Salt transport in polymeric pervaporation membrane

The salt transport in a PEBA membrane used in pervaporative desalination was studied. The concentration profile of salt in the membrane during pervaporation was investigated experimentally using a multilayer membrane. The salt was found to be sorbed in the membrane but was not removed during the pervaporative desalination process, and the salt concentration in the membrane varied linearly with position. High purity water was obtained as the permeate as long as the permeate side was kept dry under vacuum. The accumulated salt uptake in the membrane follows the order of MgCl2 > NaCl > Na2SO4. The solubility of salt in the membrane follows the order of MgCl2 > NaCl > Na2SO4. Both the permeability and diffusivity of salt in the membrane follow the order of NaCl > MgCl2 > Na2SO4. The permeability of salt in the membrane is not influenced by the feed salt concentration. It is mainly determined by the diffusion coefficients.