Search

This study aimed to determine the influence of prehydrolysis of wood chips on the kraft pulping of Populus x euramericana. Optimum cooking conditions were determined by evaluating different alkali concentrations and cooking periods. Xylanase was used to hydrolyze chips before cooking. Prehydrolysis process increased the yield and viscosity of pulp. Consequently, the mechanical properties of paper changed remarkably. In contrast, the optical properties of the unbleached kraft pulp declined due to lignin content. [ABSTRACT FROM AUTHOR]

In this study it was shown that the enzymatic removal of xylan from ECF-bleached birch kraft pulp enhances the water removal from the pulp, especially in the late stages of pulp drying. The effect of xylanase treatments on dewatering was clarified by using a moving belt former (MBF), a press simulator (MTS), and an IR-drying equipment, to simulate and to measure dewatering properties on wire, press and drying sections of a paper machine. The xylanase treatment slightly increased the pulp freeness indicating improved pulp drainage properties. At the moving belt former, however, no significant changes that would indicate enhanced dewatering in forming were observed. The xylanase treatments slightly enhanced the dewatering in wet pressing and furthermore, at the thermal drying the xylanase treatment had a positive effect on the dry solid content (DSC) development, and time to reach the 95% dry solids content was reduced by up to 15%. This was also confirmed by the decrease in the fiber saturation point (FSP) values and the amount of bulk water. Our results indicate that the xylanase treatment affected the water-binding xylan in the fiber cell wall, yielding enhanced dewatering properties, without deteriorating the pulp and paper properties.

Abstract: In this paper we describe the effect of enzyme treatments on the production of polymeric xylan, oligosaccharides and hemicellulose lean pulp by alkaline extraction of bleached hardwood kraft pulp. Enzyme treatments were carried out before one or in between two subsequent alkaline extractions by purified Trichoderma reesei xylanase and endoglucanase II (Cel 5a) as well as by a commercial monocomponent endoglucanase (FibreCareR). Without enzyme pre-treatment 61% and 7% of the pulp xylan was extracted in high purity in the first and second alkaline stage, respectively. Higher molecular mass xylan was obtained in the second than in the first alkaline extraction. Xylanase treatment before alkaline extraction hydrolyzed up to 12% of xylan to xylooligosaccharides. According to our results, preparation of polymeric xylan, and/or oligosaccharides as well as hemicellulose lean pulp with cellulose content of 93–94%, is possible by enzyme-aided alkaline extraction process. [Copyright &y& Elsevier]

A mixture of acid cellulase, acid pectinase and xylanase has been utilized for removing vegetable matters from lightly contaminated, Egyptian wool fleece. The proposed mixture is found to be effective in removing almost all the impurities based on cellulose, pectin and lignin without attacking wool keratin or affecting its inherent chemical and mechanical properties. The effect of bio-carbonization of wool on its dyeability with acid and 1:1 metal complex dyes has been studied. Kinetic studies as well as the fastness properties of the dyed fibres to washing and perspiration have also been reported. The properties of bio-carbonized wool fibres are found to be better than those of wool fibres carbonized by conventional method using sulphuric acid. [ABSTRACT FROM AUTHOR]

In this study it was shown that the enzymatic removal of xylan from ECFbleached birch kraft pulp enhances the water removal from the pulp, especially in the late stages of pulp drying. The effect of xylanase treatments on dewatering was clarified by using a moving belt former (MBF), a press simulator (MTS), and an IR-drying equipment, to simulate and to measure dewatering properties on wire, press and drying sections of a paper machine. The xylanase treatment slightly increased the pulp freeness indicating improved pulp drainage properties. At the moving belt former, however, no significant changes that would indicate enhanced dewatering in forming were observed. The xylanase treatments slightly enhanced the dewatering in wet pressing and furthermore, at the thermal drying the xylanase treatment had a positive effect on the dry solid content (DSC) development, and time to reach the 95% dry solids content was reduced by up to 15%. This was also confirmed by the decrease in the fiber saturation point (FSP) values and the amount of bulk water. Our results indicate that the xylanase treatment affected the water-binding xylan in the fiber cell wall, yielding enhanced dewatering properties, without deteriorating the pulp and paper properties. [ABSTRACT FROM AUTHOR]

• Optimization of fibers treatment process was considered for date palm fibers. • Mechanical properties of date palm fibers filled composites were investigated. • Enzymes which are free of cellulases activities contributed to cellulose-rich fibers. • Biodegradable composites at low cost and high rigidity were obtained. • High potential of DPFs filled composites for industrial sustainability was revealed. In the context of raw materials valorization, reducing pollution and producing more energy, the world is undergoing a revolutionary shift towards biodegradable materials. Biosourced materials used for biocomposites gain more and more attention regarding different properties and are means of improving properties, especially mechanical ones. The aim of this research was to evaluate the effect of various enzymatic treatments (xylanase, pectinase and xylanase + pectinase) on chemical structures, morphology and mechanical properties of date palm fiber (DPF) and reinforced DPF composites. Two types of palm residues, namely: palm and trunk, were subject of several experiments. The reaction time of fiber-enzyme treatments and enzyme activities were optimized by measuring the liberated reduced sugar. The treatments effect on the fibers surface was also examined by a Scanning Electron Microscope. Different fiber contents and fiber treatments substantially improved mechanical properties (Tension and impact resistance). Results have shown that an enzyme treatment for 8 h is enough to liberate the maximum of amorphous components. The treatment combining pectinase + xylanase enzymes contributed to more fibrillose structures and proper surface which indicates an effective elimination of lignin, hemicellulose and extractive fractions. The palm variety exhibits relatively high values of cellulose compared to trunk fiber. It was found that enzymatically treated date palm fibers enhance the composite materials rigidity by about 42 % and 29 % for trunk and palm fibers, respectively. Sustainable products with such characteristics could enhance the development and progress of sustainable industries. [ABSTRACT FROM AUTHOR]