Polypyrrole coated membranes with tunable surface wettability for effective oil-water separation by chemical oxidation

The effective treatment of water pollution is still a major problem to be solved urgently, especially the separation of oily wastewater. The development of membrane separation technology has greatly improved the recovery and reuse of domestic and industrial oily wastewater. Here, we prepared polypyrrole (PPy) coated meshes via a simple chemical oxidation polymerization method, and systematically studied the effect of different oxidants on oil-water separation efficiency. The obtained membranes possess solid structures, excellent environmental stability, low surface adhesion and good underwater superoleophobicity, which can stably maintain the underwater superoleophobic performance after soaking for 24 h in acid, alkali and salt solution, with the underwater oil contact angle of 151° or more. Under the driving of gravity, it can quickly separate various oil-water mixture, and the separation efficiency is over 95% after many cycling numbers, which has promising potential for on-demand oil-water separation.