Ionic liquids combined with membrane separation processes: A review

Combination of membrane processes and ionic liquids have received more and more attention in pollutants removal because it enhances separation efficiency but also broaden their research and application areas. This review provides a first and systematical summary on ionic liquids incorporate in membrane processes for VOCs or CO2 separation, including supported ionic liquid membranes (SILMs), Its composite polymer membranes (ILPMs), ionic liquids composite mixed matrix membranes (ILMMMs), poly(ionic liquid)s membranes (PILMs), ionic liquid gel membranes (ILGMs), and ionic liquid membrane contactors (ILMCs). Moreover, a new concept, combination of the membrane separation processes and absorption processes of ionic liquids, is introduced. Those separation processes are described detailly and compared with other conventional processes. With their separation performances and the processes of regeneration, membrane contactor shows stronger competitive advantages and it has the potential to be a major process in VOCs and CO2 separation. The advantages and disadvantages posed by all present ionic liquid membrane processes are summarized. Finally, challenges and opportunities in ionic liquid membrane separation processes are identified and discussed.