Antifouling multi-functional membrane for oil/dye wastewater treatment: Regeneration while treating mixed pollutants

Treatment of insoluble oils or soluble organic dyes in wastewater by membrane separation is considered to be one of the most effective strategies. However, simultaneously removing oils and dyes from wastewater is challenging. In this study, hydroxyl iron oxide was grown on PVDF membranes by in situ self-assembly and in situ self-growth strategies using proanthocyanidins as a bridge. The PVDF-PC-FeOOH membrane possesses excellent wettability and photo-Fenton catalytic properties (all types of underwater oil contact angles are larger than 150°, and the degradation efficiency of methylene blue within 20 min is greater than 70%). The emulsion separation flux and efficiency can reach 976.1 L·m-2h−1 and 99.7%, respectively. In addition, the photo-Fenton catalytic degradation process was discussed. The regeneration rate of the membrane is over 90%. The flux can be stabilized over a period of time in a continuous filtration process of 60 min (flux over 158.7 L·m-2h−1). Simultaneous removal of mixed pollutants and regeneration of the membrane is achieved in a single step. In multi-component oily wastewater, the membrane has selective adsorption capacity for cationic dyes, and the removal rate can achieve 98.6%. The strategy provided in the present study enhances the value of membranes for practical applications in the field concerning the filtration of oily wastewater and selective separation of dyes in the dyeing and printing industry.