Synergistic effects of enzyme pretreatment for hemicellulose separation from paper-grade pulp in ionic liquid/water

Herein, we studied the effects of pretreatment with glucanase (G), xylanase (X), and their combinations [G/X mixtures or sequential addition (G–X and X–G)] on the efficiency of ionic liquid/water (IL/w)—promoted extraction of hemicelluloses from paper-grade pulp. Mild G pretreatment effectively increased the efficiency and selectivity of hemicellulose removal, whereas severe G pretreatment resulted in high glucose loss and low selectivity. Under optimized conditions, G and X pretreatments achieved similar removal efficiencies, especially in IL/w systems with high water content (25 and 20%), whereas the former was inferior to the latter at low water content (15%). Simultaneous G/X treatment achieved more efficient and selective hemicellulose removal than sequential G–X and X–G treatments, with the former sequence outperforming the latter. Finally, sequential extraction with IL/w-20 and IL/w-15 allowed extremely effective hemicellulose removal, decreasing the xylose content of pulp to 1.5%.