Volume 5 Issue 4

The removal of transition metal ions is crucial for improving the efficiency of subsequent peroxide bleaching. Acid-washing and chelation have been proposed for such a purpose. However, their influences on the Mg(OH)2-based peroxide bleaching of hardwood pulps at a high consistency have not been well documented in the literature. In this work, we studied the influence of acid-washing using sulfuric acid or chelation using diethylenetriaminepentaacetic (DTPA) on the Mg(OH)2- or NaOH-based hydrogen peroxide bleaching efficiency, effluent properties of bleaching filtrates, and paper properties. The results showed that for Mg(OH)2-based peroxide bleaching, the pulp yield and water retention value of acid-washed pulp were higher than those of the chelated pulp; the chemical oxygen demand (COD) and turbidity of the bleaching filtrates for the acid-washed pulp were lower than those of the chelated pulp. The bleached acid-washed pulp had lower strength properties than bleached chelated pulp did. Additionally, at a high pulp consistency (25%), the Mg(OH)2-based process had a higher bleaching efficiency and superior bleaching effluent properties, but a lower strength properties, in comparison with the NaOH-based process.

The chemical composition of rice hulls produced in an artisan mill and its conversion to fermentable sugars was investigated. The carbohydrate fraction represented 59.2% (w/w) of the dry hulls. Cellulose, with 36.6%, was the main component, followed by xylan with 13.9%. An important contribution of starch (8.7%) was also detected. The content of ash (19.6%) and lignin (15.5%) was comparable with that of rice hulls obtained in industrial mills. Dilute-sulphuric acid hydrolysis at different temperatures, from 160 to 210, was evaluated for production of fermentable sugars. Due to starch hydrolysis, the concentration of glucose in the hydrolysates produced at 160°C was higher than the values that have previously been reported for industrial sorts of rice hulls under comparable conditions. The xylan-to-xylose conversion increased steadily with increase of the temperature and reached a maximum (67.7%) at 190°C. Further increases of the hydrolysis temperature decreased the yield of sugars due to their dehydration to furfural and HMF.

This research aims to study the effects of degradation on mechanical, physical, and morphological properties of empty fruit bunch (EFB) fiber- reinforced polyester composites. The unsaturated polyester resin has been used to produce thermoset polymer composites. The reinforcing effect in composites was evaluated at various fiber loadings, including an overall fiber content (by weight) of 20% and 40%. The mechanical (tensile, flexural, and impact) and physical (density, moisture content, and water absorption) properties were studied before and after the samples were buried in the soil for period of 12 months. Scanning electron microscope (SEM) analysis was conducted to visualize the effect of the quality of adhesion between the fibers and matrix. The soil burial investigation results revealed that EFB fiber-polyester composites showed highest degradation percentage as compared to polyester resin and fiberglass.

Solid state fermentation (SSF) has been used as a model for the study of metabolism and physiology of microorganisms. The aim of the present study was to enhance 6-PP production by Trichoderma harzianum 4040 in solid state fermentation using sugarcane bagasse as a residue. A fractional factorial design was used to select the components of the nutrient solution. The fermentation was carried out during 9 days, and the aroma extraction was done on the third, fifth, seventh, and ninth days using organic solvent. On the seventh day the major concentration of 6-PP was found. The variables glucose, sucrose, and MgSO4 were found to be significant statistically (p> 0.05) as components of the nutrient solution used in the production of 6-PP by filamentous fungi in SSF using sugarcane bagasse as a residue. GC-MS was used for quantification of 6-PP aroma.

This paper presents the outcomes from an extensive investigation on the structure and geometry of single hemp fibres, as well as configurations and related tensile strength (TS) of hemp fibres, with the aid of field emission scanning and optical microscopy. The results showed that 1) the TS increased with the decrease of the diameter of individual test pieces, due possibly to the stacks of multiple single fibres within the test pieces; 2) shear failure between single fibres in a test pieces played a significant role in the test results; 3) the TS was closely related to the number of both the inherent joints along the fibre length and single fibres contained in the test pieces; 4) the splits along the length and width of hemp fibres may complicate the test results, and 5) the optimized treatment prior to decortications may double the TS of hemp fibres compared to a normal retting processing. Reliable TS of single hemp fibres have been derived by a power regression, and the predicted TS were verified with an excellent agreement with experimentally tested results. The tensile strain-stress plot was found to be linear for all hemp test pieces, showing that the behaviour of single hemp fibres obeys Hooke’s law.

This paper describes a method for the removal of acid-soluble lignin from acid-hydrolyzed hemicelluloses extracted from a mixture of northern US hardwood chips, by using Amberlite XAD-4 resin, which was shown to remove 100% of furan derivatives and 90% of acid-soluble lignin. Subsequent fermentation of the resin-treated hydrolyzates gave ethanol yields as high as 97% of theoretical and showed a marked increase in the fermentation rate. Regeneration of resin performed with 75% acetone was 85% efficient with respect to acid-soluble lignin.

Polypyrrole (PPy) was chemically synthesised at two pH levels (pH = 2 and unadjusted pH, i.e. 6.6) using pre-formed carboxymethylcellulose-iron (CMC-Fe) complexes. The CMC-Fe complexes were prepared at a fixed CMC concentration, i.e. 5.5x10-5 mol/L, and with an increasing FeCl3 amount (from 4x10-3 to 5x10-2 mol/L). The quantity of iron bound to CMC was determined by the inductively coupled plasma (ICP-MS) method. In order to understand the interactions between CMC and iron, speciation of the systems was simulated by Phreeqc software. SEM analysis showed that, in some conditions (particularly at pH = 2), Py polymerised within the CMC-Fe complexes, forming particles with size ranging between 300 and 600 nm. In order to evaluate polymer electric conductivity, films were prepared by direct casting of the PPy-CMC-Fe dispersions with and without addition of film-forming CMC, and bulky PPy-CMC-Fe pellets were obtained by compression. Despite the different arrangement PPy-CMC-Fe particles in dry films, the amount of iron bound to CMC during the formation of CMC-Fe complexes was found to be the dominant parameter affecting polymer conductivity.

The purpose of this study was to resolve the question of whether various nitrogen sources and concentrations affect characteristics of selected G. lucidum ligninolytic enzymes participating in wheat straw fermentation. This is the first study reporting the presence of versatile peroxidase activity in crude extract of G. lucidum culture, as well as isoforms profile of Mn-oxidizing peroxidases. NH4NO3 was the optimum nitrogen source for laccase and Mn-dependent peroxidase activity, while peptone was the optimum one for versatile peroxidase activity. with laccase activity were obtained by native PAGE and IEF separations from medium enriched with inorganic nitrogen source, and only two bands from medium containing organic source. Medium composition was not shown to affect isoenzyme patterns of Mn-oxidizing peroxidases. Four isoforms of Mn-dependent peroxidase and three of versatile peroxidase were obtained on native PAGE. By IEF separation, five isoforms of Mn-dependent peroxidase and only two of versatile peroxidase were observed. The results demonstrated that G. lucidum has potential for mineralization and transformation of various agricultural residues and should take more significant participation in large-scale biotechnological processes.

Many companies in the U.S. are entering the wood pellets market due to the increasing importance of woody biomass utilization for energy purposes. Despite a 200% increase in U.S. production, it is difficult to obtain reliable information from the research community relative to the production costs, requirements, and market trends for wood pellets. Based on comprehensive investigations, a techno-economical model for the determination of production costs for U.S. manufacturers (internal market, with sell strategy based on bagged product) was developed, considering the most important technical and financial factors that affect pellet production. Outcomes from a case-study show that pellet production is profitable for U.S. manufacturers and distributors/retailers, with more revenue margin for retailers. Sensitivity analyses were performed, showing that a pellet plant is especially sensitive to changes to the cost of biomass and labor. In addition, changes in energy and CAPEX also affect the NPV and IRR of the project, but not as significantly as biomass and labor costs. Additional findings indicate that increasing the plant size especially increases CAPEX, with labor being the least increased cost factor; in addition, production factors have to be closely monitored for small-scale producers, due to increases in operational costs.