蜂窝陶瓷催化臭氧化降解水中痕量硝基苯的机理研究

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

实验考察了HCO3^-、CO3^2-、HPO4^2-、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（0-200mg·L^-1）先增高再降低，在浓度为50mg·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CO3^2-浓度的增加（0-20mg·L^-1）分别降低了16．57％和27．52％，随着HPO4^2-浓度的增加（0-12mg·L^-1）分别降低了13．61％和17．52％，随着H2PO4^-浓度的增加（0-120mg·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．

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· L^-1 ）, and reached the climax at the concentration of bicarbonate ion 50 mg· 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·L^-1 ）, respectively, and decreased by 13.61% and 17.52% with the addition of the concentration of HPO4^2- （0 - 12 mg·L^-1 ）, and reduced by 6.61% and 12.52% with the enhancement of the concentration of H2PO4^- （0 - 120 mg·L^-1）, and dropped by 30.06% and 46.09% with the increasing of the concentration of ten-butanol （0 - 10 mg· L^-1）. The experimental results indicated that decomposition of nitrobenzene in both processes all followed the mechanism of oxidization by OH free radical, and ten-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.