Self-cleaning photocatalytic MXene composite membrane for synergistically enhanced water treatment: Oil/water separation and dyes removal

Membrane separation has been widely used for water treatment, but the accumulation of pollutants on membrane surface is still inevitable during practical applications. Photocatalytic technology is an effective and environmentally friendly method for the degradation of pollutants. Here, we reported a simple method to prepare novel two-dimensional (2D) Bi2O2CO3@MXene photocatalytic composite membranes as well as their multi-functional abilities for water treatment. The experimental results exhibited that the composite membrane has ultrahigh water flux after incorporation of N-doped Bi2O2CO3 nanoparticles (815.3 L·m−2·h−1). In addition, the rejection ratio for three different types of oil/water emulsions was all over 99 %, and excellent dyes removals were obtained by membrane separation, adsorption and photodegradation abilities, which were approximately 99.9 % (Congo red), 98 % (Trypan blue) and 98.4 % (Rhodamine B), respectively. Most importantly, the composite membrane maintained a stable permeability and selectivity after five consecutive cycles with visible light irradiation. Density functional theory (DFT) calculation and Finite Element Method (FEM) analysis were carried out to reveal the mechanisms for the improvement of photocatalytic activity and membrane permeability, respectively.