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

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 Br-3(-) concentration were optimized. 94.2% of BrO3- (1.22 mu M) 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 Bro(3)(-) 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 Bro(3)(-) and provide a new direction to the application of nZVI.