Research Articles

This study investigated the mesophilic and thermophilic anaerobic fermentation of rape straw with biochar addition. The effects of biochar on the biogas yield, degradation of lignocellulose, bacterial community, and crystallinity were explored. The results showed that the biogas yield and methane content increased as the biochar concentration was increased. The biochar concentration of 5.0% resulted in a high biogas yield in mesophilic and thermophilic anaerobic digestion at 142.2 mL/g and 193.5 mL/g, respectively, which were 40.5% and 21.0% improvements compared with the control. The corresponding methane contents were 59.4% and 57.0%, respectively. For the lignocellulose degradation, the cellulose content in the mesophilic AD decreased from 54.0% in the pretreated rape straw to between 18.7% and 25.0%. The microbial community results showed that as the biochar concentration was increased, the relative abundance of Firmicutes initially increased before it decreased. Among the microbial community results, the relative abundances of Firmicutes and Bacteroides in the biogas residue of the mesophilic anaerobic digestion were the highest in the biogas residue with the 5.0% biochar concentration sample in the mesophilic AD, at 27.06% and 39.20%, respectively. This result revealed the mechanism of biochar to improve the biogas production of rape straw in anaerobic fermentation.

Most wood properties are affected by changes in moisture content below the wood fiber saturation point. In this study, the thickness swelling ratios of laminated veneer lumber (LVL) produced from Scotch pine (Pinus sylvestris L.) bonded by using polyvinyl acetate (PVAc), polymeric diphenyl methane diisocyanate (pMDI), and a mixture of them were evaluated. Thickness swelling of the samples was calculated after different waiting times under water. While the lowest thickness swelling ratio (1.65%) was determined from bonding with PVAc 92%- pMDI 8%, for 2 hours, the highest thickness swelling ratio (6.35%) was observed from bonding with PVAc 98%- pMDI 2% adhesive for 96 hours. As a result, adding pMDI to the PVAc adhesive reduced the rate of swelling of the test specimens. For this reason, the material can be used potentially in wet or humid places.

Several protective coatings enhanced by antimicrobial agents and/or pigments were considered for the wooden toy market: water-based matte varnish, an ultra-hygiene water-based matte varnish (WBV-UH), a polyurethane matte varnish (PUV), and an ultra-hygiene antiviral polyurethane matte varnish (PUV-UH), as well as a water-based dye (WBV 5%K), an ultra-hygiene water-based dye (WBV-UH 5%K), a polyurethane dye (PUV 5%K), and an ultra-hygiene polyurethane dye (PUV-UH 5%K), which contain 5% red nano-pigment (K). By utilizing 7 kinds of bacteria and 2 types of yeast that are commonly detected in routine, daily settings, the efficacy of the different protective coatings on wooden toy surface was investigated. The antibacterial and antimicrobial activities of the tested dye samples were based on the agar-well diffusion method. Ultimately, the study found that the addition of antimicrobial agents to several different protective coatings and dyes resulted in the presence of antimicrobial activity vs. the lack thereof with protective coatings and dyes alone. Additionally, some of the dyes with added antimicrobial agents were found to be effective against biofilm formation. Overall, the addition of pigment into the coating, alongside the addition of antimicrobial agents, proved to be highly effective in inhibiting growth and spread of microorganisms on wooden toy surface.

Windmill palm fiber (WPF) is an abundant source of cellulose fiber that can be used in textile manufacturing. In this study, acid-alkali palm fiber and acid-alkali-enzyme palm fiber were prepared to create blended yarns. The morphology, chemical composition, physical structural parameters, and tensile properties of the WPF samples and yarns were studied. The results indicated that both the acid-alkali and acid-alkali-enzyme treatments can be used as degumming methods to prepare windmill palm textile-grade long fibers with spinning ability. After chemical treatment, the cellulose content of WPF increased to more than 60%, up from 34%. However, the line densities of the acid-alkali and acid-alkali-enzyme textile-grade long fibers decreased to 5.29 ± 1.00 tex and 4.52 ± 0.82 tex, respectively. For the enzyme-treated fiber, a stratification phenomenon of the fiber cell walls and a decrease in the modulus were observed. The palm/cotton yarn had a high tensile strength and strip uniformity.

WO3-ZrO2 solid acid catalysts were prepared by the impregnation method and characterized by X-ray diffraction (XRD), transmission electron microscope (TEM), Brunauer-Emmett-Teller (BET), and pyridine adsorbed IR spectroscopy (Py-IR). The catalysts were used for catalytic deoxygenation of Jatropha curcas oil. The optimal conditions for the deoxygenation of the generated oil were obtained by response surface methodology based on Box-Behnken four-factor experiments. Response surface methodology (RSM) was applied while determining the optimal conditions for the Jatropha oil deoxygenation percentage. The rate was calculated based on Box-Behnken four-factor experiments, with reaction temperature, catalyst amount, reaction time, and reaction pressure as independent variables and the deoxygenation of Jatropha curcas oil as response values. The optimal reaction conditions obtained were a temperature of 370 °C, pressure of 2 MPa, time of 7 h, and catalyst amount of 0.22 g. The deoxygenation percentage of the generated oil under the optimal conditions was 95.1%, which was close to the theoretical value, indicating that the model was reliable. The generated oil contained more jet fuel components, with 68.1% C8-C16, 12.0% isoalkanes, 14.2% cycloalkanes, and 8.9% aromatic compounds under the optimum conditions. This study provides an effective and simple method for preparation of bio-aviation fuel.

In this study, the effect of wollastonite on mechanical, physical, and morphological properties of composites made of sesame stem (Sesamum indicum L.) and gypsum was investigated. The mixing ratio of sesame stem as a lignocellulosic material with gypsum at three levels (10:90, 20:80, and 30:70) and wollastonite at three levels (0%, 5%, and 10%, based on dry weight of cement) were considered as the variables. Fire resistance (weight loss) was tested according to ISO 11925-3 and DIN EN 634-1 and two specifications for the mechanical and physical properties. Microstructural properties of composites were evaluated by scanning electron microscopic (SEM) imaging. The results showed that boards containing wollastonite increased the physical and mechanical properties compared with gypsum board without wollastonite. The modulus of rupture, modulus of elasticity, and internal bonding of the boards decreased with increased sesame stemcontent, and its maximum value was obtained when using 10% sesame stem. The addition of 10% wollastonite is recommended to significantly improve the fire retardancy of the boards. The results from SEM images showed that the wollastonite can fill in the gaps inside the boards and create a solid structure.

A bio-based membrane was developed for building envelope applications. Biocomposites with enhanced water vapor permeability were fabricated based on poly(lactic acid) (PLA) and cellulose microfibers (CMF). To improve the interfacial adhesion between PLA and fibers, polyethylene glycol (PEG) was used as a compatibilizer for the modification of CMF. The properties of prepared PLA-based biocomposites were investigated in terms of their morphology, thermal stability, thermomechanical properties, and water vapor permeability. The morphological investigation showed the improved dispersion of cellulose fibers in the PLA matrix after modification of the bio-filler with PEG. The thermogravimetric analysis illustrated that the addition of modified CMFs increased the thermal stability of materials. Moreover, the water vapor permeability of PLA-based biocomposites was enhanced by adding modified CMFs to the PLA matrix. The results suggest that the utilization of PEG as a biopolymer compatibilizer represents a cost-effective and environmentally friendly method to improve the properties of PLA/CMF biocomposites. The developed membranes are potential materials for the fabrication of bio-based membranes with permeable properties that facilitate the transmission of entrapped water vapor through the building, eventually prolonging the service life of building envelope materials.

Silylation is an effective means of cellulose modification. However, the condensation reaction process between the hydrolysis products of the silane coupling agent and cellulose, as well as the structure of the coating, which both have a strong influence on the wettability, are still controversial. In this paper, the reactions of different methyltriethoxysilane hydrolysis products with cellulose were simulated via the density functional theory method. The reaction activity centers of the different methyltriethoxysilane hydrolysis products in an ethanol solution were analyzed via the front-line orbital theory and the Fukui function. The silylation reaction of different methyltriethoxysilane hydrolysis products in an ethanol solution on the cellulose surface were investigated via the transition state theory. The results show that although the initial hydrolysis product has the lowest grafting energy barrier, considering the whole process of grafting and condensation on the cellulose surface, the hydrolysis product with two hydroxyl groups is more favorable for the growth of organosilicon on the cellulose surface, so it is desirable to control the reaction where this product is dominant. In addition, the silylation process on the cellulose surface is more inclined to a multilayer coating mechanism.

The tensile relaxation behavior of bamboo fiber was evaluated. Bamboo fibers were extracted via a mechanical method and treated in alkaline solutions of sodium hydroxide. The relaxation tests of bamboo fibers were conducted by applying a constant strain at one end of a single bamboo fiber while the other end was fixed. The reaction force in the bamboo fiber was measured at the same time. The relaxation tests of the bamboo fibers were conducted under different temperature and moisture contents. The results showed that in the wet and/or high temperature conditions, the relaxation rate was faster than that in the dry and/or room temperature conditions. For a low strain, the bamboo fiber can be totally relaxed within 10 min under a high temperature. A nonlinear viscoelastic constitutive model was proposed to fit the relaxation curves, which could model the stress relaxation behavior of a bamboo fiber under different temperature or moisture content conditions. Compared with the experimental data, the model gave reasonable values for the relaxation behavior of the bamboo fiber.

This study aimed to investigate the suitability of the interlaminar shear (ILS) testing method for veneer-based composites. The ILS testing method is an established method for composite materials as a qualitative evaluation of the adhesion within the composite. The applicability of this method to veneer based composites enables a simple qualitative statement on the adhesion of the individual layers. The ILS method complements existing wood-based material tests that focus on bonding, using significantly smaller material dimensions.