Novel in-situ electroflotation driven by hydrogen evolution reaction (HER) with polypyrrole (PPy)-Ni-modified fabric membrane for efficient oil/water separation

Efficient separation of oil/water emulsion is still a worldwide challenge. Herein, a new conception/strategy of in-situ electroflotation driven by hydrogen evolution reaction (HER) combining with a polypyrrole (PPy)-Ni-modified fabric membrane was proposed for efficient oil/water separation. To realize this new conception, nickel-decorated polyester fabric membrane was successfully fabricated via facile electroless Ni plating process on the polypyrrole (PPy)-modified surface. The Ni-decorated fabric membrane processed superhydrophilicity, underwater superoleophobicity and excellent electrical conductivity (electrical resistance of ~14.1 Ω), which could serve as cathode for HER. The fabric membrane itself couldn't separate oil/water emulsion, but achieved extremely high permeation (above 12526.5 L m −2  h −1 ) and oil rejection (above 98.6%) for separating stratified oil/water mixtures under gravity force. By applying an extra electric field on the conductive fabric membrane, an in-situ electroflotation process driven by HER can be produced. Under the optimized electroflotation conditions (20.0 V cm −1 electric field intensity, 20 g L −1 electrolyte concentration and 30 min electroflotation time) in this study, this new process could efficiently separate oil/water emulsion with high permeation flux (840.6 L m −2  h −1 ) and oil rejection (98.5%). The present work provided a new conception of in-situ electroflotation-membrane separation process for treatment of oily wastewater, showing strong application significance.