A novel approach to Chromium rejection from sewage wastewater by pervaporation

Abstract

Pervaporation is an effective method, especially in the separation of azeotropic mixtures or in the recovery of some components from the mixtures. Although various methods have been used for the treatment of chromium-containing wastewater that has become a matter of concern for the health of aquatic ecosystems, the pervaporation has never been used before in the literature. In this study, Cr/water (Cr (III), Cr (VI)) mixtures were separated by a pervaporation using polyvinyl alcohol (PVA) and sodium Y (NaY) zeolite membranes. Study results indicated that increasing the zeolite percentage, the membrane thickness, the amount of Cr in the feed solution and, the pH all increased rejection and decreased flux. In contrast, an increase in temperature caused rejection to decrease and flux to increase. The best rejection obtained for Cr (VI) was 144.4%. For Cr (VI) removal from sewage wastewater, the maximum rejection under optimum conditions was 160% and the flux was 0.12 kg/m2h. Also, Cr (VI) was not detected in any permeates. The permeate concentration was calculated to be 97.1% in experiments with a Cr (III)/water mixture. PVA/NaY membrane showed selective permeability for Cr (VI), while it does not show selective permeability for the useful Cr (III) component.