Removal of bromate ions from aqueous solutions via electrodeionization

Abstract

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.