Efficient oily wastewater treatment by a novel electroflotation-membrane separation system consisting a Ni-Cu-P membrane prepared by electroless nickel plating

Electroflotation-membrane separation system with a conductive membrane has recently emerged as a promising tech-nology for oily wastewater treatment. However, the conductive membrane prepared by electroless plating often suffers the problems of low stability and high activation cost. To solve these problems, this work proposed a new strategy re-garding surface metallization of polymeric membrane by surface nickel-catalyzed electroless nickel plating of nickel-copper-phosphorus alloys for the first time. It was found that, addition of copper source remarkably enhanced the membranes' hydrophilicity, corrosion resistance and fouling resistance. The Ni-Cu-P membrane had an underwater oil contact angle of up to 140 degrees, and simultaneously possessed rejection rate > 98 % with rather high flux of 65,663.0 L center dot m-2 center dot h-1 and excellent cycling stability when separating n-hexane/water mixtures under gravity drive. The permeability is higher than the state-of-the-art membranes for oil/water separation. The Ni-Cu-P membrane as the cathode can be assembled into an electroflotation-membrane separation system, allowing to separate oil-in -water emulsion with 99 % rejection. Meanwhile, the applied electric field significantly improved membrane flux and fouling resistance (flux recovery up to 91 %) when separate kaolin suspensions. Polarization curve and Nyquist curve analysis further confirmed that addition of Cu element obviously enhanced corrosion resistance of the Ni modified membrane. This work provided a novel strategy to make up high-efficiency membranes for oily wastewater treatment.

Automated summary

Recently, an electroflotation-membrane separation system with a conductive membrane has emerged as a promising technology for oily wastewater treatment. However, the conductive membrane prepared by electroless plating often lacks stability and has high activation cost. To solve these problems, this study proposed a new strategy of surface metallization using surface nickel-catalyzed electroless nickel plating of nickel-copper-phosphorus alloys on polymeric membranes.