Preparation and characterization of novel poly (vinylidene fluoride) membranes using flower-like Bi 2 WO 6 for membrane distillation

Abstract

Abstract In this study, hydrophobic flat-sheet composite membranes of polyvinylidene fluoride (PVDF) were fabricated using non-woven fabrics as a support for direct contact membrane distillation (DCMD) through non-solvent induced phase separation (NIPS). The effects of three-dimensional (3D) Bi 2 WO 6 on membrance morphology, porosity, pore size, pore size distribution, hydrophobicity, thermal properties and permeability were investigated. The flower-like Bi 2 WO 6 could optimize membrane structure and improve the membrane porosity by its unique 3D hollow structure. During the desalination process of 3.5% sodium chloride solution, the salt rejection with nano-Bi 2 WO 6 membranes was higher than the pristine PVDF membrane. The maximum transmembrane permeate flux (about 13.12 kg/m 2 h) was obtained with the feed solution at 60 °C and the cold distillate water at 20.0 °C, which was higher than the commercial PVDF membrane (9.43 kg/m 2 h) and the pure PVDF membrane (12.06 kg/m 2 h). Furthermore, the hybrid membrane exhibited outstanding stability in the 100 h continuous desalination experiments. Our results demonstrated that the prepared PVDF flat-sheet composite membrane with 0.5% flower-like Bi 2 WO 6 has a very good prospect to be utilized in membrane distillation process for desalination.