Removal Of Bromate In Drinking Water By Activated Carbon Supported Noble Metal Catalyst

The traditional activated carbon process has many disadvantages such as low efficiency, lack of long-term nature for the removal of bromate. To remove these drawbacks, carbon supported with noble metal catalysts were prepared and first probed by our group for reduction of bromate in water under no any external reducing agent the conditions. The study includes the performance of the catalyst, the factor study, and the bromate removal mechanism in order to provide a new material and a new methods for the removal of bromate in drinking water.Firstly, the study carries research into removal of bromate by activated carbon supported with silver. It contains the impact of optimal preparation conditions of activated carbon supported with silver and initial concentration, pH, co-anions on activated carbon supported with silver. Results show that the optimal preparation conditions of silver-AC include calcination temperature of 400℃, calcination time of 3h, Ag/AC of 0.05%, calcination environment of N₂ and precursors of Ag(NH₃)₂⁺ ; bromate reduction by silver-AC increases as the solution pH decreases; the bigger the initial concentration was, the lower of the bromate removal efficiency by silver-AC was; the anions effect the removal of bromate by silver-AC sites, with the most influence from NO₃^- and the least from F^-.Secondly, it studies the removal of bromate with activated carbon supported with noble metal. By examing the removal efficiency of seven noble metal catalyst , namely Ru/AC, Pd/AC, Ir/AC, Au/AC, Rh/AC, Pt/AC and Ag/AC, it is found that the removal efficiency of bromate reached to 97% by using Ru / AC, and remained at 90% after four times being use. According to the bromide ion balance study, we found that the recovery rate of bromide reached to 97%, thus verified that the bromate was almost completely reduced to bromide ions by Ru/AC. On the basis of the above analyses, we proposed the path of bromate reduced to bromide by Ru/AC. In the reaction system, RuO₂ as an electron donor , provided with electron so that bromate was reduced to bromide. Meanwhile, RuO₂ changed into RuO₃. The RuO₃ was so unstable that it would break down into RuO₂ and O₂.Finally, the removal of bromate by activated carbon supported with ruthenium is studied. The study includes the optimal preparation conditions of activated carbon supported with ruthenium, impact factors and RSSCT test. Results show that the optimal preparation condition of Ru/ AC were calcination temperature of 500℃, calcinations time of 2h, Ru/AC of 0.1%, calcination environment of N₂. The degradation rate of bromate would decrease when the humic acid concentration increased; bromate reduction by Ru/AC increased as the solution pH decreased; the bigger the initial concentration was, the larger of BrO₃^- adsorption capacity by Ru/AC was, when the pH is 6.4, the removal of bromate remained at 96.3%.Co-anions inhibited the removal of bromate, the power grew on the raise of concentration. Al³⁺, Fe²⁺ could promote the degradation of bromate, the promotion enhanced on the raise of concentration. The activated carbon column filling of Ru/AC with appropriate proportion would avoid the bromate exceed 10μg/L.