The Fabrication of Oleophobic Coating and Its Application in Particulates Filtration

The stir-frying process in Chinese cooking has produced serious emissions of oily particles, which are an important source of urban air pollution. In particular, the complex composition of fine particulate may pose a threat to human respiratory and immune systems. However, current filtration methods for oily particulate fumes have low filtration efficiency, high resistance, and high equipment costs. In polypropylene (PP) electret filters, efficiency rapidly decreases and pressure drop (wind resistance) sharply increases after the adsorption of oily particles, due to the oleophilic properties of the PP fibre. We addressed this issue of filter performance degradation by fabricating a sodium perfluorooctanoate (SPFO) oleophobic coating on polyvinylidene fluoride (PVDF) fibre membranes for oily particle filtration. The SPFO coating showed a promising oleophobic effect even at low concentrations, which suggests it has oleophobic properties for different oil types and can be modified for different substrates. This fabricated oleophobic coating is thermostable and the oleophobic effect is unaffected by temperatures from 0 to 100 °C. By modifying the SPFO coating on the PVDF membrane, a high filtration efficiency (89.43%) and low wind resistance (69 Pa) was achieved without oil adhesion, so the proposed coating can be applied in the filtration and purification of oily fine particles and offers a potential strategy for preventing atmospheric oil pollution.