Mercury ion responsive wettability and oil/water separation.

A novel Hg(2+) responsive oil/water separation mesh with poly(acrylic acid) hydrogel coating is reported. The mesh can separate oil and water because of the superhydrophilicity of the poly(acrylic acid) hydrogel coating on the mesh, and switch the wettability based on the chelation between Hg(2+) and poly(acrylic acid) . The reversible change in oil contact angle of as-prepared mesh is about 149° after immersion in Hg(2+) solution. This mesh is an ideal candidate for oil-polluted water purification, especially for water that contains Hg(2+) contaminant.