Bi-functional composite foam with hierarchical structure for efficient separation of emulsified mixtures consisting of oil and water

Seeking of novel materials with special wettability is highly demanded for efficient separation of emulsified mixtures. In this study, carbonized melamine foam modified with cobalt hydroxide nanosheets was fabricated by a two-step route consisting of thermal pyrolysis and controlled chemical precipitation. The developed material exhibited a superamphiphilicity in air, and a controlled superoleophobic or superhydrophobic performance in various liquid conditions. By utilizing these properties, the composite foam was used as a bi-functional material to separate various oil-water emulsions. The results demonstrated that the developed material, solely using gravity without external stimulus, had the capability to separate not only the surfactant-stabilized oil-in-water emulsions with a high separation flux, but also the water-in-oil ones with remarkable oil purity. The facile method for the material preparation, high separation merit and excellent anti-fouling property of material provided a new candidate for the separation of emulsion systems.