Preparation of Nanoporous Poly(Vinylidene Fluoride) Membrane and Consideration of Its Performance

In this research, nanoporous poly(vinylidene fluoride) (PVDF) membrane was prepared via Non-solvent Induced Phase Separation (NIPS) method at solution temperature of 75°C and coagulation bath temperature of 20°C. Also, mechanism of PVDF membrane formation (morphology) and its performance (flux of pure water and rejection efficiency of 7 biological compounds) was investigated. In the formation of this membrane, binodal demixing was dominant mechanism and that crystallization and spinodal decomposition caused to form granular structure at membrane surface and rim of macrovoids. Size of membrane pores was measured by Barett-Joyner-Halenda (BJH) method. This method showed that the size of these membrane pores is in nanoscale (i.e. 18-27 nm). Flux of pure water and rejection of the biological compound of blue dextran at pressure of 200 kPa were for this PVDF membrane 23.60 L/m2h and 92.5% respectively that were measured by the use of ultrfiltration apparatus.