Photopolymerization enabled in-air highly oleophobic and hydrophilic SiC membranes with improved antifouling performance in oil-in-water emulsion separation

Ceramic membranes with tailored surface wettability have gained increasing attention for improving their separation efficiency and antifouling ability, while most of the previous work focused on the underwater oleophobic behavior. In this work, in-air highly oleophobic and hydrophilic SiC membranes were achieved through the UV irradiation triggered polymerization and controlled crosslinking between oleophobic perfluorodecyl acrylate (TFOA) and hydrophilic methacrylic acid (MAA). These key processing parameters including MAA content, soaking time and irradiation duration were systematically studied through examining the changes in porous microstructure, surface wettability and separation performance in oil-in-water emulsion. Results showed that the flux attenuation rate of SiC membranes can be effectively reduced by regulating the content of hydrophilic components. Due to the alternation of the surface wettability to highly oleophobic in air, the oil droplets can hardly attach on the surface of modified SiC membranes at the beginning of filtration process, and the membrane fouling was significantly slow down yet dominated by the intermediate blocking. Correspondingly, a combined cleaning procedure was proposed to regenerate the fouled SiC membranes. Further, the antifouling ability of modified and original SiC membranes was comparatively studied under the conditions of a fixed permeate volume (15 ml) and various oil concentrations (200 ∼ 1000 ppm) in the separation of oil-in-water emulsion. The advantages of modified SiC membranes become more notable when used for highly concentrated oil–water emulsion as reflected by the slower flux decline and higher stable flux. This work provides a feasible pathway to realize the in-air highly oleophobic and hydrophilic surface on ceramic membranes, and primarily demonstrates the advantages of antifouling ability in oil-in-water emulsion separation.