Our peer-reviewed sister journal: Lignocellulose
BioResources, Volume 9, Issue 2
NOTE: Each current issue of BioResources continues to build as new articles are approved.
The acid hydrolysis of lignocellulosic material (LM) is one of the most widely studied and important subprocess in the LM biorefinery. After acid hydrolysis, LM can be converted to various biofuels, biochemicals, and biomaterials through chemical or biochemical methods. However, conventional LM acid hydrolysis is not regarded as a cost-effective and environmentally-friendly process because it has drawbacks such as difficulties in acid recovery, equipment corrosion, and chemical wastes from the neutralization of acid and the removal of LM degradation products. Use of ionic liquids and solid acids during LM hydrolysis has provided potential technical tools to overcome these problems and has given new life to the LM acid hydrolysis process in the biorefinery. This editorial will discuss the role of the LM acid hydrolysis process in the LM biorefinery, provide an analysis of the conventional LM acid hydrolysis process, and briefly discuss new developments in the LM acid process. PDF
What do you do after a product has served its function and is no longer needed? Ideally, you recycle it. What do you do if people have neglected or forgotten so much of what has been learned in recent years about paper recycling? Well, one of the things that someone can do is to write a book. Very little of the contents of such a book may be new. But the book itself can be highly valuable, representing a lot of effort to select and organized material that will be helpful for the current and upcoming generations of papermaking technologists. This editorial describes a new book by Dr. Pratima Bajpai entitled Recycling and Deinking of Recovered Paper. Readers who deal with the recycling of paper will probably want to have a copy of it on a handy shelf. PDF
The wet web strength is one of the most important parameters for effective paper machine performance. A huge variety of parameters is known from many studies to have an impact on the wet web strength (WWS). In this study, a full factorial design of experiments (DOE) was used to determine the effect of different factors on the WWS. The goal was to use a DOE method within the field of paper strength research to acquire advanced information on the mechanisms of strength development at different dryness levels. The study was carried out with laboratory handsheets made of commercial unbleached softwood pulp, which was refined in a laboratory Hollander beater. The WWS was measured according to the German standard DIN 54514. The analysis of the data showed that weighing of the influencing factors on WWS is possible, which may lead to a better understanding of paper strength development mechanisms at low dryness levels. The applied method was proven to be reliable for the determination of the impact of various factors and will therefore be used in future work. PDF
Carbon fiber reinforced plastic (CFRP) was used to adhesively reinforce Chinese fir (Cunninghamialanceolata) wood specimens. This study examined the flexural static and creep performances of CFPR-reinforced wood composites that had been subjected to changes in moisture and stress levels. The major findings were as follows: 1) the cyclic creep was slightly lower for those specimens subjected to the cyclic stress condition than for those subjected to a constant stress level due to the deflection recovery under cyclic loading; 2) the environmental conditions of high temperature and high humidity assisted in accelerating the creep by increasing the moisture content of the composite and reducing the compressive strength of wood, causing the composite specimen to fail viadamage in the wood layer from compressive crushing; 3) the stress level governed the creep of the CFRP-reinforced wood composite; and 4) the Burger model was able to accurately simulate the short-term creep performance of the CFPR-reinforced wood composite. It was suggested the maximum bending stress level should be limited to 40% for the CFRP-reinforced wood composites fabricated in this study. PDF
Zahan, K. A., Pa'e, N.,and Muhamad, I. I. (2014). "Process parameters for fermentation in a rotary disc reactor for optimum microbial cellulose production using response surface methodology," BioRes. 9(2), 1858-1872.
In this study, microbial cellulose production by Acetobacter xylinum 0416 using standardized liquid pineapple waste was carried out in a 4-L rotary disc reactor (RDR). The objective of this study was to optimize the process parameters for production of microbial cellulose in the RDR. The effects of the disc rotation speed (5 to 12 rpm), pH (3.5 to 7.5), fermentation period (3 to 6 days), and inoculum concentration (3 to 20% v/v) on the microbial cellulose production were investigated. The optimum microbial cellulose yield was obtained using 10% (v/v) of inoculum concentration, whereby four days’ duration gave the most productive yield. In addition, the highest production of microbial cellulose was obtained at a low disc rotation speed of 7 rpm and a pH of 5.0. Analysis of data performed a high coefficient of determination value (R2=0.875) represented by a mathematical model of optimized microbial cellulose production, Y = -200.437 + 7.180X1 + 69.869X2 + 4.369X3 + 1.867X4 – 0.512X12 – 6.766X22 – 0.585X32 – 0.079X42. From the results, it can be concluded that the foremost factors that affect the production of microbial cellulose in RDR were pH followed by inoculum concentration, disc rotation speed (rpm), and fermentation period. PDF
Sánchez Orozco, R., Balderas Hernández, P., Roa Morales, G., Ureña Núñez, F., Orozco Villafuerte, J., Lugo Lugo, V., Flores Ramírez, N., Barrera Díaz, C. E., and Cajero Vázquez, P. (2014). "Characterization of lignocellulosic fruit waste as an alternative feedstock for bioethanol production," BioRes. 9(2), 1873-1885.
To use a new potential lignocellulosic bioresource that has several attractive agroenergy features for ethanol production, the chemical characterization and compositional analysis of several fruit wastes were carried out. Orange bagasse and orange, banana, and mango peels were studied to determine their general biomass characteristics and to provide detailed analysis of their chemical structures. Semiquantitative analysis showed that the components for each fruit waste differed with respect to chemical composition. Fourier transform infrared spectrometry (FTIR) of the residual biomass showed the presence of various functional groups – aldehydes or ketones (C=O), alkanes (C-C), and ethers (C-O-C). Even water molecules were detected, indicating the complex nature of the feedstocks. The concentrations of total sugars ranged between 0.487 g∙g-1 and 0.591 g∙g-1 of dry weight biomass. The thermal profiles (TG-DSC) of the residual fruits occurred in at least three steps, which are associated with the main components (hemicellulose, cellulose, and lignin). The decomposition by thermal analysis was completed at around 600 °C and was influenced by the nature of the component ratio. PDF
A polyaniline/clay combination was prepared via: 1) mixing polyaniline dispersion with clay; or 2) in situ polymerization of aniline in the presence of clay. To deliver electrical conductivity to cellulosic paper, the polyaniline/clay composition was applied to the paper surface by Meyer rod coating. The conductive paper was analyzed by Scanning Electron microscopy (SEM) and Fourier Transmission Infrared spectroscopy (FT-IR). For comparison purposes, conductive paper was also prepared by in situ polymerization of aniline in the presence of cellulosic fibers. The in-situ formed polyaniline was deposited on the fiber surface, and the polyaniline-deposited cellulosic fibers were made into paper sheets. It was found that at the same aniline content, paper surface coating with polyaniline/clay composition gave a much higher conductivity in comparison with the use of polyaniline-deposited cellulosic fibers for paper sheet formation. PDF
Mechanical analysis is presented for new high-strength sandwich panels made from wood-based phenolic impregnated laminated paper assembled with an interlocking tri-axial ribbed core. Four different panel configurations were tested, including panels with fiberglass fabric bonded to both outside faces with self-expanding urethane foam used to fill the ribbed core. The mechanical behaviors of the sandwich panels were strength tested via flatwise compression, edgewise compression, and third-point load bending. Panels with fiberglass exhibited significantly increased strength and apparent MOE in edgewise compression and bending, but there were no noticeable effects in flatwise compression. The foam provided improved support that resisted both rib buckling and face buckling for both compression and bending tests. Post-failure observation indicated that core buckling dominated the failures for all configurations used. It is believed that using stiffer foam or optimizing the dimension of the core might further improve the mechanical performance of wood-based sandwich panels. PDF
Nagraj, A. K., Singhvi, M., Kumar, V. R., and Gokhale, D. (2014)."Optimization studies for enhancing cellulase production by Penicillium janthinellum mutant EU2D-21 using response surface methodology," BioRes. 9(2), 1914-1923.
Extracellular fungal cellulases are key enzymes for the degradation of lignocellulosic biomass. Greater production of these enzymes could reduce the cost of biofuels production. In this study, the basal medium for cellulase production by a Penicillium janthinellum mutant (EU2D-21) in submerged fermentation conditions was optimized using response surface methodology (RSM). Initial studies using a Plackett-Burman design (PBD) showed that (NH4)2SO4 and urea are significant factors for improving β-glucosidase and FPase production. A central composite design (CCD) was applied to obtain the maximum response, which resulted in the optimal production of β-glucosidase (5.79 IU/mL) and FPase (5.76 IU/mL). These values were 1.87 and 1.67 times higher than the corresponding values obtained under un-optimized conditions. PDF
A microwave (MW) treatment method was applied to Chinese fir wood to improve its liquid permeability. It was found that the optimum parameters for the MW treatment of Chinese fir to achieve an improved permeability without significantly affecting its mechanical properties were as follows: a MW intensity of 20 kW, moisture content (MC) ranging from 40% to 60%, and a processing time of 60 s. The microscopic structure of Chinese fir wood before and after MW treatment was examined using a scanning electron microscope (SEM), which revealed that micro-checks were formed at the intercellular layer of ray cells and longitudinal tracheids; pit membranes were destroyed; and damage to cell walls was also observed. Mercury intrusion porosimetry (MIP) test results showed that the pore diameter at pit opening range increased after MW treatment (peak value of control sample: 553.7 nm; peak value of MW-treated sample: 921.1 nm) and micropores were generated, which also contributed to the improved permeability of Chinese fir wood. Positive correlations between microstructural changes and liquid permeability were found. PDF
Acrylic impact modifiers (ACRs) with different soft/hard monomer ratios (mass ratios) were prepared by semi-continuous seed emulsion copolymerization using the soft monomer butyl acrylate and the hard monomer methyl methacrylate, which were used to toughen polylactide (PLA). The effect of soft/hard ACR monomer ratio on the mechanical properties of PLA/ACR blends was investigated. The results showed that the impact strength and the elongation at break of PLA/ACR blends increased with increasing soft/hard ACR monomer ratio, while the tensile and flexural strengths of PLA had little change. The impact strength of PLA/ACR blends could be increased about 4 times more than that of pure PLA when the soft/hard monomer ratio of ACR was 90/10, which was the optimal ratio for good mechanical properties of PLA. Additionally, the possible mechanism of ACR toughening in PLA was discussed through impact fracture phase morphology analysis. PDF
Guan, M., Yong, C., and Wang, L. (2014). "Microscopic characterization of modified phenol-formaldehyde resin penetration of bamboo surfaces and its effect on some properties of two-ply bamboo bonding interface," BioRes. 9(2), 1953-1963.
The bonding interface between bamboo elements and adhesives is presumed to be significantly influenced by the degree of adhesive penetration into the porous network of interconnected cells of bamboo surfaces. In the study presented here, the average depth and effective depth of phenol-formaldehyde resin (PF) modified by different contents of lower-molecular weight (LMW) PF on bamboo surface were evaluated, making use of fluorescent microscopy characterization. The shear distribution at the bonding interface was measured by means of electronic speckle pattern interferometry (ESPI), along with tensile strength measurements, to determine the shear strain distribution on a macroscopic scale. This research combined macroscopic mechanical properties with microscopic interfacial mechanical properties, and it was found that PF modified with 10% LMW PF performed better than other modified PF. Moreover, it was assumed that the results of this study would influence the choice of bamboo-specific adhesives under different strain conditions. PDF
Laccase is a kind of polyphenol oxidase having potential in applications for pulp bleaching, waste water treatment in mills, and removal of phenols in the food industry. The normal laccase from fungus or bacterial contains four copper atoms per protein molecular, imparting a blue color. Here it is reported that a white laccase is produced by a white rot fungus Panus conchatus from its solid-state fermentation. The activity center of this laccase is Cu2FeZn, which lacks the typical type-1 blue copper color. The polyacrylamide gel electrophoresis of purified laccase showed a main polypeptide with a molecular weight of about 60 kDa. Laccase substrate 2,6-dimethoxylphenol and others, such as syringaldazine, o-tolidine, and ABTS, were readily oxidized, among which the Km for syringaldazine was the highest. The isoelectric point of this enzyme was 3.6 and it was stable at temperatures below 45 °C over a wide range of pH (4-12). PDF
In the furniture and construction industries, there is increased demand for lightweight, high-performance, and low-maintenance materials with specific properties. Increased demand necessitates testing of new and composite materials to find a viable alternatives to classical materials. In this study, two different types of cork layered plywood composites (plywood board with a cork core (PLYW-K1), and plywood board with a cork core and cork face layers (PLYW-K2)) were prepared and tested for their basic mechanical properties as well as screw withdrawal resistance. The measured properties were compared with standard particleboard (PB) and plywood board (PLYW1) to determine the difference in properties and potential applications. The results presented include preparation parameters, mechanical properties, maximum withdrawal force, and withdrawal resistance. In addition, the effect of screw diameter and material density on withdrawal resistance was observed. Results indicate that cork-layered plywood possessed superior mechanical properties and withdrawal strength at a much lower density than particleboard. In comparison to classical plywood, the improved factors were a reduction in density and production cost. PDF
The preparation of nanocellulose fibers (NFs) is achieved through pretreating cellulose in a NaOH/urea/thiourea solution, and then defibrillating the fibers through ultrasonication, resulting in a high yield of 85.4%. Extensive work has been done to optimize the preparation parameters. The obtained NFs are about 30 nm in diameter with cellulose II crystal structure. They possess high thermal stability with an onset of thermal degradation at 270 °C and a maximum degradation temperature of 370 °C. Such NFs have potential applications in transistors and batteries with high thermal stability. NFs-H were obtained by homogenizing undefibrillated fibers separated from the preparation of NFs. NFs-H were also in cellulose II crystal form but with lower thermal stability due to low crystallinity. They can be applied to make highly transparent paper. PDF
Ozen, E., Yeniocak, M., Goktas, O., Alma, M. H., and Yilmaz, F. (2014). "Antimicrobial and antifungal properties of madder root (Rubia tinctorum) colorant used as an environmentally-friendly wood preservative," BioRes. 9(2), 1998-2009.
The aim of this study was to determine the antifungal and antimicrobial properties of madder root extract when used as an environmentally-friendly wood preservative and against blue stain. Plant dyestuff was extracted from the root of madder by using an ultrasonic assisted method and then applied to Turkish oriental beech, Scots pine, oak, and walnut wood blocks with the immersion (classic) and immersion + ultrasonic assisted methods. For mordants, ferrous sulfate, aluminum sulfate, copper sulfate, and vinegar were used. In order to compare the performances of the natural paints, a synthetic dye was used. The abilities of the extracts to suppress attack by brown rot (Postia placenta) and white rot (Trametes versicolor) were investigated. Treated blocks were exposed to P. placenta and T. versicolor attacks for 16 weeks according to the TS 5563-EN 113 method. Antimicrobial activity of the extracts was determined with the agar dilution method by using the disk diffusion method for bacteria. Results showed that the mordant mixes were considerably more resistant to fungal decay compared to their untreated and synthetic counterparts. In general, control (non-mordant) and vinegar mixtures showed good performance against brown and white rot fungi. Copper mixes showed better antimicrobial activity against all types of microorganisms. In conclusion, it was found that madder root extracts and mordant mixes could be used as wood preservatives. PDF
Enzymatic hydrolysis of rapeseed meal carbohydrates was performed to increase the protein content. Rapeseed meal was first screened and further defatted. Only particles between 0.250 and 0.707 mm in size were used, and the optimum solid/liquid ratio was found to be 10% (w/v). Commercially available carbohydrase enzyme mixtures, Viscozyme® L, Pectinex® Ultra SP-L, and Celluclast® 1.5 L, were used in conditions that minimized protein solubilization from the solid phase. The highest results were achieved with Viscozyme® L, with a carbohydrate extraction yield of 80% (as determined by reducing sugars content expressed as glucose equivalent units) after 24 h of reaction at 45 ºC, pH 3.5, and an enzyme dosage equivalent to 96 fungal beta-glucanase (FBG) added to 5 g of defatted rapeseed meal. The simultaneous use of the different carbohydrases (Viscozyme®, Pectinex®, and Celluclast®) did not improve the carbohydrate hydrolysis when compared to the use of Viscozyme® L alone. Viscozyme® L treatment increased the protein content in the rapeseed meal from 41 to 68%, which allowed the solid to be classified as a protein concentrate. PDF
This paper discusses moso bamboo (Phyllostachys pubescens) with initial crack formation by a three-point bending (SENB) method. The corrected indentation load-displacement curve (ISO 13586-2000) and the crack opening displacement in determining the crack tip extended displacement of the specimen (ASTM E399-09) were measured using a COD gauge. Then, the load-displacement curve and the value of PQ were found by the method of 95% stiffness correction. The results showed that the bamboo has good fracture toughness, and, in this experiment, the fracture results showed little difference; the result for fracture toughness can be up to 17.39 MPa •m1/2. By observing the crack under the microscope and the failure mode, it was found that the crack propagation was not established in accordance with the crack opening direction; rather it extended along the fiber interface. PDF
Mohamad Rasidi, M. S., Husseinsyah, S., and Leng, T. P. (2014). "Chemical modification of Nypa fruticans filled polylactic acid/recycled low-density polyethylene biocomposites," BioRes. 9(2), 2033-2050.
Nypa fruticans (NF) is a lignocellulosic material belonging to the family Palmae or Arecaceae. Effects of NF content and chemical modification using methyl methacrylate (MMA) on tensile, thermal, and morphological properties of biocomposites were investigated. The results showed that the addition of NF decreased the tensile strength, elongation at break, and crystallinity, but increased the Young’s modulus, of biocomposites. Moreover, the addition of NF increased the thermal stability. Meanwhile, the tensile strength and Young’s modulus of the biocomposites treated with MMA were higher than the untreated biocomposites. The treated biocomposites exhibited higher thermal degradation temperature and crystallinity compared to the untreated biocomposites. The morphology study of the tensile-fractured surfaces of biocomposites indicated that chemical modification with MMA enhanced the interfacial interaction between NF and the PLA/rLDPE matrix. PDF
Ponomarenko, J., Dizhbite, T., Lauberts, M., Viksna, A., Dobele, G., Bikovens, O., Telysheva, G. (2014). "Characterization of softwood and hardwood lignoboost kraft lignins with emphasis on their antioxidant activity," BioRes. 9(2), 2051-2068.
Fractionation of softwood and hardwood LignoBoost kraft lignins, using sequential extraction with organic solvents of increasing hydrogen-bonding ability (dichloromethane, n-propanol, and methanol), was carried out. Using SEC, analytical pyrolysis, FTIR and UV/VIS spectroscopy, and chemical analytical methods, four fractions were obtained and characterized in terms of their yield, composition, functionality, lignin structural features, and antioxidant properties. In tests with free radicals (ABTS .+, DPPH ., O2 .-) and the ORAC (oxygen radical absorbance capacity) assay, the high radical scavenging capacity of the lignin’s soluble fractions was demonstrated. The antioxidant activity of the fractions was tested by their influence on thermo-oxidative destruction of model polyurethane elastomers. The TGA data clearly revealed the antioxidant effect of the three fractions, with the most prominent activity for the propanol-soluble fraction. The dichloromethane fraction has potential as an antioxidant for non-polar products. Novel correlations between lignin’s structural features and its radical scavenging activity were found that can be used for tuning lignin’s antioxidant properties. PDF
This paper evaluates the optimal composition of annual and perennial biomass feedstocks for a biorefinery. A generic optimization model is built to minimize costs – harvest, transport, storage, seasonal, and environmental costs – subject to various constraints on land availability, feedstock availability, processing capacity, contract terms, and storage losses. The model results are demonstrated through a case study for a midwestern U.S. location, focusing on bioethanol as the likely product. The results suggest that high-yielding energy crops feature prominently (70 to 80%) in the feedstock mix in spite of the higher establishment costs. The cost of biomass ranges from 0.16 to 0.20 $ l-1 (US$ 0.60 to $0.75 per gallon) of biofuel. The harvest shed shows that high-yielding energy crops are preferably grown in fields closer to the biorefinery. Low-yielding agricultural residues primarily serve as a buffer crop to meet the shortfall in biomass requirement. For the case study parameters, the model results estimated a price premium for energy crops (2 to 4 $ t-1 within a 16 km (10-mile) radius) and agricultural residues (5 to 17 $ t-1 in a 16 to 20 km (10 to 20 mile) radius. PDF
The effect of chip thickness, rake angle, and edge radius on cutting forces and chip morphology in wood plastic composites (WPCs) orthogonal cutting was investigated. Three types of WPCs, Wood flour/polyethylene composite (WFPEC), wood flour/polypropylene composite (WFPPC), and wood flour/polyvinyl chloride composite (WFPVCC), that were tested exhibited different behavior with respect to the machinability aspects. The cutting forces of WFPVCC were the highest, followed by WFPPC and WFPEC. The most significant factor on the parallel cutting force of these three types of WPCs was the chip thickness, which explained more than 90%, contribution of total variation, while rake angle, edge radius, and the interactions between these factors had small contributions. The most significant factor on the normal cutting force of WPCs was also the chip thickness, which accounted for more than 60% of the total variation. The chips produced included long continuous chips, short continuous chips, flake chips, and granule chips when cutting these three types of WPCs. PDF
The strength of the adhesion between the paper and the drying Yankee cylinder is of great importance with respect to the final properties of a tissue paper product. Therefore, the effects of a few potentially important pulp properties have been evaluated in laboratory experiments. Four highly different kraft pulps were used, and the adhesion strength was measured by means of the force required when scraping off a paper from a metal surface with a specifically designed knife mounted on a moving cart. The adhesion strength was observed to increase with increasing grammage and increasing degree of beating of the pulp. It was also found that pulps containing more fines, or with higher hemicellulose content, gave rise to higher adhesion strength. PDF
Fibrillation of chemical and mechanical pulps with different lignin contents was studied. The pulps were ion exchanged into their sodium form prior to fibrillation and fibrillated with an increasing level of energy using high-shear friction grinding. The fibrillated samples were characterized for their chemical composition, morphology, rheological properties, and water retention capacity. All pulps had a distinct tendency to form fibrillated material under high shear and compression. The lignin-containing kraft pulps fibrillated easily, and the resulting material can be utilized in applications where high viscosity, water retention capacity, and reinforcement are desired. Fibrillation of mechanical pulps resulted in more heterogeneous samples, which included fiber fragments, branched fibrillar structures, and flake-like particles. This material showed relatively low viscosity and water retention capacity when compared to the samples made from kraft pulps. Chemi-thermomechanical pulp (CTMP), when used as the raw material, yielded a more homogeneous organic filler-like material than did thermomechanical pulp (TMP). PDF
Zaaba, N. F., Ismail, H., and Jaafar, M. (2014). "The effects of modifying peanut shell powder with polyvinyl alcohol on the properties of recycled polypropylene and peanut shell powder composites," BioRes. 9(2), 2128-2142.
The effects of the chemical modification of peanut shell powder (PSP) using polyvinyl alcohol (PVOH) were studied. Both modified and unmodified peanut shell powder were used to prepare recycled polypropylene (RPP) and PSP composites. The effects of various PSP loadings (0 to 40% by weight) on the processing, tensile properties, morphology, Fourier transform infrared (FTIR) spectra, and water uptake properties were examined. Results showed that RPP composites with polyvinyl alcohol-modified PSP had higher values of tensile strength, elongation at break, and tensile modulus, but lower water resistance, than RPP composites with unmodified PSP. FTIR analysis revealed slight changes in band positions and intensities, indicating a distinct interaction between hydroxyl groups of the PSP composites and PVOH. RPP composites with PSP modified with PVOH had better interfacial adhesion between the matrix and the filler than RPP composites with unmodified PSP, as shown by scanning electron microscope (SEM) micrographs. PDF
To demonstrate the feasibility of bioaugmentation in enhancement of the biodegradation of pulping effluent, aerobic sludge was intensified with superior mixed flora. The differences between intensified aerobic activated sludge and original sludge were compared. The results showed that the chemical oxygen demand (COD) of pulping effluent treated with the intensified sludge dropped to a much lower level compared with the original sludge, which indicated that the biodegradability of sludge was enhanced by bioaugmentation. The growth kinetics of the sludges were established. The growth rate Vmax of the intensified sludge was elevated from 7.8×10-3 to 7.1×10-3, while the saturation constant Ks decreased from 0.33 to 0.21 after bioaugmentation. In addition, the degradation kinetics showed that the equation coefficient of sludge increased from 4.6×10-3 to 6.4×10-3, confirming the intensification of biodegradation as a result of bioaugmentation. PDF
In this work, the thermomechanical pulp of Pinus massoniana was pretreated with a NaOH/thiourea/urea aqueous solution to promote fiber bonded area and to increase paper strength. The effects of pulp concentration, alkali dosage, dipping time, and freezing time were evaluated through single factor experiments. The optimum conditions were found to be 15% pulp consistency, 8% NaOH, a dipping time of 15 min, and a freezing time of 60 min. Under these conditions, the paper tensile and burst index of treated pulp increased nearly 100%, and the bulk also was reduced by 10%, but there were no significant effects on folding. PDF
Cellulose was extracted from kenaf core powder by a series of bleaching processes and subsequently dissolved using an alkaline LiOH/urea solvent at low temperatures. The produced cellulose solution was mixed with polyvinyl alcohol (PVA) with different ratios of cellulose/PVA and coagulated to produce regenerated transparent films. The films were then air dried to produce transparent film. The effects of PVA content on tensile index, transparency, pore size, and printability of the films were studied. A slight reduction of 7% on the tensile index of the film was observed when the content of PVA increased to 10%. Nevertheless, the addition of 10% of PVA increased the porosity of the regenerated cellulose/PVA film, while the transparency of the film increased by 10%. The films were color-printed using a laser printer and can be recycled, in which the printed ink can be removed easily from the films with higher amount of PVA content. In addition, the films can be reprinted repeatedly several times. PDF
Two tropical biomass species, teak (Tectona grandis) and obobo (Guarea thompsonii), were obtained in the form of sawmill waste from Nigeria and evaluated to determine their potential for gasification. Pyrolysis and gasification kinetics of the samples were investigated using a thermogravimetric analyser (TGA) at temperatures of 900 ºC and 1,000 ºC. Four iso-conversional methods, one peak temperature method, and two model-fitting methods were employed to determine the kinetic parameters, i.e. the apparent activation energy Ea, and pre-exponential factor A. Values of the gasification kinetic rate constant K were determined using two gas-solid reaction models: the volumetric reaction model (VRM) and the shrinking core model (SCM). The values obtained for all three kinetic parameters showed good agreement with values derived for samples of non-tropical wood. PDF
Li, H., Liu, J., Wu, J., Xue, Y., Gan, L., and Long, M. (2014). "Comparative analysis of enzymatic hydrolysis of Miscanthus xylan using Aspergillus niger, Hypocrea orientalis, and Trichoderma reesei xylan-degrading enzymes," BioRes. 9(2), 2191-2202.
Xylan-degrading enzymes from Aspergillus niger and Hypocrea orientalis were characterized by enzyme activity assays and protein profiling with SDS-PAGE and LC-MS/MS. The hydrolysis of Miscanthus xylan by xylan-degrading enzymes from A. niger, H. orientalis, and Trichoderma reesei were comparatively studied by HPLC analysis. It was found that the glycoside hydrolase families 10 xylanase was the main xylanase secreted by H. orientalis and A. niger when using corn cob and wheat bran as inducers. Compared to the enzymes from T. reesei,the enzymes from A. niger showed better efficiency in the hydrolysis of Miscanthus xylan into monosaccharides. Nevertheless, the enzymes from H. orientalis were more preferable for the hydrolysis of Miscanthus xylan into xylo-oligosaccharides (XOS), especially xylobiose and xylotriose. Miscanthus xylan degradation was significantly influenced by the activities of β-xylosidase and α-L-arabinofuranosidase. Xylan-degrading enzymes with high ratios of β-xylosidase and α-L-arabinofuranosidase are necessary for the efficient conversion of Miscanthus xylan into monosaccharides. However, xylan-degrading enzymes with low β-xylosidase activity and high α-L-arabinofuranosidase activity were required for producing XOS. PDF
Ring width represents the total width of cells in a growing season. Relatively few studies have identified which of the parameters, cell number, size, or wall thickness is the greater contributor to variations in ring width. It is difficult to clearly explain the relationship between the climate in which a tree is located and the ring growth. In this study, the ring width and various tracheid characteristics (radial lumen diameter, double wall thickness, and number) in 298 rings of Picea crassifolia wood were investigated. Tree rings were quantitatively categorized based on their width into large, medium, and narrow classes. The tracheid number and lumen diameter were strongly correlated with annual ring width. The tracheid number had the strongest effect on the ring width. The effect of the tracheid number was three times larger than that of the lumen diameter. More earlywood cells were formed in larger rings, while larger earlywood cells were produced in years when narrow rings were formed. Wall thickness had no appreciable effect on ring width. The results of this study help to understand the relationship between the climate and the ring growth from the tree physiology perspective, when ring width is used as a climate proxy. PDF
Changes in longitudinal stress wave velocity measured during the drying process of Cathay poplar (Populus cathayana) wood at different moisture contents were investigated. The test was performed at five different positions from bark to pith on each part. Five bars, cut successively from bark to pith with different fiber proportions, were also tested. The corrected velocity was calculated by dividing the velocity by the fiber proportion to negate any possible effects of wood structure on the velocity. The results showed that the longitudinal stress wave velocity decreased with increasing moisture content. Such trends were more obvious when the moisture content was lower than the fiber saturation point (FSP). The longitudinal stress wave velocity increased with increasing fiber proportion. A linear relationship between the corrected velocity and the moisture content was observed. This linear relationship was similar to the relationship between the relative velocity and the moisture content. PDF
Si, C.-L., Wu, L., Shen, T., Huang, X.-F., Du, Z.-G., Ren, X.-D., Luo, X.-G., and Hu, W.-C. (2014). "Recovery of low-molecular weight galloyltannins from agricultural residue of Juglans sigillata dode seed husks and their tyrosinase inhibitory effect," BioRes. 9(2), 2226-2236.
The phytochemical investigation, including fractionation and purification of 70% acetone extracts of Juglans sigillata seed husks, an agricultural residue, led to the isolation of five low-molecular weight galloyltannins. The structures of the extractives were elucidated as 1,2,6-tri-O-galloyl-β-D-glucose (1), 3,4,6-tri-O-galloyl-β-D-glucose (2), 2,3,4,6-tetra-O-galloyl-β-D-glucose (3), 1,2,3,4,6-penta-O-galloyl-β-D-glucose (4), and tannic acid (5), primarily based on their spectral (NMR and MS) and chemical evidence. Galloyltannins 1-5 showed strong inhibitory activity against mushroom tyrosinase, with IC50 values ranging from 35.27 to 76.37 μM; kojic acid, which was used as a positive control, had an IC50 value of 342.14 μM. It was further found that 1-5 inhibited melanin production and exhibited intracellular tyrosinase activity, as well as down-regulated mRNA and protein expression levels of tyrosinase, in B16F10 mouse melanoma cells. Therefore, the isolated extractives from seed husks of J. sigillata may serve as potential candidates for hyperpigmentation remediation and as skin-whitening agents in the cosmetics industry. PDF
Activated carbon fiber is known as an excellent adsorbent material due to its well-developed pore structure. In this work, the porosity evolution of activated carbon fiber prepared from phenol liquefied wood with water steam activation at 650 to 800 °C for 20 to 260 min was examined by physical adsorption of N2 at -196 °C. By the series of activation processes, the specific surface area and pore volume were increased with the increase of activation time, most significantly by activation at 750 °C for 20 to 180 min and by activation at 800 °C for 20 to 260 min. The microporosity was gently and progressively developed with increasing activation time at 650 to 700 °C, while it was sharply developed at the early stage of activations at 750 to 800 °C, and then tended to almost stabilize. The mesoporosity was well developed only by activation at 800 °C for longer than 100 min. The pore size distributions were principally ultramicropores (0.5 - 0.7 nm) during activations at 650 to 700 °C. By activations at 750 to 800 °C, the supermicropores (0.7 to 2.0 nm) as well as mesopores (2 to 4 nm) became progressively more important as the activation time was increased. PDF
Liu, L., Wang, L., Yin, L., Song, W., Yu, J., and Liu, Y. (2014). "Effects of different solvents on the surface acidic oxygen-containing functional groups on Xanthoceras sorbifolia shell," BioRes. 9(2), 2248-2258.
This study reports the preparation of a novel biomaterial from a forestry residue - Xanthoceras sorbifolia shell (XSS) - by solvent modification. The effects of acid and base (hydrochloric acerbic, acetic acid, sodium hydroxide, ammonia water) and some organic solvents (ethanol, acetone, ethyl acetate, chloroform, petroleum ether, and n-hexane) on the surface acidic functional groups (SAFGs) on XSS were investigated. The amount of SAFGs was quantified using acid and alkali chemical titration methods, and the characteristics of virgin XSS were compared with treated ones by FT-IR spectroscopy. It was found that acid solutions can increase the concentration of SAFGs, while alkaline solutions reduce it. The XSS treated in 0.5 M HCl has the largest number of total acidic functional groups and phenolic hydroxyl groups. The shell extracted with 2 M acetic acid has the highest concentration of carboxyl. The SAFG contents were remarkably increased by treatments with ethanol and acetone, due to the outstanding enhancement of phenolic hydroxyl. These changes in the SAFGs of XSS brought about by treatments with various solutions could be a theoretical foundation for modifying this residue to create a new type of highly efficient absorbent material. PDF
Wu, S., Shen, D., Hu, J., Zhang, H., and Xiao, R. (2014). "Intensive interaction region during co-pyrolysis of lignin and cellulose: Experimental observation and kinetic assessment," BioRes. 9(2). 2259-2273.
Interactions between biomass constituents (cellulose, hemicelluloses, and lignin) under pyrolytic conditions have received more and more attention in recent years. A synthesized sample was prepared through mixing of cellulose and lignin with a mass:mass ratio of 1:1. The cellulose-lignin mixture (C-L-M) was heated from 20 to 800 °C using a thermogravimetric analyzer coupled with a Fourier transform infrared spectrometer (TG-FTIR). The presence of the cellulose-lignin complex was theoretically confirmed by the suggestion of a hydrogen bond network between cellulose- and lignin-related oligomers through the density functional theory (DFT) method. To estimate the strength of the interaction between cellulose and lignin in different regions, correlation coefficients r were employed to nominate three regions: region I (20 to 305 °C), in which lignin and cellulose were pyrolyzed into oligomers without interacting with one another; region II (305 to 432 °C), which was deemed the intensive interaction region, with an r value of about 0.2; and region III (432 to 800 °C), in which the pyrolysis of cellulose ceased and only lignin was further degraded. A kinetic scheme was also proposed to model the co-pyrolysis of cellulose and lignin. PDF
Functionalization of papermaking pulp fibers using inorganic particles was investigated as a novel approach. Different layered double hydroxide (LDH) particles were used in peroxide bleaching of thermomechanical pulp (TMP) and in oxygen bleaching of eucalyptus kraft pulp. LDH particles were also tested as binding sites for optical brightening agents (OBA) that are commonly used in paper production. The surface chemistry of LDH-treated pulps was examined using X-ray photoelectron spectroscopy (XPS) and apparent contact angle with water. Adsorbed LDH was not detected by XPS on the fiber surfaces after the bleaching trials, but it had a clear impact on the processes. LDH particles modified with terephthalate anions decreased the consumption of hydrogen peroxide and increased opacity by 3 units in TMP. Unmodified LDH particles enhanced the selectivity in oxygen delignification of kraft pulp, leading to 10% gain in ISO brightness and reduction of 2 units in Kappa number in comparison with conventional processes. Paper strength properties were unaffected in the presented system. After bleaching with LDH, the amount of anionic groups on pulp surfaces was increased. Also, the retention of OBA onto TMP fibers was improved with modified LDH particles. LDH proved to have great potential for current and prospective applications in pulp and paper manufacture. PDF
The in situ imaging nanoindentation technique was used to investigate the effect of age, culm height, and radial position on the cell wall mechanical properties of bamboo (Dendrocalamus farinosus) along the longitudinal direction of culms. The results indicated that among our four-sampled culm ages, the fiber cell wall had average values for the elastic modulus (MOE) and hardness (HL) of 18.56 GPa and 410.72 MPa, respectively. The ages of the culm had no significant effect on the observed MOE and HL among the 2-, 3-, 4-, and 5-year-old D. farinosus test specimens, with similar results observed at three different culm heights and radial positions. Furthermore, longitudinal MOE and HL values along the thickness of the cell wall were uneven, with average values for the middle lamella and the edge near the cavity only 20.97% to 29.78% and 9.22% to 31.71%, respectively, of the values found in the cell wall. PDF
Zhang, Z., Yue, J., Zhou, X., Jing, Y., Jiang, D., and Zhang, Q. (2014). "Photo-fermentative bio-hydrogen production from agricultural residue enzymatic hydrolyzate and the enzyme reuse," BioRes. 9(2), 2299-2310.
Reducing sugars contained in agricultural residue hydrolyzates can potentially be utilized in microbial fermentations to produce biofuels and biogas. Different types of agricultural residues were employed for photo-fermentative bio-hydrogen production, and the cumulative hydrogen production data fit well to the Modified Gompertz Model. Corncob was determined to have the highest reducing sugar yield and cumulative hydrogen production (12.64 mg mL-1 enzymatic hydrolysate, 228.94 mmol L-1) and maximum hydrogen production rate (5.9677 mmol L-1 h-1). Enzyme reuse was investigated by single factor experiment design to reduce the cost of bio-hydrogen production. Taking reducing sugar yield and activity recovery efficiency as reference, substrate re-adsorption method at different temperature and time, then enzyme immobilization method at different load and pH were investigated in the process of enzymatic hydrolysis. The efficiency of enzyme utilization was enhanced via substrate re-adsorption and enzyme immobilization methods, which resulted in a 4-fold increase in recycling efficiency. The optimal enzyme reuse condition by substrate re-adsorption was a re-adsorption time of 90 min at a temperature of 15 °C, while the optimal condition by enzyme immobilization method was a pH of 4.8 and immobilized enzyme load of 400 mg. PDF
The aim of this study was to eliminate the problems of hardness, gloss, and color change of some wood materials exposed to weathering conditions using a bleaching procedure to attempt to return the wood material to its natural state. For this, wood samples of Scots pine (Pinus sylvestris L.), Eastern beech (Fagus orientalis L.), sessile oak (Quercus petraea L.),and chestnut (Castanea sativa Mill.) were exposed to weathering conditions based on 12 months ASTM D-1641, followed by a bleaching procedure using 18% solutions of S1 (NaOH + H2O2), S2 (NaOH + Ca(OH)2), S3 (KMnO4 + NaHSO3 + H2O2), S4 (NaSiO3 + H2O2), and the commercial product S5 (Cuprinol Decking Restorer- (H2C2O4 + C2H4(OH)2). The color, gloss, and hardness changes of samples were determined according to ASTM D 2244-2, EN ISO 2813, and ASTM D 2240 standards. As a result, hardness and gloss values of all woods decreased due to weathering conditions and the wood color turned grey due to degradation. When comparing the weathered samples to the bleached samples, the hardness value was found to be highest in pine wood bleached with the S2 solution, and the gloss value was highest in oak wood bleached with the S1 solution. The greatest color change was found in pine, beech, and chestnut samples bleached with the S4 solution and in oak samples bleached with the S1 solution. PDF
In this study, the electromagnetic (EM) performance of rice husk ash (RHA) calcined from rice husk was evaluated. Porous RHA with a bulk density of 0.4 g cm-3 is mainly composed of carbon and silica. The degrees of surface melting and destruction of porous structure increase with ashing temperature, while a nitrogen atmosphere retards surface melting and destruction because of the retention of carbon. A temperature of 700 °C is the lower limit for achieving significant surface melting, whereas 800 °C in air will destroy the porous structure and conductive network formed by surface melting. All RHA samples showed low permeability values caused by the absence of magnetic components. Sufficient conductive carbon and the formation of conductive networks are prerequisites for reasonable complex permittivity values. The calculated EM wave absorption of RHA achieved a maximum reflection loss (RL) of −21 dB at 2 to 18 GHz, including 5 GHz with an RL < −10 dB, which is above the average of traditional absorbers. This study reveals a new approach for fabricating an EM wave (microwave) absorber with low density and strong absorption by using agricultural wastes as starting materials. PDF
Hernández-Domínguez, E. M., Rios-Latorre, R. A., Álvarez-Cervantes, J., Loera-Corral, O., Román-Gutiérrez, A. D., Díaz-Godínez, G., and Mercado-Flores, Y. (2014). "Xylanases, cellulases, and acid protease produced by Stenocarpella maydis grown in solid-state and submerged fermentation," BioRes. 9(2), 2341-2358.
Activity levels of extracellular hydrolytic enzymes produced by Stenocarpella maydis, a fungal pathogen of maize, have so far not been reported. Production of xylanase, cellulase, and acid protease by this ascomycete using different culture media in solid-state and submerged fermentation was studied. In solid-state fermentation, polyurethane foam was used as an inert support, and corncob, corn leaves, and broken corn were used as biodegradable supports. The highest xylanase activity was produced in the medium with xylan in both fermentation systems, reaching 18,020 U/L and 19,266 U/L for submerged and solid-state fermentation, respectively. Cellulase production was observed only in the culture medium with carboxymethylcellulose, obtaining values of 7,872 U/L in submerged fermentation and 9,439 U/L in solid-state fermentation. The acid protease was produced only in minimal medium with glucose in acidic pH, reaching the highest levels of activity in SSF (806 U/L). The corncob was the best biodegradable support for the production of xylanases and acid protease. Two isoenzymes of xylanase and cellulase were observed in both fermentation systems, and three isoenzymes of xylanase were produced on the biodegradable supports. PDF
Duong, L. D., Nam, G.-Y., Oh, J.-S., Park, I.-K., Luong, N. D., Yoon, H.-K., Lee, S.-H., Lee, Y., Yun, J.-H., Lee, C.-G., Hwang, S.-H., and Nam, J.-D. (2014). "High molecular-weight thermoplastic polymerization of kraft lignin macromers with diisocyanate," BioRes. 9(2), 2359-2371.
A high molecular-weight thermoplastic lignin-based polymer was successfully synthesized by adjusting the degree of polymerization while inducing linear growth of lignin macromers via methylene diphenyldiisocyanate. The thermoplastic lignin-urethane polymer was desirably achieved in a narrow range of reaction conditions of 2.5 to 3.5 h at 80 °C in this study, and the molecular weight of the resulting lignin-based polyurethanes (LigPU) reached as high as 912,000 g/mole, which is far above any reported values of lignin-based polymer derivatives. The thermal stability of LigPU was greatly improved by the urethane polymerization, giving the initial degradation temperature (T2%) at 204 °C, which should be compared with T2% = 104 °C of the pristine lignin. This was due to the fact that the OH groups in the lignin macromers, having low bond-dissociation energy, were replaced by the urethane bonds. In dielectric analysis, the synthesized LigPU exhibited a softening transition at 175 °C corresponding to a combinatorial dual process of the dry Tg,dry of the lignin macromers and the softening of methylenediphenyl urethane chains. This work clearly demonstrated that a high molecular weight of thermoplastic LigPU could be desirably synthesized, broadening the lignin application for value added and eco-friendly products through common melt processes of polymer blend or composites. PDF
Nayeri, M. D., Tahir, P. M., Jawaid, M., Ashaari, Z., Abdullah, L. C., Bakar, E. S., and Namvar, F. (2014). "Medium density fibreboard made from kenaf (Hibiscus cannabinus L.) stem: Effect of thermo-mechanical refining and resin content," BioRes. 9(2), 2372-2381.
The present study deals with the physical and mechanical properties of dry-formed medium density fibreboard (MDF) made from renewable biomass kenaf (Hibiscus cannabinus L.) stem as a function of adhesive level and refining conditions. Raw material was prepared by heating for 5 min at pressure levels of 6 and 8 bars. Experimental samples with a target density of 700 kgm-3 were produced with 10, 12, or 14% urea formaldehyde as a binder. Physical properties of MDF panels, such as thickness swelling (TS) and water absorption (WA) as well as mechanical properties including modulus of rupture (MOR), modulus of elasticity (MOE), and internal bonding (IB), were evaluated. Based on the test results, resin content and refining pressure have significant effects on the physical and mechanical properties of MDF panels. High resin content and pressure produced MDF boards with low WA and TS but high MOR, MOE, and IB. At 8 bars pressure and 14% resin content, the MDF recorded optimum WA (83.12%), TS (20.2%), MOR (25.3 MPa), MOE (3450 MPa), and IB (0.51 MPa). PDF
Salem, M. Z. M., Abdel-Megeed, A., and Ali, H. M. (2014). "Stem wood and bark extracts of Delonix regia (Boj. Ex. Hook): Chemical analysis and antibacterial, antifungal, and antioxidant properties," BioRes. 9(2), 2382-2395.
In the present study, the fatty acid components of the wood, bark, and essential oil of wood from Delonix regia as well as its antibacterial, antifungal, and antioxidant properties were investigated for the potential ability to control plant and human pathogens. Myristic acid was found to be a major fatty acid in the wood and bark of Delonix regia, comprising 10.77% of wood and 9.63% of bark. According to the GC-MS results, naphthalene derivatives were detected in the essential oils from the wood samples. Heptadecane and acyclic hydrocarbons were found in a high percentage (14.05%). Methanol: chloroform (1:1 v/v) wood extract showed effective activity against Bacillus subtilis, Sarcina lutea, and Staphylococcus aureus, where the bark extract was most active against Escherichia coli. The essential oil showed good antibacterial activity against Pectobacterium carotovorum. The bark extract showed the maximum percentage inhibition of fungal mycelial growth against Penicillium selerotigenum (70.37%) and Paecilomyces variotii (77.78%), and the essential oil showed moderate inhibition against Aspergillus nigra (44.44%). The total antioxidant activity of essential oil, stem wood, and stem bark extract was 84.34%, 80.33%, and 70.21%, respectively. PDF
TiO2-treated acacia hybrid (Acacia mangium x auriculiformis) wood was fabricated by combined pressure-impregnation and hydrothermal post-treatment. The wettability and microstructure morphology, as well as the crystalline structure of the titanium dioxide (TiO2) gels of the TiO2-treated wood, were studied. Contact angle measurements of the blank wood and the TiO2-treated wood indicated a significant increase in hydrophobicity, with contact angles of above 150° in treated samples. Furthermore, the water-resistant property of the treated wood was quite stable, even after immersion in boiling water. Field emission scanning electron microscopy (FE-SEM) results showed that the microstructure morphology and the size of TiO2 gels on the wood surface were dependent on the pH of the post-treatment solutions. Additionally, the presence of amorphous TiO2 gels was indicated by X-ray diffraction (XRD) analysis. The results of this study indicate that combined pressure-impregnation and hydrothermal post-treatment can create a hydrophobic wood-TiO2 composite. PDF
Min, D.-Y., Chang, H.-M., Jameel, H., Lucia, L., Wang, Z.-G., and Jin, Y.-C. (2014). "The structure of lignin of corn stover and its changes induced by mild sodium hydroxide treatment," BioRes. 9(2), 2405-2414.
Corn stover is an abundant feedstock in the US that can be used for second generation bioethanol production. However, there is little useful data on structure of the lignin of corn stover. The following principal tasks will be addressed to profile the structure of corn stover: (1) separation of corn stover into stem, cob, and leaf; (2) isolation of cellulolytic enzyme lignins (CEL) from extractive-free and the alkali-treated fractions; (3) quantification of p-coumarate and ferulate of fractions by HPLC. The results of alkaline nitrobenzene oxidation and 1H-13C HSQC NMR indicated: (1) the structure of lignin varied in the fractions; (2) a remarkable amount of p-coumarate and ferulate was identified and determined; (3) the remarkable structural changes of lignin induced by alkaline treatment were elucidated. PDF
An ultra-low density fiberboard was made of plant fiber using a liquid frothing approach. The inflammability of the plant fiber limited its application as a candidate for building insulation materials and packaging buffering materials. Si-Al compounds were introduced into the foaming system because of the high temperature resistance of Si and Al compounds. The results from energy-dispersive spectroscopy suggested that the Si and Al relatively evenly covered the surface of the fibers, and their weight ratios in the material increased as a function of the amount of Si-Al compounds. The increasing weight ratios of Si and Al affected the fire properties of the material, reducing the released amount of heat, smoke, and off-gases such as CO and CO2, as well as decreasing the mass loss percentage, shown through the use of a Cone Calorimeter. It follows that Si-Al compounds have an evident collaborative effect on the halogen fire retardant. The system can effectively restrain the fire hazard intensity and the yields of solid and gas volatiles. PDF
The present work used a combined approach of oleic acid (OA) impregnation and thermal modification to improve the hydrophobicity and dimensional stability of southern pine (Pinus spp.). The wood samples were first treated with OA at a concentration of 5 or 10%, and then underwent thermal modification at 160, 180, or 200 °C. Thereafter, the water-related properties of modified wood including water absorption (WA), equilibrium moisture content (EMC), and volumetric swelling (VS) were investigated. Alterations in cell wall structure and chemical components were analyzed by scanning electron microscopy (SEM) and Fourier transform infrared spectroscopy (FTIR), based on the mechanisms discussed. While the results showed that both OA-treatment and thermal modification can each improve the water repellency and dimensional stability of wood, the combined system proved to be more effective. The synergistic increase of water-related properties was assumed to be caused by OA increasing the hydrophobicity of thermally modified wood as well as accelerating the decomposition of hydrophilic wood components during thermal modification. This assumption was supported by both SEM and FTIR results. Therefore, this research provides an approach for improving the accessibility to the energy-efficient thermal modification. PDF
Currently, marine protein byproducts are mainly hydrolyzed and prepared for applications that depend on their physiological activity. Such uses require strict removal of heavy metal ions from the material. In this work, a green approach was proposed using peanut shells as adsorbent to remove Pb(II) from solutions containing amino acid and sodium chloride. The effects of amino acids and sodium chloride on the removal of Pb(II), as well as the influence of liquid to solid ratio, pH, temperature, and contact time on the adsorption, were studied. The results showed that the content of sodium chloride and amino acid could significantly decrease the adsorption efficiency for Pb(II). The experimental data could be described with the Langmuir adsorption isotherm model and pseudo-second order kinetic model. The adsorption capacity of the sorbent for Pb(II) was calculated from the Langmuir isotherm model and found to be 7.1 mg g-1 at pH 4. PDF
Chiranjeevi, P. V., Pandian, M. R., and Sathish, T. (2014). "Integration of artificial neural network modeling and genetic algorithm approach for enrichment of laccase production in solid state fermentation by Pleurotus ostreatus," BioRes. 9(2), 2459-2470.
Black gram husk was used as a solid substrate for laccase production by Pleurotus ostreatus, and various fermentation conditions were optimized based on an artificial intelligence method. A total of six parameters, i.e., temperature, inoculum concentration, moisture content, CuSO4, glucose, and peptone concentrations, were optimized. A total of 50 experiments were conducted, and the obtained data were modeled by a hybrid of artificial neural network (ANN) and genetic algorithm (GA) approaches. ANN was employed to model the experimental data, and the predicted values were further optimized by GA. Employment of ANN–GA hybrid methodology resulted in a significant improvement, as approximately two-fold laccase production (4244 U/gds) was achieved. PDF
Chimtong, S., Tachaapaikoon, C., Sornyotha, S., Pason, P., Waeonukul, R., Kosugi, A., and Ratanakhanokchai, K. (2014). "Symbiotic behavior during co-culturing of Clostridium thermocellum NKP-2 and Thermoanaerobacterium thermosaccharolyticum NOI-1 on corn hull," BioRes. 9(2), 2471-2483.
The symbiosis of co-culturing between Clostridium thermocellum NKP-2 and Thermoanaerobacterium thermosaccharolyticum NOI-1 is described. An efficient biomass-degrading enriched culture was isolated from soil that contained two different bacterial strains showing homology to C. thermocellum and T. thermosaccharolyticum. The enzymatic system produced from the isolated strains when cultivated individually on corn hulls demonstrated different cellulolytic and xylanolytic enzyme activities. Strain NKP-2 produced cellulose- and xylan-main chain cleaving enzymes such as carboxymethylcellulase (CMCase), avicelase, and xylanase as major enzymes, whereas strain NOI-1 produced primarily short- and side-chain cleaving enzymes such as cellobiohydrolase, β-glucosidase, β-xylosidase, acetyl esterase, and especially α-L-arabinofuranosidase. Enhancement of corn hull utilization, cell growth, and fermentation products (ethanol, butanol, acetic acid, butyric acid, H2, and CO2) was greatly increased during co-culturing compared with individual cultivation of both strains. The symbiotic behavior between both strains was one of mutualism, in which the synergistic degradation of corn hulls by co-action of cellulolytic and xylanolytic enzymes promoted hydrolysis of biomass for growth and fermented products. PDF
Zhang, Y., and Luo, W. (2014). "Adsorptive removal of heavy metal from acidic wastewater with biochar produced from anaerobically digested residues: Kinetics and surface complexation modeling," BioRes. 9(2), 2484-2499.
In this study, the adsorptive characteristics of biochar generated from anaerobically digested garden wastes (AD-char) were investigated. Metal adsorption onto AD-chars reached equilibrium in 48 h; the adsorption capacity of Cu2+ by AD-char was 182 μmol g-1, which was higher than that of Zn2+ (35.3 μmol g-1) and Mn2+ (60.7 μmol g-1). The metal adsorption was well described by the pseudo second-order kinetic and Langmuir isotherm models. pKinta1, pKinta2, and pkCu for AD-char, which described surface protonation reactions and complexation with Cu2+, were 5.75, -10.20, and -4.70, respectively, as optimized by the surface complexation model. Cu2+ adsorption onto AD-char increased with increasing pH to < 8.6, which suggests that the presence of surface alkaline functional groups can be attributed to the metal adsorption capacity of biochar. This study concluded that converting anaerobically digested food and garden wastes into biochar could be an efficient method of treating municipal solid waste and producing metal adsorbents for environmental remediation. PDF
Zhang, H., Pizzi, A., Lu, X., and Zhou, X. (2014). "Optimization of tensile shear strength of linear mechanically welded outer-to-inner flattened moso bamboo (Phyllostachys pubescens)," BioRes. 9(2), 2500-2508.
Mechanical welding technology has been widely employed in the making of bonding joints with wood. Moso bamboo, a lignocellulosic biomaterial, can also be bonded using mechanical welding technology. The surface response methodology was used to define welding parameters yielding optimal joint strength. In the range of this experiment, it was found that the vibration amplitude and the welding pressure both had a significant influence on the performance of the joint, while the welding time did not. The quadratic model was able to significantly fit the actual results and could be used to determine and optimize the bonding strength. PDF
Field and laboratory experiments were conducted to evaluate the feasibility of bioethanol production using the juice of sugarcane grown in heavy metal-contaminated soils. The results suggest that the sugar concentration was not adversely affected when the sugarcane was grown in the heavy metal-contaminated soil. Although the juice of sugarcane grown in contaminated soil contained elevated levels of heavy metals, sugar fermentation and ethanol production were not adversely affected when five selected yeast species were used to mediate the processes. The preliminary research findings obtained from this study have implications for developing cost-effective technologies for simultaneous bioethanol production and soil clean-up using heavy metal-contaminated soils for energy sugarcane farming. PDF
Yang, Z., Zhang, M., Pang, X., Lv, B. (2014). "Classifications of decorative paper using different reflection spectrophotometry coupled with soft independent modeling of class analogy," BioRes. 9(2), 2521-2528.
With the rapid development of the decorative papers industry on a worldwide scale, the aesthetic assessment of decorative papers has evolved as one of the major fields for industrial production. This study was performed to investigate the ability of visible spectroscopy and NIR spectroscopy coupled with the soft independent modeling of class analogy (SIMCA) to reflect the surface characteristics of decorative paper and to classify decorative papers with different visual characteristics. The results showed that visible spectroscopy has a higher relationship with the surface characteristics of decorative papers than the NIR data during PCA analysis due to larger variations. Additionally, when using visible spectroscopy (400 to 780 nm), the classification accuracy reached 94% to 100%, a more accurate result than could be achieved based on color data. In the results of the NIR spectroscopy (780 to 2500 nm), the classification accuracy decreased to the range 1% to 56%, except for a value of 95% for the samples that were grained with a slightly dark color, and a greater number of samples were assigned to more than one class. There were significant differences in the performance of the models built with visible spectroscopy and NIR spectroscopy, so it can be concluded that visible spectroscopy coupled with SIMCA is more useful to classify the different types of decorative papers than NIR spectroscopy. PDF
In this work, the effect of particle size on the enzymatic hydrolysis of milled and sieved sugarcane bagasse (SCB) was studied. The enzymatic hydrolysis and fermentability of superfine ground SCB (SGP400) using an enzyme cocktail strategy were also explored. Particle size reduction improved the enzymatic hydrolysis. The highest glucose yield was 44.75%, which was obtained from SGP400. The enzyme cocktail strategy greatly enhanced the glucose and xylose yield. The maximum glucose and xylose yield was from the enzyme cocktail of cellulase, xylanase, and pectinase. Synergistic action between xylanase and pectinase as well as cellulase and pectinase was quite noticeable. Hydrolysis times affected the degree of synergism. Ethanol production was carried out by employing simultaneous saccharification and fermentation (SSF) and semi-SSF using enzymes and their cocktails. Semi-SSF was found to be the better one compared with SSF. Xylanase and pectinase aided the ethanol production in both fermentation modes. Ethanol yield was 7.81 and 7.30 g/L for semi-SSF and SSF, respectively by using an enzyme cocktail of cellulase, β-glucosidase, pectinase, and xylanase. PDF
The paper production process is significantly affected by direct and indirect effects of microorganism proliferation. Microorganisms can be introduced in different steps. Some microorganisms find optimum growth conditions and proliferate along the production process, affecting both the end product quality and the production efficiency. The increasing need to reduce water consumption for economic and environmental reasons has led most paper mills to reuse water through increasingly closed cycles, thus exacerbating the bacterial proliferation problem. In this work, microbial communities in a paper mill located in Italy were characterized using both culture-dependent and independent methods. Fingerprinting molecular analysis and 16S rRNA library construction coupled with bacterial isolation were performed. Results highlighted that the bacterial community composition was spatially homogeneous along the whole process, while it was slightly variable over time. The culture-independent approach confirmed the presence of the main bacterial phyla detected with plate counting, coherently with earlier cultivation studies (Proteobacteria, Bacteroidetes, and Firmicutes), but with a higher genus diversification than previously observed. Some minor bacterial groups, not detectable by cultivation, were also detected in the aqueous phase. Overall, the population dynamics observed with the double approach led us to hypothesize a possible role of suspended bacteria in the re-formation mechanisms of resistant biofilms. PDF
Li, Q., Wang, X.-X., Lin, J.-G., Liu, J., Jiang, M.-S., and Chu, L.-X. (2014). "Chemical composition and antifungal activity of extracts from the xylem of Cinnamomum camphora," BioRes. 9(2), 2560-2571.
Cinnamomum camphora (L.) Presl. is one of the most important hardwood species indigenous to China that possesses signiﬁcant antifungal activity. The chemical composition of the extracts from the xylem parts of C. camphora was examined by various solvent extractions. Thirty different components accounting for 79.8% of the total methanol extracts from the xylem of C. camphora were identiﬁed by gas chromatography-mass (GC/MS) spectrometry. The major chemical components of methanol extracts are camphor (14.3%), α-terpineol (9.9%), and trans-linalool oxide (furanoid) (7.7%). The chemical composition of chloroform extracts are mainly camphor (17.6%), α-terpineol (11.8%), tetradecanal (5.6%), and (-)-g-cadinene (7.4%). The extracts of C. camphora were tested for resistance to two wood-decaying fungus with hyphal growth. All the C. camphora extracts showed some antifungal activity against the test fungus. The 50% effective concentration of chloroform extracts for Coriolus versicolor(C. versicolor) was 7.8 mg/mL, which was highly toxic, followed by acetone extracts. The methanol extracts with 8 mg/mL concentration had the best suppression effect for Gloeophyllum trabeum (G. trabeum) with an EC50 of 0.3 mg/mL. The results indicated that the major components of the extracts had antifungal activities; thus C. camphora could provide a renewable source for wood preservatives. PDF
Zhu, D., Gao, M., Pan, H., Pan, Y., Liu, Y., Li, S., Ge, H., and Fang, N. (2014). "Fabrication and mechanical properties of SiCw(p)/SiC-Si composites by liquid Si infiltration using pyrolysed rice husks and SiC powders as precursors," BioRes. 9(2), 2572-2583.
Dense silicon carbide (SiC) matrix composites with SiC whiskers and particles as reinforcement were prepared by infiltrating molten Si at 1550 °C into porous preforms composed of pyrolysed rice husks (RHs) and extra added SiC powder in different ratios. The Vickers hardness of the composites showed an increase from 18.6 to 21.3 GPa when the amount of SiC added in the preforms was 20% (w/w), and then decreased to 17.3 GPa with the increase of SiC added in the preforms up to 80% (w/w). The values of flexural strength of the composites initially decreased when 20% (w/w) SiC was added in the preform and then increased to 587 MPa when the SiC concentration reached 80% (w/w). The refinement of SiC particle sizes and the improvement of the microstructure in particle distribution of the composites due to the addition of external SiC played an effective role in improving the mechanical properties of the composites. PDF
To explore the collapse of eucalyptus wood cells during the drying process, continuous and intermittent drying were carried out on Eucalyptus urophylla. The shrinkage throughout the intermittent drying process was less than that of continuous drying. According to observations of cells made using scanning electron microscopy (SEM), there was a large difference in the degree of cell collapse between continuous and intermittent drying. Severe cell collapse was observed after freeze-drying at high moisture content, even after an intermittent drying process. It is clear that collapse recovery via intermittent drying was more extensive than in continuous drying. In particular, ray parenchyma and axial parenchyma recovered from collapse more than did wood fibers. PDF
Saffian, H. A., Tahir, P. M., Harun, J., Jawaid, M., Hakeem, K. R. (2014). "Influence of planting density on the fiber morphology and chemical composition of a new latex-timber clone tree of rubberwood (Hevea brasiliensis Muell. Arg.)," BioRes. 9(2), 2593-2608.
In this study, the fiber morphology and chemical constituents of a 4-year-old rubber tree (Hevea brasiliensis Muell. Arg.) from the RRIM 2000 clone series were evaluated. The effects of planting density on the fiber morphology and chemical compositions of the clone of rubber wood were also considered. It is clear that the fibers of the rubber wood samples grown under higher planting density were thicker, with a wider lumen diameter than those grown under lower planting density. There were significant interactions between planting density and the height of the tree from which the samples were taken for all measured fiber properties studied. The chemical composition of the clone of rubber wood was determined as per TAPPI standards. Each of the chemical constituents of the rubber wood displayed statistically significant (at the 95% confidence level) interactions with tree section (low, middle, or high) and planting density. Fiber morphology and chemical composition results showed that juvenile rubber trees could supply fiber to produce particleboard and medium density fiberboard. Compared to mature rubber trees (those more than 25 years old), the studied RRIM 2000 clone rubberwood trees were found to be as compatible for use in the wood industry. PDF
Lignocellulosic biomass is an economical and renewable feedstock for microbial production of bulk chemicals such as lactic acid. In many cases, simultaneous saccharification and fermentation (SSF) can achieve lower cost and higher productivity than the classical double step fermentation. Thus, in the present study, bagasse sulfite pulp was directly employed to produce lactic acid by SSF, using thermophilic Bacillus coagulans strain CC17. The effects of various factors, including CaCO3 addition time and the initial buffered pH, on lactate production were investigated. It was found that Bacillus coagulans strain CC17 could perform well at conditions that are also optimal for fungal cellulase. The addition of CaCO3 as the buffering reagent is critical for the production of lactic acid and maintaining pH. Maximum production of lactic acid was obtained by adding CaCO3 after 3 h fermentation. When pH 7 was used as the initial pH, strain CC17 produced about 20.68 g/L lactic acid from 20 g/L cellulose content of BSP with 15 FPU of Cellulast 1.5L/g cellulose and 15 CBU of Novozyme 188 /g cellulose. The results showed that this strain has potential to be used for direct lactic acid fermentation from lignocellulosic biomass via SSF. PDF
The raw material requirements for the indirect liquefaction of biomass are strict. In particular, the ratio of H2/CO must be greater than or equal to 1. However, traditional biomass gasification has problems that include a low H2/CO ratio and low carbon conversion rates. This study proposes a three-stage gasification optimization model in which pyrolysis products are separated before being put through a second gasification step. The optimized model simulation used MATLAB software and the experiments were carried out in a biomass, high-temperature entrained-flow bed. The results demonstrate that, compared to traditional mixing gasification, three-stage gasification can effectively increase the H2 content in syngas. The H2 content can reach 42.3%, which is 4.6% higher than in traditional gasification. Additionally, this process can increase the H2/CO ratio to 1.23, which is 43% higher than the ratio 0.86 in traditional gasification. This also could provide raw materials for the indirect liquefaction of syngas. Thus, three-stage gasification can eliminate the need for intermediate steps such as steam reforming and adding external H2. Experiments indicated that the best gasification conditions were a first gasification time of 0.6s and a gasification temperature of 1100 °C, under which the H2/CO ratio reached a maximum of 1.2. PDF
A green and efficient process was developed for the conversion of biomass-derived furfuryl alcohol to ethyl levulinate using eco-friendly solid acid catalysts (zeolites and sulfated oxides) in ethanol. Studies for optimizing the reaction conditions such as the substrate concentration, the reaction time, the temperature, and the catalyst loading dosage were performed. With SO42−/TiO2 as the catalyst, a high ethyl levulinate yield of 74.6 mol% was achieved using a catalyst load of 5 wt% at 398 K for 2.0 h. The catalyst recovered through calcination was found to maintain good catalytic activity (47.8 mol%) after three cycles, and it was easily reactivated by re-soaking in H2SO4 solution. Catalyst characterization was based on BET surface area, NH3-TPD, and elemental analysis techniques. PDF
Hydrolysis is a reaction to produce sugars from lignocellulosic raw materials for biochemical production. The present study elucidates the hydrolysis of cellulose and formation of glucose decomposition products catalyzed by 5% to 20% (w/w) formic acid at 180 to 220 °C with an initial cellulose concentration of 10 to 100 g/L. Microcrystalline cellulose was used as a model compound. The experimental findings indicated that cellulose hydrolysis follows first-order kinetics in formic acid. A side reaction from cellulose to non-glucose products was required to explain the experimental results. A kinetic model was developed for the hydrolysis of microcrystalline cellulose in formic acid, based on a rate constant expression in accordance with the specific acid catalysis. The model showed good agreement with the experimental data. This study demonstrates how kinetic parameters can be fitted in a case-specific manner for the hydrolysis part of the kinetic model, while the well-established glucose decomposition model is utilized directly from literature. PDF
Carvalho, A. G., Zanuncio, A. J. V., Mori, F. A., Mendes, R. F., da Silva, M. G., and Mendes, L. M. (2014). "Tannin adhesive from Stryphnodendron adstringens (Mart.) Coville in plywood panels," BioRes. 9(2), 2659-2670.
The aim of this study was to evaluate the technical viability of using tannin adhesives derived from Stryphnodendron adstringens (Mart.) Coville barks in the production of plywood. 0, 25, 50, 75, and 100% tannin-based adhesives (TF) derived from barbatimão barks were combined with commercial phenol-formaldehyde (PF) adhesive. The properties of the adhesives were determined, and plywood was produced. The panels were produced with five crossed layers, an adhesive grammage of 360 g/m² (double line), and an assembly time of 10 min. A pressing cycle at a temperature of 150 °C, specific pressure of 12 kgf/cm², and duration of 10 min was used. With the exception of the parallel modulus of elasticity, panels produced with 25, 50, 75, and 100% barbatimão-derived tannin adhesive met NBR 31:000.05-001/2 standards (ABNT 2001). The tannin barbatimão adhesive proved feasible for use in plywood panels destined for both humid and dry environments. PDF
Fractionation of lignocellulosic biomass is an important process in producing biofuels. In this study, hot water extraction of corn stover hemicellulose was carried out at 150, 160, and 170 °C. Variations of sugar content in the hydrolysate under different holding time were detected. The contents of furfural and 5-hydroxymethyl-2-furaldehyde generated during the extraction were also determined. Results showed that the main composition of the hydrolysate was xylo-oligosaccharide; the yield of oligosaccharides first increased as holding time was prolonged. After extraction at 160 °C for 210 min, 70.2% of the total xylan was dissolved, with the generation of furfural (0.90 g/L) and 5-hydroxymethyl-2-furaldehyde (0.10 g/L). The effects of extraction on alkali pulping and bleaching were also investigated. Results indicated that soda-AQ pulp obtained from the extracted material had poorer tensile and burst strengths but better tear strength. PDF
Kenaf fiber-filled polyurethane foams were prepared using the free rising method. The dielectric constants and the loss tangents of the composites were studied as functions of fiber content (0, 5, 10, and 15 parts per hundred of polyols by weight), temperature (from 30 to 200 °C), and electric field frequency (from 20 Hz to 2 MHz). The dielectric constant and the loss tangent increased with increasing fiber content. The dielectric constant was very high in the range of 101 to 102 Hz and varied little in the range of 103 to 106 Hz, but decreased rapidly above 106 Hz. The loss tangent decreased as the frequency increased. The effect of frequency on the loss tangent value was greater at frequencies below 102 Hz. Higher temperatures led to a higher dielectric constant and loss tangent. When the temperature was above approximately 120 °C, the loss tangent dramatically increased. The incorporation of kenaf fiber can improve the growth rate of the dielectric constant with increasing temperature. The dielectric constant and the loss tangent increased with increasing fiber content, indicating that both the dielectric capability and energy dissipation ability of the composites were improved. PDF
Bamboo-bundle laminated veneer lumber (BLVL) was produced by veneer lengthening technology. The objective of this study was to evaluate the effect of different veneer-joint forms and allocations on the mechanical properties of BLVL. Four veneer-joint forms, i.e., butt joint, lap joint, toe joint, and tape joint, and three lap-joint allocations, i.e., invariable allocation (Type I), staggered allocation (Type II), and uniform allocation (Type III), were investigated in laminates. The results revealed that the mechanical properties of veneer-joint BLVL were reduced in comparison with that of un-jointed BLVL. It was found that the best veneer-joint form was the lap joint laminate, of which the tensile strength, modulus of elasticity, and modulus of rupture values were reduced by 38.41%, 0.66%, and 10.92%, respectively, when compared to the un-jointed control samples. Type III showed the lowest influence on bending and tensile properties, followed by Type II. PDF
This paper presents a new kind of composite produced with small-diameter bamboo (Phyllostachys glauca McClure) and extruded tubular particleboard. The mechanical properties of the composite are significantly affected by the properties of the bamboo. First, the compression strength of the bamboo was studied. It was found that the compression strength (fc, MPa) and the maximum force of compression (Fmax, kN) of the bamboo are strongly, linearly related to its outer diameter (D, mm): fc = -0.5D+79.37 and Fmax = 0.83D–0.59. The compression strength of the composite made with the bottom part of the bamboo was larger than that of composites made with the middle and top parts. In addition, its reliability was also the best of the three groups due to the variation of the outer diameter of the bamboo from the bottom to the top. The bottom part of the bamboo is the best choice for manufacturing bamboo-reinforced extruded particleboard (BREP). PDF
Acorn starch was used for ethanol production by separate hydrolysis and fermentation (SHF) in this study. The influence of tannins on hydrolysis and fermentation was investigated using ultrasonic-assisted extraction (UAE) to decrease the amount of tannin before SHF. The tannin was shown to have a negative role in hydrolysis and fermentation, and UAE can improve the two processes. The tannin content of acorn starch decreased from 6.19% to 1.91% with the UAE pretreatment time of 200 min. When the pretreatment time was 120 min, the glucose concentration increased from 78.08 to 98.76 g/L after 24 h of hydrolysis. The highest ethanol concentration was 42.22 g/L, which was obtained from the same pretreated acorn flour fermented for 12 h. However, the maximum ethanol yield was 88.06% of the theoretical yield, while pretreatment time was 80 min. Scanning electron microscope images indicated that protein was separated from the starch granules by UAE, as well as by the molecular weight of starch which decreased significantly based on the results from gel permeation chromatography (GPC) analysis. PDF
The objective of this work was to prepare a series of composite films (polysaccharides with LaFe0.8Cu0.2O3) for the degradation of methyl orange under ultraviolet irradiation. LaFe0.8Cu0.2O3 was prepared by a sol-gel method, and the composite films were obtained by cross-linking reactions between polysaccharides (xylan and chitosan) and LaFe0.8Cu0.2O3. Physical and chemical properties of the composite films were investigated by XRD, FTIR, SEM, and BET. Moreover, the influence of the weight ratio of polysaccharide to LaFe0.8Cu0.2O3 on the methyl orange degradation reaction was also studied. Results showed that 67% of the degradation efficiency was achieved within 480 min using chitosan/LaFe0.8Cu0.2O3 (2:1) as photocatalysts, while 58% was for xylan/LaFe0.8Cu0.2O3 (1:1). The difference was due to the variety in the structure of chitosan and xylan. PDF
Biomass is a renewable and CO2-neutral source of energy having the drawback of low energy density. The energy density can be augmented by the production of bio-oil through fast pyrolysis. The high content of water-extractable organic acids (oxygenates) in bio-oil is problematic in fuels. Cultivation of Saccharomyces cerevisiae for the consumption of these undesirable components can be used to upgrade the bio-oil. It was found that the bio-oil water phase can support the growth of S. cerevisiae at concentrations up to 20 vol. % under aerobic conditions. The oxygenates formic acid, acetic acid, and propionic acid had a promoting effect for the cultivation of S. cerevisiae in the following order: acetic acid > formic acid > propionic acid. However, phenol, p-cresol, and furfural inhibited the growth of S. cerevisiae. Kinetic analysis of the consumption of oxygenates showed that the regulation of S. cerevisiae was in accordance with a logistic function model. PDF
Wan Razali, W. A., Samsu Baharuddin, A., Zaini, L. A., Mokhtar, M. N., Taip, F. S., and Zakaria, R. (2014). "Effect of seed sludge quality using oil palm empty fruit bunch (OPEFB) bio-char for composting," BioRes. 9(2), 2739-2756.
In this study, a comparison between oil palm empty fruit bunch (OPEFB) composting using palm oil mill effluent bio-char solution (POMEBS) aerobic sludge and palm oil mill effluent (POME) anaerobic sludge was reported. A set of experiments was designed by central composite design (CCD) using response surface methodology (RSM) to statistically evaluate the POMEBS aerobic sludge as microbial seeding. The bacteria count of POMEBS aerobic sludge (3.7×106 CFU/mL) at the optimum point was higher than that of POME anaerobic sludge (2.5×105 CFU/mL). Denaturing gradient gel electrophoresis (DGGE) and Fourier transform infrared spectroscopy (FTIR) were also performed. A rotary drum composter was then used to compost OPEFB with POMEBS aerobic sludge and POME anaerobic sludge, separately. Thermogravimetric analysis (TGA) showed that composting OPEFB with POMEBS aerobic sludge had a higher degradation rate compared to composting OPEFB with POME anaerobic sludge. In addition, the final N:P:K values for composting OPEFB with POMEBS aerobic and POME anaerobic sludge were 3.7:0.8:6.2 and 1.5:0.3:3.4, respectively. POMEBS aerobic sludge improved the composting process and compost quality. PDF
Li, B., Liu, H., Xu, H., Pang, B., Mou, H., Wang, H., and Mu, X. (2014). "Characterization of the detailed relationships of the key variables in the process of the alkaline sulfite pretreatment of corn stover by multivariate analysis," BioRes. 9(2), 2757-2771.
In biomass pretreatment processes, both the properties of feedstock and process parameters play important roles in the yield of downstream enzymatic hydrolysis. More importantly, like many other industrial processes, the pretreatment system is multivariate and the variables in the system are inter-related to different extents, which means that studying the relationships of the key variables is of critical importance for the improvement of downstream enzymatic saccharification yield. In this work, two multivariate analysis methods of the Principal Component Analysis (PCA) and Partial Least Square (PLS) were employed to characterize the detailed relationships of the key process variables of alkaline sulfite pretreatment of corn stover. The results showed that the total alkali charge is positively correlated with the sugar content in pretreated biomass, lignin removal efficiency, and final sugar yield; pretreatment temperature has negative impact on the recovery of polysaccharides; and total alkali charge is more influential than other pretreatment process variables (such as Na2SO3/NaOH and temperature) under the conditions studied. PDF
Four bio-oils obtained from the hydrothermal liquefaction (at 280 °C for 0 min) of untreated and pretreated cypresses were subjected to several types of chemical analyses to compare their structural features and chemical constituents. Pretreatments were carried out with alkali at 90 °C for 0.5, 1, and 2 h. The bio-oils were further divided into water-soluble oil, diethyl ether-soluble oil, and diethyl ether-insoluble oil fractions. Alkaline pretreatment had a significant effect on the contents of different components in the bio-oils. The diethyl ether-insoluble oil fraction was made up of intermediate-sized macromolecular fragments of lignin decomposed during the hydrothermal liquefaction process. The G6 resonance, β-5, β-β’, and β-O-4’ peaks (which were present in the spectra of milled-wood lignin) almost disappeared from the spectra of the diethyl ether-insoluble oil fractions obtained via hydrothermal liquefaction of pretreated and untreated cypresses. At the same time, the intensities of the peaks corresponding to methoxy groups, G2, and G5 resonances were reduced. Long-duration alkaline pretreatment created a strong, highly water-soluble oil fraction with a wide molecular weight distribution. PDF
West, M. A., Hickson, A. C., Mattinen, M.-L., and Lloyd-Jones, G. (2014). "Evaluating lignins as enzyme substrates: Insights and methodological recommendations from a study of laccase-catalyzed lignin polymerization," BioRes. 9(2), 2782-2796.
Lignin preparations from kraft and sulfite pulping, steam explosion, and enzyme saccharification processes were assessed as substrates for lignin polymerization catalyzed by Trametes hirsuta laccase (ThL). Oxygen consumption associated with laccase catalyzed oxidation of the selected lignins was measured using a microplate-based oxygen assay. Laccase-induced changes in the molecular masses of the lignin polymers were assessed with aqueous-alkaline size exclusion chromatography (SEC) and changes in monomeric phenolics by reverse-phase high pressure liquid chromatography (HPLC). Obtaining consistent results in the lignin-laccase assay system required careful pH monitoring and control. All lignin preparations were oxidized by ThL, the rate being highest for steam-exploded eucalypt and lowest for enzyme-saccharified lignin. Comparing lignins, higher lignin-laccase reactivity was correlated with lower lignin molecular mass and higher amounts of monomeric phenolics. Solubility was not an indicator of reactivity. Steam-exploded and lignosulfonate-treated pine preparations were further fractionated by ultrafiltration to determine what molecular mass fractions were the most reactive in ThL catalyzed oxidation. Both retentate (> 3kDa), and to a lesser degree permeate (< 3kDa), fractions were reactive. PDF
The aim of this study was the development of an eco-friendly dye that may be used in furniture, woodworking, and upper surface treatment, with no ill effects to human health. The plant dyestuff was extracted from pomegranate skin (Punica granatum) and black mulberry (Morus nigra) using an ultrasonic method at different rates. The extraction percentage ratios were, by weight in distilled water, 25%, 30%, 35%, 40%, 45%, and 50% and were applied to Scotch pine (Pinus sylvestris L.) and Oriental beech (Fagus orientalis L.) through an immersion method. After that, the determination of color change under the accelerated weathering conditions and the feasibility as the upper surface stain of this dyestuff were studied. The values of total color change of the natural dye samples that were applied to the test material were determined after accelerated weathering processes lasting 50, 100, and 150 h, according to ISO 2470. The results showed the best color stability in Oriental beech wood that was treated with 30% pomegranate skin or black mulberry extract as well as Scotch pine wood that was treated with 25% pomegranate skin extract or 50% black mulberry extract. Exactly the same ΔE* values were obtained with the same dyestuff and same wood type, indicating close color stability behaviors. According to the results, both pomegranate skin (Punica granatum) and black mulberry (Morus nigra) can be used to color wood materials. PDF
The surface characteristics of wood veneer are inevitably influenced by hot compression treatment, which is crucial to bonding ability in the production of veneer-based composites such as plywood and laminated veneer lumber (LVL). The objective of this study was to investigate the effect of compression at the temperature of 120 °C on the surface roughness, surface element compositions, and surface free energy (SFE) of poplar veneer. The results showed that the surface roughness of veneer decreased with increasing compression ratio (CR). X-ray photoelectron spectroscopy (XPS) analysis indicated that the oxygen to carbon atoms ratio (O/C ratio) of the veneer surface decreased, while the carbon C1 to C2 atoms ratio (C1/C2 ratio) increased due to hot compression. The SFE of veneer increased by 12% at the CR level of 11%. The improvement in wettability was mainly due to the interfacial contact area increase of the hydrophilic veneer and the decrease in hydrophobic air in the liquid-veneer interface as the CR level increased. PDF
Response surface methodology (RSM) was employed to optimize dilute alkaline pretreatment conditions for the maximum glucose yield of poppy stalk, with respect to NaOH concentration (1.0 to 3.5%, w/v), pretreatment temperature (50 to 100 °C), and pretreatment time (10 to 110 min). Recovery of glucan ranged from 61.02% to 99.14%, based on the initial glucan in the raw material. The highest lignin removal (43.43%) was obtained at the pretreatment conditions of 90 °C and 3.50% NaOH for 90 min. The optimum pretreatment conditions for maximum glucose yield after enzymatic hydrolysis were found to be 2.40% w/v NaOH, 70 min, and 80 °C. Under these conditions, experimental glucose and xylose yields were 499.35 mg/g glucan and 498.66 mg xylose/g xylan, respectively. PDF
A lignin-based quaternary amine anion exchanger (LQAE) modified from raw lignin was synthesized after the reaction with epichlorohydrin and triethylamine using an NaOH solution as the basic solvent. The reaction mechanism of the experiment was explored and validated. Effect of reaction conditions on the preparation of LQAE were investigated. The performance of the LQAE was characterized by FTIR, SEM, and elemental analysis. The adsorption rate and yield were the measurable indicators, and when the NaOH concentration was 6 M, the nitrate adsorption capacity and the yield were 36.7 mg nitrate/g anion exchanger lignin and 123.6%, respectively. PDF
The lumber ofEucalyptusurophylla×E. camaldulensis was heat-treated at either 180, 190, 200, or 210 ºC for 3 h. According to the national forestry standard methods for evaluating the machining properties of lumber, the machining properties (including planing, sanding, boring, mortising, shaping, and turning) of heat-treated and untreated control samples were investigated. The results indicated that the machining properties of the lumbers were improved after heat treatment. In the machining comprehensive evaluation system (top score is 10 points), the scores of the control and heat-treated samples at 180, 190, 200, and 210 ºC were 4.74, 7.76, 8.08, 7.46, and 6.96 points, respectively. A temperature of 190 ºC was thus optimal for the comprehensive machining properties when heat-treatment was used to modify the machinability of E.urophylla×E.camaldulensis wood. PDF
The chemical compositions of cotton stalk and bast are similar to those of hardwood and superior to those of grass fiber. With respect to the morphological characteristics of their fibers, cotton stalk is similar to hardwood and cotton bast is similar to softwood. The average length of cotton bast fibers is nearly triple that of cotton stalk fibers, and the length-to-width ratio is almost quadruple. Traditionally, cotton stalk and cotton bast are pulped together, which affects the quality and homogeneity of the pulp and complicates bleaching, limiting its use to low-grade paper. In this study, cotton bast and cotton stalk were separated and pulped individually by alkaline peroxide extrusion pulping (APEP). The orthogonal analytical method was used to determine the optimal pulping parameters. Compared to those obtained via the kraft pulp (KP) of cotton stalk as a whole, far superior yield and whiteness were obtained in APEP. Further, with APEP, lower amounts of chemicals and less energy were consumed and there was little pollution. The physical performance of APEP was slightly lower than that of KP. With respect to bast alone, the physical performance of APEP was almost as good as that of KP. PDF
Kuo, C.-H., Lin, P.-J., Wu, Y.-Q., Ye, L.-Y., Yang, D.-J., Shieh, C.-J., and Lee, C.-K. (2014). "Simultaneous saccharification and fermentation of waste textiles for ethanol production," BioRes. 9(2), 2866-2875.
Ethanol production in a simultaneous sacchariﬁcation and fermentation (SSF) process using waste textiles as feedstock was studied. The dissolution pretreatment of waste textiles in ortho-phosphoric acid resulted in at least 2 fold improvement in enzymatic hydrolysis rate and reducing sugar yield. The reducing sugars obtained from dyed or discolored waste textiles by cellulase hydrolysis demonstrated no inhibitory effect on ethanol fermentation activity of Zymomonas mobilis employed in SSF. SSF with a high waste textile loading (75 g L-1) could still be operable due to the fast liquefaction of the pretreated substrate via enzymatic hydrolysis. Approximately 50 g L-1 ethanol was achieved within 24 h. In addition to 100% cotton textiles, the 40/60 polyester/cotton (T/C) blend waste textile could also be pretreated under the same condition to achieve the comparable ethanol production yield (~0.4 g EtOH g-1 glucose) from its cotton fraction in SSF. PDF
ChineseAbutilon theophrasti fiber (AF) ranks first in the world for yield; however, its application in the textile field is limited due to its characteristics. In this study, AF was used to reinforce high-density polyethylene (HDPE). Mechanical property tests, observations of the internal combination, creep behavior, and resistance to accelerate ultraviolet (UV) aging were conducted on these composites with different mass ratios. The results showed that the addition of the fiber could improve the impact resistance of the AF/HDPE composites. However, when the additive fiber content was > 60%, the flexural properties and resistance to creep deformation of the composites significantly decreased. Under the same conditions, the hygroscopic properties of the composites increased. After exposure to accelerated UV aging, the flexural strength of the composites decreased, but their impact resistance slightly improved. Infrared analysis demonstrated that lignin and other botanical compositions induced oxidative degradation in the composites. When the fiber-to-HDPE mass ratio was 60:40, the properties of the material were optimal. PDF
Agricultural production in Malaysia has been continually growing. Most of the agricultural waste has been discarded or burnt on land; however, these agricultural wastes can serve as a feedstock for biochar production, which contributes an insignificant net amount of carbon dioxide to the atmosphere after soil incorporation. Three kinds of primary biochar were used in this study: empty fruit bunch biochar (EFB), wood biochar (WB), and rice husk biochar (RHB). EFB and WB were produced by slow pyrolysis, whereas RHB was produced by gasification. This study aimed to understand how pyrolysis technologies of native feedstocks impact the chemical characteristics and short-term soil stability of biochar. The kinetic parameters of C-mineralization suggested a tri-phasic C-mineralization process (labile, unstable, and recalcitrant carbon). The estimates indicated the existence of a very labile C-fraction in RHB with a very small decay constant K3. Fourier transform infrared spectroscopy and X-ray diffraction showed the three phases of the biochar, from the microcrystalline C of the labile fraction to the largely amorphous intermediate C of the unstable fraction, and lastly the formation of turbostratic crystallite C in the recalcitrant fraction. It has been concluded that RHB had a higher degree of aromaticity and greater stability, and therefore should be more recalcitrant to biological and chemical degradation. PDF
The purpose of this study was to determine the pyrolysis characteristics and gas properties of woody biomass and coal. The main gases from the pyrolysis of biomass, coal, and mixtures of different ratios of the two were identified using TGA-FTIR. The evolution of gases and their characteristics were investigated in real time. Thermal analysis demonstrated that the biomass sources decomposed easily and that most of their weight was lost under lower temperatures than those of coal. TGA-FTIR analysis indicated that H2, CO2, CH4, and CO were the dominant gases released during the pyrolysis of biomass and mixtures. The results indicated that woody biomass could enhance coal pyrolysis or gasification and different types of biomass could have different influences on the thermal behavior of coal. PDF
Statistical models and optimization of Eucalyptus globulus Labill. wood and bark delignification were achieved using response surface methodology (RSM). A central composite design was outlined to model the simultaneous influence of active alkali (AA), reaction temperature (T), and reaction time (t) on pulp yield (η) and kappa number (k) during the kraft pulping of wood and bark. Experimental results were fitted to a second-order polynomial with linear interaction of factors. The statistical models showed high coefficients of determination for both wood (R2η = 0.991, R2k = 0.975) and bark (R2η = 0.993, R2k = 0.984). Using these models, the optimum conditions to attain a pulp with the highest yield at an acceptable kappa number (below 17) were determined. For wood, the pulp yield was 51.6% (51.5% predicted) and the kappa number was 16.1 (16.9 predicted) under optimized conditions (AA = 21%, T = 151 ºC, and t = 118 min). For bark, the pulp yield was 51.3% (51.0% predicted) and the kappa number was 19.4 (16.9 predicted) under optimized conditions (AA = 15%, T = 166 ºC, and t = 114 min). The degree of polymerization (DP) of the carbohydrates for the optimized pulps, 1430 and 1151 for wood and bark, respectively, suggests low levels of polysaccharide degradation. The bark delignification showed similar behavior to wood. PDF
Binderless fiberboards were made from oil palm (Elaeis guineensis) empty fruit bunches with two treatments: steam explosion and Fenton reagent oxidation. Fiberboards were prepared with a targeted density of 1.20 g/cm3 and a thickness of 4 mm. A factorial experimental design 22 with two center repetitions and one repetition was applied for each treatment. The oil palm waste was oxidized with Fenton reagent using a H2O2/Fe2+ ratio of 2%/0.2% to 4%/0.4% and a pressing temperature of 170 to 190 °C. Steam explosion was carried out at a severity factor of 3.5 to 4.0 at the same pressing temperature. Both treatments were examined under two major response variables: mechanical properties (modulus of rupture, MOR, and modulus of elasticity, MOE) and physical properties (thickness swelling, TS, and water absorption, WA). Steam-exploded samples developed better physico-mechanical properties than those that underwent Fenton reagent oxidation. The best results were obtained from fiberboards treated with the highest steam explosion design conditions (severity 4 and pressing temperature 190 °C) to give optimum values of MOE 3100.09 MPa, MOR 28.49 MPa, TS 11.80%, and WA 22.74%. Binderless fiberboards made from steam explosion-treated pulp satisfied favorably well the Colombian Standard NTC 2261. PDF
A detailed study was undertaken to examine the color and chemistry changes of pine wood flour when its extractives are removed and when it is delignified. The solvent systems employed were toluene/ethanol (TE), acetone/water (AW), and hot-water (HW), while sodium chlorite/acetic acid were used for delignification (i.e., lignin removal (LR)). Samples were analyzed by attenuated total reflectance-Fourier transform infrared (ATR-FTIR) spectroscopy, Fourier transform Raman (FT-Raman) spectroscopy, and colorimetry. The study demonstrated that color parameters (i.e., CIE L*a*b*) were only slightly affected by the removal of extractives, but changed noticeably when extractions were followed by delignification. TE extraction was more effective at removing the yellow colored substances, whereas AW mostly removed red colored substances that contained C=O groups. Inclusion of a HW extraction step after extraction with AW (AW-HW) removed components that contained conjugated C=O structures. Inclusion of a delignification step after extraction with AW followed by HW extraction (AW-HW-LR) was effective at removing yellow substances that contained non-conjugated C=O groups. PDF
Hui, B., Li, J., Zhao, Q., Liang, T., and Wang, L. (2014). "Effect of CuSO4 content in the plating bath on the properties of composites from electroless plating of Ni-Cu-P on birch veneer," BioRes. 9(2), 2949-2959.
A wood-based composite was prepared via simple electroless Ni-Cu-P plating on birch veneer for EMI shielding. The effects of CuSO4·5H2O concentration on the metal deposition, elemental composition, phase structure, surface morphology, wettability, surface resistivity, and shielding effectiveness of coatings were investigated. The coatings were characterized using X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), and scanning electron microscopy (SEM). When the CuSO4·5H2O concentration was increased from 0.6 g/L to 2.2 g/L, the metal deposition was decreased from 79.61 g/m2 to 66.44 g/m2. Elemental composition showed that the copper content in the coating increased significantly, whereas the nickel content was reduced significantly and the phosphorus content was slightly reduced. The crystallinity of coatings increased, and fine-grain structure was observed, with higher copper content. Ni-Cu-P deposition improved the hydrophobic properties when the maximum static contact angle increased from 77.5° to 116.5°. The lowest surface resistivity was 367.5 mΩ/cm2, and the EMI shielding effectiveness of Ni-Cu-P-coated veneers was higher than 60 dB in frequencies ranging from 9 kHz to 1.5 GHz. PDF
Lomelí-Ramírez, M. G., Barrios-Guzmán, A. J., García-Enriquez, S., Rivera-Prado, J. J., Manríquez-González, R. (2014). "Chemical and mechanical evaluation of bio-composites based on thermoplastic starch and wood particles prepared by thermal compression," BioRes. 9(2), 2960-2974.
The present work inspects the preparation of bio-composites of cassava starch with particles of eucalyptus wood through the application of a novel method of thermal compression. Bio-composites with different amounts of wood particles (5 to 30%), with particle sizes of 4 and 8 mm, were obtained. Chemical and mechanical evaluation of these samples was carried out using optical microscopy, infrared spectroscopy (FTIR), X-ray diffraction (XRD), scanning electron microscopy (SEM), and the moisture absorption effect. The effect of the amount and size of the wood particles was tested by comparison with a thermoplastic matrix sample. Results from these evaluations demonstrated that the thermo-compression method produced bio-composites with a distribution of particles in the matrix that contributed to an increase in their tensile strength. This mechanical property is also enhanced by interfacial adhesion between the matrix and particles, as confirmed by SEM. Furthermore, the maximum amount of particles in the bio-composites (30%) showed the maximum resistance to moisture absorption. Temperature and time parameters contributed to the formation of diffraction patterns VH and EH as a consequence of the structural disruption of native starch. Finally, FTIR showed the chemical compatibility between the starch, glycerol, and wood particles. PDF
Chen, L., Gao, Q., Zhang, J., Chen, H., Zhang, S., Li, J. (2014). "Effects of assembly time on wet shear strength and formaldehyde emission of plywood bonded by urea formaldehyde resin," BioRes. 9(2), 2975-2986.
The effects of assembly time on the properties of plywood were investigated in detail in this study. Three-layer plywood was fabricated, and its wet shear strength and formaldehyde emission were measured. The assembly time was varied to create three different assembly conditions (A, B, and C). The assembly condition A consisted of UF resin mixed with NH4Cl and kept for 0 to 8 h before gluing; the assembly condition B consisted of glued veneer kept in the open air for 0 to 8 h; and the assembly condition C consisted of glued veneer pre-pressed for 0 to 8 h before hot-pressing. The thermal behavior of the adhesive applied through varying assembly times was tested by differential scanning calorimetry (DSC). Results showed that the plywood prepared under condition C exhibited the highest wet shear strength, which was 37% and 18% higher than those under conditions A and B, respectively. The plywood prepared under condition C exhibited the lowest formaldehyde emission, which was 32% and 16% lower than those under conditions A and B, respectively. The DSC results indicated that the curing process consisted of three sections and that the rate of the curing reaction was the fastest in the first section and was similar in the latter two sections. PDF
Huang, L. J., Yang, Y., Cai, Y. Y., Liu, M., Xu, T., Nong, G. Z., and Wang, S. F. (2014). "Preparation of superabsorbent resin from carboxymethyl cellulose grafted with acrylic acid by low-temperature plasma treatment," BioRes. 9(2), 2987-2999.
A superabsorbent resin (SAR) synthesized from carboxymethyl cellulose (CMC) by grafting acrylic acid (AA) was studied using single-factor analysis. The optimum preparation conditions were as follows: plasma discharge power of 250 W, processing time of 90 s, pressure of 300 Pa, m(CMC):m(AA) ratio of 1:9, m(K2S2O8):m(CMC) ratio of 1:4, and neutralization degree of 40%. Under these conditions, the resin has a salt water absorbency of 38.5 g/g and a stable chlorine dioxide solution absorbency of 27.2 g/g. The structural characterization of the SAR was also studied by Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), scanning electron microscopy (SEM), and differential scanning colorimetry (DSC). The results showed that the resin was synthesized by grafting copolymerization of CMC and AA, and the water absorbency and thermal stability of the resin were greatly improvedcompared to CMC alone. This method may provide a new way for high value-added utilization of bagasse. PDF
Hydrothermal pretreatment of corncobs in aqueous media under non-isothermal conditions is an effective means for solubilizing hemicellulose fractions and improving cellulose hydrolysis. The effects of a range of pretreatment severities (temperatures of 170 to 230 °C) on the conversion of corncobs into fermentable sugars were examined. The major differences between the conversions of untreated and pretreated corncobs were the dissolution of hemicelluloses into the prehydrolyzate and the partial removal and relocation of lignin on the external surface of biomass particles (in the form of recondensed droplets) in the pretreated corncobs. Hemicellulose dissolution increased with pretreatment temperature. The maximum sugar recovery (272.3 g/kg raw material) and the minimum accumulation of inhibitory compounds in the prehydrolyzate were observed following treatment at 190 °C. While the fibrils of the untreated raw material remained largely intact, serious disruption of the cell wall was observed in SEM images of the surfaces of pretreated samples. Accordingly, the cellulose digestibilities of residues increased from 26.8% for the raw material to almost 100% for the 190 °C-treated sample. It was concluded that low severity hydrothermal pretreatment can be successfully applied to corncobs to obtain high cellulose digestibility while operating at low enzyme charges. PDF
Autohydrolysis of Eucalyptus globulus both with and without the addition of 5 g/L formic acid was explored for different liquid-to-solid (L/S) ratios at 150 ºC for 100 min. The L/S ratio has an impact on the dissolution of wood components during prehydrolysis. The extraction yield of wood components other than lignin decreased with increasing L/S ratio, while lignin removal increased with increasing L/S ratio, irrespective of acid reinforcement. The molecular weight (Mw) of dissolved hemicelluloses and lignin remained relatively constant. The average degree of polymerization of hemicelluloses isolated from the hot water extract was between 7 and 8 over a L/S ratio range from 3:1 to 50:1. The cellulose to glucose conversion yield of pretreated wood samples improved during prehydrolysis with 5 g/L formic acid. Although the conversion yield of autohydrolyzed wood meal stayed relatively constant, the conversion yield of dilute acid-pretreated wood samples increased with increasing L/S ratio. PDF
The aims of this study were to introduce a new laboratory microwave device developed for the modification of wood properties and to examine the effect of microwave radiation on moisture loss, surface temperature, and mechanical properties (the static modulus of elasticity - MOE, and the modulus of rupture - MOR) of Norway spruce (Picea abies). The device was developed for a continuous modification process. The microwave (MW) generator works at a frequency of 2450 MHz, and the adjusted output ranges from 0.6 to 6 kW. The experiment was based on four different modes of MW modification, each of them with a varied generator output and conveyor speed. Regarding mechanical properties, the results showed that a feasible output for the MW modification of the samples was up to 3 kW, with a conveyor speed of around 0.4 m/min. The greatest moisture loss, approximately 40%, was found in the group treated at 5 kW and 0.2 m/min. The highest surface temperature, 87 °C, was measured in the group treated at 5 kW and 0.4 m/min after the second passage through the modification chamber. PDF
Copper-based compounds are some of the most important biocides for the protection of wood in heavy duty applications. In the past, copper was combined with chromium compounds to reduce copper leaching, but a recent generation of copper-based preservatives uses ethanolamine as a fixative. To elucidate the leaching of copper biocides from wood, Norway spruce (Picea abies) wood was treated with a commercial copper-ethanolamine solution with two different copper concentrations (cCu = 0.125% and 0.25%). The aim of this research was to compare the laboratory leaching standards (ENV 1250-2, CEN/TS 15119-1, and CEN/TS 15119-2) with the field leaching studies in ground and above ground. The results indicated that the first leaching peak appears in the initial phases of leaching, both in laboratory and field studies. The degree of copper leaching is also affected by the method of treatment; copper-ethanolamine preservative solutions, when applied with superficial treatments, are more prone to leaching than is vacuum-pressure treated wood. On average, between 25% and 36% of copper was leached from the impregnated wood after 42 months of exposure. PDF
The reaction kinetics of gasification are important for the design of gasifiers using biomass feedstocks, such as lignin, produced in biorefinery processes. Condensed and uncondensed lignin samples used in the present study were prepared using the SEW (SO2-ethanol-water) fractionation process applied to spruce wood chips: the dissolved lignin is precipitated during the recovery of SO2 and ethanol from the spent fractionation liquor. The gasification of char made from condensed and uncondensed SEW lignin was investigated using thermogravimetric analysis (TGA) at atmospheric pressure using either CO2 or steam. The main aim of this study was to quantify the reaction rate during the gasification process, which was found to be best described as zero-order. All experiments were performed at constant temperatures between 700 and 1050 °C to obtain the necessary information for describing the reaction rate equation in an Arrhenius form; the heating rate was 20 °C/min for both samples. The experiments led to almost similar results for both samples. The activation energies of CO2 gasification were approximately 160 kJ/mol and 170 kJ/mol for uncondensed and condensed lignin char, respectively. The activation energies of steam gasification were approximately 90 kJ/mol and 100 kJ/mol for uncondensed and condensed lignin char, respectively. PDF
Liu, H., Yang, L., Cai, Y., Hayashi, K., and Li, K. (2014). "Distribution and variation of pressure and temperature in wood cross section during radio-frequency vaccum (RF/V) drying," BioRes. 9(2), 3064-3076.
The pressure and temperature at the same location in the middle cross section of Sugi wood were measured simultaneously during radio-frequency/vacuum (RF/V) drying. The distribution and variation of pressure and temperature in the wood cross section were investigated in different drying stages. The pressure behavior during the drying process was due to the pressure reduction rate and water vapor generation rate in wood. The temperature was higher in the center and was low from the center to surface layer. Pressure and temperature did not present symmetrical distributions along the vertical direction in the cross section. The pressure was irregular during the timber heating stage and became higher in the central zones than in the intermediate and surface layer zones during the drying process. Pressure curves exhibited three stages (irregular, rapid decreasing, and slow decreasing), in combination with an initial heating stage and a constant temperature stage. Above the fiber saturation point (FSP), the pressure (P) was greater than or equal to the saturated vapor pressure (Ps), corresponding to the temperature at the same location; below the FSP the pressure was maintained by superheated vapor and was smaller than Ps. PDF
Zhang, Z., Jia, J., Li, M., and Pang, Q. (2014). "H2O2 can increase lignin disintegration and decrease cellulose decomposition in the process of solid-state fermentation (SSF) by Aspergillus oryzae using corn stalk as raw materials," BioRes. 9(2), 3077-3087.
H2O2 is both bactericidal and the main oxidant responsible for lignin degradation reaction catalyzed by manganese peroxidase (MnP) and lignin peroxidase (LiP). Thus, H2O2 treatment of corn stalk and the implementation of solid-substrate fermentation (SSF) is possible to increase the removal rate of lignin from stalk in the process of SSF and after SSF, while avoiding the need to sterilize the raw materials. To demonstrate this approach, SSF was initially carried out using corn stalk pretreated with different concentrations of H2O2 as a substrate. A. oryzae was found to grow well in the 3% H2O2-pretreated corn stalk. H2O2-pretreated corn stalk showed increased MnP and LiP synthesis and disintegration of lignin, but inhibited cellulase synthesis and cellulose degradation. Production of the SSF (200 g) on the 10th day was hydrolyzed in the presence of additional 600 mL different concentration of H2O2 aqueous solution. The total removal of lignin (73.15%) of hydrolysis for 10 h at 3% H2O2 solution was highest and far higher than that at the 12th day, as achieved by conventional SSF. Applying this strategy in practice may shorten the time of lignin degradation, increase the removal of lignin, and decrease the loss of cellulose. Thus, this study has provided a foundation for further study saccharification of corn stalk. PDF
The surface free energy and dynamic wettability of wood are important to the performance of its adhesive bonding strength. In this work, the surface free energy of poplar wood samples machined with different processes were calculated by the OWRK (geometric mean) and vOCG (acid-base) methods, and the dynamic wettability of adhesives on wood samples was studied using the S-D wetting model. The results indicate that the contact angles of reference liquids on rotary wood samples were greater than those on planed or sawn wood, and the rotary wood samples were more hydrophobic. The effect of surface roughness on contact angle was insignificant compared with surface structure morphology. The total surface free energy was almost the same for the planed and sawn wood, as calculated by the OWRK and vOCG methods, and the surface free energy of rotary wood samples was lower than that of planed or sawn wood samples. The initial and equilibrium contact angle increased as the viscosity of adhesive increased for all the wood samples, and the contact angles of rotary wood samples were greater than those of planed or sawn wood; however, the K-value was lower. The wettability of the loose side was higher than that of the tight side. Contact angles decreased when surface free energy increased, while the K-value increased. PDF
Sha, L., and Chen, K. (2014). "Preparation and characterization of ammonium polyphosphate/diatomite composite fillers and assessment of their flame-retardant effects on paper," BioRes. 9(2), 3104-3116.
Ammonium polyphosphate (APP) was synthesized by heating a mixture of phosphoric acid and urea, and APP/diatomite composite flame-retardant fillers were prepared by two methods: mixing and in situ polymerization. Flame-retardant paper was made by adding the prepared composite fillers to paper. The APP and APP/diatomite composite fillers were characterized by XRD, 31PNMR, SEM, FTIR, and TG. The flame retardation of paper containing these composite fillers was determined. Results showed that the prepared APP had a minimum solubility when the molar ratio of phosphoric acid to urea was 1:1.8. Under these conditions, its degree of polymerization was 91.21. After mixing and in situ polymerization, a large amount of APP was adsorbed into the surface of the diatomite. These two APP/diatomite composite fillers had similar thermal stabilities, butthe flame retardation of paper containing in situ polymerized composite filler was better than that of paper containing the composite filler obtained by mixing. PDF
Shi, X., Zheng, F., Pan, R., Wang, J., and Ding, S. (2014). "Engineering and comparative characteristics of double carbohydrate binding modules as a strength additive for papermaking applications," BioRes. 9(2), 3117-3131.
In this study, four engineered proteins containing two family 1 and/or family 3 carbohydrate binding modules (CBMs) were constructed and expressed as soluble forms in Escherichia coli. Their binding performances and effect on paper’s mechanical properties were comprehensively studied with the aim to design suitably engineered CBMs as novel biomaterials for use in the production of new cellulose materials. The recombinant engineered double CBMs exhibited obvious differences in their adsorption to different cellulosic substrates. The CBM3-GS-CBM3 was the most effective in enhancing paper mechanical properties in terms of folding endurance (27.4%) and tensile strength (15.5%) among the four engineered double CBMs, but it gave rise to only a slight increase in bursting strength (3.1%). On the other hand, CBM1-NL-CBM1 achieved a significant simultaneous increase in tensile strength (12.6%) and burst strength (8.8%), as well as folding endurance (16.7%). Unexpectedly, CBM3-GS-CBM1 and CBM3-NL-CBM1 had the lowest effective paper property improvement. The differences in types of CBMs and linker peptides in engineered double CBMs may contribute to the considerable differences in their cellulose binding and paper property modification. Our data suggested that CBM1-NL-CBM1 may provide a better upgrade of the secondary pulp, which makes it very suitable for fiber recycling. Meanwhile, CBM3-GS-CBM3 may have particular potential for paper manufacture requiring high folding endurance. PDF
Two field trials were conducted with untreated coconut wood (“cocowood”) of varying densities against the subterranean termites Coptotermes acinaciformis (Froggatt) and Mastotermes darwiniensis Froggatt in northern Queensland, Australia. Both trials ran for 16 weeks during the summer months. Cocowood densities ranged from 256 kg/m3 to 1003 kg/m3, and the test specimens were equally divided between the two termite trial sites. Termite pressure was high at both sites where mean mass losses in the Scots pine sapwood feeder specimens were: 100% for C. acinaciformis and 74.7% for M. darwiniensis. Termite species and cocowood density effects were significant. Container and position effects were not significant. Mastotermes darwiniensis fed more on the cocowood than did C. acinaciformis despite consuming less of the Scots pine than did C. acinaciformis. Overall the susceptibility of cocowood to C. acinaciformis and M. darwiniensis decreases with increasing density, but all densities (apart from a few at the high end of the density range) could be considered susceptible, particularly to M. darwiniensis. Some deviations from this general trend are discussed as well as implications for the utilisation of cocowood as a building resource. PDF
Sasthiryar, S., Abdul Khalil, H. P. S., Ahmad, Z. A., Nazrul Islam, M., Dungani, R., and Fizree, H. M. (2014). "Carbon nanofiller-enhanced ceramic composites: Thermal and electrical studies," BioRes. 9(2). 3143-3151.
The present research is focused on the manufacturing and analysis of the thermal and electrical properties of advanced ceramics from alumina (Al2O3) with carbon nanofiller (CNF) from oil palm ash (OPA). The oil palm ash was used to produce carbon black nanofillers with a size of 50 to 100 nm via a ball milling process after undergoing pyrolysis in a furnace at 1000 °C. CNFs were added to the alumina at varying weight fractions and sintered at 1400 °C for the production of CNF ceramic composites. The coefficient of thermal expansion (CTE), electrical conductivity (EC), and electrostatic discharge (ESD) of the ceramic composites were measured. The CTE did not increase with increasing CNF weight and behaved like an alumina matrix. The EC (I-V) showed positive results with increasing CNF weight. The ESD measurement gave predictable results on the dissipative characteristics of ceramic composites due to the insulating nature of alumina with the addition of CNF. Thus, the addition of OPA to alumina may present a suitable route for improving the electrical properties of advanced ceramics. PDF
Fruit nursery paper is a protective technical paper that is used in agriculture to improve the percentage of the fruit that meets quality standards and the fruit’s exterior qualities, such as the smooth surface finish and fruit color. In this work, a more efficient and environmentally friendly method, i.e., the printing method, was proposed in order to minimize environmental pollution, reduce the loss of carbon black, and lower the high production cost caused by the traditional method of directly adding carbon black. The effects of printing pressure and inking amount on the properties of the fruit nursery paper were investigated. The durability and safety of the fruit nursery paper produced by the printing method were also studied. The optimal inking amount and printing pressure under laboratory conditions were 1 mL and 350 N, respectively. The amount of ink transferred to the paper surface increased with increasing printing pressure, which led to better opacity but slightly decreased porosity and softness. A more important finding was that the fruit nursery paper produced by the printing method had excellent durability, and the properties can satisfy the requirements of the end use and safety standards of 94/62/EC stipulated by the Europeon Parliament and Councile directive. Based on these low-cost, environmentally friendly characteristics, the development of this new fruit nursery paper could be beneficial. PDF
The research aimed at optimizing the conditions of pretreatment of wheat straw and of enzymatic hydrolysis of the cellulose (ethanol pulp). The ethanol pretreatment process involving acid-catalytic and enzymatic hydrolysis were evaluated for bioconversion of wheat straw to glucose. The influence of the independent process variables on cellulose yields, cellulose contents, lignin contents, and the rate of lignin removed were analyzed over a broad range by the response surface methodology (RSM). The results of the factorial experiment showed that the significant external factors affecting acid-catalytic ethanol pretreatment of wheat straw were ethanol concentration, maximum temperature, acid dosage, and time at maximum temperature. By analyzing the response surface plots, the optimum process parameters for pretreatment were obtained as follows: ethanol concentration 65%, maximum temperature 180 ºC, acid dosage 1.2%, and time at maximum temperature 60 min. Pulps with residual klason lignin ranging from 9.27% to 13.56% (w/w) were prepared from wheat straw using the acid-catalytic ethanol pretreatment process and were evaluated for bioconversion using enzymatic hydrolysis of the cellulose fraction to glucose. The effects of temperature, pH value, time of enzymolysis, and cellulase dosage on the hydrolysis yield of cellulose were separately examined. PDF
Huang, X.-Y., Xie, J.-L., Qi, J.-Q., Hao, J.-F., Jiang, X.-Q., and Hu, W.-H. (2014). "Investigation of the physical and mechanical properties and chemical composition of Bambusa rigida before and after accelerated aging," BioRes. 9(2), 3174-3183.
The differences in the physical and mechanical properties and chemical composition of Bambusa rigida bamboo before and after accelerated aging tests were comparatively investigated. The results revealed that the aged specimens had lower physical and mechanical properties than the controls. The differences in chemical composition provided evidence that the reduction in physical and mechanical properties was related to the loss of low-molecular weight substances, such as extracts and inorganic matter, and the depolymerization of the carbohydrates cellulose and hemicellulose. Lignin caused the main resistance to the accelerated aging test because the aged specimens had relatively high Klason lignin content. Significant differences (p<0.05) in surface color between the control and aged specimens were observed, and variations in bamboo properties among culm heights were also evaluated in this study. The results showed that basic density and mechanical properties for both the control and aged specimens increased with increasing culm height, while the volume shrinkage showed an inverse trend. PDF
Kong, W., Ren, J., Wang, S., and Chen, Q. (2014). "Removal of heavy metals from aqueous solutions using acrylic-modified sugarcane bagasse-based adsorbents: Equilibrium and kinetic studies," BioRes. 9(2), 3184-3196.
Recently, more and more attention has been centered on developing cheaper, highly efficient, environmentally friendly adsorbents for the removal of metal ions from industrial effluents. The present work deals with the removal of metal ions from an aqueous solution using a highly efficient, biodegradable adsorbent from hydrogel prepared by the free radical graft polymerization of sugarcane bagasse with acrylic acid and acrylamide using N, N-methylene-bis-acrylamide as a crosslinker. FTIR and SEM/EDX spectroscopies were used to characterize the structure and the morphology of adsorbent before and after the metal ions adsorption. The effects of pH, contact time, and initial concentration of metal ion on the adsorption capacity were studied. The adsorption equilibrium time of Pb2+, Cd2+, and Cu2+ were 60, 90, and 180 min, respectively. The maximum adsorption capacities of Cu2+, Pb2+, and Cd2+ were 268, 700, and 320 mg/g, respectively. The adsorption data were fit to often-used models for adsorption kinetics and isotherms. It was determined that the experimental results were well fitted to the pseudo-second-order equation and Langmuir adsorption isotherms. PDF
Gawron, J., Antczak, A., Borysiak, S., Zawadzki, J., and Kupczyk, A. (2014). "The study of glucose and xylose content by acid hydrolysis of ash wood (Fraxinus excelsior L.) after thermal modification in nitrogen by HPLC method," BioRes. 9(2), 3197-3210.
This study aimed to determine glucose and xylose content by acid hydrolysis of wood samples, both unmodified and thermally modified (modification time was 2, 6, 10 hours), using high performance liquid chromatography. Optimization of the hydrolysis process on the native ash wood samples showed that 3 h was the best time in the hydrolysis process. After that time, 58.8% of glucose and 20.8% of xylose were obtained. In turn, chromatographic analysis showed incomplete hydrolysis of ash wood samples, which were modified in a nitrogen atmosphere, especially at shorter times (2 and 6 h) of modification. With longer modification times (10 h), the hydrolysis of ash wood samples was completed. The above mentioned problem was caused mainly by the increase of cellulose crystallinity degree. The decrease of this parameter was observed only after 10 h of thermal modification, which would facilitate the process of acidic hydrolysis. Additionally, it was observed that the thermal modification of ash wood at 190 °C in a nitrogen atmosphere for 10 h caused a drastic decrease in the xylose content (from 20.8% to 8.0%) and only a slight decrease in the glucose content (from 58.8% to 54.9%). PDF
Wang, X., Sun, H., Bai, H., and Zhang, L.-P. (2014). "Thermal, mechanical, and degradation properties of nanocomposites prepared using lignin-cellulose nanofibers and poly(lactic acid)," BioRes. 9(2), 3211-3224.
A variety of nanocomposites were prepared using lignin-cellulose nanofibers (L-CNF) and poly(lactic acid) (PLA) via a solvent casting process. Acid hydrolysis and high-pressure homogenization processes were used to produce L-CNF from unbleached kraft pulps. Tensile tests were conducted on thin films, and the nanocomposites containing 3 wt. % L-CNF showed a 32.4% increase in tensile strength compared to that of neat PLA. Dynamic mechanical analysis showed that the tensile storage modulus increased in the viscoelastic temperature region with increasing L-CNF content in the nanocomposites. Thermogravimetric analysis (TGA) showed that all the materials investigated were thermally stable from 25 to 310 ºC. Differential scanning calorimetry (DSC) showed a decrease in the cold crystallization temperature. A positive effect on the crystallization of PLA polymers in the nanocomposites with added L-CNF was observed using DSC and X-ray diffraction (XRD) analysis. The degradation profiles and swelling ratios of the nanocomposites improved. PDF
Three polyamine fixing agents with increasing molecular weights (m.w.), PA-Lw, PA-Mw, and PA-Hw, were used to treat a deinked pulp at three different levels of chemical dosage. The objective was to elucidate whether the retention mechanism of colloidal substances (CS) onto fibers by a fixing agent is different when the dosage is different. The results show that, for the polyamine with the lowest molecular weight (PA-Lw), it performed in the colloidal fixation mode over a wide range of dosage, but re-dispersion of CS took place in the pulp when its dosage was increased to a level high enough but still beneath the charge reversal point. For the polyamine with the highest m.w. (PA-Hw), CS re-dispersion was not observed over the whole dosage range, but a small part of the colloidal agglomeration coexisted with colloidal fixation even when the dosage was very low. For the polyamine with the middle m.w. (PA-Mw), both CS re-dispersion and colloidal agglomeration were observed. This study showed that if one wants to determine the dosage of a fixing agent during CS control better, both CS removal ratio and CS agglomeration behavior should be considered. PDF
Green liquor (Na2S + Na2CO3, GL) pretreatment is an effective pathway for improving the enzymatic digestibility of lignocellulosic biomass for the production of bioethanol. In this work, GL was employed as a pretreatment to enhance the enzymatic saccharification of poplar. During pretreatment, the increase of H-factor and TTA charge resulted in enhanced delignification and increased degradation of polysaccharides. The sugar yield of enzymatic hydrolysis increased rapidly with increasing TTA charge in GL pretreatment, while the effect of different H-factors (from 400 to 800) on sugar yield was unnoticeable. The pretreated solid recovery was 75.5% at a lignin removal rate of 29.2% under optimized conditions of total titratable alkali (TTA) charge 20%, sulfidity 25%, and H-factor 400. The sugar yield of glucan, xylan, and total sugar of GL-pretreated poplar in enzymatic hydrolysis reached up to 89.9%, 65.5%, and 82.8%, respectively, at a cellulase loading of 40 FPU/g-cellulose. PDF
Stress wave velocity has been traditionally regarded as an indicator of the extent of damage inside wood. This paper aimed to detect internal decay of urban trees through reconstructing tomographic image of the cross section of a tree trunk. A grid model covering the cross section area of a tree trunk was defined with some assumptions. Stress wave data were processed beforehand to obtain the propagation velocity and the coordinate values. An image reconstruction algorithm for detecting internal decay was proposed based on an interpolation method, which estimated the velocity values of unknown grid points by utilizing the values of the surrounding points. To test the effectiveness of this method, Cinnamomum camphora tree samples were selected and tested using a stress wave tool. The area, positions, and extent of decay in the representative samples were displayed in tomographic images constructed by the interpolation method, and the results demonstrate the performance of the method. PDF
SO3H-based acidic ionic liquids were used as Brønsted acid catalysts for synthesis of diphenolic acid (DPA) from the condensation of phenol and levulinic acid, a platform chemical from renewable materials. Evidence is presented that the product with p,p’- and o,p’-isomers was obtained. Under the optimal conditions, the 93.2 mol% yield of DPA and close to 100% selectivity to p,p’-DPA were achieved in a process promoted by [BSMim]HSO4. The favorable results can be attributed to the special structures of ionic liquids and thiol compound involvement. Furthermore, a mechanism of condensation promoted by acidic ionic liquid with ethanethiol is proposed. PDF
To facilitate melt compounding of cellulose nanofibrils (CNF) based composites, wood pulp fibers were subjected to a chemical treatment whereby the fibers were oxidized using 2,2,6,6-tetramethylpiperidine-1-oxyl radical (TEMPO). This treatment introduced negatively charged carboxylate groups to the fibers. TEMPO-treated fibers (TempoF) were added to a mixture of amylopectin starch, glycerol, and water. Granules were prepared from this mixture and processed into CNF composites by extrusion. TempoF were easier to process into composites as compared with non-treated pulp fibers (PF). SEM revealed partial disintegration of TempoF during melt processing. Consequently, TempoF gave composites with much better mechanical properties than those of conventional composites prepared from pulp fibers and TPS. Particularly, at 20 wt% TempoF content in the composite, the modulus and strength were much improved. Such a continuous melt processing route, as an alternative to laboratory solvent casting techniques, may promote large-scale production of CNF-based composites as an environmentally friendly alternative to synthetic plastics/composites. PDF
In this work, sugarcane bagasse, being an abundant and renewable resource, was used as a raw material to prepare sugarcane bagasse-g-poly(acrylic acid-co-acrylamide) (SB/P(AA-co-AM)) hydrogels. The hydrogels were prepared by free radical graft copolymerization of SB with AA and AM using N,N-methylene-bis-acrylamide (MBA) as a crosslinker. The optimal synthesis conditions were determined by investigating the water absorbency of the hydrogels. The maximum water absorbency reached 269 g/g in deionized water, and the corresponding copper ions adsorption capacity was 265 mg/g. These grafted hydrogels showed a pH-sensitive swelling behavior. Furthermore, they also exhibited excellent water retention capacity, which reserved 92.7%, 81.7%, and 76.8% for 44 h, and 83.7%, 58.6%, and 47.1% for 116 h at 5 °C, 25 °C, and 35 °C, respectively. FTIR spectroscopy and SEM were used to reveal the chemical structure and the morphology of the hydrogels. SEM/EDS further confirmed the adsorption of the copper(II) on the resulting hydrogels. Therefore, SB/P(AA-co-AM) hydrogels could have promising applications as water retention agents and metal ions adsorbents in water treatment and agricultural industries. PDF
A one-dimensional theoretical heat and mass transfer model was developed for high-frequency (HF) heating of veneer-based composites, such as laminated veneer lumber (LVL) and plywood. This model was based on the basic principles of energy and mass conservation, momentum conservation of gas flow, and gas thermodynamic relations. The response variables, including temperature, gas pressure, and moisture content (MC), were linked to basic material properties, such as veneer density, thermal conductivity, permeability, and dielectric properties. Initial and boundary conditions for solving the governing equations were also considered. The model was further validated by experiments with veneer HF heating and LVL HF heating. The model predictions agreed well with the experimental results. During veneer HF heating, the inner veneer core layers had lower MC than the outer surface layers. Compared to conventional hot platen heating, HF heating was proven to be an efficient and robust method for manufacturing veneer-based composites. PDF
Al-Juhaimi, F. Y., Hamad, S. H., Al-Ahaideb, I. S., Al-Otaibi, M. M., Ghafoor, K., Abbasi, T., and Abbasi, S. A. (2014). "Biogas production through the anaerobic digestion of date palm tree wastes - Process optimization," BioRes. 9(2), 3323-3333.
A process for the production of biogas through the anaerobic digestion (AD) of date palm tree waste (DPTW) was developed. The effects of different substrate pretreatments and operating conditions on the yield of biogas and on the chemical composition of DPTW before and after AD were studied. The best results were obtained using alkali pretreatment, with a particle size of 2 to 5 mm, a C:N ratio of 30:1, a digestion temperature of 40 °C, an initial pH of 7.0, and a volatile solids concentration of approximately 10%. The production of flammable biogas containing up to 50% methane started after about one week of operation and continued for approximately 11 weeks. The highest average biogas yield obtained was 342.2 L gas/kg of volatile solids fed to the digester. The highest maximum and average volumetric biogas production rates obtained were 674.5 and 404.4 L/m3 of digester volume per day, respectively. After digestion, there was up to a 58% reduction in the organic matter content of the substrate. Reductions in the contents of cellulose, hemicellulose, and soluble organic compounds were 68.7, 73.4, and 71.9%, respectively, while the ash and lignin contents remained mostly constant. The remaining sludge contained nutrient minerals and some organic matter which qualifies it as a potential soil fertilizer for crop production. PDF
Moon, Y.-H., Yang, J., Koo, B-C., An, J.-W., Cha, Y.-L., Yoon, Y.-M., Yu, G.-D., An, G. H., Park, K.-G., and Choi, I.-H. (2014). "Analysis of factors affecting Miscanthus pellet production and pellet quality using response surface methodology," BioRes. 9(2), 3334-3346.
The Miscanthus sacchariflorusstrain Goedae-Uksae 1 has recently been developed as an energy crop, because of its rapid growth, ease of culture, and large size. In this study, Miscanthus pellets were investigated for further practical use of renewable resources. The pellets were produced on a pilot scale and their characteristics and quality were investigated. Moisture content, density of raw materials, and die ratio (L/D) were determined to be the main factors affecting Miscanthus pelletizing. Thus, a central composite design using response surface methodology (RSM) was applied to optimize conditions for standard grade Miscanthus pellet production. The optimal values predicted by the model equation were confirmed by the experimental data. The optimum ranges of parameters for pellet production were identified as moisture content, 20 to 25%; density of raw materials, 240 to 300 kg/m3; and die ratio, 4.5:1 to 5.0:1. Under these conditions, Miscanthus pellets were produced meeting the standards of qualities, such as size, bulk density, durability, moisture content. PDF
Lignin is an important renewable source of phenolic products. In this study, alkali lignin was depolymerized to produce phenolic compounds. The effects of catalyst, solvent, reaction time, and reaction temperature on the yields of liquid products and volatile fractions were investigated in detail. Compared with the solvents water and octane, alcohols can significantly promote depolymerization of lignin due to the excellent solubility of the degradation products and intermediates. Under the conditions of 300 °C for 2 h in the solvent ethanol, the highest yields of liquid products (75.8 wt%) and volatile fraction (38.1 wt%) were obtained over a ZnCl2 catalyst. Gas chromatograph-mass spectroscopy analysis demonstrated that the volatile fraction was composed of guaiacols (15.09 wt%), phenols (15.79 wt%), and syringols (2.28 wt%). Furthermore, the mechanism for lignin depolymerization is discussed. PDF
Abd-Rahim, S. N., Sulaiman, A., Edama, N. A., Baharuddin, A. S., and Mokhtar, M. N. (2014). "Factorial design analysis of a tapioca slurry saccharification process using encapsulated enzymes," BioRes. 9(2), 3361-3368.
A three-factor two-level (23) full factorial design analysis was conducted to identify the significant factors that influence glucose production from tapioca slurry with an encapsulated enzymatic saccharification process using a stirred bioreactor. The factors investigated were pH (5 to 7), temperature (40 to 60 °C), and agitation speed (80 to 160 rpm). From the statistical analysis, a mathematical model for tapioca slurry saccharification was derived, and the variance analysis resulted in a high determination coefficient (R2=0.9993). The main effects and their interactions were also investigated. The results showed that all the main factors and the two-way interaction factors were statistically significant. The most significant factor in the tapioca slurry saccharification was found to be pH, while the interaction between pH and agitation speed was the most influential two-way interaction. PDF
Guo, F., and Fang, Z. (2014). "Shape-controlled synthesis of activated bio-chars by surfactant-templated lonothermal carbonization in acidic ionic liquid and activation with carbon dioxide," BioRes. 9(2), 3369-3383.
Shape-controlled bio-chars were synthesized in two steps: (i) ionothermal carbonization of biomass (e.g., glucose, cellulose, lignin, and bamboo) at low temperatures (150 to 180 °C) in an acidic ionic liquid (IL), and (ii) subsequent activation with carbon dioxide at higher temperature (500 °C).Acidic IL was used as both the medium and catalyst for advanced carbon materials production. During the first step the primary structurs of spherical particles were obtained. The surfactants sodium dodecyl sulfonate (SDS), ethylene glycol (EG), and sodium oleate (SO) were also used to modify the surface morphology of bio-chars and activated bio-chars. After the second step, the primary structures of bio-chars were still preserved or improved. The Brunauer-Emmett-Teller surface area and the pore diameter of activated bio-chars were 289 to 469 m2/g and 3.5 to 3.6 nm, respectively. Scanning electron microscope and transmission electron microscope images show that after modification of bio-chars with SDS, EG, and SO, activated bio-char particles agglomerated into rod-like (~200 nm diameter),nano-membrane (~70 nm thickness), and spherical (~200 nm) morphologies, respectively. The morphology of activated bio-chars was easily controlled during the synthesis, which is important for the exploitation of their peculiar properties and unique applications. PDF
Low-pressure steam explosion (LPSE) combined with alkaline peroxide (AP) pretreatment was first employed to separate hemicellulose from Lespedeza stalks. The monosaccharide composition and molecular weight distribution of the obtained hemicellulose fractions were characterized in this study. The results show that the hemicellulose extracted from Lespedeza stalks consisted of xylose, glucose, galactose, and mannose, which was a mixture of arabinoxylans and xyloglucans or β-glucans. The yield of hemicellulose fractions after AP pretreatment ranged from 11.2% (2.5% hydrogen peroxide (H2O2), w/v for 12 h) to 12.2% (3.3% H2O2, w/v for 72 h). The molecular weight of hemicellulose decreased from 2,458 g/mol to 1,984 g/mol after AP pretreatment, indicating its degradation reaction. The structure of hemicellulose was analyzed by Fourier transform infrared spectroscopy, proton nuclear magnetic resonance, and heteronuclear single quantum coherence. The AP pretreatment partially cleaved the backbone and the ether linkage between lignin and hemicelluloses. Also, branched-chain α-D-arabinofuranosyl in which β-D-xylose substituted at the C-3 position (monosubstituted) was removed, illustrating a partial debranching reaction. Therefore, the combination of low-pressure steam explosion and alkaline peroxide pretreatment (LPSE-AP) is an effective pretreatment method to separate hemicellulose from Lespedeza stalk. PDF
Abdalla, S., Pizzi, A., Ayed, N., Charrier-El Bouthoury, F., Charrier, B., Bahabri, F., and Ganash, A. (2014). "MALDI-TOF analysis of Aleppo pine (Pinus halepensis) bark tannin," BioRes. 9(2), 3396-3406.
Matrix-assisted laser desorption/ionisation time of flight (MALDI-TOF) mass spectrometry is a suitable method for examining polyflavonoid tannin oligomers because it has the capability to determine aspects of their oligomeric structure and characteristics that are too difficult to determine by other techniques. For non-purified industrially extracted Aleppo pine polyflavonoid tannin, it was possible to determine by MALDI-TOF that: (i) oligomers formed by catechin/epicatechin are present in tannin, as are mixed oligomer units with fisetinidin and robinetinidin units; the presence of flavonoid gallate and other structures was confirmed; (ii) oligomers up to 12 to 13 repeating monoflavonoid units, in which the repeating unit is at 264 Da, have been confirmed; and (iii) oligomers of the two types covalently linked to each other also occur. The presence of a small proportion of hydrolysable tannins by chemical analysis can also be explained by gallate residues attached to some of the flavonoid oligomers. PDF
Freshly harvested alfalfa was fractionated using centrifugation and filtration, whereby alfalfa was separated into a fiber-rich cake and a nutrient-rich juice. The solid cakes from the above separation processes were used as the feedstock for ethanol production using separate hydrolysis and fermentation. The filtration process proved to be more efficient at reducing the solids mass transfer to the juice than the centrifuge process. Glucose from filtered alfalfa solid cake can be efficiently fermented to ethanol with 75% of the theoretical yield. In conclusion, centrifugation was not as effective as filtration in removing particulates and colloidal matter from alfalfa. The filtration process resulted in a solid cake with a higher cellulose digestibility, which leads to a higher ethanol production. PDF
The Hildebrand solubility parameter (d-value) was applied to explain the effect of organic solvent concentration on lignin removal during organosolv extraction of lignin from enzymatically hydrolyzed cornstalks under atmospheric pressure and low temperature (≤ 75 °C) without additional catalyst. The d-value of lignin, calculated using the group-contribution method, was 13.70 (cal/cm3)1/2. The proximity of the d-value between organic solvent-water and lignin explained the delignification capacity of the organic solvent-water. The concentration of organic solvent in the aqueous mixture that led to the highest delignification (i.e., 34.5%, 41.8%, and 53.7% delignification for ethanol-water, 1,4-dioxane-water, and tetrahydrofuran-water, respectively) was around 65 to 75% vol., which was in keeping with the prediction by the solubility parameter theory. PDF
In the present paper changes of validity in Euler-Bernoulli's elementary theory of flexural vibration for homogeneous materials were tested with respect to changing severity and position of a single defect in wood. As an orthotropic material, wood has different material properties or strengths in different orthogonal directions. A set of absolutely clear specimens of oriental beech was chosen and hand drilled in different diameters (severities) at different relative distances from an end oriented in the R direction. A clear specimen showed a steady decrease in evaluated moduli of elasticity related to increasing mode numbers. After creating the defects, this steady decrease line showed some breakages. The slope breakages of modally evaluated elastic moduli in LT and LR vibrations are suggested as potential finger-prints of single hole defects in the specimen by considering the shape and rate of breakages in the decreasing lines. The recognition scenarios of slope breakages for defect severity and position are summarized. PDF
Boric acid was employed to improve the homogeneity and mechanical properties of a composite based on cellulose fibres and polyvinyl alcohol (PVOH). The influence of boric acid, under different pH values, on the mechanical properties cellulose fibres (handsheets) was investigated. The presence of the boric acid, under alkaline conditions, further improved the mechanical properties of the handsheets. A composite based on PVOH and cellulose fibres was prepared in the presence of boric acid and glycerol, a plasticizer. The employment of the boric acid, under alkaline conditions, was necessary to obtain a homogenous composite. The morphology of the final product was analysed by SEM, and their tensile properties were measured. PDF
Chemical and enzymatic modifications intended to improve the reactivity of dissolving pulp rapidly decrease its yield. In this study, a beating post-treatment intended to increase the reactivity of bamboo dissolving pulp was investigated. Beating post-treatment can create microfibrils on the surface of fibers. The reactivity of unrefined bamboo dissolving pulp prepared via pre-hydrolysis and a subsequent kraft cooking and Op-H-P (oxygen delignification enhanced with H2O2 and sodium hypochlorite) bleaching process was very low. The reactivity increased drastically as the Canadian standard freeness (CSF) of the bamboo dissolving pulp was decreased (i.e., the degree of beating increased). The CSF decreased to 236 mL from its original, higher freeness. The average fiber width was larger and the curling and kink indexes were lower in the pulp of CSF 236 m L compared to those of pulps with greater freeness. However, there was little impact of beating on the crystallinity index of bamboo dissolving pulp. PDF
This research involved the most widely used wood-species of veneers in Hungary (oak, ash, beech, cherry, and maple). The resulting changes in color produced at treatment temperatures between 80 and 200 °C in different treatment times were evaluated using the CIELab color stimulus evaluation system. For higher temperature treatments, a tight functional relationship was observed between the treatment time and the difference in color stimulus. Heat treatments within a temperature range above 160 °C produced visually perceptible results, while color change resulting from heat treatments at lower temperatures was almost imperceptible. For higher temperature treatment a tight functional relationship was observed between the difference in color stimulus and treatment time (r2>min. 0.84). Different tree species produced different extents of change in hue depending on the treatment parameters. Among the color components, the perceptible discoloration was mostly produced by the change in the lightness factor (L*). As the treatment temperature rose, the change in the red (a*) and yellow (b*) components was less significant regardless of the species. PDF
A fed-batch process and high-temperature simultaneous saccharification and fermentation (SSF) process were investigated to obtain high sugar yield and ethanol concentration. Different amounts of alkali-pretreated sugarcane bagasse were added during the first 24 h. For the highest final dry matter (DM) content of 25% (w/v), a maximal glucose and total sugar concentration of 79.53 g/L and 135.39 g/L, respectively, were achieved with 8.3 FPU/g substrate after 120 h of hydrolysis. Based on the hydrolysis experiment, two processes for ethanol production from sugarcane bagasse, simultaneous saccharification and fermentation (SSF) and separate hydrolysis and fermentation (SHF), were also compared using S. cerevisiae. The results indicated that ethanol concentration and yield in the SHF were higher, while ethanol productivity (gram per unit volume and over time) was lower. For 25% substrate loading, the ethanol productivity and ethanol concentration could reach 0.38 g.L-1.h-1 and 36.25 g/L SSF in 96 h, respectively, while that of SHF could reach 0.32 g.L-1.h-1, with an ethanol concentration of 47.95 g/L in 152 h for SHF. When high-temperature simultaneous saccharification and fermentation (SSF) process was performed by using Kluyveromyces marxianus NCYC 587 at 42 °C, 42.21 g/L ethanol (with an ethanol productivity of 0.44 g.L-1.h-1) was produced with 25% dry matter content and 8.3 FPU cellulase/g substrate, which meant 16.4% more ethanol when compared with SSF of S. cerevisiae. PDF
Fique is a biodegradable natural fiber derived from the Colombian Agavaceae family, originating in tropical America and traditionally used for the manufacture of packaging and cordages. Today, however, new uses are being developed. To meet the need for new good-quality, sustainable, low-cost construction materials for social housing, construction materials have been produced that combine different kinds of natural fibers, including fique, to improve their strength and physical properties. To assess these potential new construction materials made with fique fiber, we have characterized samples of different grammages and thicknesses manufactured using short fique fibers extracted from long fibers. We have measured the sound absorption coefficient at normal incidence in an impedance tube, air flow resistivity, and thermal conductivity as a function of grammage. PDF
Based on traditional kinetic models of the gasification process of char, a new modified random pore model (MRP) was proposed. This model can be reduced to a traditional volume model (VM), an unreacted shrinking core model (URCM), a hybrid model (HM), and a random pore model (RPM) by varying the model parameters. Furthermore, not only is the relationship between the reaction rate and conversion rate well described by MRP, as it is in other models, but the position of the maximum reaction rate is also described, which is out of the application range of other traditional models. MRP was validated by gasification of different kinds of chars under different experimental conditions, such as in a carbon dioxide atmosphere, in the presence of water vapor, or with the addition of catalyst. The char gasification process under various conditions could be simulated by MRP with better fitting results than the traditional RPM. PDF
Novel biosurfactant-producing strains were isolated from hydrocarbon-contaminated environments that exclusively utilize agro-waste as their primary carbon source for the expression of biosurfactants. These were quantified using various standardized methods. Among the agro-waste screened, Beta vulgaris (Beetroot) proved to be the most suitable substrate, for which the biosurfactants produced by three bacterial isolates–B. licheniformis STK01, B. subtilis STK02, and P. aeruginosa STK03–lowered the surface tension of the culture media to 30.0, 32.98, and 30.37 mN/m, respectively. The biosurfactants achieved considerable emulsification activity, particularly for heavy hydrocarbons, with the highest emulsification indices being 65.5% and 95% for anthracene and lubricant oil, respectively. The emulsion formed with lubricant oil was thermally stable even up to 50 °C for 21 days. The results showed the proficiency of the novel bacterial isolates used, as well as the suitability of solid agro-waste for biosurfactant production, thus suggesting that exclusive utilization of solid agro-waste is a promising option for use in biosurfactant production for environmental remediation. The outstanding emulsification activity and thermal stability demonstrated by the biosurfactants produced showed their potential applications in enhancing bioavailability and bioremediation of recalcitrant and hydrophobic environmental contaminants. PDF
The cel12B gene was cloned, optimized through directed evolution using
Derkowski, A., Mirski, R., Dziurka, D., and Popyk, W. (2014). "Possibility of using accelerated aging tests to assess the performance of OSBs exposed to environmental conditions," BioRes. 9(2), 3536-3549.
This study evaluates the impact of the number of cycles of the V313 test (EN 321 2002) on the mechanical properties of 15-mm-thick OSB/3 and OSB/4. The obtained results were compared with the properties of the boards exposed to external environmental conditions. The results of the study indicate that the tested boards were characterized with a 50% decrease in static bending strength and a 70% decrease in tensile strength perpendicular to the plane. However, both types of boards met the requirements of the standard (EN 300 2006) with respect to their modulus of rupture. The method of exposing boards to outdoor conditions has a substantial influence on the change of the physico-mechanical properties of OSBs. In the boards used in this study, however, those changes occurred slower than those evoked by the V313 test, especially after an upright exposure. For these reasons, for that type of board storage, an equation was determined that can bring the property changes following the V313 test into an acceptable range to allow for the evaluation of the board properties. In the case of vertical exposure, from the second year forward, changes in the properties of the OSB/3 were similar to those presented by the boards demonstrated from the second cycle of the V313 test. PDF
Korhonen, M. H. J., Sorvari, A., Saarinen, T., Seppälä, J., and Laine, J. (2014). "Deflocculation of cellulosic suspensions with anionic high molecular weight polyelectrolytes," BioRes. 9(2), 3550-3570.
Pulp fibers have a strong tendency to form flocs in water suspensions, which may cause their undesirable distribution in the paper sheets. This flocculation can be controlled by adding, e.g., an anionic high molecular weight polyelectrolyte in the fiber suspension. The objective of this study was to investigate the effect of anionic polyelectrolytes on deflocculation kinetics, dewatering, and rheology of cellulosic suspensions. The results showed that both microfibrillated cellulose (MFC) and macroscopic pulp fibers can be dispersed using anionic polyacrylamides (APAM). The higher the molecular weight of APAM, the higher is its effect. Adsorption experiments illustrate that anionic polyelectrolytes do not strongly attach to cellulose surfaces but they can be partly entrapped or can disperse nanocellulose fibrils (increase the swelling). Based on rheological experiments, the MFC network became weaker with APAM addition. Similar to the flocculation mechanism of cellulosic materials with polymers, deflocculation is also time dependent. Deflocculation occurs very rapidly, and the maximum deflocculation level is achieved within a few seconds. When mixing is continued, the floc size starts to increase again. Also dewatering was found to be strongly dependent on the contact time with the APAMs. These results indicate that the positive effects of anionic deflocculants are quickly diminished due to shear forces, and therefore, the best deflocculating effect is achieved using as short a contact time as possible. PDF
Jiang, J., Lu, J., Zhou, Y., Zhao, Y., and Zhao, L. (2014). "Compression strength and modulus of elasticity parallel to the grain of oak wood at ultra-low and high temperatures," BioRes. 9(2), 3571-3579.
The influence of temperature on the compression strength (fc0) in the range of -196 ºC to +220 ºC, and compression modulus of elasticity (Ec0) parallel to the grain of oak (Quercus mongolica Fisch et Turcz.) wood in the range of -196 ºC to +23 ºC were studied. Five specimens were prepared for each temperature level. The specimens were kept at each temperature level for 30 min before a mechanical test was performed in an adjustable-temperature chamber. The results indicated that there were four different failure patterns, depending on the temperature range. When the temperature was decreased from +23 ºC to -196 ºC, the fc0 and Ec0 of wood increased by 283.91% and 146.30%, respectively. The relationships between fc0 and temperature and between Ec0 and temperature could be described by a linear and a polynomial model, respectively. Moreover, the Ec0 could be used to predict fc0 using a polynomial model. However, when the temperature was increased from +23 ºC to +220 ºC, the fc0 decreased by 67%, indicating a non-linear relationship. PDF
Two kinds of macromolecules applied in papermaking were modified with β-cyclodextrin (β-CD) and loaded with ciprofloxacin hydrochloride (CipHCl) in an attempt to compare their potential applications in antimicrobial paper. β-CD grafted cellulose (β-CD-Cel) and β-CD grafted cationic starch (β-CD-CS) were prepared by grafting β-CD onto cellulose fiber and cationic starch using citric acid (CA) and epichlorohydrin (ECH) as crosslinking agents, respectively. β-CD-Cel and β-CD-CS were both loaded with an antimicrobial agent (CipHCl) to form inclusion complexes, namely β-CD-Cel-CipHCl and β-CD-CS-CipHCl. Furthermore, the inclusion complexes were added to the pulp to prepare antibacterial paper. The antimicrobial activity and physical properties of the paper were investigated. The results showed that the paper with both inclusion complexes exhibited excellent antibacterial activity, and the antibacterial activity with β-CD-CS-CipHCl was higher than that with β-CD-Cel-CipHCl. Moreover, the addition of both β-CD-Cel-CipHCl and β-CD-CS-CipHCl affected the tensile and tear strengths of the paper. The paper with β-CD-CS-CipHCl had better physical properties than that with β-CD-Cel-CipHCl because the CS acts as a reinforcing agent in papermaking. These prepared antibacterial paper sheets may be useful for preventing wound and nosocomial infections in the medical and packaging fields. PDF
Li, H., Zhang, Z., Song, K., Lee, S., Chun, S.-J., Zhou, D., and Wu, Q. (2014). "Effect of durability treatment on ultraviolet resistance, strength, and surface wettability of wood plastic composite," BioRes. 9(2), 3591-3601.
A comparative analysis of photostabilizing effects of hindered amine light stabilizers (HALSs), an ultraviolet absorber (UVA), and zinc borate (ZnB) on wood plastic composites (WPCs) was made in this study to show the influence of the accelerated weathering on the surface degradation and loss of mechanical properties of treated WPCs. The results showed that the UVA was the most effective in preventing composite from being bleached, especially when the aging time was longer than 1000 hours. With the addition of the ultraviolet stabilizers, the contact angles increased, indicating increased water wettability. The contact angle of UVA-containing samples was greater than that of the control and the other samples treated with HALSs and ZnB. Flexural properties of all materials decreased after being weathered under xenon-arc light. Materials treated with UVA had higher retention rates in flexural strength and modulus. The results show that, among the agents used, UVA was the most effective additive in preventing WPCs from ultraviolet degradation. PDF
Alkali extracted lignin (AEL), isolated from corn stalks with dilute alkali solution under mild condition, was used as a low-cost adsorbent for the removal of methylene blue (MB) from aqueous solutions. Batch adsorption studies were conducted to evaluate various experimental parameters such as pH, contact time, and initial dye concentration for the removal of MB. The kinetic data were analyzed using pseudo-first-order and pseudo-second-order kinetic models, and the adsorption kinetics were found to be well represented by the pseudo-second-order kinetic model. The equilibrium data were perfectly fitted to the Langmuir isotherm equation when compared with Freundlich isotherm equation. Based on the Langmuir adsorption isotherm model, the predicted maximum monolayer adsorption capacity was found to be 121.20 mg g-1 (at 30 ºC). The results showed that this adsorbent had a high adsorption capacity, making it a promising alternative for dye removal. PDF
Murithi, G., Onindo, C. O., Wambu, E. W., and Muthakia, G. K. (2014). "Removal of cadmium(II) ions from water by adsorption using water hyacinth (Eichhornia crassipes) biomass," BioRes. 9(2), 3613-3631.
The kinetics and equilibrium binding of Cd(II) ions onto raw water hyacinth (Eichhornia crassipes) biomass (RBH) were investigated with the view to utilize it as a low-cost biosorbent for removal of toxic metal ions from water. The biosorption was analyzed through batch experiments with respect to the effect of contact time, agitation speed, biosorbent dosage, solution pH, Cd(II) concentration, and the presence of other metal ions. Cadmium adsorption onto Eichhornia crassipes biomass was pH- and temperature-dependent, and complete Cd(II) removal from solution was achieved at all Cd(II) concentrations up to 10 mg/L. The biosorption equilibrium was described by Langmuir and Freundlich isotherms, and the RBH Cd(II) uptake capacity was 104 mg/g. The biosorption process followed the pseudo-second-order model (R2 > 0.99). The root biomass of water hyacinth had one of the highest Cd(II) sequestration efficiencies when compared to other biosorbents that have been used to remove Cd(II) from water. PDF
In this work, paper was rendered antimicrobial via applying antimicrobial-modified starch as a coating material onto the paper’s surface. The antimicrobial starch was prepared by covalently bonding guanidine polymers using a coupling reaction. Two different coating layers were applied onto the paper’s surface. The first coating layer contained clay mixed with a latex binder (clay 100 g/latex 20 g). The antimicrobial starches, which possessed different grafting ratios of the antimicrobial agent (30 wt.% and 50 wt.%), were applied as the second coating layer on the paper. The results showed that the coating thickness was approximately constant at 4 μm. In the presence of 0.5 to 1.0 wt.% antimicrobial starch on cellulose fibers, the growth inhibition of bacteria was almost 100%. Additionally, the resulting coated paper exhibited high antimicrobial activities against E. coli. Furthermore, the results showed that the coated papers prevented fungal growth. PDF
Intervention against pathogenic bacteria using natural plant material has a long history. Plant materials also have been widely used as fillers and/or reinforcers in polymer composites. Some natural fibre plants, such as hemp, are regarded to possess antibacterial activity against a wide range of pathogenic bacteria. Innovative applications can be explored if they are incorporated in polymer composites. This review aims to compile the relevant investigations on antibacterial activity of hemp and other fibre plants such as jute, flax, kenaf, sisal, and bamboo. The antibacterial character might be contributed from cannabinoids, alkaloids, other bioactive compounds, or phenolic compounds of lignin. This review is intended to encourage utilization of hemp and other natural fibre plants in value-added diversified products. Some potential applications are also discussed. PDF
Espinoza-Acosta, J. L., Torres-Chávez, P. I., Carvajal-Millán, E., Ramírez-Wong, B., Bello-Pérez, L. A., and Montaño-Leyva, B. (2014). "Ionic liquids and organic solvents for recovering lignin from lignocellulosic biomass," BioRes. 9(2), 3660-3687.
Lignin contributes to the recalcitrance of lignocellulosic biomass and affects enzymatic activity during biorefinery operations. Therefore, it must be removed before further processing. Organic solvents (organosolv) and ionic liquids are two important pretreatments for delignifying lignocellulosic biomass. They have proven beneficial for fractionating and recovering cellulose and hemicellulose, as well as lignin with useful physicochemical properties. Volatility and harsh conditions of the acidic systems that result in toxicity, corrosion, and pollution are the main problems of organosolv. Ionic liquids, generally recognized as green solvents, have also been proposed as a possible solution to the challenge of using lignocellulosic biomass. Ionic liquids can either dissolve the lignocellulosic biomass completely or dissolve it into individual fractions. This review considers the advantages and disadvantages of organosolv and ionic liquids, since both are important methods to fractionate lignocellulosic biomass in their main components which can be converted into value added products. PDF
Lindholm, P. C., Knuutinen, J. S., Ahkola, H. S. J., and Herve, S. H. (2014). "Analysis of trace pharmaceuticals and related compounds in municipal wastewaters by preconcentration, chromatography, derivatization, and separation methods," BioRes. 9(2), 3688-3732.
A significant portion of pharmaceuticals and other organic chemicals consumed by people and animals are released into municipal wastewater treatment plants. Most of them are degraded during the wastewater treatment processes, but some of them degrade only partially and may be widely transported and dispersed into the aquatic environment. This is why efficient and fast analytical methods are needed for detection of organic compounds in wastewaters at trace levels. Because wastewaters often consist of complex matrices and high-molecular mass materials, e.g., lignocellulosic biomass, which may bring challenges to the sample preparation procedures, efficient pre-concentration methods such as solid phase extraction (SPE) solid phase microextraction (SPME), or single‑drop microextraction (SDME) are needed. The most common analysis methods are gas chromatography (GC) and liquid chromatography (LC) coupled with tandem mass spectrometry (MS/MS). The aim of this review is to give an overview of chromatographic and spectroscopic methods when characterizing low- and medium-molecular weight organic pollutants, mainly focusing on pharmaceuticals, biocides, and personal care products in environmental matrices. PDF
The pulp and paper industries are attempting to bring changes to the bleaching process to minimize the use of chlorine to satisfy regulatory and market demands. Xylanases offer a cost-effective way for mills to realize a variety of benefits in bleaching. One main benefit is reducing Adsorbable Organic Halides (AOX) discharge. This is achieved primarily by decreasing chlorine gas usage. Other benefits include eliminating chlorine gas usage in mills with high chlorine dioxide substitution levels and increasing the brightness ceiling (particularly for mills contemplating Elemental Chlorine Free (ECF) and Totally Chlorine Free (TCF) bleaching sequences and in mills using large amounts of peroxide or chlorine dioxide). These benefits are achieved in the long term when the enzymes are properly selected and integrated into the process. This review summarizes the application of xylanases in the bleaching of pulp, with emphasis on the mechanism and effects of xylanase treatment on pulp and paper and the factors affecting the bleaching process and its efficiency. Brightness gains of up to 1.4 to 2.1 units have been achieved with xylanase treatment with the reduction of chlorine consumption by 15.0%. Xylanase treatment can lower the AOX amount in filtrate by 25.0% as compared to references. The Chemical Oxygen Demand (COD) can be reduced by 85%. PDF