Continuous Oil–Water Separation Using Polydimethylsiloxane-Functionalized Melamine Sponge

The development of absorbent materials with high selectivity for oils and organic solvents is of great ecological importance for removing pollutants from contaminated water sources. We have developed a facile solution-immersion process for creating poly­dimethyl­siloxane (PDMS)-functionalized sponges for oil–water separation. Sponge materials with densities ranging from 8 to 26 mg/cm3 were investigated as candidate skeletons. After functionalization, the lowest-density melamine sponge exhibits superior superhydrophobic and superoleophilic properties, absorption capacity, oil–water selectivity, and absorption recyclability. Via suction through such a functionalized sponge, we have experimentally demonstrated that various kinds of oils can be continuously separated from immiscible liquid mixtures without any water uptake. The widely available raw materials (melamine sponge and PDMS solution) and simple synthesis steps yield a cost-effective and scalable process for fabrication of absorbent materials that can be readily adopted for the cleanup of oil spills and industrial chemical leakage of low-surface-tension solvents that are immiscible with water.