Removal of bromate ions from aqueous solutions via electrodeionization

Bromate (BrO₃^-) is a disinfection byproduct formed during the chemical oxidation of water containing bromide. Due to the carcinogenic effect of bromate, its maximum permissible concentration in drinking water has been set to 10 μg/L by the World Health Organization. In this study, the removal of BrO₃^- ions from aqueous solutions via electrodeionization (EDI) was investigated. The removal rate of BrO₃^- varied with the applied potential, and at 10 V, a removal rate of 99% was achieved. However, further increasing the applied potential to 30 V had a negative effect on the removal rate. Additionally, a low bromate concentration in the product water was achieved by reducing Na₂SO₄ conductivity in the electrode compartment. The removal of BrO₃^- is pH dependent, and at pH 1, only 17.5% was removed. However, increasing the pH of the solution to 5 increased the removal rate to 99.6%. Increasing the operating time and number of cells in the EDI stack improved the removal rate of BrO₃^-, and its concentration decreased from 5 mg/L to 1.4 μg/L. The calculated flux for BrO₃^- was 2.17 × 10^-5 mol/m²s, specific power consumption was 89.98-W/hg KBrO₃, and mass-transfer coefficient was 5.4 × 10^-4 m/s at 10 V.