臭氧催化氧化控制溴酸盐生成效能与机理

比较了单独臭氧氧化和金属氧化物存在下臭氧催化氧化过程中溴酸盐的生成规律,探讨了催化剂投量、溴离子浓度、水的pH值、反应温度等对臭氧催化氧化控制溴酸盐生成的影响规律及在催化剂存在下控制溴酸盐生成的机理.结果表明,催化剂投量从0 mg/L增加到250 mg/L,能减少溴酸盐生成量85.1%;当溴离子浓度为0.5、1.0、2.0 mg/L时,臭氧催化氧化分别能减少溴酸盐生成量69.2%、83.5%和15.2%,溴离子浓度变化对催化作用的影响无明显规律;pH值升高会降低催化作用的效果;反应温度在5～25℃之间时,臭氧催化氧化能降低43%～59%的溴酸根生成量(溴离子浓度1.5 mg/L),反应温度变化不影响催化效果.催化剂通过抑制臭氧对次溴酸的氧化减少了溴酸根的生成量.催化剂表面的某些基团与硫酸根络合会削弱臭氧催化氧化控制溴酸根生成的能力,因此,利用催化剂控制溴酸盐的机理与催化剂表面性质密切相关.

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 degrees 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.