Volume 8 Issue 3

Bamboo is a potential lignocellulosic biomass for the production of bioethanol because of its high cellulose and hemicellulose contents. An acid-free ethanosolv process was proposed to overcome the problems caused by the acid catalysts commonly used in organosolv processes. In this research, ethanosolv pretreatment catalyzed by NaOH was used to enhance the enzymatic saccharification of moso bamboo. The addition of 10% (w/w on bamboo) NaOH in 75% (v/v) ethanol was demonstrated to be effective in the pretreatment and fractionation of bamboo. The pretreatment yielded a solid fraction with 60.1% cellulose. The cellulose-to-glucose conversion yield was 28.9% to 45.1%, depending on pretreatment conditions, after enzymatic hydrolysis of the solid fraction at 50 °C for 48 h using enzyme loading (15 filter paper units of cellulase/g cellulose and 30 IU b-glucosidase/g cellulose). The concentrations of fermentation inhibitors such as 5-hydroxy-2-methyl furfural (HMF) and furfural were negligible in the spent liquor after the ethanosolv pretreatment and were much lower than those in the spent liquor from H2SO4-water or ethanosolv only treatment.

Spent mushroom substrate (SMS), a renewable bio-waste from the mushroom-growing industry, was used as an adsorbent to remove methylene blue (MB) from aqueous solution. SMS was characterized using scanning electron microscopy (SEM) and Fourier-transform infrared spectroscopy (FTIR). Adsorption experiments with the SMS adsorbent were performed based on various parameters, such as adsorbent dose, initial MB dye concentration, initial pH, contact time, and temperature. The Langmuir, Freundlich, and Temkin isotherm models were employed to interpret the adsorption behavior. The results indicated that the equilibrium data were perfectly represented by the Temkin isotherm. The maximum adsorption capacity of SMS reached 63.5 mg g-1 at 303 K. The kinetics studies indicated that the pseudo-second-order model best described the adsorption of MB on SMS. The activation energy of the adsorption was 5.64 kJ mol-1. Thermodynamic parameters suggested that the adsorption was an exothermic and spontaneous physical process. The results imply that SMS is a potentially low-cost adsorbent for treating wastewater containing cationic dyes.

Variations in brown rot decay and proportions of heartwood and sapwood were investigated in eastern white cedar (Thuja occidentalis L.). This experiment tested the hypothesis that the incidence of brown rot decay depends on the site, tree age, tree height, and heartwood/ sapwood ratio. Forty-five trees were sampled and felled from three mature stands in the Abitibi-Témiscamingue region, Quebec, Canada. From each tree, disks were systematically sampled along the entire stem, and the heartwood, sapwood, and decay proportions and volumes were determined for each disk. Scanning electron microscopy showed that growth of fungi causing brown rot decay was limited and slower in latewood than in earlywood due to the narrow cell lumen, thick wall, and limited number of bordered pits in latewood tracheids. Site, tree height, and tree age had significant effects on the proportions of sapwood, heartwood, and decay. Heartwood and brown rot decay proportions decreased from the base of the tree upward, while the sapwood proportion increased. There was more decay in older trees and in those growing on moist versus dry sites; however, decay was not serious in trees younger than 80 years. In addition, brown rot decay proportion correlated strongly and positively with heartwood proportion and tree volume, but negatively with sapwood proportion.

The objective of this study was to evaluate the effect of heat treatment on properties including oven-dry density, weight loss, surface roughness, shear strength, and hardness of eastern red cedar (Juniperus virginiana L.). The anatomical structures of samples were also examined by scanning electron microscope (SEM). Two different heat treatment schedules, with temperatures of 130°C and 160°C and 3 and 7 h exposure times, were considered for the experiment. A stylus method was employed to evaluate the surface properties of heat-treated samples. Three roughness parameters, average roughness (Ra), mean peak-to-valley height (Rz), and maximum roughness (Rmax), were determined from the surface of specimens and used to evaluate the effect of heat treatment on the surface properties. The shear strength of samples bonded with polyvinyl acetate (PVAc) adhesive was also measured. All properties of the samples exposed to different heat treatment schedules were significantly different (p = 0.05) from each other. The results of this study demonstrated that the oven-dry density, surface roughness, shear strength, and hardness of the samples decreased, while their weight loss increased slightly, with increasing heat treatment temperature and time.

The objective of this study was to evaluate properties of experimental particleboard panels manufactured from wheat straw that had been pretreated with acetic anhydride, soapy solution, hot water, or steam. Wheat straw particles were mixed with commercially manufactured wood particles at a ratio of 60%. Control straw particleboards with non-treated straw and wood particles were also produced. The results showed that the pretreatment of wheat straw significantly improved both the physical and mechanical properties of the straw particleboards. Panels made from wheat straw treated with a 9% solution of acetic anhydride or boiled in a soapy solution resulted in the highest mechanical properties, with an increase in bending strength values. Regarding internal bond strength, the samples made from wheat straw particles treated with acetic anhydride and a soapy solution had 2 and 3 times higher values, respectively, than those of non-treated samples. It seems that the pretreatment of wheat straw had a greater effect on the thickness swelling of the specimens than on their water absorption.

Wood is known to contain and emit volatile organic compounds including formaldehyde. The emission of formaldehyde from wood increases during its processing to lumber and wood-based panels (i.e., particleboard and fiberboard). This increased emission can be attributed to the processing procedure of wood, which includes drying, pressing, and thermo-hydrolysis. Formaldehyde is emitted from wood under very high heat and is not expected to be a significant source of the emissions from composite wood products during normal service. Formaldehyde is also detectable even if wood has never been heated as well as under more or less ambient conditions. The presence of formaldehyde in the emissions from wood that does not contain adhesive resin has been explained by thermal degradation of polysaccharides in the wood. The emission levels of formaldehyde depend on factors such as wood species, moisture content, outside temperature, and time of storage. Additionally, the pyrolysis of milled wood lignin at 450 °C yields benzaldehyde, and the pyrolysis of spruce and pinewood at 450 °C generate formaldehyde, acetaldehyde, 2–propenal, butanal, and butanone, which can be attributed to the breakdown of the polysaccharide fraction of the wood.