臭氧化降解水中硝基氯苯I.动力学和过程分析  

Ozonation degradation of nitrochlorobenzene isomers in aqueous solution:i. discuss of kinetics and processes

作　　者：沈吉敏[1] 李学艳[2] 陈忠林[1] 齐飞[1] 叶苗苗[1] 徐贞贞[1] 

机构地区：[1]哈尔滨工业大学城市水资源与水环境国家重点实验室,哈尔滨150090 [2]同济大学污染控制与资源化研究国家重点实验室,上海200092

出　　处：《哈尔滨工业大学学报》2008年第4期540-545,共6页Journal of Harbin Institute of Technology

基　　金：新世纪优秀人才支持计划资助项目(NCET-04-0321);国家自然科学基金资助项目(50578052)

摘　　要：对典型难生物降解有机污染物对硝基氯苯(pCNB)、间硝基氯苯(mCNB)、邻硝基氯苯(oCNB)3种同分异构体的臭氧化过程进行比较研究.采用直接法测定3种硝基氯苯(CNBs)与臭氧反应的速率常数,利用竞争动力学测定CNBs与羟基自由基(.OH)的反应速率常数,同时检测臭氧化过程的无机碳(IC)、Cl-、NO3-变化以及H2O2的生成情况.3种CNBs与臭氧直接反应的速率常数分别为1.6、1.5、1.6 L/(mol.s),以硝基苯和氯苯参考化合物,测得CNBs与.OH的反应速率常数分别为2.6×109、2.8×109、3.2×109L/(mol.s);考察CNBs的臭氧化过程发现,氧化体系的pH呈减小的趋势,同时溶液颜色由无色突变到黄色然后迅速恢复到无色,体系中的无机碳(IC)、Cl-、NO3-逐渐升高,不同氧化阶段,均有H2O2产生,当目标物pCNB质量浓度为50 mg/L时,H2O2的最大质量浓度能达到1.8 mg/L.整个臭氧化过程CNBs氧化去除达到99%时,而TOC去除率仅为45%左右.CNBs在臭氧氧化的降解过程是以自由基反应为主,认为反应过程中产生的H2O2起到催化臭氧化的作用,同时单独臭氧化很难完全将体系有机物完全矿化.Kinetics and processes of ozonation degradation of p - nitrochlorobenzene （ pCNB）, m - nitrochlorobenzene （mCNB） and o -nitrochlorobenzene （oCNB） were comparatively investigated. The reaction rate constants of CNBs with · OH were measured by competition kinetics, the reaction rate constants of CNBs with O3 were measured directly, and the concentrations of IC, Cl^-, NO3^ - , H2O2 were determined as well. The secondary rate constants of these three CNBs directly reacted with O3 were 1.6, 1.5, 1.6 L/（mol · sO, respectively. The secondary rate constants of three CNBs reacted with · OH were 2. 6 ×10^9, 2.8 ×10^9, 3.2 ×10^9 L/（ mol · s） by using nitrobenzene and chlorbenzene as reference compounds. It was found that the pHvalue of the solution decreased during the process, the color of the solution turned suddenly from colorlessness to yellow, then came back to colorlessness rapidly, and the concentrations of the IC,Cl^- ,NO3 ^-in the system increased gradually. H2O2 was generated in different phases of the process, the concentration of H2O2 could reach maximum of 1.8 mg/L when the concentration of thepCNB was 50 mg/L. The removal rate of CNBs was 99% after the whole degradation, while the removal rate of TOCwas just 45%. Free radical reactions were the main reaction in the process of ozonation degradation of CNBs, and H2 O2 generated in the process could catalyze ozone to produce hydroxyl radicals. It is difficult to get completely mineralization of organics by the solo- ozonation degradation.

关 键 词：臭氧化 硝基氯苯 羟基自由基 反应速率常数 竞争动力学 

分 类 号：X703.1[环境科学与工程—环境工程]