Formation and characterization of polytetrafluoroethylene nanofiber membranes for vacuum membrane distillation

• Superhydrophobic fibrous membranes were prepared with a moniliform structure.
• The structure evolution of the fibers in the sintering process was investigated.
• The PTFE membranes having a LEP value as high as 165 kPa can be used in VMD process.
• The high porosity of the prepared membranes (about 80%) led to the remarkable flux.

The polytetrafluoroethylene nanofiber membranes for membrane distillation were prepared by sintering the precursor electrospun polytetrafluoroethylene/polyvinyl alcohol composite membranes. The effects of sintering temperature and time on the morphology and properties of the prepared membranes were investigated. The prepared membranes were characterized by contact angles, IR and SEM to observe the structure evolution of the fibers during the sintering process. A unique moniliform structure was formed in proper conditions. The relationship between fiber morphology and membrane hydrophobicity, mechanical strength and porosity were discussed. The effect of membrane thickness on the liquid entry pressure was also studied to make sure the membrane was available in vacuum conditions. Moreover, membrane was tested in vacuum membrane distillation configuration. The pure water flux and salt rejection were tested to evaluate the membrane permeability and separation property.