Research Articles

This work investigated the ability of biopretreatment with different white-rot fungi to improve the medium-temperature pyrolysis of biomass. It was found that biopretreatment can significantly increase the production of phenols and glucopyranoside up to 2.82 and 2.94 fold, respectively. Biopretreatment can also decrease the content of carbon dioxide, propanol, and propanone, making the pyrolysis more efficient and product-oriented. Moreover, distinct bio-deconstruction mechanisms can result in different pyrolysis products. By deconstructing cellulose and modifying lignin with a minimum of demethoxyation, white-rot fungus Irpex lacteus CD2 can improve the production of acetaldehyde (up to 6.72%) and methoxyl substitutes such as dimethoxyphenyl (up to 21.59 folds). By decomposing carbohydrates, carbonxyl, and methoxyl groups, white-rot fungi Pleurotus ostreatus BP2 and Echinodontium taxodii 2538 can increase the production of D-allose (up to 3.09%) and formic acid (up to 6.98%), while decreasing the methoxyl substitutes such as 2-methoxy-4-vinylphenol (up to 70.08%).

Chemical modification of natural fibres has been carried out using different methods for such purposes as reinforcement in polymer matrices and heavy metals adsorption. In this work, palm fibres were modified by zirconium oxychloride in situ. The palm fibres that had been chemically modified were compared to those in nature using fibres that passed through 20 and 40 mesh screens to evaluate the influence of particle size on modification. Palm fibres were modified with ZrO2.nH2O nanoparticles through the use of zirconium oxychloride in an acidic medium in the presence of palm fibres using ammonium solution (1:3) as the precipitating agent. Scanning electron microscopy (SEM), X-ray diffraction (XRD), infrared spectrophotometry (FTIR), and atomic emission spectrometry with inductively coupled plasma (ICP-AES) were used to characterize the hybrid materials. Results indicated that the particle size of the palm fibres influenced in the modification, because the fibres with smaller particle size had a greater deposition of inorganic material. The ICP technique revealed an increase of 21% nanoparticles ZrO2.nH2O deposited on fibres (40 mesh) when compared to fibres (20 mesh). The diameter of nanoparticles ZrO2.nH2O deposited on fibres was about 50 to 220 nm, as observed by SEM.

The formation of oxalate during oxygen delignification causes a number of operational problems in pulp and paper mills. In this work, the oxygen delignification of wheat straw pulp was carried out under various conditions and the concentration of resulting oxalate in the effluent was determined. The experimental results show that the amount of oxalate in the effluent was closely related to the reaction conditions, specifically reaction temperature, oxygen pressure, and alkali charge. Raising reaction temperature and/or oxygen pressure could promoted oxalate formation. The oxalate concentration increased linearly with the consumption of alkali but logarithmically with reduction of kappa number. An empirical model for describing the oxalate formation in the oxygen delignification of wheat straw pulp was generated with a reasonably high correlation coefficient (R2=0.909), which can provide useful guidance for control of oxalate formation during oxygen delignification through adjustment of process parameters.

Talc was incorporated as filler alongside rattan powder in polypropylene (PP) matrix to produce a hybrid composite. 20 phr of rattan powder was used for all samples. Talc filler loadings were varied from 0 to 10 phr. The composite was manufactured using a Polydrive Thermo Haake internal mixer, which provided processing characteristics for the composite. Peak and stabilization torques gradually increased with increasing talc filler loading. Tensile properties of the hybrid composites showed an increase in tensile modulus and a decline in elongation at break with increasing talc loading. The tensile strength was enhanced with the addition of talc up to a loading of 4 phr and then decreased with further talc filler loading. A water absorption test was carried out, whereby the water uptake of the hybrid composites was reduced with higher talc filler loading. Thermal degradation of the composites was analyzed by studying thermogravimetric analysis (TGA) thermograms and derivative thermogravimetry (DTG) curves, which showed improvement in the thermal stability of the composite with higher talc content. The morphological studies carried out on tensile-fractured surfaces of the hybrid composites explained the enhancement and deterioration of tensile properties with regard to different filler loadings.

In this work, a xylanase-producing strain, Streptomyces griseorubens LH-3, was cultured, and the crude xylanase was prepared. Analysis of its enzymatic properties revealed that the crude xylanase possessed good thermal stability at temperatures below 60 °C, exhibited a wide pH range from 4.0 to 9.0, and was cellulase-free. This crude enzyme was used to treat eucalyptus kraft pulp, and the release of chromophores was the highest at the dosage of 20 IU g-1 dry pulp. Compared with the untreated group, biobleaching of eucalyptus kraft pulp with this enzyme increased the brightness of the pulp by 12.9% and reduced the Kappa number by 27.4%. Biobleaching of eucalyptus kraft pulp with this enzyme obtained the same final pulp brightness compared with that of the control; however, hydrogen peroxide consumption was reduced by 17% and the yield and viscosity of the pulp was increased by 1.47% and 1.53%, respectively. This crude xylanase has promising potential for industrial applications.

One-step fermentation of wheat bran (WB) by Aureobasidium pullulans 2012 to produce ferulic oligosaccharides (FOs) was developed. As the WB concentration was increased, the xylanase activity and yield of FOs increased; the optimum concentration of WB was 50 to 60 g/L, which enhanced xylanase synthesis and the preparation of FOs. A moderate amount of xylan and peptone promoted xylanase synthesis and FO production. The addition of metal ions and surface active agents suppressed the yield of FOs. The optimum medium composition for FO preparation was 10 g/L xylan and 1 g/L peptone added to 60 g/L WB solution. Under these conditions, an FO yield of 774 nmol/L was achieved. According to observations by scanning electron microscopy, the internal structure of WB was obviously disrupted after fermentation. This process featured one-step fermentation of WB without further hydrolyzing, which greatly decreased the raw material cost and thus facilitated its practical application.

The purpose of this study was to determine the dimensional stability of oriented strand boards (OSBs) with the core layer made of fine wood chips when the boards were exposed to air of variable relative humidity (30%, 65%, and 85%). The share of fine wood chips, intended for the particleboard core layer or originating from comminution of unrefined particleboards, accounted for 50% or 100% of the core layer mass. This study revealed much greater changes in the length of the board’s shorter axis, regardless of the type of fine wood chips in the core layer. These changes increased with an increasing share of this type of chips in the core layer. More pronounced changes in thickness were observed for particleboards containing 50% of the fine chips. The research also showed that the relative changes in linear dimensions were slightly smaller in OSBs containing 50% of wood chips from the comminution of unrefined particleboards than in the boards with a core layer made from wood chips designed for this purpose.

Mercerized fibers were prepared from native cotton fabrics via NaOH solution treatment at different concentrations. . In addition, the cotton fibers were converted into a swollen and rough state after mercerization treatment. The results of Fourier transform infrared spectrometry and wide-angle X-ray diffraction indicated that the cellulose molecular structure changed (e.g. the degree of disorder of O-H stretching vibration increased, while the crystallinity index decreased) in the process of mercerization. Thermogravimetric analysis determined that the cellulose II fibers were more thermally stable than the cellulose I fibers. The mechanical properties of cellulose fiber-reinforced polyethylene oxide (PEO) composites showed that both original and mercerized cotton fibers enhanced the tensile strength of the PEO matrix. These properties directly contributed to the advantages of mercerized textile products (e.g. higher luster, holds more dye, more effectively absorbs perspiration, and tougher under different washing conditions).

This study investigated optical and strength properties of light-weight coated (LWC) printing paper. Two different pigments, namely nanoclay and precipitated calcium carbonate (PCC) with rhombohedral particle shape, were used with acrylic styrene latex to coat base paper using a blade method. Strength properties such as: tensile, burst, and tear indices, stiffness and optical properties including brightness, yellowness, and opacity were measured. Surface topography was studied using atomic force microscopy (AFM). Comparison between the coated paper and the control sample demonstrated that surface of the paper coated with nanoclay was more uniform than the paper coated with PCC. Although there were no significant differences in terms of the strength of these paper samples, burst and tear strength were enhanced by up to 10 and 16% in some or all treatments, respectively. There was a slight increase in paper opacity with PCC because it has a narrower particle size distribution in comparison with that of nanoclay. Yellowness of the papers treated with nanoclay was degraded about 20% as compared to the control sample, while some small differences were also noticed in brightness and opacity of the papers.

Bark is one of the most under-utilized types of lignocellulosic biomass in the forest industry. In this study, bark fast pyrolysis was optimized for phenols yield using response surface methodology (RSM), considering the pyrolysis temperature, gas flow rate, and biomass particle size. The bio-oil generated under optimal conditions was then characterized by gas chromatography-mass spectrometry (GC-MS), ultimate analysis, and several physical methods. A regression equation was estimated based on the statistical analysis. It was found that the optimal conditions for phenols yield were 485 °C (pyrolysis reaction temperature), 28 L/min (gas flow rate), and 0.35 mm (biomass particle size), giving an experimental phenols yield of 13.2 wt%. The bio-oil obtained in optimum conditions met ASTM standard D7544-12 and contained up to 30.42% phenols. This renewable, phenol-rich bio-oil may be a good feedstock for phenolic-based chemicals, such as phenolic resin and phenoplast.