Enhancing the selective separation of hemicelluloses from cellulosic fibers in NaOH/ZnO aqueous solution

To achieve a breakthrough in the application of cold caustic extraction, it is necessary to limit the amount of alkali and to dissolve the hemicelluloses sufficiently. A NaOH/ZnO aqueous solution system was used to separate hemicelluloses from bleached bamboo pulp efficiently and selectively. The NaOH/ZnO process proved to be more successful in the removal of hemicelluloses. Under the conditions of 0.5% ZnO concentration, the NaOH/ZnO aqueous solution system decreased the hemicelluloses content to 4.99%, which was lower than 7.46% of the control sample treated with NaOH alone at the same 7% NaOH concentration. Correspondingly, the NaOH/ZnO system led to an increase in alpha-cellulose content with significantly improved hemicelluloses removal efficiency and selectivity. As a result of the NaOH/ZnO process, a higher degree of polymerization was observed, and the cellulose I structure was always maintained, which provided good benefits for the subsequent utilization of cellulose.