Experimental and Theoretical Study of Lignin Extraction by Ionic Liquids From Straw

Lignin is a natural polymer and it can be the source of aromatic compounds. However, efficient means of seperating lignin from straw is still a problem needed to solve. In this work, dissolution experiments were carried out. Three ionic liquids with the same cation [emim]ClA[emim]OAcA[emim]MeSO₄ were selected and sythesised , in order to dissolve lignin from straw with the optimal conditions respectively. The lignin was regenerated by precipitation, then the exteraction yields of the above liquids were obtained, so we can get the order of lignin solubility for varying anoins. Microscopically, the interaction between ionic liquids and lignin was also studied by quantum chemical calculations. Thus, the relationship between exteraction yield and interaction energy was revealed. It also indicates that the solubility of lignin in ionic liquid was mainly influenced by the anions part of ionic liquids.