Mn(Ⅱ)/O_3降解草酸作用机制的定量化解析  

Quantitative study on mechanism of Mn(Ⅱ) catalytic ozonation of oxalic acid

作　　者：臧兴杰[1] 张华[1] 石锐[1] 童少平[1] 马淳安[1] 

机构地区：[1]浙江工业大学化学工程与材料学院,绿色化学合成技术国家重点实验室培育基地,浙江杭州310032

出　　处：《化工学报》2009年第2期428-434,共7页CIESC Journal

基　　金：国家自然科学基金项目(50578146)~~

摘　　要：利用Mn(Ⅱ)/O3氧化体系降解了草酸,探讨并定量化解析了Mn(Ⅱ)催化臭氧化降解草酸的作用机制。结果表明,加入Mn(Ⅱ)能明显提高臭氧化降解草酸的效率,体系Rct值也有所增大。Mn(Ⅱ)/O3降解草酸的途径主要包括以下3种方式:第一,臭氧的直接氧化反应;第二,羟基自由基(水中溶解臭氧分解产生)的氧化反应;第三,Mn(Ⅳ)和Mn(Ⅶ)等高价锰对草酸的氧化反应。溶液pH值不但直接影响Mn(Ⅱ)/O3降解草酸的效率,而且还决定了三者的贡献大小。在本实验条件下,当pH值为2.9时,Mn(Ⅱ)/O3降解草酸的表观反应速率常数为28.280×10-4s-1,三者对草酸降解的百分比贡献为fO3∶fOH∶frest=2.1∶19.0∶78.9;当pH值为5.3、8.0和10.0时,草酸降解的表观反应速率常数分别为1.597×10-4s-1、1.535×10-4s-1和1.545×10-4s-1,三者的百分比贡献分别为fO3∶fOH∶frest=24.9∶28.4∶46.7、fO3∶fOH∶frest=23.6∶54.5∶21.9和fO3∶fOH∶frest=19.6∶74.4∶6.0。Oxalic acid was degraded by Mn（Ⅱ） catalytic ozonation, and its mechanism was discussed by a quantitative analysis. The experimental results demonstrated that the ozonation efficiency increased with adding Mn（ Ⅱ ） catalyst to oxalic acid solution, and that Rot of the ozonation system also increased. The degradation of oxalic acid by Mn（Ⅱ ） catalytic ozonation included three parts ： direct ozonation, oxidation reaction of hydroxyl radical produced from the decomposition of the dissolved ozone, oxidation reaction of Mn（Ⅳ） and Mn（Ⅶ） . The pH of solution not only influenced the degradation efficiency of Mn（ Ⅱ ）/O3, but also determined the contributing proportions of three different oxidation reactions. When the pH was 2.9, the apparent rate constant of degradation of oxalic acid by Mn（Ⅱ ）/O3 was 28.280×10^-4s^-1, and the contributing proportion of three-oxidation reactions was fO3∶fOH∶frest=2.1∶19.0∶78.9. However, when the pH values were 5.3, 8.0 and 10.0, the apparent rate constants were 1.597×10^-4s^-1、1.535×10^-4s^-1 and 1.545×10^-4s^-1, respectively, and the contributing proportion of the three oxidation reactions were fO3∶fOH∶frest=24.9∶28.4∶46.7、fO3∶fOH∶frest=23.6∶54.5∶21.9 and fO3∶fOH∶frest=19.6∶74.4∶6.0,respectively.

关 键 词：草酸 臭氧 降解 Mn(Ⅱ) 

分 类 号：X703[环境科学与工程—环境工程]