Synthesis, Purification and Recycling of Ionic Liquid

As one of the most popular green solvents and catalysts, ionic liquids have been applied to various application fields including separation and purification, electrochemistry, chemical reaction, cellulose dissolution and so on. However, its further development has been restrained by the preparation and recycling methods due to its unique structure and physical-chemical property. Based on the status, current researches on the synthesis, purification and recycling of ionic liquids are reviewed, including many new techniques and tendencies. A series of synthesis methods are summarized and compared, and then the main influencing factors about the purity of ionic liquids as well as various ways of purification are discussed. The pretreatment of raw materials and the choice of synthetic procedure play key roles on the purification of ionic liquids. Finally, the recovery of ionic liquid is analyzed including distillation, membrane separation, two aqueous phase systems, extraction and so on. It is proposed that the choice of recycling method should be based on the different nature of ionic liquids.