Influence of organic solvent on the separation of an ionic liquid from a lignin–ionic liquid mixture

Sixteen solvents added in lignin–ionic liquid mixture provide four types of solubility characteristics. The distinct characteristics can be classified by considering solubility parameters including ET Scale, Kamlet–Taft parameters and solubility parameters. Group 1 solvent shows promising solvents for lignin–ionic liquid separation, contributing full dissolution of ionic liquid with lignin precipitation. Isopropanol, the most potential solvent has solubility properties as following normalized molar electronic transition energies (ETN) = 0.57, hydrogen-bond acidity (α) = 0.76 and Hildebrand solubility parameter (δT) = 23.58. This study examines potential solvents for ionic recovery, provides simple method of separation and leads to the feasibility of using ionic liquids in industrial applications.