Chemically stable superhydrophobic polyurethane sponge coated with ZnO/epoxy resin coating for effective oil/water separation

A simple immersion method to fabricate a superhydrophobic polyurethane sponge with oil-water separation efficiency, reusability and chemical stability. [Display omitted] •A simple immersion method to fabricate superhydrophobic polyurethane sponge.•This superhydrophobic PU sponge shows excellent oil-water separation efficiency, reusability.•The prepared superhydrophobic PU sponge was stable from pH 1–11, allowing it to be applied in a wide range of environments. In this study, a superhydrophobic polyurethane sponge was prepared by a simple immersion method. The strategy was based on coating a ZnO/epoxy resin solution onto the skeleton of a porous polyurethane sponge, followed by reacting it with a mixture of stearic acid/acetic acid/ethanol solution. The prepared superhydrophobic polyurethane sponge with a contact angle of 156 ± 3° can selectively separate mixtures of water and various oily solvents. The separation efficiencies of the superhydrophobic polyurethane sponge for a variety of oil/water mixtures were all above 98 %. Moreover, the prepared superhydrophobic polyurethane sponge had superior reusability and maintained a separation efficiency of more than 97 % after ten oil/water separation cycles, and it was chemically stable from pH 1–11. This superhydrophobic polyurethane sponge may offer a new oil/water separation strategy due to its excellent separation efficiency, reusability, and chemical stability.