The addition of Cu Zn

Dissolving pulp; Cellulase; High consistency; Viscosity; Fock reactivity
1. Introduction
Green and natural raw material, characterized as sustainable and compatible with the environment, is in high demand, in light of the depletion of petroleum resources (Dodds and Gross, 2007). Cellulose, as the most abundant biopolymer on earth, is a green raw material that can be used to produce many products, such as rayon, ABT-199 acetate, nitrocellulose and cellulose ether (Jahan et al., 2011 and Tian et al., 2014). The production of cellulose (known as dissolving pulp in the paper industry) from lignocellulosic biomass, is increasing, and this is particularly true in Canada and China (Miao et al., 2014 and Wang et al., 2015).
Endoglucanases rich cellulase can effectively attack the cellulose structure, which will increase its accessibility towards reactants and facilitates the xanthation reactions in the rayon manufacturing process. In the literature, many studies were carried out, for example: Ibarra et al. (2010) reported that the endoglucanase with cellulose binding domain was effective in increasing the reactivity and decreasing viscosity of dissolving pulp. Miao et al. (2014) observed the enhancement of accessibility and reactivity of hardwood dissolving pulp when using cellulase treatment. Wang et al. (2014) reported that the high reactivity (about 80%) was achieved by endoglucanases rich cellulase treatment when upgrading bleached softwood paper grade pulp to dissolving pulp.