Evaluation of current and future solvents for selective lignin dissolution: A review

Lignin is a renewable biopolymer from industrial crops that can be used for several value-added products. Moreover, lignin is an underexploited side stream of pulp and paper industries and biorefineries that is used for the production of energy at mill or as a low-value resource for dispersants or binding applications. In order to produce gasoline and high-value chemical products, an integrated process of separation and purification must be applied. Research in this field started in the early years of the 20th century, however, in recent decades a wide range of solvents have been proposed including organic solvents (Organosolv) and ionic liquids (ILs). Therefore, the present review addresses the recent research advances in the separation and recovery of lignin, covering various solvents namely organic solvents (Organosolv) and ionic liquids (ILs). The finalisation of the ultimate industrially feasible process is still a required task and this study points out the most promising solvents, challenges and limitations for the selective lignin separation.