Electrospun Poly (Vinylidene Fluoride-Co-Hexafluoropropylene) Nanofibers Membranes for Brine Treatment by Membrane Distillation

The major challenge for membrane distillation (MD) is membrane wetting resistance induced by pollutants in the feed solution. The proposed solution for this issue was to fabricate membranes with hydrophobic properties. Hydrophobic electrospun Poly (vinylidene fluoride-co-hexafluoropropylene) (PVDF-HFP) nanofibers membranes were produced for brine treatment using the direct contact membrane distillation (DCMD) technique. These nanofibers membranes were prepared from three different polymeric solution compositions to study the effect of solvent composition in the electrospinning process. Further, the effect of the polymer concentration was investigated by preparing polymeric solutions with three different polymer percentages: 6, 8, and 10%. All nanofibers membranes obtained from electrospinning were post-treated at varying temperatures. The effects of thickness, porosity, pore size, and LEP were studied. The hydrophobicity was determined by contact angle measurements, which were investigated by optical contact angle goniometry. The crystallinity and thermal properties were studied by DCS and XRD, while the functional groups were studied by FTIR. The morphological study was performed by AMF and described the roughness of nanofibers membranes. Finally, all nanofibers membranes have enough of a hydrophobic nature to be used in DCMD. PVDF membrane filter disc and all nanofibers membranes were applied in DCMD to treat brine water. The resulting water flux and permeate water quality were compared, and it was discovered that all produced nanofibers membranes showed good behavior with varying water flux, but the salt rejection was greater than 90%. A membrane prepared from DMF/acetone 5-5 with 10% PVDF-HFP provided perfect performance, with an average water flux of 44 kg.m-2.h-1 and salt rejection of 99.8%.