Bromate removal in the ion-exchange process

To remove bromates from water, use was made of anion exchange in the process of Donnan dialysis conducted with an anion-exchange membrane. Under such conditions, the removal of bromates from a one-component solution was found to be very high (more than 90%). It was observed that the presence of accompanying anions (NO3− and HCO3−), whose concentrations were by several orders of magnitude higher than the concentrations of bromates, brought about a decrease in the rate and efficiency of bromate removal from the feed. In the process with the Selemion AMV membrane the removal of bromates amounted to approximately 84% at a salt concentration of 300 mM NaCl in the receiver. Anion exchange in Donnan dialysis with Neosepta AFN (a membrane characterized by a high ion-exchange capacity and a high water content) proceeded at a faster rate and was found to be more efficient only with respect to the ions that dominated in the feed, i.e. nitrates and bicarbonates. In this process the removal of BrO3− ions was less efficient than in the process conducted with the Selemion AMV membrane, and failed to exceed 70%.