Removal of bromate ions from water in the processes with ion-exchange membranes

Abstract

In this paper effects of bromates and accompanying anions removal from water in the processes with the use of ion-exchange membranes, like Donnan dialysis (DD) and electrodialysis (ED), have been analyzed. Also the suitability of electrodialytically recovered NaCl solution for removing bromates from water in the process of Donnan dialysis has been checked. The process of Donnan dialysis with the anion-exchange membrane (Selemion AMV, Neosepta ACS) makes it possible to remove efficiently the bromate ions from natural water with a relatively low concentration of salt in the receiving solution (100mM NaCl). Mono-anion-selective membrane (Neosepta ACS) applied in the process of Donnan dialysis is particularly useful for removing bromates from water with a domineering participation of large anions: bicarbonates and sulfates. Electrodialysis with the use of AMX/CMX membranes allows to remove bromates from water efficiently, together with a high efficiency of removing residual anions: bicarbonates, chlorides and sulfates. Electrodialysis with the ACS/CMX membranes, where the ACS membrane is a mono-anion-selective one, allows to reach a similar effect of removing bromates, bicarbonates, and chlorides, whereas sulfates are effectively retained by the ACS membrane. The process of electrodialysis with the ACS/CMX membranes makes it possible to recover efficiently NaCl from the spent receiving solution after the Donnan dialysis. Reuse of the regenerated salt solution (as a receiving solution in the process of Donnan dialysis) makes it possible to reach high efficiency of bromates removal.