Catalytic Bromate Removal from Water by Using Activated Carbon Supported with Ruthenium (AC/Ru) Catalyst

As a disinfection by-product with carcinogenic properties, bromate (BrO₃^-) concentration is limited to below 10 μg/L in water. In this work, activated carbon supported with ruthenium (Ru/AC) catalyst was prepared to reduce bromate, and its removal pathways were investigated comprehensively. By using Ru/AC catalyst, 200 μg/L bromate could be reduced to no more than 10 μg/L in a 2 h reaction under room temperature and neutral pH. Bromate reduction by Ru/AC conformed to the pseudo-first-order kinetics, during which initial bromate concentration, pH, temperature, and co-existed anions displayed significant effects on BrO₃^- removal efficiency. From a mass-balance analysis, bromate was deemed to be thoroughly reduced to bromide and oxygen by Ru/AC catalyst, and its removal pathways included two steps, that is, bromate was first adsorbed onto the Ru/AC surface, and then it was reduced to bromide by the synergistic function of RuO₂ and AC. Experiments revealed that Ru/AC catalyst was effective in bromate reduction, as that bromate was reduced to bromide without any intermediate formation.