关键词: 木质素磺酸钠, 提纯, 分子量分布, 超虑法

Abstract: Commercial sodium lignosulfonate(raw SL) was purified with ionic-resin method, ultrafiltration, long chain aliphatic amine extraction and solvent extraction. The structure, composition and molecular weights distribution of raw SL and purified SL were characterized by the Infra-red spectrum, elementary analysis and gel chromatography. The experimental results indicate that solvent extraction doesn't purify raw SL efficiently. Ionic-resin method, ultrafiltration and long chain aliphatic amine extraction removed impurities with molecular weight less than 1000; the content of lignosulfonate in purified SL was raised from 59% to 90%; the number average molecular weight and weight average molecular weight of purified SL were increased. In addition, the molecular weights distribution of purified SL became more uniform. Long chain aliphatic amine extraction could get rid of reducing sugar efficiently, the content of reducing sugar in the purified SL was reduced by 50%. The yield of purified SL with ultrafiltration is the highest, which can reach 31%. In comparison with the raw SL, the weight average molecular weight of the purified SL increase over once. Considering the purified SL yields, the purification efficiency and the purification technology, ultrafiltration is the best favorable purification method.

Key words: Sodium lignosulfonate, Purification, Molecular weights distribution, Ultrafiltration