Anion-encapsulated porous liquids with ZIF-8 preferential adsorption for ultrahigh-performance separation of organic-organic mixtures

Abstract

Despite the growing interest in porous liquids, their potential for membrane-based liquid separations remains largely unexplored. Herein, we report an anion-encapsulated type III porous liquid developed by homogeneously dispersing ZIF-8 in the ionic liquid trihexyltetradecylphosphonium chloride ([P₆,₆,₆,₁₄][Cl]). Both experimental and computational studies confirm that the resulting ZIF-8/[P₆,₆,₆,₁₄][Cl] system exhibits high fluidity at room temperature due to the enhanced mobility of chloride ions within the ZIF-8 framework. When used as a selective component for the separation of challenging mixtures such as dimethyl carbonate and methanol, the membrane exhibits superior performance, with significantly higher selectivity and an order of magnitude higher permeance of dimethyl carbonate compared to previously reported membranes. This enhanced separation capability is attributed to the unique liquid properties of the porous liquid and the selective adsorption affinity of ZIF-8. These results highlight the promising role of type III porous liquids in facilitating efficient membrane separations.