Exceptional self-cleaning MXene-based membrane for highly efficient oil/water separation

Abstract

Two-dimensional (2D) MXene-based separation membranes exhibit significant promise for oily wastewater treatment. The intercalation of TiO2 nanoparticles between MXene nanosheets can not only enlarge their interlayer distance for faster transportation of water molecules, but also promote their photocatalytic oxidation for removal of membrane fouling by oil droplets. However, the uniform loading of ultra-small TiO2 nanomaterials between MXene layers without aggregation is challenging. Herein, taking advantages of inherent Ti elements of MXene, we grew ultra-small TiO2 by in-situ one-step oxidation of MXene nanosheets to prepare 2D MXene@TiO2 heterojunctions. They were then loaded on polyethersulfone (PES) support by vacuum filtration for the PES-MXene@TiO2 composite membrane (MXTM) with exceptional water permeance and anti-fouling and self-cleaning properties. It achieves a remarkably high flux of 3045 L·m−2 h−1·bar−1 and oil/water emulsion separation efficiency over 99.8%. Moreover, the MXTM membrane exhibits remarkable hydrophilicity, evidenced by an abrupt reduction in water contact angle from 43.8 to less than 5° within 10 s, which could retard the progress of oil adhesion on the membrane surfaces. The extended Derjaguin-Landau-Verwey-Overbeek theory confirmed high interaction energy between the membrane and pollutants. Furthermore, the MXTM membrane excels in self-cleaning and anti-fouling property, retaining a flux recovery rate of >98% in 10 cycles by visible light driven photodegradation of foulantsirradiation. This innovative 2D self-cleaning membrane offers excellent anti-fouling properties for efficient oil/water separation.