Conversion of bleached soda bagasse paper-grade pulp to dissolving-grade pulp using different hemicelluloses removing post-treatments with emphasis on IONCELL-P process

Abstract

Paper-grade pulp, rich in hemicellulose content, is a cheap source for producing dissolving pulps. The main challenge in the conversion of a cheap paper-grade pulp to a higher-valued dissolving pulp is the selective removal of hemicelluloses, while maintaining the pulp reactivity. This paper presents a comparison of different hemicellulose extraction methods such as cold caustic extraction, IONCELL-P(ulp) and xylanase treatment on converting fully bleached soda bagasse paper-grade pulp to dissolving pulp. IONCELL-P(ulp) treatment, using an optimized1-ethyl-3-methylimidazolium acetate/water as the extraction medium, yielded 85% xylan removal, which is comparable to the cold caustic extraction or a combination of xylanase treatment and cold caustic extraction. A complete separation of the two polymers by IONCELL-P(ulp) is not possible due to the overlap of the molecular masses of the cellulose and xylan molecules, an inherent characteristic of sugarcane bagasse pulp. All the investigated methods effectively removed xylan, with differences in the selectivity and the reactivity of the remaining pulp.