Pervaporative desalination of high-salinity water

Desalination of high salinity water by pervaporation using hydrophilic poly(ether-block-amide) membranes was investigated. A flux of 1680 g/(m2 h) and almost complete salt rejection (>99.9%) were achieved at 65 °C. Increasing salt concentration from 1 to 20 wt% resulted in a 50% reduction in water flux, whereas the salt rejection was not influenced. The salt rejection was not influenced by the salt type (i.e., NaCl, MgCl2 or Na2SO4) either. With an increase in temperature, the water flux through the membrane increased in spite of a decrease in the water permeability coefficient. The temperature dependence of water flux obeyed an Arrhenius type of relationship. Batch operation over a period of 10 h showed that the water flux decline could be recovered by washing the membrane with deionized water and there was no irreversible fouling during the pervaporative desalination process.