| Utilization of enzymes in pulp and paper industry bring many benefits such as reducing the dosage of chemicals, improving the characteristic of pulp and alleviating the pressure of environment pollution.The enzymatic properties of xylanase AU-PE89 and its application in wheat straw pulp bio-bleaching were investigated. Wheat straw pulp bio-bleaching with recombination xylanase XYN II, Trichoderma reesei xylanase pretreatment in wheat straw pulp bleaching in pilot system, the relationship between xylanase prebleaching and consequent bleaching chemicals consumption were also studied. The main results were as follows:The optimal pH of xylanase AU-PE89 was 6.0 and its optimal temperature was 50℃. Controlling temperature in the range of 45～55℃, xylanase AU-PE89 demonstrated high performance of bio-catalysis.Comparing 3 different sequences of xylanase pretreatment, the pulp brightness of XCEH and CXH were 76.75% and 75.33%, respectively, which was higher than that of the control CEH 75.29% and CEHX sequence 73.12%.The optimal conditions of xylanase pretreatment in bleaching of wheat straw pulp were pH 6.0～7.0, 50～55℃, xylanase dosage 5IU/g dry pulp, reaction time 40～60min. The optim??rebleaching effects of xylanase AU-PE89 were pulp brightness 75.24% ISO, damp-heat yellowing value 1.16, breaking length 5.85 km, tear index 5.13 mN·m2/g and burst index 3.89 kPa·m2/g.Employing xylanase AU-PE89 and recombination xylanase XYN II in prebleaching of wheat straw pulp could reduce the dosage of Cl2 40～50% and more than 50% , respectively. |
