Superhydrophobic electrospun FPI/PTFE nanofiber membranes for robust vacuum membrane distillation

[Display omitted] •The micro/nano structure of FPI nanofiber membranes was regulated by electrospinning combined electrospraying techniques.•The first application of FPI nanofiber membranes in vacuum membrane distillation.•The prepared FPI nanofibrous membrane had excellent hydrophobicity, durability and desalination performance. In this study, we firstly proposed a fluorinated polyimide (FPI) /polytetrafluoroethylene (PTFE) nanofiber membrane for vacuum membrane distillation (VMD) by electrospinning FPI and double eletcrospraying PTFE particles. The resultant FPI /PTFE nanofiber membrane possessed desirable superhydrophobicity (water contact angle (WCA) of 155.3°), anti-wettability and durability due to the rough micro/nano structure of the membrane surface. The surface morphology and chemical composition of obtained FPI nanofiber membranes were characterized by SEM, FTIR, XRD and XPS, and the effects of PTFE content on the VMD performance were investigated. Results showed that the liquid entry pressure (LEP) of FPI/PTFE nanofiber membranes increased significantly after PTFE particles were introduced (LEP of 158 kPa). In the VMD process, the FPI/PTFE nanofiber membrane showed stable MD flux (33.49 L·m2·h−1) and excellent salt rejection (99.96%). Furthermore, the FPI/PTFE nanofiber membrane maintained its favorable performance, resulting in stable MD flux (30.21 L·m2·h−1) and salt rejection (99.96%) after the 120 h continuous long-term operation. It shows a promising future for VMD of FPI/PTFE nanofiber membranes.