Changes of cellulose accessibility to cellulase due to fiber hornification and its impact on enzymatic viscosity control of dissolving pulp

Abstract

This study was to determine the effect of fiber hornification on the viscosity decrease of prehydrolysis kraft-based dissolving pulp using a commercial endoglucanase-rich cellulase. Three pulp samples, namely never-dried (ND), air-dried (AD) and oven-dried (OD), were used. The results showed that the enzymatic performance in the viscosity decrease was affected by the fiber history: the ND sample showed the strongest viscosity drop, followed by the AD sample, and the lowest was obtained from the OD sample. These results were explained by the concept of cellulose accessibility to cellulase (CAC), which decreased with the increasing degrees of hornification (DH) in the order of ND, AD and OD samples. The CAC of the samples and the cellulase adsorption on the samples were highly correlated to the DH, which consequently influenced the enzymatic treatment efficiency in viscosity control. The kinetics of the viscosity decrease during the cellulase treatment, showed an initial rapid phase, followed by a slow phase.