Porous and carboxyl functionalized titanium carbide MXene sheets for fast oil-in-water emulsion separation

Titanium carbide MXene as a novel two-dimensional nanomaterial receives more attention in membrane separation, but its low water permeability has limited its application in wastewater treatment. Hence, we developed a new type of “oxidation-etching” method to fabricate porous titanium carbide MXene sheets to optimize the water channel. Meanwhile, carboxyl functionalized surface modification endowed porous MXene sheets with more hydrophilic groups, which was good for the improvement of membranes’ wettability. The as-prepared membranes exhibited superior underwater wettability, concretely, underwater contact angle up to 159.2° and sliding angle as low as 1.0°. Most importantly, the membrane displayed a high permeance (8083 L m −2 h −1 bar −1 ) for separating the oil-in-water surfactant-stabilized emulsion and was superior to most of the MXene membranes reported so far. It also exhibited an excellent separation performance for those emulsions prepared from high viscosity oil phases. This study reports a new “oxidation-etching” method to fabricate porous MXene sheets and carboxyl functionalized ensures the membrane with excellent underwater wettability and emulsions separation performance. • A new type of “oxidation-etching” method to fabricate porous titanium carbide MXene sheets. • Porous strategy can significantly reduce the transmission distance and increase water permeability. • Carboxyl functionalized ensured the membrane with excellent underwater wettability. • The membrane showed a high permeance (8083 L m −2 h −1 bar −1 ) for separating the oil-in-water surfactant-stabilized emulsion.