Volume 9 Issue 2

This paper presents a new kind of composite produced with small-diameter bamboo (Phyllostachys glauca McClure) and extruded tubular particleboard. The mechanical properties of the composite are significantly affected by the properties of the bamboo. First, the compression strength of the bamboo was studied. It was found that the compression strength (fc, MPa) and the maximum force of compression (Fmax, kN) of the bamboo are strongly, linearly related to its outer diameter (D, mm): fc = -0.5D+79.37 and Fmax = 0.83D–0.59. The compression strength of the composite made with the bottom part of the bamboo was larger than that of composites made with the middle and top parts. In addition, its reliability was also the best of the three groups due to the variation of the outer diameter of the bamboo from the bottom to the top. The bottom part of the bamboo is the best choice for manufacturing bamboo-reinforced extruded particleboard (BREP).

Acorn starch was used for ethanol production by separate hydrolysis and fermentation (SHF) in this study. The influence of tannins on hydrolysis and fermentation was investigated using ultrasonic-assisted extraction (UAE) to decrease the amount of tannin before SHF. The tannin was shown to have a negative role in hydrolysis and fermentation, and UAE can improve the two processes. The tannin content of acorn starch decreased from 6.19% to 1.91% with the UAE pretreatment time of 200 min. When the pretreatment time was 120 min, the glucose concentration increased from 78.08 to 98.76 g/L after 24 h of hydrolysis. The highest ethanol concentration was 42.22 g/L, which was obtained from the same pretreated acorn flour fermented for 12 h. However, the maximum ethanol yield was 88.06% of the theoretical yield, while pretreatment time was 80 min. Scanning electron microscope images indicated that protein was separated from the starch granules by UAE, as well as by the molecular weight of starch which decreased significantly based on the results from gel permeation chromatography (GPC) analysis.

The objective of this work was to prepare a series of composite films (polysaccharides with LaFe0.8Cu0.2O3) for the degradation of methyl orange under ultraviolet irradiation. LaFe0.8Cu0.2O3 was prepared by a sol-gel method, and the composite films were obtained by cross-linking reactions between polysaccharides (xylan and chitosan) and LaFe0.8Cu0.2O3. Physical and chemical properties of the composite films were investigated by XRD, FTIR, SEM, and BET. Moreover, the influence of the weight ratio of polysaccharide to LaFe0.8Cu0.2O3 on the methyl orange degradation reaction was also studied. Results showed that 67% of the degradation efficiency was achieved within 480 min using chitosan/LaFe0.8Cu0.2O3 (2:1) as photocatalysts, while 58% was for xylan/LaFe0.8Cu0.2O3 (1:1). The difference was due to the variety in the structure of chitosan and xylan.

Biomass is a renewable and CO2-neutral source of energy having the drawback of low energy density. The energy density can be augmented by the production of bio-oil through fast pyrolysis. The high content of water-extractable organic acids (oxygenates) in bio-oil is problematic in fuels. Cultivation of Saccharomyces cerevisiae for the consumption of these undesirable components can be used to upgrade the bio-oil. It was found that the bio-oil water phase can support the growth of S. cerevisiae at concentrations up to 20 vol. % under aerobic conditions. The oxygenates formic acid, acetic acid, and propionic acid had a promoting effect for the cultivation of S. cerevisiae in the following order: acetic acid > formic acid > propionic acid. However, phenol, p-cresol, and furfural inhibited the growth of S. cerevisiae. Kinetic analysis of the consumption of oxygenates showed that the regulation of S. cerevisiae was in accordance with a logistic function model.

In this study, a comparison between oil palm empty fruit bunch (OPEFB) composting using palm oil mill effluent bio-char solution (POMEBS) aerobic sludge and palm oil mill effluent (POME) anaerobic sludge was reported. A set of experiments was designed by central composite design (CCD) using response surface methodology (RSM) to statistically evaluate the POMEBS aerobic sludge as microbial seeding. The bacteria count of POMEBS aerobic sludge (3.7×106 CFU/mL) at the optimum point was higher than that of POME anaerobic sludge (2.5×105 CFU/mL). Denaturing gradient gel electrophoresis (DGGE) and Fourier transform infrared spectroscopy (FTIR) were also performed. A rotary drum composter was then used to compost OPEFB with POMEBS aerobic sludge and POME anaerobic sludge, separately. Thermogravimetric analysis (TGA) showed that composting OPEFB with POMEBS aerobic sludge had a higher degradation rate compared to composting OPEFB with POME anaerobic sludge. In addition, the final N:P:K values for composting OPEFB with POMEBS aerobic and POME anaerobic sludge were 3.7:0.8:6.2 and 1.5:0.3:3.4, respectively. POMEBS aerobic sludge improved the composting process and compost quality.

In biomass pretreatment processes, both the properties of feedstock and process parameters play important roles in the yield of downstream enzymatic hydrolysis. More importantly, like many other industrial processes, the pretreatment system is multivariate and the variables in the system are inter-related to different extents, which means that studying the relationships of the key variables is of critical importance for the improvement of downstream enzymatic saccharification yield. In this work, two multivariate analysis methods of the Principal Component Analysis (PCA) and Partial Least Square (PLS) were employed to characterize the detailed relationships of the key process variables of alkaline sulfite pretreatment of corn stover. The results showed that the total alkali charge is positively correlated with the sugar content in pretreated biomass, lignin removal efficiency, and final sugar yield; pretreatment temperature has negative impact on the recovery of polysaccharides; and total alkali charge is more influential than other pretreatment process variables (such as Na2SO3/NaOH and temperature) under the conditions studied.

Four bio-oils obtained from the hydrothermal liquefaction (at 280 °C for 0 min) of untreated and pretreated cypresses were subjected to several types of chemical analyses to compare their structural features and chemical constituents. Pretreatments were carried out with alkali at 90 °C for 0.5, 1, and 2 h. The bio-oils were further divided into water-soluble oil, diethyl ether-soluble oil, and diethyl ether-insoluble oil fractions. Alkaline pretreatment had a significant effect on the contents of different components in the bio-oils. The diethyl ether-insoluble oil fraction was made up of intermediate-sized macromolecular fragments of lignin decomposed during the hydrothermal liquefaction process. The G6 resonance, β-5, β-β’, and β-O-4’ peaks (which were present in the spectra of milled-wood lignin) almost disappeared from the spectra of the diethyl ether-insoluble oil fractions obtained via hydrothermal liquefaction of pretreated and untreated cypresses. At the same time, the intensities of the peaks corresponding to methoxy groups, G2, and G5 resonances were reduced. Long-duration alkaline pretreatment created a strong, highly water-soluble oil fraction with a wide molecular weight distribution.

Lignin preparations from kraft and sulfite pulping, steam explosion, and enzyme saccharification processes were assessed as substrates for lignin polymerization catalyzed by Trametes hirsuta laccase (ThL). Oxygen consumption associated with laccase catalyzed oxidation of the selected lignins was measured using a microplate-based oxygen assay. Laccase-induced changes in the molecular masses of the lignin polymers were assessed with aqueous-alkaline size exclusion chromatography (SEC) and changes in monomeric phenolics by reverse-phase high pressure liquid chromatography (HPLC). Obtaining consistent results in the lignin-laccase assay system required careful pH monitoring and control. All lignin preparations were oxidized by ThL, the rate being highest for steam-exploded eucalypt and lowest for enzyme-saccharified lignin. Comparing lignins, higher lignin-laccase reactivity was correlated with lower lignin molecular mass and higher amounts of monomeric phenolics. Solubility was not an indicator of reactivity. Steam-exploded and lignosulfonate-treated pine preparations were further fractionated by ultrafiltration to determine what molecular mass fractions were the most reactive in ThL catalyzed oxidation. Both retentate (> 3kDa), and to a lesser degree permeate (< 3kDa), fractions were reactive.

The aim of this study was the development of an eco-friendly dye that may be used in furniture, woodworking, and upper surface treatment, with no ill effects to human health. The plant dyestuff was extracted from pomegranate skin (Punica granatum) and black mulberry (Morus nigra) using an ultrasonic method at different rates. The extraction percentage ratios were, by weight in distilled water, 25%, 30%, 35%, 40%, 45%, and 50% and were applied to Scotch pine (Pinus sylvestris L.) and Oriental beech (Fagus orientalis L.) through an immersion method. After that, the determination of color change under the accelerated weathering conditions and the feasibility as the upper surface stain of this dyestuff were studied. The values of total color change of the natural dye samples that were applied to the test material were determined after accelerated weathering processes lasting 50, 100, and 150 h, according to ISO 2470. The results showed the best color stability in Oriental beech wood that was treated with 30% pomegranate skin or black mulberry extract as well as Scotch pine wood that was treated with 25% pomegranate skin extract or 50% black mulberry extract. Exactly the same ΔE* values were obtained with the same dyestuff and same wood type, indicating close color stability behaviors. According to the results, both pomegranate skin (Punica granatum) and black mulberry (Morus nigra) can be used to color wood materials.

Response surface methodology (RSM) was employed to optimize dilute alkaline pretreatment conditions for the maximum glucose yield of poppy stalk, with respect to NaOH concentration (1.0 to 3.5%, w/v), pretreatment temperature (50 to 100 °C), and pretreatment time (10 to 110 min). Recovery of glucan ranged from 61.02% to 99.14%, based on the initial glucan in the raw material. The highest lignin removal (43.43%) was obtained at the pretreatment conditions of 90 °C and 3.50% NaOH for 90 min. The optimum pretreatment conditions for maximum glucose yield after enzymatic hydrolysis were found to be 2.40% w/v NaOH, 70 min, and 80 °C. Under these conditions, experimental glucose and xylose yields were 499.35 mg/g glucan and 498.66 mg xylose/g xylan, respectively.