Robust and multifunctional 3D superhydrophilic/superoleophobic sponge for rapid oil/water separation and water purification

Advanced materials that possess distinguishable superwettability have been extensively applied for oil/water separation. Among them, superhydrophilic/superoleophobic materials are defined as a water contact angle <5° and an oil contact angle >150°, are considered as the ideal candidate for oil/water separation because of their superior antioil-fouling. However, there are two main issues that need to be addressed for superhydrophilic/superoleophobic materials: (1) Two-dimensional (2D) superhydrophilic/superoleophobic materials are time-consuming and unable to obtain high fluxes during oil/water separation; (2) The reported three-dimensional (3D) superhydrophilic/superoleophobic materials are often ineffective for separating emulsions with size <20 μm, thus cannot obtain balance between high throughput and successful separation of different types of oil/water mixtures. In addition, in complex real-world wastewater environment, such materials cannot remove water-soluble organic pollutants existed in industrial wastewater, which restrict the practical use requirements in water purification. Herein, a robust and multifunctional superhydrophilic/superoleophobic sponge integrated with a photocatalysis property was fabricated by the combination of the amphoteric fluorosurfactant FS-50 and titanium dioxide (TiO2) nanoparticles on the sponge surface. The as-prepared sponge not only showed high water flux of 13,735 L m2 h−1 and 1754 L m2 h−1 for immiscible oil/water mixtures and oil-in-water emulsion, respectively, but also could continuously reuse with an almost constant flux arised from their superior antioil-fouling. Notably, benefiting from the photocatalysis property of titanium dioxide and adsorption property of porous sponge, contaminated water can be completely degraded and purified under ultraviolet (UV) irradiation.