In situ transformation of hierarchical FeOOH/CuO arrays with electro-cleaning capability for oil-in-water emulsion separation and electro-fenton degradation of organic dye

With the increasing oily wastewater discharges and crude oil leakage accidents, the eco-environment and human health is seriously harmed. Membrane technology is an ideal choice for industrial oil/water separation, but the gradually structural fouling has severely hampered the long-term practical applications. Herein, membrane separation, electroflotation and electro-Fenton technologies are successfully coupled through structural design and regulation. The FeOOH nanosheet/CuO nanowire coated on copper mesh is prepared via chemical oxidation and thermal dehydration. The FeOOH nanosheets are in situ converted and tightly encapsulated on the surface of CuO nanowires, while the hierarchical nano-array structure and interconnected FeOOH coating ensure the superhydrophilic, underwater superoleophobic and electroflotation self-cleaning capabilities. Therefore, the 3*Fe/CuO-5 membrane exhibits high water flux (≥1400 L h−1 m−2), separation efficiency (≥99.2%) and excellent electroflotation self-cleaning capability (within 2 min) in oil-in-water emulsion separation. Moreover, the heterogeneous electro-Fenton system composed of 3*Fe/CuO-5 membrane exhibits good degradation efficiency of 30 mg L−1 methylene blue within 100 min. Thus, the as-prepared 3*Fe/CuO-5 membrane is promising in industrial wastewater purification due to its rapid oil separation and soluble organic purification ability.