Abstract:
Alkaline cellulase-free xylanase from alkaliphilic Bacillus firmus K- 1 which was stableand active at alkaline condition was used for prebleaching of sugarcane bagasse, eucalyptus andpine Kraft pulps at 5 0OC and pH 9 with various enzyme concentrations and time. The hydrolysisrate of xylan in eucalyptus-pulp was better than that of xylan in sugarcane-bagasse pulp, althoughxylan in pine pulp was very difficult to hydrolyze by the enzyme. After bleaching with ClO2, thebrightness of the enzyme-treated eucalyptus and sugarcane bagasse pulps was increased at 5.34(from 52.02 to 57.36) and 2.79 (from 53.04 to 55.83) unit, respectively when compared with theuntreated pulps. It was also found that after treating with the enzyme, C10, used for bleaching ofeucalyptus and sugarcane bagasse pulps could be reduced 20% and 69%, respectively. Moreover,the bleaching time of the enzyme-treated eucalyptus and sugarcane bagasse pulps could bereduced 50% (from two to one hour) when compared with the untreated pulps. In addition, afterbleaching the enzyme-treated eucalyptus and sugarcane bagasse pulps, some physical propertiesof paper such as burst index, tear index and tensile index were improved.