Electrostatic Assembly of a Titanium Dioxide@Hydrophilic Poly(phenylene sulfide) Porous Membrane with Enhanced Wetting Selectivity for Separation of Strongly Corrosive Oil–Water Emulsions

The efficient treatment of oil–water emulsions in extreme environments, such as strongly acidic and alkaline media, remains a widespread concern. Poly­(phenylene sulfide) (PPS)-based porous membranes with excellent resistance to chemicals and solvents are promising for settling this challenge. However, the limited hydrophilicity and the poor hydrated ability of the hydrophilic PPS (h-PPS) membranes reported in the literature prevents them from separating oil–water emulsions with high efficiency, large fluxes, and good antifouling performances. In this study, a firm rough TiO₂ layer is constructed on a h-PPS membrane via electrostatic assembly to improve the surface hydrophilization. The introduction of the TiO₂ layer increases the wetting selectivity and decreases the oil adhesion, which makes it capable to efficiently treat oil-in-water emulsions (efficiency > 98%). Most importantly, the underwater critical oil intrusion pressure almost doubled after the incorporation of the TiO₂ layer, which allows the membrane to withstand pressurized filtration, achieving a high flux of ∼4000 L m^–2 h^–1. This is more than 2 orders of magnitude larger than the flux of the reported h-PPS. Furthermore, the TiO₂@h-PPS membrane displays long-term stability in separating oil–water emulsions in strong acid and strong alkali, showing a promising prospect for the treatment of strongly corrosive emulsions.