THE LEACHABILITY OF LIGNIN FROM KRAFT PULPS AFTER XYLANASE TREATMENT

In this work the effect of hemicellulases on birch kraft pulp was eval uated by following the amount of lignin leached from kraft pulp after enzymatic treatment. The difference in the amount of lignin leached by 0.01M NaOH solution from the xylanase-treated and untreated pulps can be regarded as a measure of the efficiency of the xylanase pretreatme nt prior to bleaching. An increase in the amount and average molar mas s distribution of lignin extracted from the xylanase treated pulps was observed as compared with the reference pulps. In addition, different leaching kinetics of lignin were observed in the conventional and flo w-through digested (FTD) pulps. The method can be used for evaluation of the increased bleachability of kraft pulps after enzymatic modifica tions of fibre surfaces.