Surface charge-induced efficient recovery of ionic liquids from aqueous phase

Ionic liquids (ILs), which consist of pure cations and anions, are widely used in diverse applications and regarded as one of the best choices of "green solvents." However, the lack of effective green methods for recovering ILs and the safety issues caused by entering environment severely hinder the application of ILs in the green chemistry. Here, we show that rationally tuning the surface charge of a poly(tert-butyl acrylate) (PtBA)-coated porous mesh can selectively let ILs pass through, thus providing an efficient and convenient strategy to recover ILs. The surface charge of the porous mesh can be precisely controlled by regulating the hydrolysis degree of the chemically grafted PtBA coating. PtBA-coated porous mesh with a proper surface charge can be tuned to be IL-philic for a specific IL but hydrophobic, and thus can be applied to recover various kinds of ILs from the aqueous phase. This study offers a new platform for the development of functional membranes for efficient recovery of ILs.