Under seawater superoleophobic PVDF membrane inspired by polydopamine for efficient oil/seawater separation

Under seawater superoleophobic polyvinylidene fluoride (PVDF) membrane inspired by mussel is successfully fabricated for both surfactant-free and surfactant-stabilized oil/seawater separation. The conventional PVDF membrane is modified by a simple solution-immersion method, which was immersed in dopamine aqueous solution for 24 h. The morphology and chemistry of dopamine inspired PVDF membrane was characterized by scanning electron microscope (SEM), atomic force microscopy (AFM), attenuated total reflectance Fourier transform infrared spectra (FTIR-ATR) and X-ray photoelectron spectroscopy (XPS) respectively. The as-prepared membrane obtained stable superoleophobicity under seawater with an oil contact angle of 152±0.3° and extremely low oil-adhesion. Separation experiments for both surfactant-free and surfactant-stabilized emulsions showed that our membrane exhibited high oil/seawater separation efficiency (oil concentration in filtrate below 80 ppm) and substantially high permeability, which are several times higher than that current traditional filtration membrane. Fouling resistance to proteins was also investigated for long-term use purpose. This study provides a facile solution-immersion method to fabricate under seawater superoleophobic membrane, highlighting its great potential in practical oil/seawater separation.