Volume 8 Issue 1

Dewaxed Olea europaea L. was subjected to delignification followed by alkali extraction with 10% KOH containing 1% H3BO3. The released hemicelluloses were fractionated by precipitation through acidification and ethanol solutions with increasing concentrations from 20 to 30, 40, 50, 60, 70, and 90%. The structure of the subfractions obtained was comparatively characterized by sugar analysis, molecular weight, FT-IR, and NMR spectroscopy. Results indicated that 23.5% of hemicelluloses (% of the dewaxed material) were isolated by the alkaline extraction. An increase of ethanol concentration resulted in the precipitation of the more branched hemicelluloses as indicated by the increase of the ratios of arabinose to xylose and uronic acids to xylose. The hemicellulose subfractions Ha (precipitated by acidification to pH 5.5) and H30 (precipitated by 30% ethanol solution) had a similar structure, which was assumed to be glucuroxylan together with a small amount of α-glucan, whereas the hemicellulose subfraction H70 (precipitated by 70% ethanol solution) had a more complicated structure, which was mainly composed of a (1→4)-linked β-D-xylopyranosyl backbone with various side chains. The comprehensive structural characterization of the hemicelluloses of this species provides fundamental information for their potential applications in the fields of materials, chemicals, and energy production.

In this work, kitchen waste was used as substrate for bio-pesticide production by solid-state fermentation. It was assessed to be well suited for the growth of Bacillus thuringiensis in the experiments. The culture medium contents were optimized by an orthogonal test. The optimum mixture was 55.21% kitchen waste, 22.08% wheat bran, 11.04% soybean cake power, 11.04% grain hulls, and 0.63% mixed ions. In the optimized conditions, a spore count of 5.01 × 1010 CFU/g and entomotoxicity of 15200 IU/mg were obtained after 48 h fermentation, while 2.51 × 1010 CFU/g spore count and 12900 IU/mg entomotoxicity were obtained from the conventional medium. Oil and salt had few adverse effects on Bacillus thuringiensis growth, yield of spores, and toxicity when the concentration of oil and salt were controlled below 10% and 0.4% to 1.2%, respectively. Fermentation medium of 35 kg was successfully used to produce bio-pesticides from solid-state fermentation in a scale-up experiment. Therefore, the present study proved the feasibility of using kitchen waste for the production of bio-pesticides. It seemed to be a promising alternative to conventional media to reduce costs.

This work presents dimensional and shape changes of aspen wood due to surface embossing. The influences of wood treatment, degree of pressing, and initial moisture content on the stability of wood were investigated. The stability of the wood was investigated through dimensional changes (volumetric and linear shrinkage) and shape changes (permanent deformations). The aspen wood was treated by steaming and radio frequency (RF) heating. The treatment did not have a significant effect on the moisture and shape stability of wood after pressing. The non-treated wood showed better stability after pressing.

The paper examines copper ion removal and recovery from mining waters using chitosan and cross-linked chitosan beads as insoluble sorbents in acidic and basic solutions. Batch adsorption experiments were carried out as a function of pH, adsorbent dosage, contact time, and initial Cu(II) ion concentration. Equilibrium data were fitted using Langmuir, Freundlich, Elovich, and Temkin models. The experimental data were best represented by using a pseudo-second order kinetic model and a Langmuir isotherm model. Recovery of Cu(II) ions from sorbents was successfully achieved by treating sorbents with an aqueous EDTA solution. A potentiometric method has been employed to detect the Cu(II) ions in synthetic water samples after the adsorption process. The results demonstrated that Cu(II) ions can be efficiently removed from synthetic aqueous solutions, similar to mining waters, using chitosan and cross-linked chitosan beads.

The aim of this paper was to analyze energy-related properties of forestry and agricultural wastes for energy production purposes, and to compare them with fossil fuels. The forestry wastes used were red cedar, Eucalyptus,and Pinus wood shavings. The agricultural wastes analyzed were rice husk, coffee wastes, sugar cane bagasse, maize harvesting wastes, and bamboo cellulose pulp. The forestry wastes presented more suitable properties for bioenergy production than the agricultural wastes. Desirable energetic properties were found for coffee wastes. The opposite was verified for rice husks. Among the biomass studied, coffee wastes presented the highest equivalent in fossil fuel volume and hence may lead to the highest decrease in CO2 emissions by fossil fuels used in Brazil for steam and heat production. The results suggests that CO2 benefits can be obtained if bioenergy is generated in the same locale where biomass is produced, avoiding CO2 cost of logistics and leading to greater end-use efficiency. The present work promotes the widespread use of different lignocellulosic wastes for bioenergy production and gives useful information for the planning and the control of power plants using biomass.

Unbleached and oxygen-prebleached pulps were produced both in industrial and laboratory scale using Eucalyptus urograndis woods from two different sites (A and B) as a raw material. Quantitative chemical analysis of wood and pulp was performed, aiming to find a correlation with bleaching performance. Fiber dimensions measurements in wood were also performed. Carbohydrates and lignin composition in wood from A and B were found to be similar, while extractives in acetone presented variations of about 0.5% between wood from site A and B. Laboratory-made unbleached pulps from A and B had brightness varying 0.3% ISO, whereas pulps from industry presented variations over 4% ISO from each other. By virtue of its high unbleached pulp brightness, the industry-made sample A presented a higher bleachability than its sample B counterpart. The higher bleachability of the industry-made sample A was traced to its much higher content of hexenuronic acids (HexA), which was caused by differences in pulping conditions in mill sites A and B.

Norway spruce (Picea abies [L.] Karst.) is an important forest species, comprising approximately 55.9% of the growing stock of Czech forests. The variations in the wood densities from three different locations were evaluated with respect to their mechanical and physical properties. Also, mechanical properties and formaldehyde emission of particleboard (PB) and medium-density fibreboard (MDF) panels produced from Norway spruce wood were investigated. The overall average density of the spruce wood was 509.22 kg/m3, ranging from 400.95 ± 27.92 to 617.50 ± 29.91 kg/m3 by location. Most of the panels exceeded the requirements of EN standards for the measurements of MOE, MOR, and the internal bond. Furthermore, the results showed highly significant differences (p < 0.001) among the panels for PB and MDF, which could be related to inter-panel variations. The formaldehyde emissions of PB and MDF were below the E1 emission limits. Moreover, positive correlations were found between the formaldehyde emissions (perforator and gas analysis methods) and board density. The results of this study verify our knowledge of wood density variation as affected by location as well as the age of trees and their relationship to mechanical and physical properties. Consequently, the variation in mechanical properties of the produced panels as well as the formaldehyde emission can further contribute to creating models to predict the quality of the product.

This study evaluated biological resistance of composites produced from polypropylene and either wood or bamboo by using two different levels of particle content and three different particle sizes. Composite specimens containing higher particle content and smaller particle size resulted in increased mass losses in decay resistance tests against Tyromyces palustris, a standardized test fungus, Schizophyllum commune, and Pycnoporus coccineus. As particle content increased, mass losses in laboratory termite resistance tests increased; however, decreased particle size caused slightly decreased mass losses. Higher mass losses in bamboo-composites were obtained compared to mass losses in wood-composites in biological resistance tests. There is no significant effect of particle size on water absorption and thickness swell. The IR spectrums of composite specimens showed that significant changes were seen in the wood components following the application of heat during the manufacturing process. While the IR spectrum of WPC specimens with 70% wood was similar to the wood, the composite specimen with 50% wood displayed similarities to polypropylene.

This study investigates how drying affects the quality of bamboo kraft pulps. Two bamboo pulps, cooked to different kappa numbers (i.e. 10 and 26) and D(EOP)D bleached to approximately the same brightness, were used to examine the relationship between cooking, drying, refining, and pulp/fiber properties. Drying of the two pulps caused, as expected, a loss in tensile and burst strength while the tear index was improved. The bleached high kappa pulp required less energy to reach a certain Schopper Riegler value and exhibited greater strength properties than the low kappa number pulp. These differences were also maintained after drying. Results showed that the properties of the pulp before drying determined the final strength potential of the pulp after drying. Thus, kraft cooking of bamboo to high kappa number prior to bleaching gave pulps with improved response to refining and pulp strength properties, which in turn influenced the properties of the dried pulps.

The purpose of this work was to determine the main factors influencing the phenolic content of bark during acid hydrolysis. The optimization of polysaccharides hydrolysis was done by response surface methodology. The hydrolysis was performed under atmospheric pressure in an aqueous solution of sulfuric acid. An experimental design was applied to analyze the effects of the reaction time (5 to 24 hours), acid concentration (3 to 20%), and solid/liquid ratio (1/10 to 1/5) on the weight loss, lignin content, holocellulose content, and sugar yield for the hydrolysis. The pretreated bark had a high lignin content of 60% resulting from hemicelluloses hydrolysis and phenolic compound condensation.