Volume 5 Issue 4

Date Palm Fiber (DPF) is one of the most available natural fibers in the Middle East, especially in Iran and the Persian Gulf region. This research provides a new insight into DPF, with consideration of morphological, chemical characteristics, and bulk density, as well as morphological and mechanical properties of DPF/HDPE wood plastic composite. There are three parts of date palm that are used for producing fiber, the trunk, rachis, and petiole. Results indicated that there is significant difference between trunk and petiole on fiber length but rachis has no significant differences relative to the other parts. The aspect ratios have significant differences among of three parts, with the highest and lowest values measured for the petiole and trunk, respectively. The chemical composition of various parts of the date palm tree differed significantly; with the highest amounts of cellulose and lignin content belong to rachis. Bulk density was measured for three parts of date palm, and the lowest amount was 0.082 g/cm3. The highest strengths were achieved in composites with 30 and 40% fiber content, depended on which original parts of the tree were used.

Production of ethanol from concentrated D-xylose solutions and hemicellulose hydrolysate of sweet sorghum bagasse was achieved by using Pichia stipitis NCIM 3497 and an isolated yeast Debaryomyces hansenii sp. These yeasts werecapable of producing ethanol from solutions containing 800 g/L D-xylose, and the optimum sugar concentration was found to be 150 g/L at pH 4, 30oC, with a production time of 72 hours. These yeasts were capable of utilizing multiple sugars. Hemicellulose hydrolysates of sweet sorghum bagasse were obtained by dilute acid hydrolysis and autohydrolysis including steam explosion treatment. The hydrolysate was treated by an over-liming process for detoxification and pH adjustment. Ethanol yield from hemicellulose hydrolysate was found to be higher than that of synthetic medium containing D-xylose. These yeasts can be used in production of ethanol from concentrated hemicellulose hydrolysates containing high pentose sugars obtained while treating lignocellulosic biomass at high substrate concentrations.

The chemical properties and soda-ethanol pulping of Carpolobia lutea was investigated as an alternative raw material for pulp and paper production. The influence of temperature, time, and concentration of pulping liquor on the pulp yields and residual lignin contents was evaluated using a central composite design. The maximum variation in the minimum residual lignin content was caused by changes in time, while temperature and time were responsible for the variation in the highest pulp yield. A maximum pulp yield of 48.53% was obtained at low values of the process variables. The selectivity of lignin dissolution was independent of the working conditions but allowed quantitative estimations to be established between the yield and residual lignin content within the range studied. Combined effects of temperature and time revealed that pulping at high temperature for a short time may be more advantageous, especially when high rate of delignification and substantial savings in time is required.

This paper describes an investigation of the influences of chlorine dioxide treatment on fibre surface lignin. The fibre surface characteristics and the interfacial behaviour of the sisal fibre/phenolic resin composites were also studied by SEM, AFM, and XPS. The results show that the surface of the untreated fibre contains a large amount of lignin with granular structure and non-granular structure. The surface lignin concentration is up to 51% for the untreated fibre, and then it decreases to 24% and 20% for fibres treated with 1.5 % and 2.0% chlorine dioxide, respectively. The removal of lignin from the fibre surface can enhance the interfacial strength of the composites, giving rise to increases by 36% and 28% in tensile strength and internal bonding strength. These results indicate that the surface properties of single sisal fibres can be tailored to improve the fibre/resin interface. Chlorine dioxide treatment has potential for surface modification of sisal fibre in engineering the interfacial behaviour of composites.

According to the character of straw pellet fuel cold molding technology, the compressing process was modeled by Finite Element Modeling (FEM) structure analysis tools. This indicated the variation laws between the stress and the strain, and the influence of the structure parameters of the die on the stress and the strain. It’s concluded from the work that when the length-to-diameter ratio of the die was 5.2 and the conicity of the die was 45o, the compress molding showed better degree of bonding and finish. This provided theoretical evidence for the study of the molding mechanism of the straw pellet and the selection of the structure parameters of the die.

Mixtures of starch and lignocelluloses are available in many industrial, agricultural, and municipal wastes and residuals. In this work, dilute sulfuric acid was used for simultaneous pretreatment of lignocellulose and hydrolysis of starch, to obtain a maximum amount of fermentable sugar after enzymatic hydrolysis with cellulase and β-glucosidase. The acid treatment was carried out at 70-150°C with 0-1% (v/v) acid concentration and 5-15% (w/v) solids concentration for 0-40 minutes. Under the optimum conditions, obtained at 130°C, 1% acid, and 7.5% solids loading for 30 min, the starch was almost completely converted to glucose. However, the acid treatment was not successful for efficient hydrolysis of pure cellulose. A mixture of pine softwood and potato as representatives of lignocellulosic and starch components, respectively, were treated at the optimum conditions for acid hydrolysis of starch. The dilute-acid treatment resulted in 1.2, 60.5, and 23.6% hydrolysis of glucan, xylan, and mannan of pine wood and 67% of potato starch to fermentable sugars. After the acid treatment, the solid residue of the mixture was subjected to enzymatic hydrolysis. The enzymatic hydrolysis under the optimum conditions resulted in conversion of 76% of the glucan in the treated softwood. Therefore, using acid treatment of the mixture is a promising process for pretreatment of wood in addition to the hydrolysis of starch.

Microbial biomass having 46% crude protein content and enriched with essential amino acids as well as extracellular xylanase activity (100-150 IU/ml) was produced by an efficient fungal strain, Penicillium janthinellum (NCIM St-F-3b). Optimization studies for maximum xylanase and biomass production showed that the fungus required a simple medium containing bagasse hemicellulose as carbon source and ammonium sulphate as the nitrogen source. Therefore bagasse, which is a waste product of the sugar industry, can be efficiently used in microbioal biomass protein preparation for animal feed.

Dwarf-green coconut fibers were modified by alkali treatment and characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), as well as thermogravimetric (TGA), mechanical, and dielectric analyses. Changes in composition, structure, and morphology of the coconut fibers were observed after sodium hydroxide treatments due to the removal of lignin, hemicellulose, and other impurities. The XRD data were in agreement with the morphological analysis, where the crystallinity fraction increased with the concentration of alkali solution and fell off above 10%. The infrared spectrometry showed the partial dissolution of hemicellulose, lignin, and pectin, which was clearly identified by the band at 1736 cm-1. Thermogravimetric analysis showed a double degradation process for the untreated dwarf-green coconut fibers, while a single one was observed after the pretreatment. The tensile properties showed an increased elongation at break, modulus, and strength, and the dielectric results showed a decrease of all parameters (permittivity, dielectric loss, and conductivity), reflecting the reduced dipole and ion mobility associated with the loss of amorphous components.

The effect of hemicellulose extraction of pine wood chips by water prehydrolysis on subsequent kraft cooking and paper properties was studied. Prehydrolysis reduced the required cooking time by approximately 40% and increased kappa number reduction in oxygen delignification. Prehydrolysis decreased the overall brownstock pulp yield on wood by 7.2 percentage units. Consequently, valuable products would need to be produced from the prehydrolyzate to compensate for the resulting increase in wood consumption. In DED-bleaching, lower bleaching chemical dosages were needed with prehydrolyzed than with unhydrolyzed pulps to obtain similar final brightness. As expected, removal of hemicelluloses led to a decrease in the tensile index and increase in the tear index. At a given density, the strength potential of prehydrolyzed pulps was higher than that of unhydrolyzed pulps. There was an up to more than fivefold increase in beating revolutions in a PFI-mill needed to obtain comparable tensile indices. This significant reduction in beating response might pose problems in the commercialization of prehydrolyzed pulps. In general, differences between the paper properties of prehydrolyzed pulps and unhydrolyzed pulps are attributed to decreased inter-fiber bonding in prehydrolyzed pulps.

Current deinking processes use potentially environmentally damaging chemicals in large quantities. The use of enzymes could be an attractive alternative to certain other chemicals used in deinking. In this research, the effects of different HLB (hydrophile-lipophile balance) values and enzymatic treatments on the deinking of old newspaper pulp (ONP) was studied, and optical properties and mechanical strengths of deinked pulps (DIP) were determined. Enzymatic treatments of old newspaper pulps were performed at two temperatures, 20°C and 50°C. Nonionic surfactants with different HLB values were used as the flotation agent. The flotation was conducted for pulps with and without enzymatic treatment. The results showed that brightness values for the floated pulp without enzyme treatment were slightly greater than for the enzyme-treated deinked pulp. Also, dirt count for treated pulps with commercial cellulase and floated with ethoxylated fatty alcohol of HLB 12 at 50°C was lower than that of other pulps. The mechanical strengths of the enzymatically deinked pulps, in terms of burst, tensile, folding endurance, E-MOD, and elongation, were increased, but tear strength for the floated pulps with ethoxylated fatty alcohol of HLB 12 was increased at 50°C without enzymatic treatment. Also, the deinking efficiency of handsheets made from treated pulps with commercial cellulase and ethoxylated fatty alcohol of HLB 12 was highest. The treated pulps with enzyme only, with a combination of commercial cellulase and lipase at 50°C, showed the lowest freeness value in comparison with other pulps.