Electro-responsive carbon membranes with reversible superhydrophobicity/superhydrophilicity switch for efficient oil/water separation

Membrane filtration has shown great potential for the separation of oil-water mixtures. The separation of oil water mixtures is essentially an interfacial issue, and thus controllable surface wettability of membrane is extremely significant for efficient and cost-effective oil/water separation. Herein, poly-3-methylthiophene (P(3-MTH))/carbon membranes (CMs-P) with switchable surface wettability between superhydrophobicity and superhydrophilicity were designed. The CMs-P, prepared from coating P(3-MTH) on the highly porous and electrically conductive carbon nanofiber membranes, could exhibit the wettability switch by doping or dedoping the P(3-MTH) with ClO4- under electro-stimuli. The switch can be quickly achieved in less than 30 s and shows desired recyclability. Driven by gravity only, the prepared CMs-P are capable of completely separating free oil water mixture. Furthermore, the separation efficiency reaches to 99.5% for surfactant-stabled emulsions with various oil-water ratios. This work presents new insights into the study for smart gating membranes and the design of novel functional oil/water separation devices.