Self-cleaning photocatalytic BiOI/Ti3C2 composite membrane for oil-water emulsion separation and dye removal

• Photocatalytic BiOI/Ti 3 C 2 composite membranes were prepared by introducing the BiOI nanoflowers with a narrow band gap into the Ti 3 C 2 membrane. • BiOI/Ti 3 C 2 composite membranes demonstrated separation capability for oil/water emulsions. • BiOI/Ti 3 C 2 composite membranes achieved a high dye removal ratio according to the sieving, adsorption and photocatalytic degradation functions of the membrane. • BiOI/Ti 3 C 2 composite membranes have a good self-cleaning ability under light irradiation. Membrane separation technology is widely used for wastewater treatment, but wastewater containing oil droplets and soluble pollutants results in severe membrane fouling. Photocatalysis technology is an efficient and eco-friendly way to degrade contaminants. In this work, photocatalytic BiOI/Ti3C2 composite membranes were prepared via a simple self-assembly vacuum filter method for oil-water emulsion separation and dye degradation. The pure water flux of the optimal BiOI/Ti3C2 composite membrane (M3) reaches 4720 Lm-2h-1bar-1, 1.2 times higher than that of pure Ti3C2 membrane. Simultaneously, the composite membrane M3 has a high flux and oil rejection ratio (over 97 %) for oil/water emulsions. In addition, the composite membrane M3 has an excellent flux and dye removal effect for methylene blue(0.9954), rhodamine B(0.9984), and methyl orange (0.8670), respectively. More importantly, the composite membrane M3 exhibits a high permeation flux and rejection ratio for methylene blue under visible light irradiation after five consecutive cycles, indicating the M3 membrane has a good self-cleaning ability. Furthermore, the mechanisms of separation and photodegradation were discussed. This work provides a new strategy combining membrane separation and photocatalysis technology to treat multi-component oily wastewater.