深度共熔溶剂对桉木组分的溶解选择性

Solubility Selectivity for the Components of Eucalyptus in Deep Eutectic Solvents

摘要:

制备了不同季铵盐三丁基甲基氯化铵(MTBAC)、四甲基氯化铵(TMAC)、苄基三乙基氯化铵(TEBA)和氯化胆碱(ChCl)分别与DL-乳酸(HL)以摩尔比1:9合成的深度共熔溶剂，并将用于溶解桉木粉中木质素。结果表明，由苄基三乙基氯化铵/DL-乳酸(TEBA/HL)合成的深度共熔溶剂处理桉木粉，在90 ℃下反应10 h，木质素溶解率达92.3wt%，综纤维素溶解率仅为8.3wt%；同时，木质素与综纤维素溶解选择性系数之比K达到158.5，表明TEBA/HL对木质素的溶解选择性最佳。通过红外光谱(FT-IR)分析各分离产物，证明提取物中有木质素特征官能团。通过凝胶渗透色谱(GPC)分析表明分离产物相对分子质量均有所降低。通过固体13C核磁共振谱(CP/MAS 13C NMR)分析90 ℃下TEBA/HL中分离产物结构，证明其结构征符合阔叶材木质素结构特点。

Abstract:

Different kinds of deep eutectic solvents were synthesized with different quaternary ammonium salts, methyl tributyl ammonium chloride, tetramethylammonium chloride, benzyl triethyl ammonium chloride and choline chloride, and DL-lactic acid with molar ratio of 1:9, respectively, and used to dissolve the lignin in eucalyptus. It was found that deep eutectic solvents of benzyl triethyl ammonium chloride/DL-lactic acid (TEBA/HL) had best solubility selectivity, as the dissolution ratio of lignin was 92.3wt% after 10 h under 90 ℃ and the dissolution ratio of total cellulose was only 8.3wt%, meanwhile, the specific value (K) of solubility selectivity coefficient between lignin and total cellulose reached to 158.5, suggesting the best solubility selectivity for lignin of TEBA/HL. FT-IR spectrum analysis showed that the structure of the extraction materials contained characteristic functional groups of lignin, and GPC analysis suggested that the molecular weights of the extraction materials were all reduced. CP/MAS 13C NMR analysis suggested that structure characteristics of the extraction materials from TEBA/HL at 90 ℃ were close to lignin of hardwoods.