Minimizing bromate formation with cerium dioxide during ozonation of bromide-containing water

This work investigated the effect of several metal oxides including alpha-FeOOH, alpha-Fe2O3, gamma-FeOOH, and CeO2 on bromate formation potential (BFP) during ozonation of bromide-containing water. Results indicate that CeO2 could most effectively minimize the BFP among these metal oxides taking ozonation alone as control. The BFP minimization by O-3/CeO2 favored a relatively low Br- concentration (i.e., <1.0 mg L-1) and pH < 7. Water temperature ranging from 5 to 25 degrees C had no significant impact on the percent reduction of BrO3. Further investigation indicates that the effective BFP minimization can be ascribed to neither the surface adsorption of BrO3- or Br- on CeO2 nor the surface reduction of BrO3 to HOBr/OBr- by CeO2. It seems to have relationship with the activity of surface Ce(IV) sites. The CeO2 can lower the concentration of H2O2 which is formed during ozone decomposition and promotes BrO3 formation. Another possible reason for the BFP minimization is that the CeO2 could possibly reduce BrO- to HOBr/OBr- during the decomposition of H2O2. (C) 2008 Elsevier Ltd. All rights reserved.