Underwater superoleophobic-underoil superhydrophobic Janus ceramic membrane with its switchable separation in oil/water emulsions

Herein, we reported a facile and effective method to fabricate Janus ceramic membrane (JCM) and applied the membrane in the separation of oil/water emulsions. The original hydrophilic ceramic membrane was modified by hexadecyltrimethoxysilane (HDTMS), and the obtained hydrophobic membrane was exposed to O₂/N₂ plasma to achieve a bistratal hydrophilic-hydrophobic structure. Basically, JCM has underwater superoleophobicity and underoil superhydrophobicity on its hydrophilic plasma-treated and hydrophobic modified side, respectively; thus, it possesses an intelligent separation capability in many systems, including oil-in-water (O/W) emulsions with its hydrophilic side and water-in-oil (W/O) emulsions with its hydrophobic side. Moreover, on the hydrophilic side, JCM possesses an outstanding anti-fouling property, which is due to its higher surface free energy. The hydrophobic side could sieve W/O emulsions driven solely by gravity. An apparatus that could support changing-over filtration between W/O and O/W emulsions is devised and the long-time stability is also authenticated. We envision that our work can lead to the further development of Janus membranes in ceramic materials.