Superoleophobic TiO2@SSM membranes with antifouling and photocatalytic ability for efficient microbubbles flotation emulsion separation and organic pollutants degradation

Abstract

In this paper, a stainless steel mesh coated with titanium dioxide (TiO2@SSM) membrane was developed for the separation of stable oil-water emulsions and the degradation of soluble pollutants. The TiO2@SSM membrane showed excellent underwater anti-oil adhesion performance and efficient emulsion separation under gravity (flux of 207.7 L m−2 h−1 and efficiency of 99.58 % for toluene-water emulsion). The emulsion could also be pre-broken by microbubble flotation to enhance the separation performance of the TiO2@SSM membrane (microbubble flotation followed by separation has a flux of 369.3 L m−2 h−1, and efficiency of 99.71 %). And the synergistic operation of separation and microbubble flotation can increase the flux to 451.6 L m−2 h−1. The membrane showed outstanding stability and could be recycled for more than 20 times without significant deterioration, and demonstrated chemical stability for corrosion resistance test (pH 0–14). In addition, the membrane, which is easily modified with silver nanoparticles, achieves improved photocatalytic degradation properties (efficiency from 58.8 % to 88.7 %) and microbubble flotation effect (flux of 613.4 L m−2 h−1). This work provides a rational strategy for the preparation and optimization of inorganic functional membranes for effective emulsion separation and dye degradation, and demonstrates promising applications of the separation and purification in oil-containing sewage and wastewater remediation.