Fabrication and characterization of polyvinylidenefluoride-co-hexafluoropropylene (PVDF-HFP) electrospun membranes for direct contact membrane distillation

Polyvinylidene fluoride-co-hexafluoropropylene (PVDF-HFP) membranes were prepared via the electrospinning method. Three sets of mats, with different fiber diameters and physical properties, were obtained by varying polymer concentration from 10 to 15wt%. Membranes were formed by hot pressing the prepared mats to fuse the fibers. As prepared mats were hot pressed in order to control the membranes dimensional stability and mechanical strength and to alter the pore size and pore size distribution. The effects of hot pressing and variation of fiber diameter on pore size distribution, porosity, contact angle, gas permeation, and liquid water entry pressure (LEP) of the fabricated membranes were all studied. Optimized membranes were obtained with mean pore size, porosity, contact angle and LEP of 0.26μm, 58±5%, 125°±2.41 and 19.1psi, respectively. Fabricated membranes were tested for desalination by direct contact membrane distillation and a water flux value of 20-22Lh^-1m^-2 was obtained with a salt rejection (SR) ratio of 98%.