Electrochemically induced pitting corrosion of Ti anode: Application to the indirect reduction of bromate.

Bromate (BrO 3 − ) is a carcinogenic disinfection by-product of drinking water. The conventional electrochemical reduction of BrO 3 − generally occured at the cathode. In this study, we investigated the reduction process of BrO 3 − via electrochemically induced pitting corrosion of titanium (Ti) anode in a two-compartment electrolytic cell. Ti electrode was oxidized to produce reactive Ti ions, e.g., Ti 2+ and Ti 3+ , led by electrochemically induced pitting corrosion. These multivalent Ti species effectively reduced BrO 3 − to Br − . The pitting potential ( E Pit ) of Ti electrode was 1501 mV (SHE) at pH 7.0. However, the product analysis showed that the amount of reduced BrO 3 − was not in accordance with that of generated Br − , and a 19.8% loss of bromine mass should contribute to the formation of solid by-products. With the presence of coexisting anions (Cl − , NO 3 − , and SO 4 2− ), BrO 3 − at initial concentration of 100 μg/L also could be reduced to below the maximum contaminant level (MCL) of 10 μg/L, as well as the Cl − and NO 3 − were reduced simultaneously. BrO 3 − reduction by electrochemically induced corrosion of Ti electrode is feasible, but its practical application is limited by the high energy costs and unwanted Ti dissolution. [ABSTRACT FROM AUTHOR]