effect on it. Spectral analysis of the product showed that the crosslinking reaction took place between AZC and cassava starch. The average particle size was 528.6 nm. Scanning Electron Microscope (SEM) images of the paper surface were consistent with the other measured surface properties. PDF
Nanoscience and nanotechnology provide numerous opportunities for enhancing the properties of wood composites. Formaldehyde emissions from wood composites are of great importance because of their negative impact on human health. Developing low formaldehyde-emitting particleboard and plywood panels as environmentally friendly composites by nanotechnology was the object of this study. The urea formaldehyde and melamine urea formaldehyde resins that were used to produce particleboard and plywood panels, respectively, were reinforced with various nanomaterials at different loading levels. Formaldehyde emission tests were carried out according to standard TS 4894 EN 120. The results acquired in this work indicated that nanomaterial reinforcement significantly affected the formaldehyde emission properties of the particleboard and plywood panels. Formaldehyde emissions of the composite panels decreased after reinforcement with nanoSiO2, nanoAl2O3, and nanoZnO materials at proper loading levels. Therefore, using nanotechnology, it is possible to produce environmentally friendly wood composite panels with low formaldehyde emissions. PDF
Nasir, M., Gupta, A., Beg, M. D. H., Chua, G. K., Jawaid, M., Kumar, A., and Khan, T. A. (2013). "Fabricating eco-friendly binderless fiberboard from laccase-treated rubber wood fiber," BioRes. 8(3), 3599-3608.
The emission of formaldehyde vapors from adhesives such as urea formaldehyde (UF) and phenol formaldehyde (PF) is a main concern for the wood composite industry. The ability of laccase enzymes to modify the fiber in pulp industries has given hope to the wood composite industry to prepare composites without using external adhesives. In the present work, rubber wood fiber was treated with different amounts of laccase enzymes at varying time intervals. Although laccase is known to cause changes to lignin, FTIR analysis of treated fiber revealed no significant difference in the chemical composition of cellulosic fiber as compared to the untreated fiber. SEM analysis exhibited a thin uniform layer of lignin deposition on the fiber surface that may be precipitated back when the reaction reaches equilibrium. XRD showed a 10% increase (maximum) in the crystallinity index of treated fibers as compared to untreated fiber. The treated fibers were dried and pressed at different platen temperatures for various time intervals without any adhesive. Mechanical properties such as MOE, MOR, and IB were done to analyze the performance of binderless fiberboard as per ASTM D1037. Binderless fiberboard of density 750 (±10) MPa that was fabricated from the fiber treated at 6 U/g enzyme for 60 min and pressed at 200 °C for 6 min showed good performance. PDF
In the papermaking process, the removal and control of dissolved and colloidal substances (DCS) is a key issue for reducing the usage of fresh water. The use of nano TiO2 for removal of dissolved substances (DS) and colloidal substances (CS) was investigated through monitoring the titration process of nano TiO2 colloids to sodium laurate (C11H23COONa, DS simulacra) and stearic acid (C17H35COOH, CS simulacra) solution with COD (chemical oxygen demand), DLS (dynamic light scattering), SEM (scanning electron microscope), and zeta potential, respectively. The results indicated that most of the simulacra molecules could be removed from the aqueous solution by the flocculation with nano TiO2 colloids. The removal of CS by nano TiO2 colloid arose from heterocoagulation rather than from charge neutralization, in which nano TiO2 was adsorbed onto the surface of CS particles and bridged CS to form flocs. While in the removal process of DS by nano TiO2, the negative-charged portion of the DS molecule was adsorbed onto the surface of nano TiO2 particles with a mono- or multilayer, eliminating the repulsive force between nano TiO2 particles and resulting in their flocculation. PDF
The existence of tar compounds in producer gas is one of the major problems found in biomass gasification; these compounds need to be removed before the producer gas can be used. In order to predict the need for producer gas cleaning for catalytic conversion into traffic fuels and chemicals, the gas has to be accurately characterised and defined. In this study, tar compounds from producer gas of two small-scale downdraft gasifiers were collected, identified, and quantified. Based on the results, there were several tar compounds present in the gas flow. Toluene and naphthalene were the most abundant compounds, totalling more than 70% of the total volume of tars while tar concentration levels were in the range of 200 to 400 mg/Nm3. These concentrations were found to be consistent with values presented for similar-type gasifiers using wood chips. PDF
Santos, S. M., Carbajo, J. M., and Villar, J. C. (2013). "The effect of carbon and nitrogen sources on bacterial cellulose production and properties from Gluconacetobacter sucrofermentans CECT 7291 focused on its use in degraded paper restoration," BioRes. 8(3), 3630-3645.
Bacterial cellulose (BC) synthesized by Gluconacetobacter sucrofermentans has a high degree of crystallinity, durability, great resistance, and biocompatibility. This study evaluates the effect that carbon and nitrogen sources, present in HS (Hestrin–Schramm) culture medium, have on BC from G. sucrofermentans CECT 7291 used to restore damaged documents. The initial pH of the medium and the temperature were set for all assays, which were conducted in static conditions. The cellulose layers were obtained at four time points. The growth media were characterized at each time point (pH and carbon source consumption). Cellulose layers were washed, pressed, dried, and characterized by determining their pH, dry weight, and optical and mechanical properties. The best combination of carbon and nitrogen sources proved to be fructose plus yeast extract–corn steep liquor, with or without ethanol, which provided a good balance between BC production and carbon source consumption, and generated a resistant and homogeneous cellulose layer. PDF
Acrylic styrene latex was used in combination with nanoclay at two different loading levels and calcium carbonate at four loading levels to improve printability characteristics of mechanical printing paper. SEM micrographs indicated filling of the voids and covering of the printing paper surface. Different rheological behavior of the coating that contained two coating pigments, in addition to their different viscosity, was clearly evident. Calcium carbonate was more advantageous due to the reduction in pumping costs. Paper coating improved roughness and air-permeability properties. Water absorption of the coated paper was decreased by at least 50% which significantly affects the dimensional stability of the paper during web offset printing. Specular gloss and print density were significantly increased at a 1% probability level by coating the surface of the paper. Contrary to the control sample, picking of the paper (which is of great importance after printing and for linting on the printing cylinder) did not occur. PDF
Bai, H., Wang, H., Sun, J., Irfan, M., Han, M., Huang, Y., Han, X., and Yang, Q. (2013). "Purification and characterization of beta 1,4-glucanases from Penicillium simplicissimum H-11," BioRes. 8(3), 3657-3671.
In this study, β-1, 4-endoglucanase from Penicillium simplicissimum H-11 was purified to homogeneity using ammonium sulfate followed by Sephadex G-100 chromatography. The purity of the enzyme was confirmed by HPLC and 12% SDS-PAGE, indicating a single peak with a molecular mass of 33.2 kDa. This protein had mostly α-helix structures, as confirmed by FTIR spectrometry. The optimum pH and temperature were 3.2 and 60 °C with pH stability of 2.8~5.6 and temperature stability of 50 °C for 12 h and 4 h, respectively. A metal profile of the enzyme showed that Mg2+ and Sn2+ were strong activators, while Cu2+ was a strong inhibitor. An interesting feature of this enzyme is that it can effectively hydrolyze microcrystalline cellulose, filter paper, and CMC-Na, thus revealing both endo- and exo-glucanase features of the enzyme. The kinetic constants Km and Vmax were 14.881 mg/mL and 0.364 mg/mL/min, respectively, against CMC-Na as a substrate. PDF
An engineered composite that combines a wood fiber core, a bicomponent fiber face, and a bicomponent fiber back was evaluated for its elastic response using laminate theory. Using the properties of the individual laminae as input variables, the laminate’s elastic modulus, axial strain, and lateral strain were determined by means of the model, and compared with values determined experimentally. The model yielded an axial elastic modulus of 950 MPa, which did not differ substantially from the measured value of 920 MPa. Statistical analyses showed that the measured and calculated strains were not significantly different in either the axial or lateral directions. The model underpredicted the strains along the fiber direction of the bicomponent fiber sheets by approximately 4%. A greater difference (12%) between predicted and measured values was observed in the lateral direction. PDF
Ren, X.-Y., Zhang, Z.-T., Wang, W.-L., Si, H., Wang, X., and Chang, J.-M. (2013). "Transformation and products distribution of moso bamboo and derived components during pyrolysis," BioRes. 8(3), 3685-3698.
Transformation and products distribution of moso bamboo (Phyllostachys edulis) and its derived components during pyrolysis were investigated by thermogravimetric analyzer coupled with Fourier transform infrared spectrometry (TG-FTIR) and analytical pyrolysis coupled with gas chromatography/mass spectrometry (Py-GC/MS) techniques. The pyrolysis of moso bamboo was generally an integrated result of the decomposition of its several derived components by examining the degradation process parameters and pyrolysis kinetics. The main peaks of the infrared (IR) spectrum for gases released at the highest intensity were assigned to be CO2, CO, CH4, H2O, acids, aldehydes, aromatics, ethers, and alcohols. Pyrolysis temperature played an important role in the products distribution of moso bamboo by affecting the products' yield and secondary cracking of heavy compounds. 500 °C was an inflection point for product release during moso bamboo pyrolysis. Further cracking of aromatic compounds and furans into lighter products was observed with increasing pyrolysis temperature. PDF
A spectrophotometric for the determination of hydrogen peroxide in pulp bleaching effluents is reported. The method is based on hydrogen peroxide instantly reacting with vanadium pentoxide in sulfuric acid solution, forming a peroxovanadate complex that has an absorption maximum at 454 nm. It was found that the optimum conditions were as follows: detection wavelength of 454 nm, a V2O5:H2O2 mole ratio of 2.2, and a sulfuric acid concentration of 0.5 mol/L. In order to eliminate the interference from dissolved lignin, fines, and suspended solids, the samples were acidified and centrifuged for spectroscopic quantiﬁcation. The results showed that the method has an excellent measurement precision (RSD < 0.3%) and accuracy for the quantification of hydrogen peroxide content in pulp bleaching effluents. The present method is simple and accurate, making it suitable for applications in the pulp and paper industry. PDF
In situ synthesis of gold nanoparticles on paper sheets was achieved without any external reducing reagents and heat treatments. Surface-activated pulp fibers with carboxyl and aldehyde contents of 1.18 and 0.349 mmol g–1, respectively, which were obtained from softwood kraft pulp using 2,2,6,6-tetramethylpiperidine 1-oxyl (TEMPO), were fabricated into paper sheets with polyamideamine epichlorohydrin (PAE) resin with a papermaking technique. The TEMPO-oxidized pulp papers were flexible, lightweight, and easy to handle in a wet state due to the PAE-mediated reinforcement. Simple immersion of the white TEMPO-oxidized paper in an aqueous solution of tetrachloroauric acid at room temperature brought about distinct color change from white to red-purple, strongly suggesting the formation of gold nanoparticles. Post-oxidized aldehyde-free paper provided no color variation, and thus the aldehyde groups on pulp fibers made a significant contribution to the in situ synthesis of gold nanoparticles. The organic–inorganic paper materials of TEMPO-oxidized pulp and gold nanoparticles demonstrated the catalytic activity for the reduction of 4-nitrophenol to 4-aminophenol in an aqueous system. PDF
Spruce bark particles were used as an insulation fill material for the thermal insulation of a timber frame wall which was subjected to a simulated winter temperature difference between indoor and outdoor climate. The temperature profile development of the wall’s cross section was modeled using Fourier’s transient heat flow theory. It was shown that bark layers conducted heat more slowly than commonly known blow-in insulation materials because of their low thermal diffusivity. Moreover, material moisture development due to water vapor streams caused by vapor pressure differences between the inside and outside climate was studied, and it supported general timber construction rules. PDF
Wang, M., Li, W., Liu, S., Liu, D., Yin, L., and Yuan, H. (2013). "Biogas production from Chinese herb-extraction residues: Influence of biomass composition on methane yield," BioRes. 8(3), 3732-3740.
The Chinese traditional medicine industry is developing quickly in China, and there is a growing demand for the reasonable treatment of Chinese herb-extraction residues (CHER) that are generated during the process of preparing such medicines. Different from other biomass materials, the nutrient composition of CHER discharged from different producers may vary widely, which makes the study of CHER recycling quite difficult. The present study concerns the effect of nutrient composition on the specific methane yield from the anaerobic digestion of CHER in batch trials under mesophilic temperatures. Large differences were found in the nutrient compositions of the six kinds of CHER, and the total fat and neutral detergent fiber contents affected the specific methane yield more significantly than did the total protein and total sugar contents. The specific methane yields of the six kinds of CHER were 199, 208, 211, 144, 151, and 201 mL CH4 per gram of volatile solids. From the digestion experiments, a multiple linear regression equation, the Methane Energy Value Model (MEVM), was derived; this model estimates the methane yield from the nutrient composition of CHER. The model requires further validation and refinement. PDF
This work investigates the influence of wedge shape and depth of pressing on creation of stresses, as well as the influence of these stresses on quality of wood surface during wood embossing. For the identification of stresses, SolidWorks software was used, through which a simulation was made for the progression of monitored stresses which occur when pressing the wedges with various shapes to different depths of pressing. Based on these findings, it was possible to monitor factors that were modified so that embossing would achieve the desired shape and dimensionally stable surface without undesirable quality defects. PDF
Raw and laccase-treated kenaf fibre (KF) were used individually to reinforce recycled polypropylene (RPP) using extrusion and injection moulding. Laccase was used to modify the surface of the fibre to improve the compatibility between fibre and matrix. Enzyme concentration and soaking time were considered as the treatment parameters. Maleic anhydride grafted polypropylene (MAPP) was used with a ratio of 1:10 as coupling agent to fibre. Fibres were characterized by density, energy dispersive X-ray (EDX), X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), and scanning electron microscopy (SEM), whereas composites were characterized by density, melt flow index (MFI), mechanical tests (tensile, flexural, and impact), thermogravimetric analysis (TGA), differential scanning calorimetry (DSC), field emission electron microscopy (FE-SEM), and water uptake analysis. Density, O/C ratio, and crystallinity of the treated fibre were increased. An optimum fibre loading of 40% gave the highest tensile properties. Tensile strength improved due to coupling agent by 37%, whereas treatment of fibre did the same by 40%. Flexural, impact, and thermal properties of the composites and crystallinity of the matrix were improved due to treatment. Morphological images of the composites showed better adhesion, and moisture absorption was reduced by 37% due to treatment and use of coupling agent. PDF
Dax, D., Eklund, P., Hemming, J., Sarfraz, J., Backman, P., Xu, C., and Willför, S. (2013). "Amphiphilic spruce galactoglucomannan derivatives based on naturally-occurring fatty acids," BioRes. 8(3), 3771-3790.
A class of nonionic polysaccharides-based surfactants were synthesised from O-acetyl galactoglucomannan (GGM), water-soluble hemicelluloses from spruce, using naturally-occurring saturated fatty acids, CH3(CH2)nCOOH (n = 7, 12, and 16). Hemicelluloses can be recovered from waste-streams of papermaking and agricultural processes or isolated by hot water extraction of plant tissues integrated into a biorefinery process. Fatty acids can be recovered as byproducts of the agricultural and food industries. Different synthesis routes were applied to yield amphiphilic derivatives with either a grafted or block structure. Fatty acids activated with 1,1′-carbonyldiimidazole (CDI) were grafted to the backbone of GGM molecules on their hydroxyl groups. Alternatively, synthesised amino-activated fatty acids using ethylenediamine were reacted with the reducing end of GGM. By adjusting the reagent ratios, GGM-based surfactants with different hydrophilic to hydrophobic ratios were prepared. Their surface activity was assessed by measuring the surface tension in water. This study presents an approach to design carbohydrate-based surfactants using naturally-occurring fatty acids that may find potential applications in such areas as food, cosmetic, and paint formulations. PDF
Hemmasi, A. H., Ghasemi, I., Bazyar, B., and Samariha, A. (2013). "Studying the effect of size of bagasse and nanoclay particles on mechanical properties and morphology of bagasse flour/recycled polyethylene composites," BioRes. 8(3), 3791-3801.
The effect of the size of bagasse and nanoclay on mechanical properties and morphology of bagasse flour/recycled polyethylene nanocomposite was studied. The content of bagasse flour was considered to be constant at 40%, with the size of the remaining flour on sieves of mesh 40, 70, and 100, and the accompanying nanoclay content being 0, 2, and 4 wt%, respectively. It was found that tensile strength, flexural strength, and tensile and flexural modulus were increased by decreasing the size of the particles to mesh 70. Notched impact strength was also increased by reduction of the flour dimensions. Increasing the nanoclay content up to 2 wt% led to enhanced tensile and flexural strengths as well as tensile and flexural moduli of the composite material. These properties were hurt by the addition of 4 wt% nanoclay. On the other hand, increasing the nanoclay content up to 4 wt% is expected to decrease notched impact strength of the composites. X-ray diffraction (XRD) data indicated that the order of intercalation was higher at 2 wt% nanoclay in comparison with the samples containing 4 wt% nanoclay, and the d-spacing of layers decreased with increasing of nanoclay particles content. PDF
Pretreatment with white-rot fungi can effectively remove lignin and decompose the structure of biomass to enhance subsequent enzymatic hydrolysis. This study developed a novel fungal pretreatment of biomass, which was operated under non-sterile conditions. The white-rot fungus Irpex lacteus colonized stably on the non-sterile substrates and effectively degraded lignin. After non-sterile fungal pretreatment for 42 days, lignin was degraded by 43.8%. The maximum sacchariﬁcation efficiency was 7-fold higher after enzymatic hydrolysis compared to that of raw corn stover. Furthermore, the production of ethanol from corn stover improved. During non-sterile biological pretreatment, several microorganisms coexisted with Irpex lacteus, and the microbial community generated abundant by-products that greatly improved the efficiency of enzymatic hydrolysis. Non-sterile fungal pretreatment presents a feasible and promising technology for the production of biofuels by integrating on-farm wet storage systems. Moreover, it provides a low-cost bioconversion process and a stable, secure, and environmentally friendly energy supply. PDF
Nie, X. N., Liu, J., She, D., Sun, R. C., and Xu, F. (2013). "Physicochemical and structural characterization of hemicelluloses isolated by different alcohols from rice straw," BioRes. 8(3), 3817-3832.
Six alcohol-soluble hemicellulosic preparations from rice straw were comparatively studied, and their physicochemical characterizations were examined. The treatments of the dewaxed rice straw with 60% methanol, 60% ethanol, 60% n-propanol, 60% n-butanol, 60% ethanol containing 0.01 M HCl, and 60% ethanol containing 0.25 M NaOH at 75 ºC for 3 h were able to solubilize 10.4, 10.4, 6.2, 6.5, 7.4, and 55.0% of the original hemicelluloses, respectively. The results showed that methanol and ethanol had similar solubilization capacity of hemicelluloses and gave slightly higher solubility compared to n-propanol and n-butanol. The major monosaccharide of the four neutral alcohol-soluble hemicellulosic fractions was xylose (31.78-36.80%) followed by glucose (26.35-39.39%), galactose (15.05-17.17%), and arabinose (14.93-15.58%), whereas the alkaline ethanol-soluble hemicellulosic fraction contained the highest amount of xylose (59.62%). By combining 1H, 13C, and 2D-HSQC NMR with FT-IR spectroscopy, the alkaline ethanol-soluble hemicellulosic fraction can be structurally defined as 4-O-methyl-α-D-glucurono-L-arabino-D-xylans. PDF
In the present work, a type of PU film was made from peroxy-acid-derived wheat straw lignin by reacting varying amounts of lignin ranging from 10 to 50 wt% (with respect to PEG), polyethylene glycol (Mn = 1000), and tolylene 2,4-diisocyanate without catalyst. The effects of lignin content on the tensile property and thermostability of the lignin polyurethane films obtained were investigated. The thermal conductivity of lignin polyurethane films was also studied. Results showed that when the lignin content increased, the glass transition temperature (Tg) and tensile strength of the lignin polyurethane film increased, but the onset decomposition temperature and elongation at break decreased. When the lignin content was 40 wt%, the lignin polyurethane film had the best overall properties. In addition, compared with PU films, lignin PU films showed better heat-insulating properties. PDF
Chen, W. L., Liang, J. B., Jahromi, M. F., Ho, Y. W., and Abdullah, N. (2013). "Optimization of multi-enzyme production by fungi isolated from palm kernel expeller using response surface methodology," BioRes. 8(3), 3844-3857.
Response surface methodology (RSM) was used to optimize the co-production of a mixture of crude cellulosic and hemicellulosic enzymes (endoglucanase, xylanase, and mannanase) by Aspergillus terreus K1 in solid-state fermentation (SSF) using palm kernel expeller (PKE) as the sole carbon source. These enzymes have gained renewed interest due to their efficacy to improve the digestibility of PKE for use in diets of mono-gastric animals (poultry, pigs, and fish). The results showed that temperature, moisture, inoculum concentration, and initial pH had significant (P< 0.05) effects on the enzymes production. Using PKE as a solid substrate, maximum endoglucanase, mannanase, and xylanase (17.37, 41.24, and 265.57 U/g DM, respectively) were obtained at 30.5 °C, 62.7% moisture, 6% inoculum, and pH 5.8. The enzyme activities recorded were close to the predicted values (19.97, 44.12, and 262.01 U/g DM, respectively). PDF
Yoshihara, H., and Kondo, H. (2013). "Effect of specimen configuration and lamination construction on the measurement of the in-plane shear modulus of plywood obtained by the asymmetric four-point bending test," BioRes. 8(3), 3858-3868.
In this study, the in-plane shear modulus of 3-, 5-, and 7-ply lauan wood (Shorea sp.) was measured by conducting an asymmetric four-point bending (AFPB) test with various specimen depth/length ratios and subsequently performing a flexural vibration (FV) test and finite element analysis (FEA). The results obtained from the experiment and the FEA revealed that the in-plane shear modulus was dependent on the depth/length ratio of the specimen. The dependence of the in-plane shear modulus obtained from the AFPB test was more significant than that obtained from the FV test. Additionally, the in-plane shear modulus values obtained from the AFPB test varied more significantly than those obtained from the FV test. In determining the in-plane shear modulus of plywood, the FV test was therefore superior to the AFPB test. PDF
Mao, J.-Z., Zhang, X., Li, M.-F., and Xu, F. (2013). "Effect of biological pretreatment with white-rot fungus Trametes hirsuta C7784 on lignin structure in Carex meyeriana Kunth," BioRes. 8(3), 3869-3883.
Carex meyeriana Kunth was subjected to biological pretreatment with the white-rot fungus Trametes hirsuta C7784, and the structural changes of the lignin were investigated. Results showed that there was a slight decrease in carbohydrate content after pretreatment for 3 weeks, but a noticeable decrease in lignin and carbohydrate contents after 6 weeks. Detail structural analysis of the isolated lignin from the samples revealed that Carex meyeriana Kunthlignin consisted mainly of p-hydroxyphenyl (H), guaiacyl (G), and syringyl (S) units with minor p-coumarate and ferulate units. The predominant lignin interunits were β-O-4´ ether linkages, followed by phenylcoumaran, together with a lower portion of resinol and tricin substructures. After pretreatment for 6 weeks, the contents of β-β´ and β-5´ linkages notably decreased, suggesting that the fungus preferentially attacked these linkages. The pretreatment led to an increase of S/G ratio from 0.64 in the control to 0.83 in the sample pretreated for 6 weeks. The comprehensive understanding of the structural changes of lignin offers new insights into the biological degradation of Carex meyeriana Kunth by white-rot fungus. PDF
Strand, A., Lindqvist, H., Vähäsalo, L., Blomquist, M., and Sundberg, A. (2013). "Analysis of interactions between colloidal wood pitch and various mineral particles by flow cytometry," BioRes. 8(3), 3884-3900.
The interactions between colloidal wood pitch and various commercially available mineral particles were assessed. The experiments were conducted by adding PCC, GCC, kaolin, and bentonite particles to laboratory-made pitch emulsions, and the mixtures were analyzed using flow cytometry. The results showed that most of the tested minerals were quite hydrophilic. The hydrophobicity of the mineral particles increased significantly in the presence of colloidal pitch, which showed that interactions between the pitch and the mineral surfaces occurred. The charge of the mineral particles was very important; the pitch–mineral populations formed with cationic minerals were more hydrophobic than those formed with anionic minerals. Water-soluble galactoglucomannans from spruce diminished the adsorption of pitch onto cationic minerals, while they had no significant effect on the adsorption of pitch onto anionic minerals. PDF
Maleic anhydride-acylated chitosan (MAAC) was prepared and employed to improve the wet strength of handsheets. UV-Vis spectroscopy, elemental analysis, and chemical titration methods were used to analyze the resultant MAAC. Pretreatment and curing conditions were investigated when MAAC was used to improve the wet strength of handsheets. The results revealed that the wet strength performance was highest at a pretreatment pH of 6 and that the wet strength index and the ratio of wet to dry strength increased with increasing pretreatment temperature and MAAC dose. A higher curing temperature was beneficial and improved the wet strength performance of paper. Polyamideamine-epichlorohydrin (PAE) resin performed better than MAAC with varied soaking durations. However, MAAC also reached about 80% of the wet strength of PAE and showed its potential as an alternative to PAE. PDF
Tanifuji, K., Takahashi, S., Shiell, K., Jahan, M. S., Ni, Y., and Ohi, H. (2013). "Improvement of ethanol fermentation from oligosaccharides in spent sulfite liquor with Pichia stipitis by combined calcium oxide and ion exchange resin treatments," BioRes. 8(3), 3912-3923.
The objective of this study was to develop an effective method for the removal of inhibitory compounds without decreasing oligosaccharides in spent sulfite liquor (SSL). The oligosaccharide fermentation was subsequently conducted by using Pichia stipitis, which is one of the feasible strains that can produce ethanol from oligosaccharides. The effect of inhibitory compounds on ethanol fermentation from cellobiose by P. stipitis was investigated. No ethanol was produced from cellobiose in the presence of more than 5 g/L of acetic acid. At 1 g/L of acetic acid, 2.6 g/L of ethanol was obtained after 40 h of fermentation. The removal of acetic acid in the SSL by the combined CaO and ion exchange resin treatments was also studied. The acetic acid concentration of softwood SSL was decreased from 5.2 to 0.9 g/L without decreasing oligosaccharides concentration by the combined method. Finally, the improvement of ethanol fermentation from oligosaccharides in the SSL by using the combined CaO and ion exchange resin treatments was studied. 1.3 g/L of ethanol was obtained from the SSL treated by the combined methods, while 6.5 g/L of total oligosaccharides were consumed. No ethanol was obtained from the untreated SSL. PDF
In this work, fresh poplar logs were chemically impregnated with a pulse-dipping machine. The impregnated timbers were compressed and dried by use of a multilayer hot-press drying kiln. With a compression rate of 28.67%, such an approach not only enhanced the density and mechanical properties of the treated wood, but also influenced the set recovery from the compressive deformation. Extra urea was added into the modifier to optimize the effect of the set recovery; however the result was a slight decrease in the mechanical properties. The positions of the X-ray diffraction (XRD) peaks did not change, which indicated that the structure of the cellulose was not noticeably affected by this treatment. The Fourier transform infrared spectroscopy (FT-IR) analysis showed that the intensity amide (N–C=O) absorption peak increased significantly due to the chemical impregnation. Scanning electron microscopy (SEM) showed that the high strain in the hot-press process drastically reduced the volume of void spaces in the specimens and deformed the cell lumens. PDF
The upgrading of bio-oil in supercritical ethanol was investigated using furfural and acetic acid as model compounds with the aim of exploring the reaction pathways. The effects of catalysts, temperature, cold H2 pressure, and the presence of other compounds were studied. Based on products analysis, upgrading with Pt/HZSM-5 improved performance over Pd/HZSM-5 and Ru/HZSM-5. Moreover, the catalytic performance of Pt/HZSM-5 could be enhanced by adding Ni as a second metal. Complete conversion of acetic acid and 83.06% conversion of furfural were achieved at 320 °C and 1.0 MPa of cold H2 pressure. The presence of acetone was found to increase the conversion of furfural. Through gas chromatography–mass spectrometry (GC-MS) analysis, the reaction pathways of furfural and acetic acid were clarified. It was concluded that it is possible to combine different reactions including esterification, hydrogenation, ring opening, isomerization, aldol condensation, and acetalization in supercritical ethanol. PDF
Ramzan, M., Asgher, M., Sheikh, M. A., and Bhatti, H. N. (2013). "Hyperproduction of manganese peroxidase through chemical mutagenesis of Trametes versicolor IBL-04 and optimization of process parameters," BioRes. 8(3), 3953-3966.
This is the first report on chemical mutagenesis of Trametes versicolor IBL-04 to develop a hyper-producing mutant for overproduction of manganese peroxidase (MnP) using sugarcane bagasse as a substrate. A freshly prepared inoculum of indigenously isolated T. versicolor IBL-04 was treated with 100 µg mL-1 (v/v) ethyl methane sulfonate (EMS) and ethidium bromide (EB) separately for different time periods. The selected mutants and parent strain were cultured in solid-state fermentation (SSF) conditions to select the hyper-producing mutants. After selection of hyper-producing EMS- and EB-treated mutants, the fermentation parameters, including substrate type, incubation time, initial pH of the medium, temperature, moisture level, and carbon-to-nitrogen ratio (C:N), were optimized by adopting the Classical Optimization Strategy. T. versicolor IBL-04 treated for 90 min with EMS (EMS-90 mutant) gave maximum MnP production (935 U mL-1) after 8 days of fermentation. Supplementation with carbon and nitrogen sources significantly enhanced mutant growth, and under optimum conditions, the maximum MnP production by the mutant strain increased to 3045 U mL-1. The results indicated that the random chemical mutagenesis significantly enhanced the MnP production. The increased production of MnP by the EMS-90 mutant strain suggest its potential for commercial-scale enzyme production and biotechnological applications. PDF
To better utilize low-density softwood, a thermo-hydro-mechanical densification process performed in an open system was studied to enable the manufacture of densified wood with a hard surface, strong bonding, and good dimensional stability. This study was aimed at optimizing three densification parameters, i.e., compression ratio (CR), temperature, and time, for balsam fir (Abies balsamea (L.) Mill.). The Brinell surface hardness, bond strength, and thickness recovery ratio of densified fir were examined. It was found that the optimal densification parameters were a CR of 60%, a temperature of 230 ºC, and a time of 20 minutes. The surface hardness and bond strength of optimized densified fir were about 30 and 8 MPa, respectively. The thickness recovery ratio of the densified fir after a 2-hour cold water soaking and another 2-hour boiling treatment was about 10%. Because the densified fir in this study was used for indoor applications only, its thickness recovery ratio could be minimal under conditions of use. PDF
Rathke, J., Riegler, M., Weigl, M., Müller, U., and Sinn, G. (2013). "Analyzing process related, in-plane mechanical variation of high density fiber boards (HDF) across the feed direction," BioRes. 8(3), 3982-3993.
Mechanical properties of the core layer (in-plane) of high density fiberboards (HDF) were analyzed across the width of the board (i.e., across the feed direction). The tests were performed by means of a newly developed double cantilever I beam (DCIB) testing system, with analysis of internal bond strength and bending strength. The specimens were selected from a large-scale experiment in a central European HDF plant, including a completely different machine setting for each sample set. Homogeneous density and property distributions across the feed direction of the boards were generally assumed. During this trial the question arose as to whether processing leads to unequal mechanical properties across the feed direction. In total, 20 sample sets were tested longitudinally and laterally to the feed direction at eight measurement points, revealing 320 test specimens per testing procedure. In contrast to standard testing procedures, the specific fracture energy and the stress intensity factor revealed significant differences between the centre and the edge across the feed direction. This study revealed variations of mechanical properties across the width of the board using the DCIB approach. PDF
The pyrolysis reaction of rice straw under microwave irradiation in bromide 1-ethyl-3-methyl imidazole ([Emim]Br) ionic liquid (IL) was investigated in this work. The effects of reaction temperature, mass ratio of IL to straw, reaction time, and microwave irradiation power on the yield of bio-oil were considered. An orthogonal experimental method was adopted to obtain the optimal technological conditions for pyrolysis: a reaction temperature of 160 °C, a mass ratio of IL to straw of 2:1, a reaction time of 15 min, and a microwave irradiation power of 700 W. The yield of bio-oil reached 28.2% at optimum conditions. The percent recovery of IL ranged from 84% to 87%. The recycled IL could be reused as straw pyrolysis solvent and did not affect the bio-oil yield because its structure was not damaged after being used in pyrolysis as a solvent. PDF
Liu, G., Shi, H., Ping, Q., Zhou, J., Zhang, J., Li, N., Niu, M., Fatehi, P., Xiao, H., and Ni, Y. (2013). "Complex formation of PEO and lignin in prehydrolysis liquor and its enhancing effect on lignin removal," BioRes. 8(3), 4004-4015.
Hemicelluloses dissolved in the pre-hydrolysis liquor (PHL) of kraft-based dissolving pulping processes can potentially be used to produce high value-added products such as fuel ethanol and xylitol. However, the isolation of lignin in PHL is a problem that remains unsolved and obstructs the utilization of those parts of hemicelluloses. Based on the principle of lignin isolation by acidification, the feasibility of using polyethylene oxide (PEO) to enhance the removal of lignin from PHL was tested in this work. The formation of lignin/PEO complexes was confirmed by means of turbidity, particle size, Fourier transform infrared spectroscopy (FTIR), and thermo-gravimetric analysis (TGA). The removal rate is affected by lignin content, chemical oxygen demand (COD), and decolorizing, and the results show that sulfuric acid acidification or PEO flocculation alone do not have an obvious effect on lignin removal from PHL. However, a much higher removal rate, compared to 2.81% (only acidification at pH 2) and 1.2% (only PEO on original PHL), of 22.75% is obtained by the sequential process of acidification and addition of PEO (pH 2 and PEO 350 mg/L in PHL). PDF
Vargas-Radillo, J. J., Ruiz-López, M. A., Rodríguez-Macías, R., Barrientos-Ramírez, L., Manríquez-González, R., Navarro-Arzate, F., Salcedo-Pérez, E., and López-Dellamary Toral, F. A. (2013). "Fermentable sugars from Lupinus rotundiflorus by cumulative pretreatments using UV light, freezing, and boiling in alkaline medium, followed by enzymatic hydrolysis," BioRes. 8(3), 4016-4028.
A pretreatment in tandem composed of sunlight or sun-like UV-irradiation, freezing-thawing, soda swelling, and boiling (never drying between treatments), was applied to a slurry of ground-up Lupinus rotundiflorus, followed by enzymatic hydrolysis. The effects were studied through an experimental design in which the factors were employed cumulatively to statistically evaluate the effect of each factor on enzymatic saccharification. Results showed that swelling and physical disarrangement of the lignocellulosic complex probably occurred with little or no delignification and soda consumption. The disarrangement of the cell wall and tissue structures generated by the combined effects of UV-light, freezing-thawing, soda swelling, and boiling contributed to a yield of up to 67.0% of fermentable sugars with respect to hydrolyzed material (82.8% of theoretical fermentable sugars). This yield was comparable to that obtained in control samples using Whatman No.1 paper, which produces a very high yield of fermentable sugars after hydrolysis. Finally, the acceptable overall results showed that improved saccharification of lignocellulosic materials by means of natural agents is feasible. PDF
The effects of press pressure on laboratory-made parallel strand lumbers (PSLs) that were manufactured from fast-growing rotary-peeled I-77/51(Populus deltoides) hybrid poplar clones' veneer strands with a urea formaldehyde (UF) adhesive using press pressures ranging from 7.5 to 15 kg cm-2 in increments of 2.5 kg cm-2 were investigated. The physical and mechanical properties of PSL were affected by the press pressures. However, press pressures did not affect the combustion properties. Results indicated that higher press pressures lead to higher densification or compaction rates and specific gravities (SGs). For improved physical and mechanical properties, higher press pressures were found to be necessary. A press pressure of 12.5 kg cm-2 was found to be the optimum press pressure in relation to PSL properties. There are positive correlations among SG and mechanical properties as well as press pressures. The results may provide valuable information to assess the behavior of structural composite lumbers, including PSLs, that are manufactured using low and high press pressures. Utilization of fast-growing tree species is possible because their strength properties are improved through pressing. PDF
The color and appearance of timber is influenced by a variety of physical and chemical effects. Especially the chemical composition and the surface structure play a major role. In particular, the influence of chromophore extractives and the effect of thermal degradation processes on the color of wood are widely discussed in the literature. The present study deals with the influence of the surface nanostructure on the visual appearance of wood. This new perspective should generally demonstrate various influences on the appearance of natural inhomogeneous surfaces. Therefore, two methods were used to change the nanoroughness of lignocellulose materials. With different oil coatings and UV-irradiation, the surface structures of the samples were changed, and the measured roughness using atomic force microscopy was then correlated with the collected brightness differences. The results show that a clear correlation exists between the nanoroughness altered by oil coatings or UV irradiation and the brightness of the wood surface. Due to various other influences, such as chemical changes and light refractions of the treated wood structure which also influence the color of wood, no quantification can be given at this point. PDF
Fibers obtained from dissolved air flotation rejects were oxidized using a TEMPO oxidation system to prepare oxidized recovered fibers. The effects of oxidization time on carboxyl content, water retention value, and physical properties of handsheets were evaluated. The effects of pH, amount of oxidized recovered fibers, and aluminum sulfate on paper properties were also considered. The results showed that carboxyl content and water retention values increased with the increasing of oxidized time. FTIR analysis indicated that carboxyl groups were connected to the surface of fibers. SEM micrographs showed that fibers were integrated more closely in the paper sheet, benefiting from the addition of the oxidized recovered fibers. Tensile index, burst index, and folding endurance were respectively increased by 71.7%, 38.5%, and 600% when 3% of oxidized recovered fibers was added to the pulp at pH 5, with 0.5% aluminum sulfate addition, based on the original pulp. Tensile index and folding endurance were increased by 40.2% and 433.3%, respectively, when 1% oxidized recovered fibers (the oxidized time was 60 min) were added into pulp for recycled pulp. This finding may lay the foundation for greater re-use of fiber obtained from dissolved air flotation rejects. PDF
Pressing beech veneers at high temperatures has been shown to be a reliable method for manufacturing laminated boards without adhesives. The reasons behind the self-bonding phenomenon as well as the causes of the waterproof character gained by the boards being pressed at 250 °C were investigated. Water leachates from the dried and the hot-pressed veneers were analysed by UV-spectroscopy, high-performance liquid chromatography (HPLC), and solid-state cross-polarization magic angle spinning carbon-13 nuclear magnetic resonance (CP/MAS 13C NMR). Press-plate temperatures during hot pressing were 200, 225, and 250 °C. After pressing, an increased content of 5-(hydroxymethyl)furfural (not at 250 °C) and conjugated phenols was observed in the bonding lines (interfaces) compared to the inner part of veneers of the self-bonded boards. Furfural contents were low and relatively similar, but 5-(hydroxymethyl)furfural (HMF) showed an abrupt decrease in the bonding line when the temperature increased from 200 °C to 225 °C and especially to 250 °C. The contribution of caramelization to browning and bonding is suggested. In studies with CP/MAS 13C NMR, a higher content of phenolic units in beech lignin was observed during hot pressing at 225 °C. Homolytical cleavage of b-O-4 structures in lignin as well as the condensation reactions involved are discussed. PDF
Li, Q., Xie, J., Zhao, L., Xue, Q., and Pei, J. (2013). "Optimization of fermentation conditions for laccase production by recombinant Pichia pastoris GS115-LCCA using response surface methodology and its application to dye decolorization," BioRes. 8(3), 4072-4087.
In this work, recombinant Pichia pastoris GS115-lccA was cultured and expressed with the highest laccase activity of 2357 U/L with ABTS (2, 2'-nazinobis-(3-ethylbenzthiazoline-6-sulphonate)) as reacting substrate. To achieve the higher laccase activity, multiple key factos were screened (using a Plackett-Burman design of experiments methodology) related to the fermentation conditions for producing GS115-lccA. Subsequently, a Box-Behnken response surface methodology was employed for further optimization. The optimum fermentation conditions of the fermentation were obtained as follows: 0.603% methanol added into the culture every 24 h, medium optimal initial pH 7.1, and liquid medium volume of 20.4% provided the highest enzyme activity of 5235 U/L. The decolorization experiments of dyes (Reactive Blue KN-R and Acid Red 35) were carried with the laccase cultured by recombinant P. pastoris GS115-lccA. This purified enzyme showed excellent decolorization capacity. After 24 h, the decolorization of Reactive Blue KN-R with 100 mg/L at 50 °C, pH 4.5 using 20 mM acetate buffer with 2 U/mL purified enzyme was 91.33%, and for Acid Red 35, the decolorization was 78.96%. All results suggested that this laccase may be suitable for the wastewater treatment of similar azo and anthraquinone dyes from the deinking and dyeing industries. PDF
Hazwani, H. A., Ainun, Z. M. A., Nurul, I. M. Z., Abdullah, L. C., and Zakaria, S. (2013). "Effects of physical treatments on the hydrophobicity of kenaf whole stem paper surface using stearic acid," BioRes. 8(3), 4088-4100.
Kenaf (Hibiscus cannabinus L.) is a relatively new industrial crop which has been identified as an alternative source of fiber in the papermaking industry in Malaysia. In this study, experimental unbleached kenaf kraft paper samples were used as a substrate to produce water-resistant paper by employing a special coating. In the preparation of the coating formulation, commercially precipitated calcium carbonate (PCC) was used as the filler, in addition to 0 to 0.32 w/w g of hydrophobic stearic acid (SA). Polymer latex (PL) was added at 0.4 to 0.16 w/w g into the coating compound to control the surface roughness of the samples. The paper morphology was examined by employing a scanning electron microscope (SEM). Hydrophobic kenaf kraft paper prepared in this study had water contact angle (θ) greater than 90°. Hydrophobic paper made with formulation PL4c resulted in the highest value contact angle of 147°. The process of surface coating by dipping increased the water contact angle and this treated paper achieved a high hydrophobic level. For mechanical properties, the coated kenaf paper showed decreasing tensile strength as the addition of stearic acid increased. PDF
The purpose of this study was to investigate the feasibility of using resonance-based acoustic technologies for sorting Chinese poplar logs for laminated veneer lumber (LVL) products. Representative poplar logs were sampled. Each log was first tested for acoustic velocity and then peeled into veneer. Each veneer sheet was subsequently dried and measured with a production-line veneer tester. LVL beams were made, and their stiffness was non-destructively measured by both time-of-flight (TOF) acoustic method and free-beam vibration methods. Based on the LVL dynamic modulus of elasticity (MOE) values, logs were sorted into several grades with known grade outturns. The results showed that there was a strong correlation between resonance-based acoustic velocities of logs and dynamic MOE of veneer and LVL. Thus, it is feasible to predict the stiffness of LVL products based on log resonance-based acoustic velocity measured. The resonance-based acoustic measurement is easy to use and reliable, which can help increase the grade outturn and in turn value recovery of Chinese poplar logs. It was estimated that the log grade outturns were approximately 31.1% for LVL grade 1, 38.6% for LVL grade 2, and 26.1% for LVL grade 3. PDF
Varhimo, P. U. A., Konn, J., Lillandt, M. K.-J., and Paltakari, J. T. "Brightness reduction of mechanical pulp in the wet end of a paper machine: The effect of different ions in the circulation water," BioRes. 8(3), 4117-4133.
Darkening of the fines and fiber fraction of peroxide-bleached thermo-mechanical pulp (TMP) was studied on a laboratory scale using a device that simulates the short circulation of a paper machine. Selected chemicals were dissolved in the circulation water to study the effect of different cations and anions. Ferrous ions darkened the fines and fiber fraction by increasing the light absorption. It is very important to keep the iron content of the pulp and white water as low as possible because even low contents of iron have a negative effect on the brightness of produced paper. Also, chloride ions decreased the brightness by increasing the light absorption of the fines and fiber fraction. Calcium ions increased both the light absorption and light scattering of the fines fraction. The increased light absorption dominated and the brightness decreased. Calcium chloride is used very commonly as a model chemical for calcium ions in laboratory tests, but the use of it is not recommended, if the darkening phenomena are studied, because chloride ions decrease the brightness. Aluminum ions increased the brightness of the fines fraction by increasing the light scattering. Manganese, sodium, sulfate, or carbonate ions did not affect the optical properties. PDF
Karimi, A., Taghiyari, H. R., Fattahi, A., Karimi, S., Ebrahimi, G., and Tarmian, A. (2013). "Effects of wollastonite nanofibers on biological durability of poplar wood (Populus nigra) against Trametes versicolor," BioRes. 8(3), 4134-4141.
The effect of impregnation with wollastonite nanofibers, a nontoxic mineral material, on the biological durability of poplar wood (Populus nigra) against a white-rot fungus (Trametes versicolor) was studied. Wollastonite nano-suspension with a concentration of 6.3% was used; the size range of the nano-wollastonite (NW) was 30 to 110 nm. Results showed that decay exposed for 16 weeks in accordance with the standard DIN-52176 specifications resulted in a 47.5% mass loss in control specimens, while in the NW-impregnated specimens, only 3.6% mass loss occurred. Mechanical tests on separate sets of specimens impregnated with NW without exposure to the decay organism showed no significant difference in the mechanical properties. Thus, it can be concluded that impregnating poplar wood with NW as a preservative significantly increases the biological durability of poplar wood against deterioration by Trametes versicolor. Furthermore, it does not have negative effects on the mechanical properties in the impregnated poplar specimens. PDF
The objective of this study was to increase the selectivity of hydrocarbons in bio-oil by changing the degree of closure of the reactor. Using pine sawdust with a particle size of 0.5 to 0.8 mm as the pyrolysis material and HZSM-5 with a SiO2/Al2O3 ratio of 60 as the catalyst, biomass catalytic pyrolysis experiments were carried out in a fixed bed reactor. The bio-oil compositions as a function of the closure time of the reactor and the catalyst-to-biomass weight ratios were investigated. The deactivation of the catalysts was also evaluated. The selectivity for the hydrocarbons obtained in the bio-oil was 18.99% at conditions of 550 °C reaction temperature and 20 wt% HZSM-5 catalyst usage with no closure time. When the closure time of the fixed bed reactor was 1 h, the selectivity of the hydrocarbons reached 95.28%, and the heating value reached 32.5 MJ/kg; however, the organics yield in the liquid product was only 6.2%. This investigation verified that the quality of the bio-oil could be improved significantly through the closure of the reactor, which could be due to pyrolysis vapors that could be treated by the coupling effect between a high pressure and catalytic pyrolysis. PDF
Li, S.-M., Sun, S.-L., Ma, M.-G., Dong, Y.-Y., Fu, L.-H., Sun, R.-C., and Xu, F. (2013). "Lignin-based carbon/CePO4 nanocomposites: Solvothermal fabrication, characterization, thermal stability, and luminescence," BioRes. 8(3), 4155-4170.
This work explored the synthesis of carbon-based luminescent materials using cheap, natural resources. Lignin-based carbon/CePO4 nanocomposites were successfully synthesized using previously extracted lignin solution and CePO4, or NaH2PO4•2H2O and Ce(NO3)3•6H2O by the solvothermal method at 200 °C for 24 h, respectively. The lignin solution was previously prepared by the extraction of wood powder in a mixed solvent of dimethyl sulfoxide (DMSO)/lithium chloride (LiCl). All of the obtained lignin-based carbon/CePO4 nanocomposites were characterized by scanning electron microscopy (SEM), energy-dispersive X-ray spectra (EDS), Fourier transform infrared spectrometry (FT-IR), thermogravimetric analysis (TGA), differential thermal analysis (DTA), and photoluminescence (PL). SEM micrographs showed that the CePO4 concentration had an influence on the size, microstructure, and morphology of the carbon/ CePO4 nanocomposites. The experimental results indicated that the obtained lignin-based carbon/CePO4 nanocomposites had excellent PL properties. PDF
Carbon fibers were synthesized using a low-cost, economical method. Fresh rubber wood fibers (Hevea brasiliensis) were burned using a furnace in an inert condition at 350 to 450 oC for 2-4 hours, and after that the fibers were ground at 18000 rpm for 20 to 40 seconds. The effect of carbon fibers as a reinforcement agent on mechanical, physical, and morphological properties was investigated. In the composite preparation, carbon fiber dosages (0, 0.1, 0.25, and 0.5 wt.%) were used as variable factors, along with a urea formaldehyde content of 10%. The morphology of the specimens was characterized using X-ray diffraction (XRD), Thermogravimetric analysis (TGA), and Field Emission Scanning Electron Microscopy (FESEM). The mechanical tests indicated that when carbon fibers were added, the modulus of rupture (MOR) and internal bonding strength (IB) improved significantly. From the TGA graph it was observed that the thermal stability of the composites based on carbon fiber was higher than composites without it. The thermocouple readings showed that at a higher loading of carbon, the core temperature of the board increased faster than for the control board. PDF
The thermal and dielectric properties of medium density fiberboard (MDF) with different moisture contents were measured by light flash and the parallel-plane capacitor method, respectively. The results show that increasing moisture content has a positive effect on both thermal properties and dielectric properties. The higher the moisture content, the higher the thermal conductivity and dielectric properties were. The thermal conductivity of MDF with different moisture contents varies in the temperature range of 25 to 150 ºC in a double-hump pattern rather than a proportional pattern. The dielectric constant decreases with increasing frequency up to 1000 MHz. The dielectric loss factor undulates within the frequency range of 1 to 100 MHz, and the peak value occurs at around 10 MHz. The results presented in this study can be used for radio frequency heating, wood building energy, material design, and radio frequency evaluation. PDF
Zhang, R., Liu, F., and Liu, H. (2013). "Fast acidogenic fermentation of corn stover through a two-step method: Nitric acid hydrolysis combined with the fermentation of hydrolysate," BioRes. 8(3), 4193-4207.
This study investigated a novel route for fast acidogenic fermentation of corn stover through a two-step method. Corn stover was first hydrolyzed by nitric acid, and the hydrolysate was then used for acidogenic fermentation. The results showed that the yields of soluble xylose, arabinose, and glucose in hydrolysate obtained from HNO3 hydrolysis of corn stover at the optimum condition achieved 96.86% of initial xylose, 98.54% of initial arabinose, and 18.58% of initial glucose, respectively. Acidogenic fermentation of hydrolysate proved to be effective, compared to acidogenic fermentation of raw corn stover; the production of volatile fatty acids (VFAs) increased by 54.8%, fermentation time decreased by 50%, and the distribution of VFAs was more suitable for subsequent methanogenic fermentation. This research provided an effective, suitable, and economical method for biogas production from corn stover. PDF
Four different extracts were obtained by extracting Cinnamomum camphora xylem with hot water, methanol, ethyl acetate, and chloroform. Thereafter, wood (Masson pine) was impregnated with these different extracts, and the decay resistance performance of the wood treated with the extracts was studied. The results showed that the mass loss of wood treated with 4% ammoniacal copper quats (ACQ), 4% boric acid, 4% camphor, and extracts made with 10% water, 10% methanol, 10% ethyl acetate, and 10% chloroform were 1.78%, 5.7%, 13.08%, 40.85%, 9.39%, 18.66%, and 21.45%, respectively. The samples impregnated with 4% ACQ, 4% boric acid or 10% methanol extract could meet the demand of degree I (LY/T 1283-2011) for preservation and showed strong resistance to fungal decay. The results from optical microscopy and SEM indicated that treated hyphae (methanol extracts) exhibited an obvious morphological change: the cell wall became rough, and the cell expanded, became twisted, and exhibited uneven growth of hyphae, indicating that the extracts affected the structure and function of the hyphae. The low number of hyphae present within the cell walls revealed that treatment with methanol extracts provided strong resistance to fungal decay. PDF
Liu, G. F., Chen, C. F., Wu, G. M., and Kong, Z. W. (2013). "Preparation and antimicrobial activity of rosin-based carbamate group-containing quaternary ammonium salt derivatives," BioRes. 8(3), 4218-4226.
A novel rosin-based carbamate was prepared by the reaction of N,N-dimethylaminopropylamine with rosin-based cyclic carbonate. Using LiBr in conjunction with ethylene glycol as a catalyst, carbon dioxide was treated with triglycidyl ester of maleopimaric acid to prepare the rosin-based cyclic carbonate. The carbamate was then quaternized to form three rosin-based carbamate group-containing quaternary ammonium salt derivatives. The chemical structures of all new compounds were characterized by IR, 1H NMR, and 13C NMR. The antimicrobial activities of the carbamate and quaternary ammonium salt derivatives were investigated. The bioassay test results showed that all derivatives exhibited strong inhibition against Staphylococcus aureus, Escherichia coli, Bacillus subtilis, Bacillus thuringiensis, and Streptomyces microflavus. However, no visible antifungal activity was found against Saccharomyces cerevisiae or Aspergillus niger, except for the activity of the carbamate derivative against S. cerevisiae. PDF
Rahman, M. R., Lai, J. C. H., Hamdan, S., Ahmed, A. S., Baini, R., and Saleh, S. F. (2013). "Combined styrene/MMA/nanoclay cross-linker effect on wood-polymer composites (WPCs)," BioRes. 8(3), 4227-4237.
In the present study, batai wood (Paraserianthes moluccana) was impregnated with a combination of styrene, methyl methacrylate, and nanoclay in order to improve compression strength, thermal stability, and surface morphology. Styrene (ST) and methyl methacrylate (MMA) cross-linker introduced a co-polymerization reaction with cellulose in the wood cell wall and produced wood polymer composites (WPCs), as confirmed by Fourier Transform Infrared (FT-IR) Spectroscopy. The mechanical properties of the WPCs were significantly increased compared to the raw wood. Thermal properties of both raw wood and WPCs were evaluated by thermogravimetric analysis (TGA). WPCs exhibited higher thermal stability relative to the raw wood due to the co-polymerization reaction. The surface morphologies of the fracture surface for both the raw wood and WPCs were recorded using scanning electron microscopy (SEM). The SEM micrographs reveal that after polymerization, WPCs show smoother texture and adhesion compared to that of raw wood. PDF
Sarifuddin, N., and Ismail, H. (2013). "Comparative study on the effect of bentonite or feldspar filled low-density polyethylene/thermoplastic sago starch/kenaf core fiber composites," BioRes. 8(3), 4238-4257.
The present work evaluated the potential of the addition of bentonite and feldspar as fillers on the mechanical and physical properties of low-density polyethylene (LDPE)/thermoplastic sago starch (TPSS)/kenaf core fiber (KCF) composites. For this purpose, 3 to15 phr of fillers were incorporated into LDPE/TPSS/KCF composites that were fabricated via a melt-mixing molding system. Results showed that the tensile strength and modulus were improved significantly with the addition of bentonite in comparison with feldspar. Thermal studies confirmed the improvement in thermal stability of composites filled with bentonite as well as feldspar. An increased percentage of water absorption was also observed in these composites compared with the control (LDPE/TPSS/KCF composites) system. PDF
Rice husk constitutes the largest by-product of the rice milling industry. Numerous research studies have been conducted on the utilization of rice husk powder (RHP), but research on incorporating RHP into natural rubber latex foam (NRLF) is lacking. The purpose of this study was to use RHP as a filler for NRLF. A compression test was performed on RHP-filled NRLFs, and they were compared with the control NRLF. The compression set increased, while the recovery percentage decreased, as RHP loading increased. The stress versus strain curve showed increasing stress with increasing RHP loading. The increase in thermal stability and decreased (Qf/Qg) value of RHP-filled NRLFs indicated good interaction between RHP and NRLF. RHP incorporation can contribute to NRLF industries with environmentally friendly products such as mattresses and cushioning materials by lowering costs. PDF
This work aims to develop a new ionic liquid, used as an aprotic green ä solvent, to dissolve kraft lignin from black liquor. The kraft lignin was extracted through precipitation with carbon dioxide at atmospheric pressure. 1,8-Diazabicyclo[5.4.0]undec-7-ene-based ionic liquids were obtained by quaternization of the nitrogen atom with a hydrogen atom or an alkyl chain. The yields of the synthesis of the ionic liquids varied between 76 and 80%. Dissolving experiments were carried out using the lignin isolated from the black liquor of a kraft process. Up to 20% (w/w) of the lignin can be dissolved in butyl-1,8 diazabicyclo[5.4.0] undec-7-enium chloride ([DBUC4]+[Cl-]), hexyl-1,8 diazabicyclo[5.4.0] undec-7-enium chloride [DBUC6]+[Cl-], and octyl-1,8 diazabicyclo[5.4.0] undec-7-enium chloride [DBUC8]+[Cl-]. The time it takes to dissolve the lignin in these three liquids shows that its solubility is influenced mostly by the nature of the cations. The lignin solubility was reduced in relation to the increased length of the grafted carbon chain. The thermogravimetric analysis (TGA) showed these liquids can be used as lignin solvents from room temperature up to 300 °C (onset of degradation). Steric exclusion chromatography showed a slight decrease (6%) in the molecular weight of the lignin dissolved in these ionic liquids. PDF
This article reports the results of temperature measurements carried out on 50-mm-thick Norway spruce (Picea abies [L.] Karst) wood samples exposed to infrared (IR) radiation. The varied property with respect to the optimization of the drying technology was the initial moisture content of samples. During the experiments, temperature profiles were registered on the surface and in the core of the samples under controlled technological conditions. Based on our osmotic approach, the variability in the curves was interpreted with respect to the stagnation temperature below the fiber saturation point (FSP). We conclude that the amount of liquid water necessary for osmosis must still be available locally in the core. With decreasing initial average moisture content, the time interval of the osmotic process also decreases. In this context our results support the hypothesis that the presence of free water in the wood tissue is necessary for the osmotic mechanism even if the average moisture content falls below the FSP. PDF
Homogenous chemical modification of ball-milled eucalyptus wood with palmitoyl chloride was investigated using a dimethyl sulfoxide/N-methylimidazole solvent system at room temperature. The parameters were optimized, including the reaction time and the dosage of palmitoyl chloride. The results indicated that prolonging the reaction time from 15 min to 120 min resulted in an increase in the weight percentage gain (WPG) of eucalyptus from 9.5 to 22.8%, while a further increase of the reaction time to 180 min led to an increase in WPG of 19.3%. An increase of the mass ratio of palmitoyl chloride-to-wood from 1:2 to 5:1 resulted in an improvement of WPG from 8.7 to 46.0%, while a further increase of the mass ratio of palmitoyl chloride-to-wood to 6:1 led to a decrease in WPG (39.7%). The physico-chemical properties of the esterified wood were investigated with FT-IR and CP/MAS 13C-NMR spectroscopies. The results indicated that the palmitoyl ester group was successfully attached to the eucalyptus. The esterification of lignin and carbohydrates occurred at room temperature and the thermal stability of eucalyptus increased after esterification. PDF
Dumitrascu, A.-E., Ciobanu, V. D., and Lepadatescu, B. (2013). "Valorization of wood resources for the cutting of decorative veneer in the context of sustainable development of Romanian forests," BioRes. 8(3), 4298-4311.
The overall aim of the research was to better understand the influence of raw material characteristics on the quality of decorative veneer, to identify phenotypes of oak and sessile oak valuable for veneer use, and to promote quality in relationship with sustainable development of Romania’s forests. This paper describes specific aspects regarding wood defects and quality conditions imposed on raw materials for veneer slicing. The experiments focused on identifying and analyzing defects in oak veneer found in six regions from Romania. Taking into account the dimensional and quality requirements, and obtaining a sufficient quantity of decorative oak veneer, Pareto diagrams corresponding to each region were created. The Pareto analysis allowed for a hierarchy of main defects and also enabled adequate decision-making for improving the quality of the studied products in accordance with specific international standards. Also, by knowing the types of defects, decisions can be made to conserve natural resources and to utilize wood resources by sustainable reuse of waste. PDF
Shimizu, S., Posoknistakul, P., Yokoyama, T., and Matsumoto, Y. (2013). "Quantitative difference in the rates of the β-O-4 bond cleavage between lignin model compounds with and without γ-hydroxymethyl groups during the alkaline pulping process," BioRes. 8(3), 4312-4322.
To examine the effect of the presence of γ-hydroxymethyl groups on the rate of the β-O-4 bond cleavage during the alkaline pulping process, the rates of the β-O-4 bond cleavage of non-phenolic lignin model compounds without a γ-hydroxymethyl group, 2-(2-methoxyphenoxy)-1-(3,4-dimethoxyphenyl)ethanol (G’G) and 2-(2,6-dimethoxyphenoxy)-1-(3,4-dimethoxyphenyl)ethanol (G’S), were compared with those of analogous model compounds with a γ-hydroxymethyl group, 2-(2-methoxyphenoxy)-1-(3,4-dimethoxyphenyl)propane-1,3-diol (GG) and 2-(2,6-dimethoxyphenoxy)-1-(3,4-dimethoxyphenyl)propane-1,3-diol (GS), under alkaline pulping conditions. The disappearance of G’G or G’S was accompanied by the quantitative liberation of 2-methoxyphenol or 2,6-dimethoxyphenol, respectively, indicating that the disappearance resulted from the β-O-4 bond cleavage. The disappearance rate of G’G or G’S was in between those of the erythro and threo isomers of GG or GS, respectively. This result seems to be reasonably explained when the steric repulsions of the three staggered conformations are taken into consideration. The disappearance rate of G’G or G’S increased, but the increment became moderate with increasing hydroxide concentration. PDF
Danish, M., Hashim, R., Mohamad Ibrahim, M. N., and Sulaiman, O. (2013). "Characterization of physically activated Acacia mangium wood-based carbon for the removal of methyl orange dye," BioRes. 8(3), 4323-4339.
In this experiment, Acacia mangium wood was physically activated in the presence of CO2 gas at an activation temperature of 500 ºC for 2 h. The total surface area of the activated carbon was found to be 395.91 m2/g, 81.06% of which was due to micropores. Fourier transform infrared spectroscopy showed that the major functional groups on the surface of activated carbon were carboxylate, hydroxyl, and lactone groups. An isotherm study of methyl orange dye adsorption by the activated carbons was conducted. Langmuir, Freundlich, Temkin, and Dubinin-Radushkevich (D-R) isotherms were applied to find the adsorption characteristics of the activated carbon. The results showed that the isotherm data followed the Langmuir isotherm with maximum adsorption capacity of 7.54 mg/g at a temperature of 25 °C and an equilibrium time of 48 h. A dimensionless equilibrium constant, RL equal to 0.3280 was also determined to prove that adsorption was favorable but not very effective. PDF
The withdrawal capacity of screws in heat-treated spruce wood (Picea abies Karst.) was measured in the radial and tangential directions. Wood was heat-treated at temperatures of 150, 170, 190, 210, and 230 °C. Screw withdrawal capacity decreased as the degree of thermal modification was increased. Also, image analysis was used to measure the size of the deformed wood area around the screw, which increased with higher thermal modification temperatures. This leads to the practical recommendation that connections in heat-treated wood should be constructed with screws with larger diameters and deeper penetration. Moreover, larger spacing between screws is needed to ensure sufficient withdrawal capacity compared to non-treated wood. PDF
Hardwood KP bleaching effluents, before (influent) and after (effluent) biological treatment, were characterized and compared to identify the main bio-recalcitrant organic compounds in the effluent. The results indicate that biological treatment reduces CODcr and BOD5 by 67% and 88%, respectively. However, various bio-recalcitrant organic compounds were still retained in the biologically-treated effluent, which exhibits an increase in effluent color. Spectroscopic analysis suggests that colored substances are the most recalcitrant materials in the effluent. Di-n-octyl phthalate and 6,6’-di-tert-butyl-2,2'-methylenedi-p-cresol are the predominant residual materials in the biologically treated effluent. These two materials are the main recalcitrant organic compounds in the effluent and contribute to the major part of the residual CODcr in the biologically treated effluent. PDF
Elephant grass (Pennisetum purpureum) (EG) is a fast-growing plant with high biomass productivity in the range of 30-45 bone dry t/ha/yr. This high productivity qualifies EG as a potential raw material for bleached pulp production. This study evaluated elephant grass as a raw material for paper pulp production. This was accomplished through determining its full chemical and morphological characterization, pulpability at kappa numbers 15 and 20 via the kraft and soda-AQ processes, and its pulp bleachability to 90% ISO brightness. The results were compared with those of a commercial hybrid eucalyptus wood clone (Eucalyptus urophylla x Eucalyptus grandis) (EUCA) that is widely planted in Brazil. Concerning its chemical composition, the elephant grass presented a high ash (60,100 mg/kg) and total extractives content (14.8%). However, the elephant grass showed good potential for pulp production. The kraft process was the ideal cooking process at kappa number 20, producing the highest screened yield (47.9%), bleachability (0.163 Δkappa/TAC), and good viscosity (812 dm3/kg). For EUCA, the ideal cooking process was the kraft process at kappa number 20, resulting in a screened yield of 52%, bleachability of 0.217 Δkappa/TAC, and final viscosity of 886 dm3/kg. This high productivity qualifies EG as a potential raw material for bleached pulp production. PDF
A two-stage lignocellulosic biomass fractionation process consisting of a formic- or acetic acid-reinforced wood autohydrolysis step followed by an ethanol-water treatment was applied to a mixture of Southern hardwood chips. The wood products in the hydrolysate were mostly monomeric xylose, other monomeric sugars, polymeric hemicelluloses, acetic acid, and a relatively small amount of lignin. The second step mostly dissolves sulfur-free lignin, while the fibrous residue consists mainly of cellulose fibers, which may be used for liquid fuels or pulp production. The yield composition, and quality of these products were determined as a function of treatment conditions, with the aim to develop an economic and robust biorefinery fractionation technology. PDF
Carboxylic acid groups were introduced onto thermomechanical pulp (TMP) long fiber surfaces by 2,2,6,6,- tetramethylpiperidine-1-oxyl radical (TEMPO)-mediated oxidation in the present study. The number of introduced carboxylic groups was closely related to the NaClO dosage, and more flexible fibers with lower curl and kink index were generated. Lignin was dissolved during the TEMPO-mediated oxidation, and its content was 24.2% with a carboxylic content of 1444 mmol/kg, in contrast to the control, which had 33.6%. Meanwhile, significant decreases in uncondensed lignin and β-O-4 lignin were observed during the TEMPO-mediated oxidation. The generation of carboxylic acid groups enhanced both the tensile and burst strengths of oxidized TMP significantly, and the value was 70% higher than the control with a carboxyl content of 1444 mmol/kg. However, side reactions during TEMPO-mediated oxidation led to a decline in intrinsic fiber strength, which may have contributed to the decline in paper tear strength. PDF
Wheat is a very important agricultural product, and is among the grains that has the highest sustenance value in the world. Every year large amounts of wheat hull is produced which has a low economic value. The present study aimed to characterize the structure of wheat hull and wheat hull ash obtained after burning wheat hull at 400 to 1000 °C for 5 h. This study also investigated the potential of wheat hull as a source for the production of silica xerogel. X-ray diffraction patterns, scanning electron microscope micrographs, the chemical properties, the particle morphology, particle size, surface chemistry of wheat hull, wheat hull ash, and its silica xerogels were determined by the use of various instruments and analysis techniques. A temperature of 700 °C was found to be the optimum ashing temperature with maximum amorphous silica content. The BET surface area of ashes ranged from 7.21 to 0.11 m2/g. The study demonstrated that silica xerogel powder with 93.9% silica content was obtained by the use of wheat hull after heat treating at 700 °C for 5 h. PDF
In this work, a biodegradable fiberboard was prepared from modified bleached bamboo fibers. Cationic guar gum (CGG) was deposited onto the fibers, and the corresponding changes in physical properties of the composite were determined. Bleached bamboo fiber was modified by depositing cationic guar gum (CGG) onto the fibers. The treated fibers were then used to prepare biodegradable fiberboard. A 56.21% increase in tensile strength and a 54.40% increase in strain were obtained with the addition of 1.5 wt% of CGG. The bamboo fiber treated with CGG exhibited better thermal stability than the pure bamboo fiber. The surface morphologies of the unmodified and modified samples were analyzed using atomic force microscopy (AFM) in the tapping mode and scanning electron microscopy (SEM), which revealed differences in the fine structure of fibers, showing coarser surfaces spread across the fibers. PDF
Ishola, M. M., Babapour, A. B., Gavitar, M. N., Brandberg, T., and Taherzadeh, M. J. (2013). "Effect of high solids loading on bacterial contamination in lignocellulosic ethanol production," BioRes. 8(3), 4429-4439.
Contamination by lactic acid-producing bacteria is frequently a major challenge in ethanol processes. In this work, high solids loading was used both to keep bacterial infection under control in simultaneous saccharification and fermentation (SSF) of lignocellulosic biomass and to increase the ethanol productivity of the process. With no sterilization of the substrates, lactic acid bacteria contaminated the fermentation process with 8 and 10% suspended solids (SS) substrates, consumed both pentoses and hexoses, and produced lactic acid. However, a high solids loading of 12% SS prevented lactic acid formation, which resulted in higher ethanol yield during the SSF process. This high SS resulted in an ethanol concentration of 47.2 g/L, which satisfies the requirement for industrial lignocellulosic ethanol production. PDF
Paulownia wood (PW) flour was evaluated as a reinforcement for thermoplastic composites. Composites of high-density polyethylene in pellet form (HDPE), 25% by weight of PW, and either 0% or 5% by weight of maleated polyethylene pellets (MAPE), were produced by twin screw compounding followed by injection molding. Formulations of PW flour composed of specific particle sizes (≤590 to ≤75 µm) were also compared. Molded test composites were evaluated for their tensile, flexural, impact, and thermal properties. Composites made with PW and MAPE had significantly improved tensile and flexural properties compared to neat HDPE. The impact strength of all composites using MAPE was 30% improved over HDPE. Benchmarking PW composites to similar preparations of pine wood flour composites demonstrated that PW can produce a comparable and in some cases a superior bio-fiber composite. The effect of environmental exposure was examined by soaking tensile bars of HDPE-PW blends in distilled water for 28 days to observe changes in their physical and mechanical properties. Finally, differential scanning calorimetery and thermogravimetric analysis were conducted on PW composites to evaluate their thermal properties and the implications these may have on selecting processing conditions for the bio-fiber reinforcements. PDF
Strand length, free-fall distance (FFD), and plate spacing was varied to control the strand alignment distribution of strandboard. To determine the strand angle distribution, photographs of strands were recorded as digital image data, and strand angle analysis was conducted using a modified von Mises distribution function. A part of this measurement was used as a reference for the alignment in the board produced. The results of strand alignment distributions showed that the k value was a function of strand length, FFD, and plate spacing. The k value can be improved by adjusting the plate spacing closer to the strand width, shortening the FFD, and using long strands. The power equation model can describe those relations. The bending properties and linear expansion (LE) were greatly affected by the FFD and the plate spacing. The use of low FFD and narrow plate spacing improved the bending properties. The decreasing bending properties in the parallel direction could be comparable to the increasing ones in the perpendicular direction. The contribution of bamboo strand in the longitudinal direction affected these results. PDF
Tee, Y. B., Talib, R. A., Abdan, K., Chin, N. L., Basha, R. K., and Md Yunos, K. F. (2013). "Thermally grafting aminosilane onto kenaf-derived cellulose and its influence on the thermal properties of poly(lactic acid) composites," BioRes. 8(3), 4468-4483.
The effects of thermally grafting hydrolysed 3-aminopropyltriethoxysilane (APS) onto kenaf-derived cellulose and the influence of incorporating them into poly(lactic acid) (PLA) were investigated. Composites containing 30 wt.% cellulose (C) and silane-grafted cellulose (SGC) were melt-blended into PLA before being hot pressed into 0.3-mm films. The silane grafting of cellulose was confirmed via Fourier transform infrared spectroscopy (FTIR) with the presence of Si-O-Si, Si-O-cellulose, -Si-C-, and Si-O-C bonds, and –NH2 groups despite post ethanol washing. Using thermogravimetric analysis (TGA), it was determined that the thermal stability of the cellulose improved by 8 °C after silane grafting. As for the composites, PLA/SGC improved the thermal stability by 12 °C as compared to PLA/C. From differential scanning calorimetry (DSC), adding C into PLA slightly reduced the glass transition temperature, Tg, of the PLA from 59 °C to 57 °C, which remained unchanged with silane grafting. PLA displayed double melting peaks from its melt-recrystallization behaviour. While the final melting temperature at 150 °C was not affected, incorporating C and SGC influenced the intensity of the melting peaks. The significant reduction in crystallisation temperature from 113 °C to 102 °C and 105 °C, and the increase in crystallinity by almost two fold, indicated that cellulose was an effective nucleating agent. PDF
Aging systems of wine brandies have been a target of investigation to reduce the costs and aging time. In this study, the extractives and Klason lignin contents of wood fragments used in the aging of wine brandies in stainless steel tanks were evaluated. Two types of wood fragments, known as staves and tablets, and two wood botanical species, Limousin oak (Quercus robur L. from the Limousin region of France) and Portuguese chestnut (Castanea sativa Mill.), with heavy toasting levels were used. The wood extractive and Klason lignin contents were analyzed before and 30 months after the aging of wine brandy. The results showed that the chestnut wood presented the highest content of extractives, while the Klason and total lignin contents were higher in the oak wood. A highly significant effect from the tablets was found on the extractives and Klason lignin contents, while the soluble lignin content was more affected by the staves. Oxygenation of the wine brandies during the aging process negatively affected the release of extractives and lignin from the wood to the brandy, and therefore will impact the overall quality of the brandy. PDF
Wheat straws were split longitudinally using a specially designed straw splitter. Oriented structural boards made from the split straw strands were fabricated with polymeric diphenylmethane diisocyanate (pMDI) resin. The effects of the split straw strand length, resin content, and panel density on the properties of oriented structural straw board (OSSB) were investigated. Dimensional analysis showed that the average length of split straw strands after screening of the fines was 83.74 mm. More than 70% of the straw strands were in the range of 50 to 90 mm in length. The bending properties of the OSSB were highly related to the length of the split straws. The modulus of rupture (MOR) and modulus of elasticity (MOE) increased significantly as the split straw length was increased, particularly from 11 mm to 45 mm. The preferable length of the split straw was at least 40 mm to satisfy the MOE requirements. For a given pMDI content level, the internal bond (IB) strength increased linearly with an increase in panel density, which is consistent with previous results for wood-based panels. This study demonstrated that satisfactory OSSB can be made using approximately 3% pMDI at an average panel density of 640 kg/m³ to comply with the North American OSB products standard. PDF
Jia, L., Sun, Z., Ge, X., Xin, D., and Zhang, J. (2013). "Comparison of the delignifiability and hydrolysability of wheat straw and corn stover in aqueous ammonia pretreatment," BioRes. 8(3), 4505-4517.
The impact of an aqueous ammonia pretreatment on the structural properties, delignifiability, and hydrolysability of wheat straw and corn stover was investigated. The results showed that the aqueous ammonia pretreatment had an excellent delignification ability and that the corn stover exhibited higher susceptibility to an aqueous ammonia attack than wheat straw. In total, 35.6% and 70.0% of the lignin in wheat straw and corn stover were removed, respectively, by the aqueous ammonia pretreatment at 75 ºC with 21% ammonia and a solid:liquid ratio of 1:10 for 20 h. Both lignin and polysaccharides in the corn stover exhibited higher susceptibility to aqueous ammonia than those in wheat straw. In addition, the hydrolysability of corn stover was more susceptible to aqueous ammonia than it was to wheat straw. A chemical structure analysis of different substrates showed that the aqueous ammonia pretreatment removed lignin, broke ester bonds between lignin and hemicelluloses, increased the specific surface area and crystallinity index, and, finally, enhanced the hydrolysis yield. PDF
Duong, L. D., Luong, N. D., Binh, N. T. T., Park, I.-K., Lee, S. H., Kim, D. S., Lee, Y. S., Lee, Y. K., Kim, B. W., Kim, K, H., Yoon, H. K., Yun, J. H., and Nam, J.- D. (2013). "Chemical and rheological characteristics of thermally stable kraft lignin polycondensates analyzed by dielectric properties," BioRes. 8(3), 4518-4532.
In light of the difficulties and disagreements in determining the property-processing structure relations of lignin-based polymers, dielectric analysis was used to identify the thermal and rheological characteristics of a lignin-based polycondensate and the pristine lignin. Using dielectric analysis, the pristine lignin with Mw=6000 g/mol, was clearly identified as giving the wet glass transition temperature (Tg,wet) and the evolution of gases (i.e., burning) at around 80 ºC to 125 ºC followed by subsequent cross-linking reactions over 150 ºC to give the dry glass transition temperature (Tg,dry) of lignin at around 130 ºC to 140 ºC. Connecting the lignin macromers using sequential condensation reactions with caprolactone and sebacoyl chloride, the lignin based polycaprolactone (LigPCL) polycondensates were synthesized as a thermoplastic polymer composed of lignin macromers and aliphatic polyester chains with Mw=10500 g/mol. The synthesized LigPCL presented good thermal stability and rheological melting behavior without evolving odor or fumes. In particular, the T2% (defined at 2% of weight loss) of the LigPCL and pristine lignin were 200 ºC and 80 ºC, respectively. The melt viscosity was measured at 103Pa.s at 120 ºC, ensuring facile melt-blending processing with various commodity polymers to be used in eco-friendly polymer composite development. PDF
The performance of a process called sulfite pretreatment to overcome recalcitrance of lignocelluloses (SPORL), which was carried out at high pH, was preliminarily investigated as a means of improving bagasse substrate enzymatic digestibility (SED). The lignin removal significantly affected the SED resulting from the SPORL-high-pH treatment. Lignin removal was found to be well-correlated with SED when the Boltzmann function was used to fit the curve. In this fitting curve, SED increased slowly initially and then rose up quickly with lignin removal (from 0% to 10%, and then from 10% to 35%) and finally reached an asymptotic value (80%, based on o.d. glucan in the pretreated substrate). Removing lignin to about 35% to 40% would be sufficient to significantly improve the SED of bagasse to the asymptotic value (80%) during enzymatic hydrolysis, while low cellulase and b-glucosidase (15 FPU/g and 22.5 CUB/g o.d. cellulose in the substrate, respectively) were loaded. Furthermore, combining this Boltzmann function and the SPORL-high-pH delignification model would be useful for predicting neutral-sulfite pretreated SED. PDF
Har, C.-L., Hii, S.-L., Yong, C.-K., and Siew, S. P. (2013). "Statistical screening of factors affecting production of fermentable sugars from sugarcane bagasse under solid-state conditions," BioRes. 8(3), 4546-4562.
A Plackett-Burman design (PBD) combined with a steepest ascent approach is a powerful technique to screen the important operating parameters for the production of reducing sugars from sugarcane bagasse (SB). In this study, the most significant parameters (p< 0.05), as identified by PBD, were as follows: pretreatment duration, pH of pretreatment process, loading of enzyme cellulase, SB loading, and moisture content of SB. Analysis of variance (ANOVA) results showed that the model of reducing sugar productivity was able to provide a high correlation between the response and its parameters. Thus, the path of steepest ascent (PSA) method was used to assess the optimal region of variables for improved reducing sugar productivity from SB. The PSA analysis revealed that by treating 7.25 g of SB (with 84% moisture content) for 82.0 minutes at a pH of 8.8, followed by the addition of 34.0% v/w of cellulase, a reducing sugar productivity of 0.03 g/L could be achieved per hour during the enzymatic saccharification process. PDF
In order to obtain “clean” liquefied lignin, selective liquefaction of lignin from bio-ethanol production residue (BEPR) was conducted using an aromatic solvent, furfuryl alcohol. The effects of liquefaction time, temperature, and liquid ratio on the liquefaction yield were investigated. The results indicated that with the increasing of liquefaction temperature (120 to 170 °C) or liquid ratio (3 to 5:1), the liquefaction yield of lignin (LYL) increased, respectively. Liquefaction times of 15 to 120 min had no significant effect on the liquefaction yield. When liquefaction was conducted at 170 °C for 15 min with a ratio of 5/1 liquefying solvent to raw material, the LYL reached its highest level of 80.23%. Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), and Gel permeation chromatography (GPC) analyses confirmed that the liquefaction process had great selectivity for lignin. Ash and carbohydrates in the raw material could be removed as liquefied residue. PDF
Pereira, B. L. C., Carneiro, A. de C. O., Carvalho, A. M. M. L., Colodette, J. L., Oliveira, A. C., and Fontes, M. P. F. (2013). "Influence of chemical composition of Eucalyptus wood on gravimetric yield and charcoal properties," BioRes. 8(3), 4574-4592.
The objective of this study was to assess the chemical properties of wood from six clones of Eucalyptus spp. relative to charcoal yield and its properties, determine the correlations between the evaluated parameters and identify a clone of Eucalyptus having the greatest potential for charcoal to steelmaking use. The study of chemical properties included analysis of elemental composition, contents of cellulose, hemicelluloses, lignin, and ash, the syringyl/guaiacyl ratio (S/G), and the index of crystalline cellulose in the wood. The pyrolysis of wood was done in an electric laboratory oven. The gravimetric yield in charcoal, the content of volatile matter, fixed carbon and ash, higher heating value, and elementary composition were determined. Data were subjected to an analysis of variance, and after the difference between them was established, the Tukey test was applied. The Pearson correlation was employed as well. The results indicated that the contents of carbon, oxygen, and hydrogen in the wood significantly affected the charcoal yields and its higher heating value. Higher rates of crystalline cellulose favored the gravimetric yield in charcoal. The S/G ratio contributed more to the charcoal yield when compared to total lignin content. PDF
Larch tannin resin (LTNA) was prepared by a microwave modified cross-linking reaction. The adsorption of chromium(VI) from an aqueous solution by LTNA was studied using batch adsorption experiments. LTNA has a large number of pores, the size of which are about 250 nm. After adsorption, the internal structure of the LTNA resin assumed an obvious three-dimensional network. The adsorption of Cr(VI) on LTNA was investigated as a function of pH, dose of adsorbent, and adsorption time. The results indicated that the removal of Cr(VI) was pH-dependent. The optimum adsorption was observed at pH 1.0, and the maximum adsorption capacity was 9.134 mg/g. The Cr(VI) adsorption by the LTNA gel obeyed the Langmuir adsorption isotherm. The kinetic processes of Cr(VI) adsorption onto LTNA could be acceptably explained by the pseudo-second order kinetic rate model. Thermodynamic parameters revealed the spontaneity and exothermic nature of adsorption. Desorption of adsorbed Cr(VI) was successfully realized with a 0.1 M NaOH solution. PDF
Sodium hydroxide (NaOH) has been used as an alkali source in conventional hydrogen peroxide bleaching. In the present work, partial and total replacement of NaOH with magnesium hydroxide (Mg(OH)2) as the alkali source for hydrogen peroxide bleaching of deinked pulp was studied. The bleached pulp was studied with respect to brightness, post color (P.C.) number, and mechanical properties (i.e., the tensile, tear, and burst indices). The bleaching effluent was measured for residual peroxide, pH value, and chemical oxygen demand (COD). The main results from this work were that the brightness and mechanical properties of bleached pulp increased while the P.C. number declined when NaOH was partially replaced with Mg(OH)2. However, the total substitution of NaOH with Mg(OH)2 resulted in a slight decrease in the brightness and mechanical properties in comparison with NaOH as the sole alkali source. Additionally, the residual peroxide of the bleaching filtrate increased from 3% to 61% and the COD load of the bleaching effluent decreased from 20% to 25% when NaOH was replaced with Mg(OH)2 at various replacement ratios. PDF
High-density polyethylene (HDPE) and natural fiber composites were prepared by melt compounding and injection molding. The influence of fiber type (i.e., pine, bagasse, rice straw, and rice husk) and the addition of coupling agents on the composite properties were investigated. The use of 30 wt% fiber enhanced the tensile and flexural properties of neat HDPE, but decreased the impact strength. The comprehensive mechanical properties of HDPE/natural fiber composites were significantly improved by the addition of 2 wt% maleated polyethylene (MAPE). The toughness was further enhanced with the use of 5 wt% maleated triblock copolymer styrene-ethylene/butylene-styrene (MASEBS). The composites had higher crystallization peak temperatures and lower crystallinity levels than neat HDPE, and their thermal stability was lower than that of HDPE. The reduced storage modulus and increased loss tangent showed that MASEBS performed as a flexibilizer in composites. PDF
Yuan, Q., Su, C., Huang, J., Gan, W., and Huang, Y. (2013). "Process and analysis of electromagnetic shielding in composite fiberboard laminated with electroless nickel-plated carbon fiber," BioRes. 8(3), 4633-4646.
To develop a composite fiberboard with high electromagnetic shielding effectiveness (SE) and an easily industrialized process, electroless nickel-plated carbon fiber technology was used to improve the conductivity and electromagnetic properties of carbon fiber and carbon fiber sheets. The SE of composite fiberboards laminated with nickel-plated carbon fiber with different arrangements was also studied. The results showed that the best plating scheme in this study was a NiSO4 concentration of 35 g/L, plating temperature of 70 °C, pH of 9, and plating time of 15 min. When nickel-plated carbon fiber in a grid arrangement was added to the core between two fiberboards, the minimum and maximum SE of 19 x 19 grid arrangement was 41.54 dB and 63.73 dB in the 200 to 1000 MHz frequency range, respectively, and reached medium grade. SE of composite fiberboard laminated with double layers of plated carbon fiber sheet ranged from 45.29 dB to 52.01 dB and reached medium grade. It is thus feasible to use two-layer nickel-plated carbon fiber with a 19 × 19 grid arrangement to make composite fiberboard with high SE, mechanical properties greater than the national standard, and an easily industrializable process. PDF
Biodegradation of lignocellulosic waste from chestnut residues is an important biological process of added value for this sector according to the Chestnut National Plan for agriculture. Dynamic parameters during biodegradation under natural conditions of chestnut burr, leaf, and plant biomass litter are reported in this study. Microbiological and physical-chemical characterisation of chestnut wastes was carried out to monitor this specific biodegradation, to understand the progress and limits of the process and to analyse the compost-like organic substance obtained. Physical-chemical parameters, such as temperature, pH, and water activity, were influenced by the composition of the raw materials and by seasonal climatic conditions. Moreover, microbiological monitoring was assessed by culture-dependent and independent methods. Cellulolytic, hemicellulolytic, and ligninolytic populations were counted to determine different microbial activity during biodegradation process. The functional microbial groups analysed showed different trends, but all were found at high concentrations (7 to 9 log CFU/g). In addition, PCR-DGGE was performed for bacterial and fungal populations to evaluate the microbial diversity. The similarity level during the process was generally very high, both for bacterial and fungal populations. These data are the first on suitable natural degradation for chestnut forests. PDF
Mao, A., Hassan, E. B., and Kim, M. G. (2013). "Low mole ratio urea-melamine-formaldehyde resins entailing increased methylene-ether group contents and their formaldehyde emission potentials of wood composite boards," BioRes. 8(3), 4659-4675.
A previous study of synthesizing low mole ratio urea–formaldehyde (UF) and urea–melamine–formaldehyde (UMF) resins, which included an acidic reaction step at the beginning of the typical resin synthesis procedure to obtain higher uron-type methylene–ether group contents, was repeated with the acidic reaction step extended to a higher viscosity. Compared to previous resins, the synthesized resins showed additional increases in the uron-type and linear-type methylene–ether groups, resulting in longer storage times, longer pot lives, longer gel times, and comparable internal bond strengths and water absorption values of particleboards; however, the formaldehyde contents (FC) of boards increased. It was concluded that the extended acidic reaction resulted in increased formaldehyde emission potential of boards because of additional methylene–ether groups formed. The results led to the hypothesis that the FC values of current UF resin-bonded boards are mainly due to the methylene–ether-type groups present in significant levels in UF and UMF resins. PDF
Ni/Cu/Al/Fe hydrotalcite precursor was synthesized by a co-precipitation method. The activity of the reduced precursor for one-step conversion of maltose into sorbitol in the presence of H2 and extremely low phosphoric acid was investigated. XRD and XPS tests provided the essential properties of the precursor and prepared magnetic catalyst. Effects of various processing parameters towards the reaction performance were studied in detail. A desired sorbitol yield of 93.1% was attained at 458 K for 3 h with a catalyst dosage of 20%. A catalyst recycling experiment demonstrated that Ni4.63Cu1Al1.82Fe0.79 was a better catalyst and could be reused three or four times. The specific reasons for catalyst deactivation were considered in depth. PDF
Thermally-modified wood is not sufficiently durable for exposure to environments in which severe biological deterioration is likely. So in this study, samples of southern yellow pine sapwood were first subjected to thermal modification and then impregnated with the alkaline copper quat-type D (ACQ-D) wood preservative. Three heating temperatures (180, 200, and 220 °C) and two concentrations of ACQ-D solution (0.90% and 1.35%) were used in the experiments. The copper retention, percentage of copper leaching, and concentrations of copper ions in the leachates collected during the leaching tests were evaluated using inductively coupled atomic emission spectrometry (ICP-AES). Fourier transform infrared spectroscopy (FTIR) analysis was also used to interpret the differences in leaching performance between thermally-treated and unheated wood samples. The pseudo-second-order model of copper leaching was developed with the experimental leaching data, which could determine the amounts of copper ion leaching and predict the final percentage of copper leaching during the leaching process. As a result, compared to the control group, the copper retention of the thermally- modified wood samples was lower, while the percentage of copper leaching was higher. This observation could be explained by the lower number of copper ion fixation sites in the thermally-treated wood. PDF
A long-term onsite assessment of the hygrothermal performance of a wood frame wall system is presented in this work. The system was applied in a wood demonstration house within the Lake Tai climate zone of Suzhou, China. The hygrothermal performance of the cavity insulation wall was determined from the temperature, relative humidity, and from the temperature of the wood material surface throughout the year. The results clearly indicated the effect of the cavity insulation, cladding cavity ventilation, and air-vapor barrier. Thermal performance was very good due to the wall cavity insulation. Cladding cavity ventilation was effective at low relative humidity of the insulated wall cavities. Condensation and mold growth were not found inside the wall during the test period. The wood frame wall system had good hygrothermal performance and may be widely used in hot summer and cold winter climate zones in China. PDF
Bamboo is a potential lignocellulosic biomass for the production of bioethanol because of its high cellulose and hemicellulose contents. An acid-free ethanosolv process was proposed to overcome the problems caused by the acid catalysts commonly used in organosolv processes. In this research, ethanosolv pretreatment catalyzed by NaOH was used to enhance the enzymatic saccharification of moso bamboo. The addition of 10% (w/w on bamboo) NaOH in 75% (v/v) ethanol was demonstrated to be effective in the pretreatment and fractionation of bamboo. The pretreatment yielded a solid fraction with 60.1% cellulose. The cellulose-to-glucose conversion yield was 28.9% to 45.1%, depending on pretreatment conditions, after enzymatic hydrolysis of the solid fraction at 50 °C for 48 h using enzyme loading (15 filter paper units of cellulase/g cellulose and 30 IU b-glucosidase/g cellulose). The concentrations of fermentation inhibitors such as 5-hydroxy-2-methyl furfural (HMF) and furfural were negligible in the spent liquor after the ethanosolv pretreatment and were much lower than those in the spent liquor from H2SO4-water or ethanosolv only treatment. PDF
Spent mushroom substrate (SMS), a renewable bio-waste from the mushroom-growing industry, was used as an adsorbent to remove methylene blue (MB) from aqueous solution. SMS was characterized using scanning electron microscopy (SEM) and Fourier-transform infrared spectroscopy (FTIR). Adsorption experiments with the SMS adsorbent were performed based on various parameters, such as adsorbent dose, initial MB dye concentration, initial pH, contact time, and temperature. The Langmuir, Freundlich, and Temkin isotherm models were employed to interpret the adsorption behavior. The results indicated that the equilibrium data were perfectly represented by the Temkin isotherm. The maximum adsorption capacity of SMS reached 63.5 mg g-1 at 303 K. The kinetics studies indicated that the pseudo-second-order model best described the adsorption of MB on SMS. The activation energy of the adsorption was 5.64 kJ mol-1. Thermodynamic parameters suggested that the adsorption was an exothermic and spontaneous physical process. The results imply that SMS is a potentially low-cost adsorbent for treating wastewater containing cationic dyes. PDF
Variations in brown rot decay and proportions of heartwood and sapwood were investigated in eastern white cedar (Thuja occidentalis L.). This experiment tested the hypothesis that the incidence of brown rot decay depends on the site, tree age, tree height, and heartwood/ sapwood ratio. Forty-five trees were sampled and felled from three mature stands in the Abitibi-Témiscamingue region, Quebec, Canada. From each tree, disks were systematically sampled along the entire stem, and the heartwood, sapwood, and decay proportions and volumes were determined for each disk. Scanning electron microscopy showed that growth of fungi causing brown rot decay was limited and slower in latewood than in earlywood due to the narrow cell lumen, thick wall, and limited number of bordered pits in latewood tracheids. Site, tree height, and tree age had significant effects on the proportions of sapwood, heartwood, and decay. Heartwood and brown rot decay proportions decreased from the base of the tree upward, while the sapwood proportion increased. There was more decay in older trees and in those growing on moist versus dry sites; however, decay was not serious in trees younger than 80 years. In addition, brown rot decay proportion correlated strongly and positively with heartwood proportion and tree volume, but negatively with sapwood proportion. PDF
The objective of this study was to evaluate the effect of heat treatment on properties including oven-dry density, weight loss, surface roughness, shear strength, and hardness of eastern red cedar (Juniperus virginiana L.). The anatomical structures of samples were also examined by scanning electron microscope (SEM). Two different heat treatment schedules, with temperatures of 130°C and 160°C and 3 and 7 h exposure times, were considered for the experiment. A stylus method was employed to evaluate the surface properties of heat-treated samples. Three roughness parameters, average roughness (Ra), mean peak-to-valley height (Rz), and maximum roughness (Rmax), were determined from the surface of specimens and used to evaluate the effect of heat treatment on the surface properties. The shear strength of samples bonded with polyvinyl acetate (PVAc) adhesive was also measured. All properties of the samples exposed to different heat treatment schedules were significantly different (p = 0.05) from each other. The results of this study demonstrated that the oven-dry density, surface roughness, shear strength, and hardness of the samples decreased, while their weight loss increased slightly, with increasing heat treatment temperature and time. PDF
The objective of this study was to evaluate properties of experimental particleboard panels manufactured from wheat straw that had been pretreated with acetic anhydride, soapy solution, hot water, or steam. Wheat straw particles were mixed with commercially manufactured wood particles at a ratio of 60%. Control straw particleboards with non-treated straw and wood particles were also produced. The results showed that the pretreatment of wheat straw significantly improved both the physical and mechanical properties of the straw particleboards. Panels made from wheat straw treated with a 9% solution of acetic anhydride or boiled in a soapy solution resulted in the highest mechanical properties, with an increase in bending strength values. Regarding internal bond strength, the samples made from wheat straw particles treated with acetic anhydride and a soapy solution had 2 and 3 times higher values, respectively, than those of non-treated samples. It seems that the pretreatment of wheat straw had a greater effect on the thickness swelling of the specimens than on their water absorption. PDF
Wood is known to contain and emit volatile organic compounds including formaldehyde. The emission of formaldehyde from wood increases during its processing to lumber and wood-based panels (i.e., particleboard and fiberboard). This increased emission can be attributed to the processing procedure of wood, which includes drying, pressing, and thermo-hydrolysis. Formaldehyde is emitted from wood under very high heat and is not expected to be a significant source of the emissions from composite wood products during normal service. Formaldehyde is also detectable even if wood has never been heated as well as under more or less ambient conditions. The presence of formaldehyde in the emissions from wood that does not contain adhesive resin has been explained by thermal degradation of polysaccharides in the wood. The emission levels of formaldehyde depend on factors such as wood species, moisture content, outside temperature, and time of storage. Additionally, the pyrolysis of milled wood lignin at 450 °C yields benzaldehyde, and the pyrolysis of spruce and pinewood at 450 °C generate formaldehyde, acetaldehyde, 2–propenal, butanal, and butanone, which can be attributed to the breakdown of the polysaccharide fraction of the wood. PDF