Volume 12 Issue 4
- Researchpp 7041-7055Wei, Y., Wang, M., Zhang, P., Chen, Y., Gao, J., and Fan, Y. (2017). "The role of phenolic extractives in color changes of locust wood (Robinia pseudoacacia) during heat treatment," BioRes. 12(4), 7041-7055.AbstractArticlePDF
To investigate the effects of phenolic extractives on the discoloration of black locust wood (Robinia pseudoacacia) during heat treatment, phenolic compounds were extracted using an accelerated solvent extraction. The main components of the phenolic extractives were analyzed. The phenolic compounds were heat treated at 120 and 140 °C in nitrogen, oxygen, and saturated steam. The results showed that the a* values shifted toward red and the b* values shifted toward yellow after the heat treatment. The changes in the color parameters were more pronounced when the samples were treated at 140 °C in saturated steam compared with treatment at 120 °C in oxygen or nitrogen atmosphere. During heat treatment, hydroxyl groups in the phenolic components were oxidized to form carbonyl groups, or the adjacent hydroxyl groups formed quinoid structures. It was possible that the sample underwent condensation reactions to produce conjugated double-bond structures that led to the increase in color parameters.
- Researchpp 7056-7068Altuntas, E., Yilmaz, E., Salan, T., and Alma, M. H. (2017). "Combined effect of zinc borate and coupling agent against brown and white rot fungi in wood-plastic composites," BioRes. 12(4), 7056-7068.AbstractArticlePDF
Fungal resistance was investigated for wood-plastic composites (WPCs) containing zinc borate, maleic anhydride grafted polyethylene (MAPE) as a coupling agent, wood fiber (Pinus sylvestris), and high-density polyethylene (HDPE). Decay resistance, water absorption, and surface hardness (Shore D) of the WPCs were tested. The reinforced wood-plastic composites were exposed to brown-rot fungus (Coniophora puteana, Postia placenta) and white-rot fungus (Trametes versicolor) in agar tests. The results showed that zinc borate improved the decay resistance of the WPCs against brown and white rot fungus according to their weight losses. Moreover, the water absorption and surface hardness tests indicated that the physical properties of the composites were weakened after fungal decay tests. The usage of MAPE and zinc borate alone or together was effective against both rot fungus species in WPCs. The synergy of 1% zinc borate and 3% MAPE in WPCs could considerably increase the fungal attack resistance. Scanning electron microscopy (SEM) revealed that both brown and white rot fungus attacked the surface of WPCs samples without both MAPE and zinc borate.
- Researchpp 7069-7083Brandão, T. S. O., Pinho, L. S., Hughes, A. F. S., Souza, J. L., Rosa, C. A., Teshima, E., Brandão, H. N., and David, J. M. (2017). "Characterization of the jambolan (Syzygium cumini L.) fruit wine processing," BioRes. 12(4), 7069-7083.AbstractArticlePDF
Yeasts were isolated and the alcohol genic features were tested for their direct use in the wine processing of jambolan. In addition, changes in the total phenolic compounds during the maceration-fermentation process were investigated. Yeasts were selected from the spontaneous fermentation of the jambolan pulp, and the feasibility and fermentative production of its alcohol was tested. Out of the group of yeasts selected, the one that stood out was subjected to DNA extraction and sequencing. The yeast was identified as Saccharomyces cerevisiae, and the fermentation tests came back as 80.6% and the ethanol production yield was 8.35%. The chemical composition of raw materials was analyzed by spectrophotometrics and high performance liquid chromatography (HPLC) methods. The overall results also indicated that the evolution during the maceration-fermentation process of phenolic compound concentrations was influenced by the varietal factor. The concentration of phenolic compounds increased 30%, while the concentration of tannins increased 27.4% in the final product.
- Researchpp 7084-7095Ji, X., Ma, H., Tian, Z., Lyu, G., Fang, G., Chen, J., and Saeed, H. A. M. (2017). "Production of xylose from diluted sulfuric acid hydrolysis of wheat straw," BioRes. 12(4), 7084-7095.AbstractArticlePDF
The objectives of this study were to generate fermentable xylose by sulfuric acid hydrolysis of wheat straw and investigate the effect of hemicellulose removal on the physical and chemical properties of the unhydrolyzed solid residue (USR). Different reaction conditions, including concentration of sulfuric acid (COS), temperature, and time, were tested for their effects on the yield of xylose and the USR. The ideal hydrolysis conditions for xylose production were 0.5% of COS at 140 °C for 90 min, with the xylose yield of 0.185 g/g wheat straw. The Fourier transform infrared spectroscopy (FTIR) and X-ray diffraction (XRD) analyses showed that the acid hydrolysis only caused slight changes in the functional groups and the crystal form of wheat straw at mild conditions, while higher temperature or higher COS exacerbated these changes.
- Researchpp 7096-7106Chen, Q., Mi, T., Chen, G., and Li, Y. (2017). "Green synthesis of nano-silver particles using plant active substance from lemongrass extract," BioRes. 12(4), 7096-7106.AbstractArticlePDF
Biosynthesis of nanoparticles by plant extracts is currently under exploitation. Plant extracts are very cost effective and eco-friendly and thus can be an economic and efficient alternative. This study investigates the mechanism of preparation of nano-silver using a plant active substance from lemongrass extract. The lemongrass ethanol extract was prepared using an ultrasonic cell crusher. Spherical silver nanoparticles were prepared with lemongrass extract and silver nitrate. The reaction mechanism of the preparation of nano-silver by plant extracts was analyzed by infrared and X-ray photoelectron spectrometer (XPS) measurements. The uniform and stable spherical silver nanoparticles with an average particle size of 22.99 nm were synthesized. Amide compounds in plant extracts may act as reductants and protective agents. The biomass of plants produces their nanomaterials through a process called biomineralisation. Thus, plant active substances can be used widely, and biological methods are completely feasible and worth studying for the chemical procedures, which are environmentally friendly and convenient.
- Researchpp 7107-7117Mirski, R., Dziurka, D., and Derkowski, A. (2017). "Dimensional stability of oriented strand boards with external layers made of non-strand chips: Changes in board length," BioRes. 12(4), 7107-7117.AbstractArticlePDF
The dimensional stability of oriented strand boards (OSB) was evaluated in terms of the changes in their length, static bending strength, and modulus of elasticity. Outer layers of these boards were manufactured from particles other than strand chips. The boards were exposed to an air relative humidity of 30%, 65%, or 85%. Dimensional alterations were determined separately for absorption (from 65% to 85% RH) and desorption (from 65% to 30% RH) changes. Changes in the mechanical properties of the boards were evaluated after they underwent two cycles of the conditioning process and were compared with the baseline values. The study implied that relative changes in the mechanical properties and length increased when there was a reduction in the size of chips that formed the outer layers. A linear relationship was established between the relative changes in the board length determined for the axis that was more susceptible to deformation and the modulus of elasticity. These changes were inversely proportional to the value of the modulus of elasticity.
- Researchpp 7118-7132Chee, S. S., Jawaid, M., and Sultan, M. T. H. (2017). "Thermal stability and dynamic mechanical properties of kenaf/bamboo fibre reinforced epoxy composites," BioRes. 12(4), 7118-7132.AbstractArticlePDF
An increased awareness of environmental concerns has increased the need for innovation to produce high performance engineering materials with natural renewable resources. In this study, 3 types of natural fibre (mat form) reinforced epoxy composites were prepared by the hand lay-up method, namely, kenaf (K)/Epoxy, bamboo (B)/Epoxy, and bamboo charcoal (BC)/Epoxy. The thermal stability of the specimens was investigated by thermogravimetric analysis (TGA) and the dynamic mechanical properties. Viscous elastic behaviour of the specimens was investigated via a dynamic mechanical analyzer (DMA). The TGA results revealed that the BC/Epoxy composite showed the highest thermal stability compared to K/Epoxy and B/Epoxy with the highest initial and final decomposition temperature at 348 °C and 463 °C, respectively. It also showed the highest charcoal content at 11.5%. From the DMA results, the K/Epoxy composite showed better dynamic mechanical properties with the highest complex modulus (E*) strength and the lowest damping behaviour (peak height of Tan δ). The DMA analysis also revealed that the glass transition temperature of the composites fell between 60 °C to 90 °C. This preliminary study may give a new path to develop a novel hybrid composite that offers unique properties unachievable in a single material system.
- Researchpp 7133-7144Chin, S. X., Chook, S. W., Chia, C. H., Lau, K. S., Zakaria, S., and Tasirin, S. M. (2017). "Graphene oxide as support and regenerative substrate for lead ions in catalytic conversion of lactic acid," BioRes. 12(4), 7133-7144.AbstractArticlePDF
Graphene oxide (GO) was used as a catalyst support and for regeneration of a homogeneous catalyst in the catalytic conversion of glucose to lactic acid (LA). First, a solid base catalyst was prepared through the adsorption of Pb2+ ions by GO through ionic interaction with oxygenated groups of GO. The collected GO-Pb catalyst was characterized, demonstrating the successful loading of Pb2+ onto GO sheets using FTIR and XPS. The GO-Pb catalyst was subsequently used for the conversion of glucose into LA. A maximum LA yield of approximately 30% was achieved in 30 min. The catalyst demonstrated the ability to be used for at least five cycles. In contrast, the leached Pb2+ ions during the hydrothermal process were regenerated through adsorption with fresh GO. The regenerated catalyst demonstrated the possibility of the regenerated Pb2+ ions for further catalytic conversions of lactic acid. This study could be essential to produce valuable chemicals through the use of heterogeneous catalysts that are produced via a simple and environmental benign process.
- Researchpp 7145-7160Edhirej, A., Sapuan, S. M., Jawaid, M., and Zahari, N. I. (2017). "Tensile, barrier, dynamic mechanical, and biodegradation properties of cassava/sugar palm fiber reinforced cassava starch hybrid composites," BioRes. 12(4), 7145-7160.AbstractArticlePDF
The hybrid composite was prepared from cassava bagasse (CB) and sugar palm fiber (SPF) by casting technique using cassava starch (CS) as a matrix and fructose as a plasticizer. The chemical composition and physical properties of SPF and CB were studied in this work. SPF was added at different loadings of 2, 4, 6, and 8% dry starch to the CS/CB composite films with 6% CB. The addition of SPF influenced the hybrid properties. It was observed that the addition of 6% SPF to the composite film increased the tensile strength and modulus up to 20.7 and 1114.6 MPa, respectively. Also, dynamic-mechanical properties of the hybrid composites were investigated using a DMA test. The incorporation of SPF increased the storage modulus (E’) value from 0.457 GPa of CS to 1.490 GPa of CS-CB/SPF8 hybrid composite film. Moreover, the incorporation of SPF slightly decreased the water vapor permeability (WVP) compared to the CS/CB composites film. It can be concluded that the incorporation of SPF led to changes in cassava starch composite film properties, potentially improving the bio-degradability, WVP, and mechanical properties of the film. Based on its excellent properties, CB/SPF-CS hybrid composite films are suitable for various purposes such as packaging, automotive, and agro-industrial applications, at lower cost.
- Researchpp 7161-7177Altuntas, E., Yilmaz, E., Salan, T., and Alma, M. H. (2017). "Biodegradation properties of wood-plastic composites containing high content of lignocellulosic filler and zinc borate exposed to two different brown-rot fungi," BioRes. 12(4), 7161-7177.AbstractArticlePDF
The decay resistance of zinc borate-reinforced wood-plastic composites (WPCs) was studied against two types of brown-rot fungi (Rhodonia placenta and Coniophora puteana). The WPCs with 70% wood fibers (Pinus sylvestris L.) were reinforced with 1% and 2% zinc borate. The reinforced WPCs were exposed to a decay test according to the EN 113 (1996) standard. The composite samples were characterized by their weight losses and water absorption capacity (WAC) as well as by Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), thermogravimetric analysis (TGA), and differential thermal analysis (DTA). The weight losses and WAC results showed that zinc borate improved the decay resistance of the WPCs to a certain degree against brown rot fungi. The FTIR and SEM results showed that the brown rot fungi attacked the WPCs. It was concluded that the use of 1-2% zinc borate provided resistance to fungal attack on WPCs to a certain degree.