Tohid Vazirnejad - Department of Chemical Engineering, University Of Tehran, Tehran, Iran
Javad Karimi-Sabet - Nuclear Fuel Cycle School, Nuclear Science and Technology Research Institute, Tehran, Iran
Seyed Mohammad Ali Mousavian - Department of Chemical Engineering, University Of Tehran, Tehran, Iran

Polyvinylidene fluoride (PVDF) hollow fiber membranes were prepared by the dry/wet spinning phaseinversion technique. Fibers used for Membrane Distillation(MD) process must have at least one hydrophobic surfaceand high overall porosity with small pore sizes. Dimethylacetamide(DMAC) was used as polymer solvent and severalchloridic nano-salts (NaCl, KCl, BaCl2 and CaCl2) used as non-solvent additive in DMAC. The goals of using this saltare forming pore in dope solution that improved porosity in fibers structure. Four experiments were performed fordetermination of optimum salt type for increasing the overall porosity while keep pore sizes in hollow fiber structuresmaller than 0.4 micrometer. Other spinning parameters were maintained the same at these experiments. The preparedmembranes were characterized through SEM observation and contact angle test. Finally, the optimum membrane weretested for desalination by Direct Contact Membrane Distillation (DCMD) and compared with fiber that produced atsame spinning parameters and without nano salt additive. An optimal hollow fiber membrane was fabricated using theBaCl2 nano particles with contact angle of 93.80, overall porosity of 85% and pore size of 0.29 μm. This optimummembrane exhibits the highest permeate flux (16.902 Kg/m2hr compared to 11.015) and salt rejection factor of 99.9%.

Polyvinylidene Fluoride; Membrane Distillation; Hollow Fiber; Salt Additive