Electrospun rough PVDF nanofibrous membranes via introducing fluorinated SiO2 for efficient oil-water emulsions coalescence separation

Oily wastewater pollution is grievous and challenging all over the world and how to effectively and economically remove emulsified oils from wastewater is a tough problem. A novel rough polyvinylidene fluoride (PVDF)-F-SiO2 nanofibrous membrane as the polyester (PET) substrate was fabricated by the facile one-step electrospinning technology with introducing fluorinated SiO2 nanoparticles for effective oil-water coalescence separation. Fluorinated SiO2 could increase the microscopic roughness, leading to a higher hydrophobicity. The obtained PVDF-F-SiO2 nanofibrous membrane had a high under oil contact angle (UOCA) of 122.3° indicating a high under-water hydrophobicity. The prepared membrane could perform the high oil-water emulsion coalescence separation efficiency with 99.2 % for treating surfactant-free hexadecane-in-water emulsions after 5 cycles. The PVDF-F-SiO2 nanofibrous membrane demonstrated high separation efficiencies under different flow rates, initial oil concentrations, and oil types in emulsified oil-water systems. More importantly, the SDBS-surfactant-stabilized hexadecane-in-water emulsion could be separated with efficiencies above 82.0 % after 5 cycles, which showed promising potential in treating oily wastewater.