Tuning of phase separation parameter using weak co-solvent in the preparation of native PVDF membrane for water purification

Abstract

Membranes are widely used for treating a variety of aqueous and solvent streams. Polyvinylidene difluoride (PVDF), is an excellent film forming polymer with outstanding chemical, thermal and mechanical stability. However, additive-free PVDF membranes with hydrophilic character to apply them in water purification was needed. All polyvinylidene fluoride (PVDF) membra nes were prepared via non-solvent induced phase separation (NIPS) method by tuning the phase separation parameters to match specific application. By tuning the phase inversion parameters like co-solvent concentration and evaporation time, the preparation of native polyvinylidene difluorideb (PVDF) for water purification application can be fabricated with hydrophilic membrande. In this research, preparation parameters in synthesizing PVDF membranes with using nonsolvent induced phase separation (NIPS) method were explored. The controlling parameters in the synthesis of these membranes are identified are type and composition of volatile co-solvent and evaporation time among others. The addition of a volatile co-solvent, ethanol and its concentrations (5 and 10 wt %) were varied to investigate its role in producing native PVDF membranes. The evaporation time in the range of 0, 30 and 60 s have been investigated since this can affect the microstructures of the membranes. The membranes were characterized in by SEM, porosity, contact angle and UV-Vis Spectrophotometry.