EFFECTS OF XYLANASE PRETREATMENT ON THE BLEACHING PROPERTIES OF WHEAT STRAW PULP

摘要

This work examines the effects of endo-xylanase and xylosidase pretreatments on the bleaching characteristics of wheat straw pulp.The results show that the brightness of bleached pulp pretreated with endo-xylanase and xylosidase increased by 4.0% and 3.4%,respectively,and that,at a chlorine dosage of 5%(on pulp),the strength of bleached pulps was higher than that of the control.When used together,endo-xylanase and xylosidase act synergistically in the pretreatment of wheat straw pulp prior to bleaching.The brightness of the bleached pulp pretreated with a mixture of endo-xylanase and xylosidase increased respectively by 0.6% and 1.2% greater than that with endo-xylanase and xylosidase solely.However,the bleached pulp strength was inferior to that obtained by either endo-xylanase or xylosidase pretreatment.Electron microscopy revealed that the enzymatic pretreatments produced more numerous and larger pores on the surfaces and cross sections of fibers than those existing in untreated pulp.