Using of xylanase and cold caustic extraction to remove hemicellulose from bagasse bleached pulp for dissolving pulp production

In this study, a bagasse bleached paper-grade pulp from Pars pulp and paper mill was subjected to xylanase (X) treatment and combined with cold caustic extraction (CCE). The positive effect of the enzyme was observed on the removal of hemicelluloses and with increasing the dosage of xylanase treatment (0.01-0.05 g/g pulp), the extraction of hemicelluloses from the pulp increases, but there is still high remaining hemicelluloses in the pulp. The xylanase treatment increased the polydispersity index (8.21-8.46) resulting in a broader molar mass distribution. High molecular weight cellulose fraction (DP>2000) increased by the xylanase treatment and the highest amount was thus observed by 0.05 dosage of the enzyme. The cold caustic extraction compared to the combined treatment results in a significant extraction of hemicelluloses from the pulp. The viscosity and brightness of pulps (82.04 and 454 ml/g, respectively), on the other hand, increase by the cold caustic extraction. Also, a narrow molar mass distribution can be obtained by this treatment which has much potential for targeted production of cellulose. Overall, the results of this study indicate the success of the conversion of paper-grade pulp to dissolving pulp with a cold alkaline treatment.