Investigation of a thermophilic xylanase for bleaching of kraft paper pulp

In this study, TCF bleaching sequence which the first step is Geo71 endoxylanase delignification was performed. TCF bleaching sequence stages were determined as a "XOQP". Pine and eucalyptus kraft pulp were used in the experiments. Optimization conditions of pine pulp was determined as a 10% consistency, 30UI/g Geo71 endoxylanase, pH 7,0, 70ºC, 2 hour. Optimization conditions of eucalyptus pulp were determined as a 5% consistency, 30UI/g Geo71 endoxylanase, pH 7,0, 70ºC, 2 hour. Control samples were subjected to the same treatment conditions without enzyme addition. Geo71 endoxylanase treatment as the first stage reduced the kappa number of pine and eucalyptus by 4,81 and 5,54 units. Thus the final XOQP bleached pulp showed a kappa number of 13,05 (reduction of 73,51%) for pine pulp and kappa number of 6,55 (reduction of 66,27%) for eucalyptus pulp. Handsheet paper was produced from pine and eucalyptus kraft pulp which applied bleaching sequence. And then physical and optical properties were determined to kraft pulps. Using the Geo71 endoxylanase treatment, the ISO brightness of pulp was increased when compared to non-enzymatic treated bleached pulp prepared using identical conditions. In result of pyhsical analysis, the physical properties of pine and eucalyptus kraft pulps were not determined a loss.