Ozone Bleaching of Atmospheric Acetic Acid Hardwood Pulp from Betula platyphylla var. japonica Hara

Abstract

Summary Atmospheric acetic acid pulp from Japanese white birch was bleached with 1–5% ozone with and without intermediate mild alkaline extraction. Concentrated acetic acid was a more effective bleaching media than water. Mild alkaline extraction of ozone-prebleached pulp was found to be very effective in delignification of the pulp and did not have any undesirable effects on pulp properties. A sufficiently delignified acetic acid pulp was obtained with multi-stage ozone bleaching in Z1Z2Z3 or Z1EZ2EZ3 bleaching sequence with a total ozone consumption of 2.17% on oven-dry pulp. The pulp from a Z1EZ2EZ3 sequence still contained 3.51% acetyl groups, which was 75% of the original amount of acetyl groups in unbleached acetic acid pulp.