Modeling of direct contact membrane distillation process: Flux prediction of sodium sulfate and sodium chloride solutions

Membrane distillation (MD) can be used to process highly concentrated aqueous solutions to recover water. In this study we tried to model direct contact membrane distillation process in three different temperature systems using mass and energy balance. Data used in this study were the water flux behavior using two aqueous salt solutions of sodium sulfate (Na2SO4) and sodium chloride (NaCl) which were extracted from C.M. Tun et.al in a MD set up. Membrane flux behavior and other model parameters for a GVHP hydrophobic membrane were calculated. Initial concentration of sodium sulfate and sodium chloride was 2 M and 4.5 M, respectively, which was tested in three temperature systems of feed/permeate, 60/20, 60/30 and 50/30. It was found that both concentration and temperature polarization influenced the performance of MD. Mean relative absolute error for systems 60/20, 60/30 and 50/30 was 7.29%, 7.52% and 8.75% for sodium sulfate and 4.34%, 10.99% and 5.01% for sodium chloride, respectively.