Synergistic effect of underwater superoleophobicity and photo-Fenton oxidation on improving anti-fouling performances of filtration membranes for oily wastewater separation

Underwater superoleophobic membranes can inhibit the adhesion of oil droplets and efficiently reduce oil-fouling. However, under the action of transmembrane pressure, the oil inevitably adheres to the membranes, which is difficult to be removed by facile washing. Here, an excellent coupling of underwater superoleophobicity and photo-Fenton oxidation is reported for desired anti-fouling performances. Briefly, composite polypropylene (PP) membranes with stable underwater superoleophobicity and excellent photo-Fenton oxidation efficiency were constructed by depositing hydrophilic α-FeOOH nanorods and mussel-inspired coating in turn. Various stable water-in-oil emulsions can be effectively separated with the obtained membranes. Most importantly, in the presence of H₂O₂ and visible light, α-FeOOH nanorods can photo-Fenton oxidize oil and dye that break through the underwater superoleophobic defense layer. Therefore, the reversible fouling ratio (Rr-L) and the flux recovery ratio (FRR-L) improve to 76.8 ± 3.2% and 87.2 ± 2.4% respectively, while the irreversible fouling ratio (Rir-L) decreases to 9.9 ± 0.2% for separation pump oil-in-water emulsion containing methylene blue. This work has great potential and strategic value in the treatment of oily wastewater and the preparation of advanced filtration and anti-fouling membranes.