Fractionation of lignin from eucalyptus bark using amine-sulfonate functionalized ionic liquids

A series of amine-sulfonate functionalized ionic liquids (ASF-ILs) were synthesized, characterized, and evaluated for the dissolution of model biopolymers (cellulose, xylan, kraft lignin and lignosulfonate). The ASF-ILs were prepared in high atomic efficiency. Most of the ASF-ILs dissolve kraft lignin and lignosulfonate efficiently at 373 K, with solubilities of 0.220–0.385 g for kraft lignin and of 0.150–0.290 g for lignosulfonate per gram of ASF-ILs. In contrast, xylan and cellulose are scarcely soluble (