A smart switchable bioinspired copper foam responding to different pH droplets for reversible oil-water separation

A novel pH-responsive smart device has been developed for continuous separation of oil/water mixtures. Smart surfaces are obtained by electroless silver deposition followed by surface modification with a mixed solution of thiol containing carboxylic groups and methyl groups (HS(CH2)(11)CH3 and HS(CH2)(10)COOH). It was found that the wettability of the as-prepared copper foams can switch reversibly between superhydrophobicity and hydrophilicity according to their pH response. The as-prepared copper foam can easily remove the organic solvents either on water or underwater. Furthermore, the as-prepared copper foams can be applied to separate an oil-and-water mixture bidirectionally with high efficiency. This study provides a simple and environmentally friendly route to fabricate oil-water separation materials which have potential applications in industrial fields, such as in water treatment and petroleum refining. In particular, this smart surface is switchable under various pH conditions.