Alkaline Xylanase Produced by Trichoderma reesei: Application in Waste Paper Pulp Bleaching

In this work, a facile, green approach to natural biomass bleaching is reported. It was found that Trichoderma reesei could produce alkaline xylanase and xylanase is highly active in alkaline environments. It has good environmental adaptability and could be used to reduce the use of bleaching chemicals for the pretreating process and degradation of hemicellulose so as to break the linkages of Lignin-carbohydrate complexes (LCCs). These particular properties benefit the pulp bleaching process and can improve the physical properties of the resulting paper. The optimum bleaching process conditions were as follows: dosage, 12 U/g; pH, 8 to 9; time, 60 minutes; and temperature, 70 °C. The xylanase can decrease the chemical oxygen demand (COD) of bleaching effluent by 41% as compared to the blank. Finally, after xylanase pretreatment, the whiteness, yellow index, tensile index, burst index, and elongation of the resulting paper were 54.8% ISO, 1.73, 33.93 N·m/g, 2.91 KPa·m/g, and 2.91%, respectively.