Volume 8 Issue 4

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.

Effects of heat treatment on some physical properties of poplar and plane wood specimens were investigated. The main aim was to compare effects of heat on some physical properties of low-density poplar wood and high-density oriental plane wood. Heat treatment was conducted at temperatures of 150 and 200 °C for 3 h in the presence of air at atmospheric pressure. After the heat treatment, the mass loss; oven-dried density; tangential, radial, and volumetric swelling; fiber saturation point; and moisture content were determined. Regression analyses between mass loss and volumetric swelling were performed. The findings were analyzed statistically with ANOVA and the T-test. The results showed that heat treatment at 200 °C influenced the physical properties of both poplar wood and plane tree wood. In addition, the heat treatment had a little greater effect on the swelling and fiber saturation point of poplar wood than it did on the properties of plane wood.

This study investigates the relative ability of natural bamboo fiber used in textile manufacturing to resist attack by bacteria and fungi. These tendencies were determined with the dynamic test method for evaluating antibacterial activity and were compared with the of other textile fibers, such as cotton, jute, flax, ramie, and regenerated bamboo fiber. The bacteria studied were Escherichia coli (8099) and Staphylococcus aureus (ATCC 6538), and the fungal species was Candida albicans (ATCC 10231). The relationships between the bacteriostatic ability of natural bamboo fiber and its physical state, hygroscopicity, and extractives were tested to explore the possible influencing factors. The results show that natural bamboo fiber has no natural antibacterial properties, as compared with natural cotton bacteriostatic rates against the bacteria were all zero. The physical state did not impact the natural resistance of natural bamboo fiber to the bacteria and the fungus. The resistance of the plant fiber may be related to its hygroscopicity, and some extraction methods could improve the ability of natural bamboo to resist microorganisms.

A novel superabsorbent was prepared by utilizing carboxymethyl starch and carboxymethyl cellulose biocomposites as a grafting backbone. The scheme of the CMS-CMC double backbone structure was speculated. It was proposed that the superabsorbent possesses a three-dimensional network with an interpenetrating structure. The response surface methodology was used to optimize the parameters. Interactions among the most influential variables, i.e., the dosage of CMC, the acrylic acid to acrylamide mass ratio, and the neutralization degree of acrylic acid were estimated. A mathematical model was developed, which fit the experimental results well for all of the response variables. The optimal conditions included 28.8 % of CMC dosage, a 1.6 mass ratio of acrylic acid to acrylamide, and 73.4 % of neutralization degree of acrylic acid to achieve 815.2 g/g of water absorbency.

The feasibility of using lignocellulosic biomass as a source for preparing carbon adsorbents has received rigorous attention over the last few decades. Many studies have discussed its great potential as a renewable feedstock for preparation of carbonaceous adsorbent materials. This review paper provides an overview of the different types of carbonization techniques that so far have been applied to convert lignocellulosic biomass to carbon adsorbents. The effects of various process parameters on the conventional pyrolysis process are reviewed. The paper focuses on the mechanism for the formation of carbons, its wide variety of applications for waste effluents, and the regeneration techniques so far adopted by researchers. Low-cost carbons derived from lignocellulosic biomass have demonstrated excellent capabilities for the removal of organic and inorganic contaminants, including some pharmaceutical compounds, from the waste aqueous stream.