EFFECT OF BLACK LIQUOR ON WHEAT STRAW SODA-AQ COOKING AND LIGNIN

摘要

The impacts of black liquor replacement cooking (BLRC) on wheat straw Soda-cooking and lignin characteristic were investigated in this study. The residual AQ, alkali, and dissolved and degraded lignin, as well as carbohydrates in the wheat straw black liquor had great influence on wheat straw Soda-AQ cooking. The influence can be controlled by the different black liquor replacement ratios (BLRR). The cooking with around 60% BLRR resulted in a good delignification selectivity, which shows a high SiO2 content, yield and viscosity of the pulp, and alkali saving although delignification velocity could be slow to some extent. The residual AQ, and dissolved and degraded carbohydrates in the black liquor are beneficial to the selectivity. The dissolved and degraded lignin in the black liquor can restrict the delignification. It was not observed that the lignin condensation and β-O-4 structure reaction by the black liquor replacement cooking to be different from that by the normal cooking.