Effect of phosphoric acid in the pre-hydrolysis process of dissolving pulp production from bamboo-willow

Bamboo-willow is a type of fast-growing wood with a high hemicellulose content. In the present study, the effects of phosphoric acid addition on the main components of bamboo-willow and pre-hydrolysis liquor (PHL) were explored, and subsequently the pre-hydrolyzed bamboo-willow chips were cooked, O–H–P bleached, and acid post-treated to produce dissolving pulp. The results showed that adding phosphoric acid to the pre-hydrolysis stage effectively removed hemicellulose and increased the cellulose content of the pre-hydrolyzed bamboo-willow. The major component of the hemicelluloses was xylan/xylose, which represented approximately 62% to 78% of the total sugars in the PHL. Glucose was the most abundant sugar that was produced, apart from xylose, and represented approximately 12% to 25% of the total sugars in the PHL. Additionally, 73% to 83% of the total sugars in the PHL were in an oligomeric form. The obtained bamboo-willow dissolving pulp could be used to produce viscose rayon with a 92.1% α-cellulose content, 4.77% hemicellulose content, and 675 degree of polymerization.