Performance Optimization of Highly Hydrophobic PVDF Membrane for Treatment of Aqueous NaCl Solution by Vacuum Membrane Distillation

The highly hydrophobic membranes were applied in the vacuum membrane distillation(VMD) of pure water and 0.03 g/L aqueous NaCl solution. Orthogonal method was employed to optimize the preparation of PVDF membrane. The result of designdirect analysis was consistent to that of direct measurement. The optimized conditions are: the mass fractions of casting solution are 15% PVDF/51% TEP34% DMAc; the mass fraction of mixed solvent(TEPDMAc) in the first coagulation bath is 60%; the membrane thickness is 0.17 mm; the mass ratio of TEP to DMAc in the first bath is 60∶40. The removal rate of NaCl can be over 99.90%.