Membrane Distillation(MD) is a process for producing pure water, concentration of solution, purification of wastewater effluents and etc. has widely studied. This process is new and for low costs and energy saving is a good replacement for common sepration processes such as distillation and Reverse Osmosis (RO). In this project the Poly(vinylidene fluoride) (PVDF) falt sheet membranes were prepared by a phase sepration method and multi wall carbon nanotube (MWCNTs) was used to improve the charactristics of membranes. For evaluation of prepared membranes, membrane thickness, hydrophobicity, permeability, pore sizes and morphology were checked. Four parameters, thickness of casting, weight percent of polymer in solution, weight percent of carbon nano tube and temperature of solution were controlling factors. The taguchi method was choosed. For evaluation of all variables and responces at the same time. The obtained results showed that among the controlling factors, thickness of casting was the most effective factor on membrane thickness test. Composition of nano particles in solution was the most effective factor on contact angel of membrane and the optimum amount of contact angel was obtained 135°. Effective on pore sizes and the carbon nano tubes composition was the most effective factor. The maximum pore size was obtained 0.472 ?m. In pure water flux test, the nano particles composition had the greatest effect on pure water flux and decreased with increasing the amount of nano particle in solution. The optimum flux of pure water was obtained 12.312 Kg/m 2 h. FTIR tests showed that carbon nano tubes hadn’t any effect on PVDF boundles. SEM images showed that the membranes containing carbon nano tube had smaller pore sizes rather than the membrane without carbon nano tube. The saline water flux test were performed with four obtained optimized membranes and 30 g/l NaCl solution. The maximum flux was obtained 9.562 Kg/m 2 h. The MWCNTs without functional groups was effective in improving the hydrophobicity.
