Robust superhydrophobic-superoleophilic polytetrafluoroethylene nanofibrous membrane for oil/water separation

A robust polytetrafluoroethylene (PTFE) nanofibrous membrane was prepared by a simple electrospinning-sintering strategy for efficient oil/water separation. Specifically, a PTFE@PVA hybrid nanofibrous membrane in which PTFE particles were uniformly distributed in PVA nanofiber was first prepared by electrospinning, then a sintering treatment was applied to obtain the PTFE nanofibrous membrane. Electron microscopic characterization revealed that the membrane was formed by a sintering mechanism of a fast decomposition of PVA followed by a slower fusion of PTFE particles. Spectroscopic characterization confirmed that the PVA polymer was completely decomposed after 8 h of sintering. The resulting membrane had a ratio of fluorine to carbon atomic ratio of 2.0, indicating that a pure PTFE nanofibrous membrane was obtained. The as-prepared PTFE membrane exhibited superhydrophobic property with a water contact angle of 155.0° and a sliding angle of 5.1°. Its tensile strength was as high as 19.7 MPa, indicating excellent mechanical strength. The membrane was successfully applied for gravity-driven oil/water separation with a permeate flux of 1215 L m−2 h−1. Moreover, its excellent corrosion resistance and mechanical stability suggest that the PTFE nanofibrous membrane could stand harsh environment existing in industrial oil/water separation processes.