羟基化锌催化臭氧化水中痕量p-CNB的动力学和机理  

Kinetics and mechanism of ZnOOH catalyzed ozonation of trace p-chloronitrobenzene in water

作　　者：徐贞贞[1] 陈忠林[1] 贲岳[2] 齐飞[1] 沈吉敏[1] 

机构地区：[1]哈尔滨工业大学市政环境工程学院城市水资源与水环境国家重点实验室,黑龙江哈尔滨150090 [2]国核电力规划设计研究院水务部,北京100032

出　　处：《化工学报》2009年第7期1687-1692,共6页CIESC Journal

基　　金：国家自然科学基金项目(50578052);国家高技术研究发展计划项目(2007AA06Z339)~~

摘　　要：以实验室制备的羟基化锌(ZnOOH)为催化剂,探讨了其催化水中臭氧分解和降解水中痕量对氯硝基苯(p-CNB)的途径,并通过ESR实验验证了自由基反应机理。结果表明:ZnOOH可促进水中臭氧分解,使其一级分解速率常数提高了187%。反应20 min时,O3/ZnOOH对p-CNB的去除可以达到96.1%,比单独O3提高了1倍多。ZnOOH催化臭氧分解过程中促进了羟基自由基生成,用叔丁醇捕获生成的羟基自由基后,ZnOOH催化臭氧氧化p-CNB的反应速率常数降低了至少10倍。催化剂表面羟基含量与催化臭氧化水中p-CNB的效果之间没有直接的关系。当溶液pH值接近表面零质子电荷点pHpzc即表面几乎电中性时,O3/ZnOOH降解p-CNB效果最好。Zinc oxyhydroxide （ZnOOH） prepared in laboratory was used as catalyst to determine rate constants of the catalyzed ozone decomposition and the catalytic ozonation of p-chloronitrohenzene （p-CNB） in water. The mechanism of catalytic ozone decomposition was discussed and then determined by electron spin resonance （ESR） test. The effect of solution pH on the catalytic activity of zinc oxyhydroxide was investigated. The results showed that the first-order rate of ozone decomposition increased by 1.87 times in the presence of zinc oxyhydroxide. At the reaction time of 20 min, the p-CNB removal efficiency of ZnOOH/O3 was about 96.1%, one time more than that of O3. An enhancement of hydroxyl free radicals was obtained in the ZnOOH catalyzed ozone decomposition. The addition of radical inhibitor, such as t-butanol, significantly depressed the rate constant of catalytic ozonation of p-CNB, by at least 10 times. No correlation was found between surface hydroxyl groups and the activity of catalytic ozonation of p-CNB. The state of surface charge has some relation with the catalytic activity of ZnOOH, as the nearly zero charged surface （the solution pH was close to pHpzc） was favorable for the catalytic ozonation of p-CNB.

关 键 词：羟基化锌 催化臭氧化 动力学机理 羟基自由基 

分 类 号：X703.1[环境科学与工程—环境工程]