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

Abstract

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)₁₁CH₃ and HS(CH₂)₁₀COOH). 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.