New System for Efficient Removal of Lignin with a High Proportion of Chlorine Dioxide

Abstract

Chlorine dioxide is used extensively as the bleaching agent in the clean pulp bleaching process. To further improve the efficiency of chlorine dioxide delignification, this study discusses the effect of a new system of a high proportion of chlorine dioxide on lignin removal. When the mass ratio of chlorine dioxide to lignin was 4 in this system, 50% of lignin was removed in a short time. To optimize the new bleaching system, the effects of temperature and pulp consistency on the new system were studied. The ratio of lignin removed was 50% when the reaction time was 30 min, temperature was 25 °C, and the pulp consistency was 5%. Compared with traditional chlorine dioxide bleaching, high proportion of chlorine dioxide bleaching can shorten the reaction time by 50%, reduce the reaction temperature to 25 °C, and greatly reduce energy consumption and adsorbable organic halogen (AOX) production by 45%. The new system provides a novel idea for clean bleaching of pulp.