Amphiphobic PFTMS@nano-SiO₂/ePTFE Membrane for Oil Aerosol Removal

Synthetic expanded polytetrafluoroethylene (ePTFE) membrane has a wide range of applications, including aerosol and dust removal, and exhibits high dust-removing efficiency, high air permeability, and cost-effectiveness. However, the intrinsic oleophilic surface of ePTFE limits its application in the oil-bearing gas-solid separation process. Herein, we report a surface modification method to prepare amphiphobic ePTFE membranes via coating of a layer of 1H,1H,2H,2H-perfluorooctyltrimethoxysilane (PFTMS) - modified nano-SiO₂ onto the surface of ePTFE fibers. The oil contact angle of the modified ePTFE membranes was increased from 0 to 123°, while retaining the initial water contact angle of 142°. The amphiphobic membrane shows excellent oil aerosol filtration efficiency with a comparative low pressure drop and high oil rejection rate of 99.5%. Remarkably, the membrane can be reused after simple rinsing with water. The oil aerosol filtration efficiency of membrane remained as high as 98.5% after five cycles of filtration and cleaning.