硫酸盐法制浆黑液酸析木质素的研究

STUDY ON THE LIGNIN ACIDIFYING PRECIPITATION IN KRAFT PULPING BLACK LIQUOR

本文探讨了采用酸沉降法从硫酸盐法造纸黑液中提取木质素时，黑液酸度对木质素提取量和性状的影响，以及木质素提取量与滤液化学特性变化的关系。结果表明，在黑液酸化沉降木质素的过程中，木质素的提取量和性状与酸度紧密相关，滤液化学特性的变化也与木质素提取量有密切关联；提取木质素最适pH值为pH3．0－pH4.0，此时滤液CODer的降低率为60％－70％，BOD5的降低率为40％－60％,色度降低率大于90％。

Effect of acidity of kraft pulping black liquor to lignin extract-ing content and property is herewith discussed with the relation between lignin extracting content and property of filtrate. The results show that lignin extracting content and property are closely related to acidity of pulping black liquor. It concerns also with the variable chemical property of filtrate and lignin extracting content. The optimum acidity value is ranging from pH3. 0-pH 4.0 for extracting lignin from pulping black liquor. The decrement of CODcr and BOD5 would be 60%-70% and 40%-60% respectively, including＞90% decrement of colour.