Adsorption of Hemicellulose Extracts from Hardwood onto Cellulosic Fibers. I. Effects of Adsorption and Optimization Factors

The adsorption of dissolved hemicelluloses derived from US southern mix hardwood to cellulosic fiber is an efficient way for hemicellulose utilization. Retaining more hemicelluloses on the cellulose fibers leads to a higher pulp yield, better beatability and improved pulp strengths. The primary aim of the current work was to investigate the hemicellulose adsorption process through treating Kraft pulp in the extract liquor. The main effects of the process factors and their interactive effects were discussed via statistical analysis. The optimization of the adsorption process was also studied. In the process of hemicellulose adsorption, three main factors – fiber consistency, extracts-to-fiber ratio and temperature – showed significant effects upon adsorption. A higher extracts-to-fiber ratio and higher temperature contributed to enhancing the hemicellulose adsorption yield. The quadratic function that characterizes the relationship between fiber consistency and adsorption yield was determined. Overall, a high concentration of extract liquor is necessary to achieve a high hemicellulose adsorption yield. There exists a strong and profound interaction between temperature and fiber consistency, therefore an optimal control of both temperature and fiber consistency in adsorption would improve adsorption efficiency. Since fiber consistency is easier to control, it serves as a key parameter for increasing the adsorption yield.