A general strategy for the separation of immiscible organic liquids by manipulating the surface tensions of nanofibrous membranes

Oil/water separation membranes with different wettability towards water are attractive for their economic efficiency and convenience. The key factor for the separation process is the roughness-enhanced wettability of membranes based on the intrinsic wetting threshold (IWT) of water, that is, the limitation of the wettability caused by hydrophobicity and hydrophilicity. However, the separation of organic liquids (OLs) remains a challenge. Herein, we manipulate the surface tensions of nanofibrous membranes to lie between the IWTs of the two OLs to be separated so that the nanofibrous membranes can be endowed with superlyophobicity and superlyophilicity for the two liquids, and thus lead to successful separation. Our investigations provide a general strategy to separate any immiscible liquids efficiently, and may lead to the development of membranes with a large capacity, high flux, and high selectivity for organic reactions or liquid extraction in chemical engineering. Going separate ways: The surface tensions of nanofibrous membranes have been manipulated to lie in between the intrinsic wetting thresholds (IWTs) of the two organic liquids to be separated. This endows the nanofibrous membranes with superlyophobicity and superlyophilicity for the two liquids, respectively, and thus leads to a successful separation.