Using Porous Liquids to Perform Liquid‐Liquid Separations

Porous liquids are new types of fluid sorbent investigated mainly for the separation of gas mixtures. Here, we explore their application to the separation of miscible liquids, MEG (monoethylene glycol)/water and EtOH/water) as proof of principle. Recovery of used MEG is industrially important but its extraction from water is difficult. PLs ZIF 8@PDMS (PL1, PDMS = polydimethylsilicone) or ZIF‐8@sesame oil (PL2) each consisting of 25wt% of the hydrophobic microporous material ZIF‐8 dispersed in PDMS/sesame oil, were formulated and found to be exceedingly physically stable. 5 nm PEEK membranes were used to provide permeable barriers between the PL and the alcohol/water phase. MEG was selectively extracted through the membrane from 50wt% MEG/water mixtures into the PL phase. It was effective for MEG/water mixtures as dilute as 3:97wt%. The PL could be regenerated and re‐used, suggesting its potential for continuous cyclic extraction. Furthermore, PL3 (silicalite‐1@PDMS) has demonstrated effectiveness in achieving selective alcohol extraction from beverages. It shows great potential for lowering the alcohol concentration in gin/wine due to its excellent chemical stability and nontoxicity. Overall, the enhanced adsorption properties of PLs due the presence of empty pores, which provides unusually high gas solubilities, also makes them, in principle, applicable to liquid‐liquid separations.