Kinetics of Hardwood Carbohydrate Degradation during Kraft Pulp Cooking

Most of the studies on hardwood carbohydrate degradation focus upon the understanding of carbohydrate behavior of a single wood species. These studies tend to determine the activation energies associated with the three different cooking phases and for the different reactions that participate in carbohydrate degradation. In the current study, a variety of hardwood species were comprehensively characterized and the kinetics of carbohydrate degradation was studied. The kinetics of glucan, xylan, and total carbohydrate dissolution during the bulk phase of the kraft pulping process were investigated. A wide range of carbohydrate dissolution rates was obtained and correlated to chemical features and delignification rates for nine different hardwood species. It was determined that carbohydrate dissolution was dependent upon the rate of delignification. Species with high carbohydrate dissolution also presented high lignin removal rates. Our results indicate that the presence of lignin carbohydrate complexes positively influences pulping process selectivity during the bulk reaction phase.