An environmentally benign approach to prepare superhydrophobic magnetic melamine sponge for effective oil/water separation

The methods to modify commercially available sponge used for recovering spilled oil and organic solvent from water usually possess the drawbacks of high cost, complicated fabrication procedures and secondary pollution. Herein, a superhydrophobic magnetic melamine sponge (MS) was fabricated via in situ synthesis of Fe3O4 particles and dip coating of Candelilla wax (CW). The facile modification process made a transition of MS from amphipathic nonmagnetic sponge to superhydrophobic magnetic sponge. Owning to the high porosity of MS, hierarchical microstructures of Fe3O4 particles and hydrophobic hydrocarbon chain of CW, the modified MS possesses low bulk density (0.0173 g/mL), excellent absorption capacity (55-104 g/g), remote controllability, high water contact angle (WCA, 158.8 degrees), good hydrophobicity maintenance and durability. The obtained sponge also has the abilities to continuously absorb and collect light oil from water surface assisted by a vacuum pump and to separate heavy oil under water as a filter driven by liquid weight. More importantly, our modification strategy may find a new way to prepare superhydrophobic sponge by extending the coating reagent to a series of plant waxes.