Construction of Janus silicon carbide membranes with asymmetric wettability for enhanced antifouling in water-in-oil emulsification process

Given that the membrane emulsification process involves the interaction between the membrane surfaces and two different phases (i.e., oil and water), separately manipulating the wettability of each surface would be crucial to achieve the high emulsification efficiency. Herein, the Janus silicon carbide (SiC) membranes were designed and prepared by using an emerging reactive sintering method and the subsequent chemical grafting modification on one of the hydrophilic surfaces. The surface wettability was selectively controlled by using hexadecyltrimethoxysilane (HDTMS) and 1H, 1H, 2H, 2H-perfluorooctyltrichlorosilane (FOTS) as the hydrophobic or amphiphobic modifiers, respectively. Meanwhile, the modified side of Janus SiC membranes showed super-hydrophobicity under oil. It was found that the hydrophobic surface can inhibit the spread of water on membrane surface and the oleophobic surface can reduce the pollution of the membrane, which both affected the membrane emulsification performance. The water-in-oil (W/O) emulsions with mean water droplet size of 1.26–1.57 μm can be prepared using amphiphobic-hydrophilic Janus membranes at a high emulsification flux (1910 L·m⁻²·h⁻¹). Importantly, the pure water permeance only declined 15.6% of the original value after three times of membrane emulsification. Moreover, the polluted membranes can be easily and effectively regenerated by ultrasonic cleaning in ethanol with a flux recovery ratio of 95.8%. Therefore, the amphiphobic Janus SiC membranes showing improved anti-fouling ability can be effectively utilized in the emulsification of high-viscosity oil.