Electrochemical reduction of bromate using noble metal-free nanoscale zero-valent iron immobilized activated carbon fiber electrode

Abstract

Bromate (BrO3−) is a disinfection by-product in drinking water and has been proven to be potentially carcinogenic to humans. Herein, electrocatalytic BrO3− reduction using a noble metal-free nanoscale zero-valent iron immobilized activated carbon fiber (nZVI/ACF) electrode was investigated. The operating conditions including Fe content, initial solution pH, applied current intensity, and initial Br3− concentration were optimized. 94.2% of BrO3− (1.22 μM) was removed and completely transformed into bromide (Br−) within 90 min by 3.0%-nZVI/ACF at the applied current intensity 10 mA. The electrocatalytic BrO3− reduction could be achieved under a wide dissolved oxygen (DO) (0.5–7.8 mg L−1) and pH (3.0–10.0), and the decreasing DO and pH was favorable to the electrocatalytic reaction. The mechanism study demonstrated that the electrocatalytic BrO3− reduction was accomplished via the direct reduction of nZVI (31.8%), electrocatalytic reduction by nZVI (41.9%) and ACF (26.3%). nZVI/ACF electrode could maintain its high electrocatalytic activity after five successive cycles. The experimental results suggested that nZVI/ACF could achieve the fast and effective removal of BrO3− and provide a new direction to the application of nZVI.