Volume 14 Issue 3

Effects of adding small amounts of cellulose nanofibers and nanoclay particles on physical and morphological properties of biodegradable composites made of starch thermoplastic polymer and industrial sawdust were investigated. For this purpose, these nanoparticles were mixed with wood plastic composites (WPCs) at 0%, 3%, and 5% weight percent. Water absorption, thickness swelling, thermal dynamic mechanical tests, and also degradation tests were performed according to corresponding standard test methods. The results showed that adding small amounts of cellulose nanofibers and nanoclay particles can be successfully used as filler and improve overall performance of the above-mentioned WPCs.

The hemicellulose content of cellulosic material from poplar chemi-thermomechanical pulp (CTMP) was controlled by a microwave-assisted formic acid (MFA) extraction process. The environmentally friendly, self-bonded, and cellulose-rich fiber sheets (around 0.3 mm thick and 280 g/m2 grammage) were fabricated via a molding and compression process. The results showed that the MFA treatment effectively controlled the hemicellulose content in the range from 6.8% to 20.4%. Mechanical testing results showed a good linear relationship between the tensile strength and the hemicellulose content, where a higher hemicellulose content obtained a stronger tensile strength. Meanwhile, as hemicellulose content decreased, the onset temperature, representing the thermal stability, increased from 318.1 °C to 335.7 °C and the elastic modulus, representing the mechanical stiffness, increased from 0.047 MPa to 0.068 MPa. Additionally, as the hemicellulose content decreased, the water-resistance of the cellulose-rich fiber sheets improved. During the hemicellulose removal process, the strength of single fibers was found to have a dominant role in the mechanical strength of the cellulose-rich fiber sheets, rather than the inter-fiber bonding strength. This was contrary to research on the delignification process, where the inter-fiber bonding strength was found to be more important than the strength of single fibers in deciding the material strength.

To develop a large-scale production of the protease of Bacillus subtilis strain D-2, the full-length gene apr-D2 (1,149 bp) encoding the alkaline protease was cloned into plasmid pET-32a and expressed as a secretory protein in Escherichia coli. Sequence analysis of the deduced amino acid sequence revealed high homology with the catalytic domains of the subtilisin serine proteases. From SDS-PAGE analysis, the recombinant protein had a molecular mass of 60.4 kDa. The expressed protease was secreted into the culture medium in a functional active form. The purified recombinant protease showed a pH optimum of 10.5 and temperature optimum of 55 °C, and it was stable in the pH range from 5.0 to 13.0. The enzyme activity was slightly enhanced by Ca2+, Mg2+, Ba2+, and SBT1. However, it was highly inhibited by Ag+ and PMSF. A theoretical structural model of mature protein was constructed by comparative modeling, which showed a putative catalytic triad (Asp-32, His-64 and Ser-221) with high similarity to the template. The structural characteristics that confer enzymatic specificity of the protease were analyzed. Taken together, the data suggested that the secretory expression system with pET-32a in E. coli was successfully constructed. Additionally, enzymatic specificity analysis of the alkaline protease indicated that it was suitable for various processing industries.

The aim of this research was to investigate the effects of various temperatures of thermal treatment of red meranti (Shorea accuminata) wood on mass concentration and size distribution of wood dust produced by a hand-held belt sander. The experiment was conducted during the sanding of the meranti wood in the natural state and using specimens that were heat-treated via the ThermoWood® technology at the temperatures of 160 °C, 180 °C, 200 °C, and 220 °C. An analysis of variance was used to measure the significance of the effects. Average values of the inhalable and respirable fractions of wood dust mass concentration determined via the optical and gravimetric method was highest at the treatment temperature of 160 °C. The results showed that mass concentration was not significantly influenced by thermal treatment.

Bamboo culms or bamboo plywood possessing a native green surface color are highly valuable for use in interior decoration. However, the green surface color of bamboo can easily become discolored in ambient environments without any protection. In order to maintain the green surface color of Neosinocalamus affinis bamboo, this study used copper sulfate (CuSO4), phosphoric acid (H3PO4), and acetic acid (CH3COOH) solutions as protectors. The changes in surface color and characteristics of the bamboo samples before and after the treatment were evaluated. The results showed that the N. affinis bamboo samples treated with 2% CuSO4 solution at 80 °C for 3 h exhibited an attractive green color, with a* and b* values of -7.61 and 5.13, respectively. The indoor durability test result indicated that bamboo samples treated with CuSO4, CuSO4/H3PO4, and CuSO4/CH3COOH solutions all had excellent color durability. After the treatment, the relative copper content on the bamboo surface slightly increased, while the magnesium content decreased. The chlorophyll structure was changed, and reactions between chlorophyll and copper ions may have occurred. The silicon was almost completely removed, and the surface structure of the treated bamboo changed, resulting in good permeability for the treatment.

The screening of new potential microbes for the selective degradation of lignin makes agricultural straws available to achieve the complete conversion to biofuel. Because of the capability of laccase to oxidize phenolic compounds and to reduce the molecular oxygen of water, laccase has attracted much interest in recent years for its industrial applications. In this study, a fungal strain with a relatively high laccase activity was isolated from corn farm residue and identified as Trametes KS-2. The maximum laccase activity was 631 U/L for Trametes KS-2 when glucose/corn stalk (1/1, w/w) and peptone were used as the carbon source and nitrogen source, with 0.09 mmol of Cu2+ at pH 5.5 and 28 °C for 10 days. Laccase activity of Trametes KS-2 was relatively stable in the presence of salt and an ionic liquid. Scanning electron microscopy analysis indicated the morphological alteration of lignocelluloses via Trametes KS-2 treatment. Remarkable degradation of lignin in corn stalk was achieved with Trametes KS-2. After 15 days, the lignin was noticeably reduced to 76 mg, and the degradation rate was increased to 65.4%. Trametes KS-2 could be potentially utilized in the microbial degradation of lignin for lignocellulosic biomass and the industrial production of laccase.

Euscaphis japonica var. wupingensis is a variety of E. japonica in the family Staphyleaceae. The biological characteristics of E. japonica var. wupingensis have been well described, but few studies have been conducted on its constituents. After repeated separation using column chromatography and preparative high performance liquid chromatography (HPLC), ten compounds were isolated from the methanol extract of fruit of E. japonica var. wupingensis. The structure of the components was characterized on the basis of spectroscopic data, including nuclear magnetic resonance (NMR), and mass spectra (MS). These compounds included five chromone derivatives: isobiflorin (1), biflorin (2), 2-methyl-5,7-dihydroxy-chromone-7-O-ß-D-glucopyranoside (5), 5,7-dihydroxy-2-methyl-4H-chromen-4-one (6), and quercetin-3-O-D-arabinoside (7), and four tannins: eugeniin (3), ellagic acid (8), 3, 3′-di-O-methylellagic acid 4-(5”-acetyl) -α-L-arabinofuranoside (9), 3,3′-di-O-methylellagic acid (10), and methyl 3,4,5-trihydroxybenzoate (4). The antioxidant activity of the isolated compounds were tested. Ellagic acid (8) exhibited potent 2,2-diphenyl-1-picrylhydrazyl (DPPH) scavenging activity with an SC50 value of 4.05 M.

The substantial release of oil palm ash into ground water has been a serious concern to the environmentalist due to the enormous generation of oil palm ash waste from oil palm incineration. The effective utilization of this agrowaste is yet to be fully exploited. In this context, herein we, investigated the potential of oil palm ash nanofiller as an effective reinforcement in epoxy-based composites. Transmission electron microscopy (TEM) revealed that the prepared oil palm ash nanoparticles had circular morphology with particle size in the range of 20 to 25 nm. X-ray diffraction patterns of the prepared oil palm ash nanoparticles revealed the crystalline nature of the oil palm ash nanoparticles. Tensile strength and tensile modulus of the epoxy composites were substantially improved to 64, 67, 70, and 75 MPa and 1.01, 1.05, 1.16, and 1.18 MPa at oil palm ash nanofiller loading of 1%, 2%, 3%, and 4%, respectively. The impact strength of nanocomposite was enhanced from 2.7015 ± 0.13 kJ/m2 to 3.98 ± 0.17kJ/m2 at 3% of oil palm ash nanofiller loading. The optimum values of mechanical properties were attained at 4% filler loading, after which further loading resulted in the decrement of mechanical properties of epoxy nanocomposite. Thermal stability of the epoxy nanocomposite was enhanced substantially to 435 °C by the incorporation of oil palm ash nanofillers. This study proved that nano-sized oil palm ash could be an efficient reinforcement in polymer composite.

Lignin peroxidase (LiP), which has been studied extensively in white-rot Basidiomycetes with regard to bio-pulping and bio-bleaching, plays a role in the biodegradation of plant cell wall lignin. In the current study, LiP obtained from a wild isolate of Phanerochaete chrysosporium immobilized on polyurethane foam cubes was purified 21-fold using ammonium sulphate precipitation and size exclusion chromatography. The enzyme with a molecular mass of 55 kDa exhibited a considerably higher pH tolerance and thermostability compared with the native enzyme. It showed a strong affinity for the substrate veratryl alcohol and had kinetic constant values of 142.86 µmol and 65 µM. Cysteine, sodium azide, mercaptoethanol, and silver nitrate inhibited the activity, while ethanol, EDTA, Cu2+, Mn+, Na+, and Fe2+ exhibited induction. Purified LiP completely decolorized (100%) bromo phenyl blue, bromothymol blue, and bromocresol green. The 96 and 72% degradation obtained with phenol and congo red was also higher compared to crude LiP. Treatment with LiP showed reduction in ADL as compared to untreated straws, with a maximum of 2.87 units obtained in JR followed by 2.66 units in PS. The digestibility of all straws increased, the response varying from a maximum of 21.27 units in PRM to a minimum of 12.32 units obtained in LM.

The xylan recovered from alkaline black liquor (ABL) of oil palm frond (OPF) has the potential to be converted into value-added products that hold promise, especially for the pharmaceutical industry. This research highlights the maximum xylan relative recovery extracted from ABL by varying the extraction parameters such as the concentration of sodium hydroxide (NaOH) (2 to 10%) (w/v), reaction temperature (60 to 140 °C), and extraction time (30 to 150 min), followed by a 2-stage precipitation method. 6 M of hydrochloric acid (HCl) was used in the first stage to separate the lignin sub-fraction (LF) from the ABL, and 95% ethanol was used in the second stage to obtain xylan sub-fraction (XF). The optimal condition of 6% NaOH (w/v), 100 °C, and 60 min was able to recover 84% of xylan, with low contamination of lignin (7.7%) and glucan (0.3%) in XF, while higher contamination of lignin (19.3%) and glucan (10.9%) with lower amount of xylan (8.8%) were found in LF. The amount of lignin and glucan in LF through the first precipitation was higher than in XF from the second precipitation, leaving remaining fraction of XF mainly composed of xylan. In sum, the developed process reduced the alkali consumption while retaining a high xylan recovery under mild process conditions.