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

摘要

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 Z_1Z_2Z_3 or Z_1EZ_2EZ_3 bleaching sequence with a total ozone consumption of 2.17 % on oven-dry pulp. The pulp from a Z_1EZ_2EZ_3 sequence still contained 3.51 % acetyl groups, which was 75 % of the original amount of acetyl groups in unbleached acetic acid pulp.