Design of a Janus F-TiO2@PPS Porous Membrane with Asymmetric Wettability for Switchable Oil/Water Separation

Extremely asymmetric wettability, high wetting selectivity, instantaneous superwetting behaviors (low trans membrane resistance), and superior resistance to chemicals and solvents are needed for Janus membranes for switchable oil/water separation. However, it is still challenging to obtain Janus membranes with such properties. In this study, a surface with metastable hydrophobicity is constructed on one side of the chemically stable superhydrophilic TiO2@PPS membrane by adjusting the hydrophobization depth and the morphology of the hydrophobic layer via a water-oil interfacial grafting. The prepared Janus membrane exhibits a high water contact angle difference of similar to 150 degrees between its two surfaces with maintaining the superior penetrability of the original membrane, which makes it capable to separate both oil-in-water and water in-oil emulsions with high fluxes and accuracy. The separation efficiency is higher than 98% for the separation of the two kinds of emulsions. The fluxes of the surfactant-free toluene-in-water and water-in-toluene emulsions are up to 6.4 X 10(2) and 9.5 X 10(2) L m(-2) h(-1), respectively. Furthermore, the Janus membrane exhibits desirable antifouling performance and reusability during usage.