Do we understand the recyclability of ionic liquids?

Recyclability is one of the reasons why ionic liquids (ILs) are attracting the attention of a growing number of scientists and engineers, but do we understand the recyclability of ILs in a real sense? For this purpose, this review focuses on the methods need for their separation from their "working" environment. Here we proposed that the appropriate separation method should be selected according to different systems. To better understand the separation of ILs, fundamental research on the existence forms (ions, ion pairs or supermolecule) of ILs in solvents is vitally important.