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分别以三丁基甲基氯化铵(MTBAC)、四甲基氯化铵(TMAC)、苄基三乙基氯化铵(TEBA)和氯化胆碱(Ch Cl)为氢键受体与DL-乳酸(HL)以物质的量比为1∶9合成了深度共熔溶剂,考察了深度共熔溶剂的黏度及Hildebrand溶解度参数(δ)随温度的变化,并且将其应用于溶解桉木粉中的木质素。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溶解选择性最佳,用其处理40~60目的桉木粉,在90℃下反应10 h,木质素溶解率达92.3%,棕纤维素溶解率仅为8.3%,同时,木质素与棕纤维素溶解选择性系数之比(K值)为158.5,而MTBAC/HL、TMAC/HL及Ch Cl/HL的K值分别为113.8、16.8及49.7。FTIR测试结果表明:提取物中有木质素特征官能团。GPC测试结果表明:MTBAC/HL与TEBA/HL溶解分子量较大的木质素分子能力更强,MTBAC/HL和TEBA/HL分离产物的重均分子量分别是4 375和4 814,TMAC/HL和Ch Cl/HL分离产物重均分子量分别是3 674和3 977。CP/MAS13CNMR测试结果表明:90℃下TEBA/HL分离产物结构符合阔叶材木质素结构特征。
Methyltrimethylammonium chloride (MTBAC), tetramethylammonium chloride (TMAC), benzyltriethylammonium chloride (TEBA) and choline chloride (ChCl) Lactic acid (HL) was synthesized with a deep co-solvent at a mass ratio of 1: 9. The viscosity of the co-solvent and the Hildebrand solubility parameter (δ) with temperature were investigated and used to dissolve eucalyptus Lignin. The results showed that the deep eutectic solvent synthesized by benzyltriethylammonium chloride / DL-lactic acid (TEBA / HL) had the best solubility. Eucalyptus powder with 40-60 mesh was treated with it and reacted at 90 ℃ for 10 h, the lignin dissolution rate reached 92.3% and the brown cellulose dissolution rate was only 8.3%. Meanwhile, the ratio (K value) of the lignin to brown cellulose dissolution selectivity coefficient was 158.5, while the MTBAC / HL, TMAC / HL and The K values for Ch Cl / HL were 113.8, 16.8 and 49.7, respectively. FTIR test results showed that: the extract has lignin characteristic functional groups. The results of GPC showed that MTBAC / HL and TEBA / HL were more capable of dissolving lignin with larger molecular weight, and the weight average molecular weights of MTBAC / HL and TEBA / HL were 4 375 and 4 814, respectively. TMAC / HL and Ch The weight average molecular weights of Cl / HL isolated products were 3 674 and 3 977, respectively. The results of CP / MAS13CNMR test showed that the structure of TEBA / HL separation product conformed to the structural characteristics of hardwood lignin at 90 ℃.