Simple preparation superhydrophobic melamine sponge via one-step emulsion polymerization for continuous oil/water separation in harsh environment

The oil spill and industrial oily wastewater in large quantities has caused severe harm to the environment and human health, which make an urgent requirement to develop low-cost, eco-friendly, stable performance and highly efficient oil/water separation materials. Herein, a superhydrophobic/superlipophilic melamine sponge with excellent hydrophobic stability was successfully fabricated via one-step emulsion polymerization. During polymerization, trimethylolpropane triacrylate (TMPTA) and polyethylene imine (PEI) form robust micro-spheres, and polydimethylsilane (PDMS) cross-links to form hydrophobic coating on the original sponge skeleton. The modified sponge could continuously separate various immiscible oil/water mixtures under harsh conditions (including strong acids, strong bases, salts). Even after 10 consecutive cycles, the separation efficiency for toluene and petroleum ether exceeds 99.87%. In addition, the as-prepared sponge exhibited extraordinarily high oil absorption capacities (with a maximum saturated oil absorption of 107.31 g/g for chloroform) and excellent reversible compressibility (up to 100 compression cycles). More importantly, the pore size of modified sponge was adjusted through a simple mechanical compression strategy so that the compressed sponge met the particle size screening requirements to effectively separate the surfactant-stabilized water-in-oil emulsions. Based on the simple preparation protocol, fluorine-free raw materials, and excellent properties, the MS-TMPTA/PEI-PDMS sponge presented here have extremely promising application potential in oil/water separation.