Reducing bromate formation by catalyzed ozonation

The yield of bromate formed in catalytic ozonation in the presence of metal oxides was studied with bromide bearing water. The effects of catalyst dose, bromide concentration, pH, and temperature on the formation of bromate during catalytic ozonation were also discussed. Lab scale experiments showed that catalytic ozonation could decrease 85.1% bromate formation by increasing cerium oxide dosage from 0 to 250 mg/L. Catalytic ozonation can decrease 69.2%, 83.5% and 15.2% bromate formation when bromide concentrations are 0.5, 1.0 and 2.0 mg/L respectively. The effect of bromide concentration on the reduction of bromate in the catalytic ozonation was not clear. The increase of pH showed negative effect on reducing bromate formation in the catalytic ozonation. Catalytic ozonation can decrease 43%-59% of bromate formation with the temperature in the range of 5-25°C (bromide concentration was 1.5 mg/L). The variation of temperature in water had not significant influence on the inhibition of bromate formation in catalytic ozonation. The low bromate formation in catalytic ozonation was due to the inhibition of the reaction between molecular ozone and hypobromite by the catalyst. Since the inhibition of bromate formation in catalytic ozonation was weakened by the presence of sulfate, the function of the catalyst should be related to surface sites of the catalyst.