Bleaching of Wheat Straw Soda-AQ Pulp including A Permanganate Deliginification Stage

摘要

Permanganate is a strong oxidant, and reacts with lignin in pulp at acidic conditions. The delignification conditions of wheat straw NaOH-AQ pulp were studied, and a low chlorine bleaching process was proposed. The results show that permanganate is a good delignificatin agent, and its optimum charge relates to pulp kappa number. The pulp delignified with permanganate has better bleachability. For example, pretreated by 1% permanganate, the pulp with 14.6 kappa number could be bleached to 76,5% ISO brightness by 5% hypochlorite, and its brightness and physical properties are better than those of the CEH pulp.