The Use of Ultrasound in Bio-Treatment of Jute Yarn with Laccase Enzyme

Background and Objective: Jute fiber is highly sensitive to the action of light. Significant features of the photochemical changes lose its tensile strength and develop a yellow color. It has been proved that the phenolic structure of lignin is responsible for the yellowing of jute fiber. In order to remove lignin, jute yarns were treated with laccase enzyme in different treatment times and ultrasonic powers. Lower whiteness index and higher yellowness index values were obtained by the laccase-ultrasound system in contrast to conventional laccase treatment. Methods: The laccase enzyme which entered the fibers by applying ultrasound, decreased the tensile strength while the loss in tensile strength was lower at high ultrasound intensities. FT-IR spectrum showed that the band at 1634 cm-1 assigned to lignin completely disappeared after laccase treatment in the presence of ultrasound. The absence of this peak in the laccase-ultrasound treated jute yarn suggests complete removal of lignin. Change in the morphology of fibers was observed by SEM before and after enzymatic delignification. The laccase-ultrasound treated yarns showed a rougher surface and more porosity. On the other hand, it was more effective in fibrillation of the jute fibers than the conventional method. Finally, bio-treated jute yarns were dyed with basic and reactive dyes. Results: The results indicated that at low intensities of ultrasound and relatively long reaction times, lignin can be more effectively removed and dye strength (K/S) increased to a higher extent. Laccase-ultrasound treatment increased the color strength by 33.65% and 23.40% for reactive and basic dyes respectively. Conclusion: In the case of light fastness, the conventional laccase treated yarns provided better protection than laccase-ultrasound treated yarns.

Optimization of Laccase/Mediator System (LMS) Stage Applied in Fractionation of Eucalyptus globulus

In a biorefinery framework, a laccase/mediator system treatment following autohydrolysis was carried out for eucalyptus wood prior to soda-anthraquinone pulping. The enzymatic and autohydrolysis conditions, with a view to maximizing the extraction of hemicelluloses while preserving the integrity of glucan, were optimized. Secondly, pulping of solid phase from Eucalyptus globulus wood autohydrolysis and the enzymatic process was carried out and compared with a conventional soda-anthraquinone (AQ) pulping process. The prehydrolysis and enzymatic delignification of the raw material prior to the delignification with soda- Anthraquinone (AQ) results in paper sheets with a lower kappa number and brightness and strength properties close to conventional soda-AQ paper and a liquid fraction rich in hemicellulose compounds that can be used in additional ways. The advantage of this biorefinery scheme is that it requires a lower concentration of chemical reagents, and lower operating times and temperature in the alkaline delignification stage, which represents an economic and environmental improvement over the conventional process.

Enzymatic delignification and hexenuronic acid removal in cellulosic papermaking pulp using a haloperoxidase

A novel approach for lignin and hexenuronic acid removal from cellulosic pulp based on the combination of a vanadium haloperoxidase and a tertiary amine co-catalyst.

Mycotechnology for Lignocellulosic Bioethanol Production

One of the major challenges for society in 21st century is to find a sustainable eco-friendly renewable liquid fuel for replacing petroleum based fossil fuels. Bioethanol is one ofthe most consumable biofuel in the world. Lignocellulosic plant biomass can be an untapped source of fermentable sugars for significant production of bioethanol. But, the polyphenolic lignin of the biomass hinders the digestibility of cellulose, thus the goal of any pre-treatment technology is to remove this structural component to improve the cellulose accessibility for enzymatic saccharification. A wide range of pretreatment methods and their combinations have been reported for delignification, but recently, the environment friendly approach of microbial pre-treatment has received much attention for enzymatic delignification and saccharificaton of biomass. The extracellular lignin degrading enzymes and cellulase enzyme complex from fungi are now considered for biological delignification and saccharification, respectively.