The impact of xylanase on bleaching of Larch Kraft Pulp

The xylanase pretreatment of pulp can reduce the consumption of chloric bleaching agents and the pollution of environment. In this paper the dark-colored unbleaching Larch Kraft Pulp was pretreated by NY-III xylanase produced from Pseudomonas flu 01. The results showed as follow the optimum pretreatment conditions were enzyme usage 10 IU/g, treatment time 3h, pulp consistency 5%. By NY-III xylanase treatment, the chlorine dosage in conventional ECH bleaching process of Larch Kraft pulp could be reduced 17%, while remaining the final brightness and no adverse effect on pulp yield and strength. The another important advantage of using this enzyme is that there is no need to adjust pH value by buffer solution. Otherwise the study shows that the pulp pretreatment by chelating agent prior to enzyme treatment call improve the activity of enzyme and enhance the bleaching effect. The observation of pulps by SEM is useful to further learn the mechanism of xylanase pretreatment.