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

This work investigated the effect of several metal oxides including α-FeOOH, α-Fe2O3, γ-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 O3/CeO2 favored a relatively low Br− concentration (i.e., <1.0 mg L−1) and pH < 7. Water temperature ranging from 5 to 25 °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.