Volume 13 Issue 1

Production of fumaric acid and xylooligosaccharides from corncob was investigated using a combined process. Corncob was fractionated into a cellulose-rich fraction and a hemicellulose-rich fraction by an alkali pretreatment. The cellulose-rich fraction was converted into fumaric acid by Rhizopus oryzae in fed-batch simultaneous saccharification and fermentation (SSF). Maximal fumaric acid concentration reached 35.22 g/L at a final 15% (w/v) solid loading in the fed-batch SSF. The hemicellulose-rich fraction was converted into xylooligosaccharides (XOSs) by endo-β-1,4-xylanase. The yield of XOSs was 62.35% after 24 h of xylanase hydrolysis. Xylobiose, xylotriose, and xylotetraose were the three major components in the XOSs. A mass balance analysis demonstrated that 100.6 g of fumaric acid and 148.1 g of XOSs were produced from 1000 g of dry corncob matter. The production of fumaric acid and XOSs by the combined process could make the utilization of corncob more efficient and more promising.

The catalytic effects of various acids (sulfuric acid, hydrochloric acid, phosphoric acid, and formic acid) on the depolymerization of organosolv lignin under mild microwave heating (approximately 100 W, 160 °C for 30 min) were investigated. The liquid product was separated from the solid residue and analyzed by gel permeation chromatography (GPC) and Fourier transform infrared spectroscopy (FTIR). The solid residue was analyzed with thermogravimetric analysis (TG-DTG) and observed by scanning electron microscopy (SEM). The experimental results showed that sulfuric acid exhibited a better catalytic effect than the other acids. The SEM and TG-DTG results showed that the solid residue from sulfuric acid-catalyzed depolymerization was not only remarkably smaller than that of the other groups, but also presented a faster thermal decomposition rate. The molecular weight (Mw, weight-average) of the liquid product (Mw = 1020) from sulfuric acid-catalyzed depolymerization was also lower than that of the other groups.

Ozone is a non-chlorine bleaching agent that can reduce pollution in the pulp bleaching stage. In this work the ozone bleaching of eucalyptus kraft pulp was performed as part of a kinetics study to explain factors affecting the properties of bleached pulp. The bleaching efficiency was closely related to the rates of mass transfer and self-decomposition, as well as the intensity of ozonation. For ozone bleaching of 3% consistency pulp, a brightness of 68% ISO, viscosity of 579 mL/g, and kappa values of 7.9 were achieved under an optimal condition with pH 2 and organic reagent NP-10 supplied. In this condition, the ozone mass transfer and intensity of ozonation were promoted, while self-decomposition declined.

The electrosorption capacity of an electrode strongly depends on the surface properties of the electrode material, such as the surface area, pore microstructure, and pore size distribution. Carbon-based electrode materials for capacitive deionization (CDI) or electrosorption processes suffer from problems with high manufacturing costs, poor electrical conductivity, and poor wettability. The thin-film coating of SiO₂ on porous biomass carbon may provide an alternative electrode material for double-layer applications. In this paper, the activated porous biomass carbon (AWSC) was first obtained through a simple potassium hydroxide (KOH) activation of wheat straw carbon (WSC) as the precursor, and then thin-film SiO₂ coated AWSC (SiO₂@AWSC) was prepared by a sol-gel coating process. Scanning electron microscope (SEM) imaging of SiO₂@AWSC demonstrated that a SiO₂ thin-film was deposited on the surface of AWSC without changing the opening structure. Compared to WSC, the Brunauer-Emmett-Teller (BET) surface area of SiO₂@AWSC was greatly increased, and presented obvious micropore and mesopore distributions. Further electrochemical analyses were performed via cyclic voltammetry, galvanostatic charge/discharge, and electrochemical impedance. The electrochemical results showed that SiO₂@AWSC electrodes showed increased electrosorption capacitance, which were attributed to a large specific surface area, a porous structure, and enhanced wettability.

The bleaching of pulp prepared by a displacement digester system (DDS) for displacement cooking of bamboo (Neosinocalamus) was established by comparing the results from elemental chlorine-free (ECF) bleaching and totally chlorine-free (TCF) bleaching. This process produced the optimal performance of obtained pulp via O-D₀-E_OP-D₁ bleaching, where the Kappa number of DDS pulp was 18 to 22, and the Kappa number of oxygen delignified pulp was 10 to 12. The brightness of the obtained pulp was over 86% ISO, the yield was up to 46%, and the viscosity was approximately 800 mL·g^-1. In contrast, O-Q-P₁-P₂ bleaching was advantageous for pulp with kappa number less than 5 after oxygen delignification. The brightness of obtained pulp was up to 81% ISO, the yield was over 40%, and the viscosity was about 650 mL·g^-1. In TCF bleaching, the water consumption was 20 m³·t^-1, the chemical oxygen demand (COD) content was 30 kg·t^-1, and the absorbable organic halogen (AOX) content was zero. The water consumption of ECF bleaching was 4 times that of TCF bleaching, while the COD content was 16 kg·t^-1 and the AOX content was 2 kg·t^-1.

Wood cladding is used in the residential market. However, the use of wood cladding in nonresidential and large multi-residential projects can sometimes be difficult. This paper highlights the barriers to the use of this material and draws recommendations to overcome them. A triangulation approach was used to enhance the validity of the findings with a deep literature review, interviews with different stakeholders, and analysis of several websites. The cross-compared analyses indicated that four main obstacles have hampered the use of wood cladding in non-residential projects. In order of importance, these obstacles are the recurring maintenance needed, restricting regulations (building code fire-safety and architecture implementation), appearance issues, and technical considerations regarding detailing and installation. To overcome the barriers of wood use in the non-residential market, three development axes are proposed based on communication with stakeholders, product adaptation for non-residential markets, and new product development with regards to product maintenance performance. These recommendations can guide manufacturers in adapting their product development strategies.

The mode II fracture toughness of bamboo scrimber was evaluated. A compact shear specimen was chosen as the specimen, while the stress intensity factor K_IIC was chosen as the index for the mode II fracture toughness. In total, 54 specimens containing two different grain modes and three different thicknesses were manufactured and subjected to static loading with specially designed loading clamps. The failure modes were observed, and the crack initiating loads were obtained. The stress intensity factor was calculated and analyzed. The failure of all specimens was due to brittleness and occurred instantaneously. Thus, the linear elastic fracture mechanics is applicable to the mode II fracture of bamboo scrimber. The stress intensity factor K_IIC was 459.9 MPa·m^1/2 for the F-L grain mode and 358.0 MPa·m^1/2 for the S-L grain mode. There was no significant difference in the stress intensity factor K_IIC of specimens where the thickness ranged from 10 mm to 30 mm; a specimen with a thickness of 10 mm can be used to determine the fracture toughness of the bamboo scrimber.

The properties of irradiated and non-irradiated recycled polypropylene (RPP)/peanut shell powder (PSP) composites were investigated relative to the effects of 6 months exposure to natural weathering. RPP/PSP composites were prepared by melt-mixing and compression molding with 0 to 40 wt.% PSP loading. The fabricated composites were then irradiated using a 2.0 MeV electron beam accelerator at a fixed dose of 20 kGy. The properties of non-irradiated and irradiated composites after exposure to natural weathering were compared and characterized by tensile properties, scanning electron microscopy (SEM), carbonyl indices (CI), differential scanning calorimetry (DSC), and weight loss analysis. The results in tensile strength and tensile modulus of irradiated RPP/PSP composites increased, while elongation at break decreased. The thermal stability of irradiated composites was also improved compared with non-irradiated composites. Pores and fungus penetration were observed from the SEM morphology, while an increase in carbonyl index and weight loss of both composites were evidenced that degradation occurred. The overall results indicated that the irradiated RPP/PSP composites were more resistant to natural weathering degradation than the non-irradiated RPP/PSP composites.

The pyrolysis characteristics of untreated pine and fire retardant-treated pine (Pinus densiflora) were measured by using thermogravimetric analysis according to the ASTM E1131-08 (2012) regulation. Fourier transform infrared spectroscopy was used to monitor changes in chemical groups of fire-retardant treated specimens before and after the combustion test. In addition, the microstructures of the untreated specimen and the fire-retardant treated specimen after cone calorimeter testing were determined by scanning electron microscopy. Combustion gas toxicity was evaluated according to the test method described in Naval Engineering Standard 713 (1990). The emitted combustion gases of all specimens were carbon dioxide (CO2), carbon monoxide (CO), nitrogen oxide (NOX), and acrylonitrile. The thermal decomposition rate was reduced by about one-third that of the fire-retardant treated specimen compared to the reduction rate of the untreated specimen. These results are useful for guiding the safe utilization of fire retardant-treated wood and wood-based materials for building applications.

Wood-based industries are an important part of the European Union (EU) manufacturing sector because their growth can help in achieving EU’s industrial policy goal of raising manufacturing’s gross domestic product (GDP) to 20% by 2020. In this paper, special emphasis is placed on the influence of macro-economic factors on small and medium enterprises (SMEs) employment in the wood industry. The research objective was to test whether traditional macroeconomic indicators of economic growth are significant determinates of SMEs employment dynamics. For estimation of employment dynamics, a two-step Arellano-Bover/Blundell-Bond (a system generalized method of moments) estimator with robust standard errors was used. The model contained the following independent variables: real GDP growth rate; industrial production of wood processing industry; the number of wood processing enterprises; and exporting of manufactured goods of wood processing. The findings confirmed that the increase in GDP growth rate, the industrial production of wood processing, and exporting of manufactured goods of wood processing had statistically significant and positive impacts on SMEs employment. It was also found that the existence of a high number of enterprises had a positive impact on employment.