蜂窝陶瓷催化臭氧化降解水中痕量硝基苯的机理研究

实验考察了HCO3-、CO32-、HPO42-、H2PO4-和叔丁醇等羟基自由基抑制剂存在条件下,单独臭氧氧化和臭氧/蜂窝陶瓷氧化对水中硝基苯降解效果的影响规律,初步推测了反应机理.结果表明,2种工艺对硝基苯的去除率都随着HCO3-浓度的增加(0～200 mg·L-1)先增高再降低,在浓度为50 mg·L-1时去除率达到最大值;单独臭氧氧化和臭氧/蜂窝陶瓷对硝基苯的去除率随着CO32-浓度的增加(0～20 mg·L-1)分别降低了16.57%和27.52%,随着HPO42-浓度的增加(0～12 mg·L-1)分别降低了13.61%和17.52%,随着H2PO4-浓度的增加(0～120 mg·L-1)分别降低了6.61%和12.52%,随着叔丁醇浓度的增加(0～10mg·L-1)硝基苯去除率降低了30.06%和46.09%.证明单独臭氧氧化和臭氧/蜂窝陶瓷氧化对硝基苯的降解遵循·OH氧化机理,叔丁醇更适合作为自由基抑制剂用来推断单独臭氧氧化和臭氧/蜂窝陶瓷氧化降解硝基苯的反应机理.单独臭氧氧化对硝基苯的去除率随着pH值的升高(3.02～10.96)而增大,臭氧/蜂窝陶瓷氧化对硝基苯的去除率在pH=9.23时达到最大值.

Study on Mechanism of Ceramic Honeycomb-Catalytic Ozonation for the Decomposition of Trace Nitrobenzene in Aqueous Solution

The experiment investigated effects of the presence of hydroxyl radical inhibitor on degradation efficiency of trace nitrobenzene in aqueous solution in the processes of ozonation alone and ceramic honeycomb-catalyzed ozonation, including HCO3-, CO3(2-), HPO4(2-), H2PO4- and tert-butanol, and studied preliminarily on their mechanism. The results indicated that degradation rate of the two processes both increased firstly and decreased subsequently with the increase of the concentration of HCO3- (0 - 200 mg x L(-1)), and reached the climax at the concentration of bicarbonate ion 50 mg x L(-1) under the same experimental condition. The degradation rates of ozonation alone and ozonation/ ceramic honeycomb both declined by 16.57% and 27.52% with the increase of the concentration of CO3(2-) (0 - 20 mg x L(-1)), respectively, and decreased by 13.61% and 17.52% with the addition of the concentration of HPO4(2-) (0 - 12 mg x L(-1)), and reduced by 6.61% and 12.52% with the enhancement of the concentration of H2PO4- (0 - 120 mg x L(-1)), and dropped by 30.06% and 46.09% with the increasing of the concentration of tert-butanol (0 - 10 mg x L(-1)). The experimental results indicated that decomposition of nitrobenzene in both processes all followed the mechanism of oxidization by OH free radical, and tert-butanol is a more suitable indicator for the radical type reaction. The removal rate of ozonation alone rose with the increase of the concentration of pH (3.02 - 10.96), but that of ozonation/ceramic honeycomb process reached the maximum at pH = 9.23.