Magnetic superhydrophobic polyurethane sponge modified with bioinspired stearic acid@Fe₃O₄@PDA nanocomposites for oil/water separation

Nowadays it is imminent to treat oily wastewater as the frequent occurrence of oil spills and discharge of oily wastewater requires rapid remediation of the damaged environment. Inspired by mussels, this study provides a simple and cost-effective method for preparing magnetic polyurethane sponges with superhydrophobicity and superlipophilicity by combination of self-polymerization of dopamine, covalent deposition of magnetic Fe₃O₄ nanoparticles, and modification of hydrophobic stearic acid. The prepared sponges have been comprehensively evaluated for its superhydrophobic stability in acid-base corrosion solution, high temperature, different salt solutions and organic solvents as well as the separation efficiency and application potential. Results show that the prepared sponge exhibits good chemical stability and a high selectivity in absorption of oil or organic substances in the aqueous solution with a water content in oil less than 0.2%. Besides, with superior absorption capacity and reusability, the prepared sponge can absorb 42 times as much oil as its own weight and be reused 50 times without any obvious decrease of performances. Thus, the prepared sponge has promising potential in the field of oil-water separation.