纳米与微米级零价铁降解2,4,6-三氯酚动力学比较  

Comparison of degradation kinetics of 2,4,6-trichlorophenol using nanometer-and micrometer-sized Fe^0

作　　者：金盛杨[1,2] 王玉军[1] 李连祯[1,2] 周东美[1] 王慎强[1] 

机构地区：[1]中国科学院南京土壤研究所土壤与农业可持续发展国家重点实验室,江苏南京210008 [2]中国科学院研究生院,北京100049

出　　处：《中国环境科学》2010年第1期82-87,共6页China Environmental Science

基　　金：国家"863"项目(2006AA06Z356);国家"973"项目(2007CB936604)

摘　　要：研究了在反应表面积相近条件下,纳米与微米级零价铁(Fe0)降解水相中2,4,6-三氯酚(TCP)的动力学差异.结果表明,纳米与微米级Fe0降解TCP过程均符合准一级反应动力学,表观反应速率常数Kobs分别为0.0165h-1和0.0046h-1,其比值(3.6)接近纳米与微米级Fe0对TCP的初始吸附量比值(2.9).造成2种Fe0降解与吸附效率差异的主要原因在于颗粒表面点位单元活性不同.Fe0对TCP的作用可分为2个阶段:前一阶段非反应点位主导的吸附作用高于反应点位主导的降解作用,后一阶段刚好相反.反应过程中,纳米与微米级Fe0反应组体系pH值从初始的5.7分别升至10.5和8.2,体系pH值处于酸性范围时可提高TCP降解速率.纳米Fe0在反应过程中表面氧化不断增加,其中大部分铁氧化物沉积在颗粒表面,少量以离子态存在于水相中.The differences of degradation kinetics of 2,4,6-trichlorophenol（TCP） by nanometer-and micrometer-sized zero-valent iron（Fe^0） with approximate surface area in aqueous solution were studied.The results showed that both degradation equations of TCP by nanometer-and micrometer-sized Fe^0 were fitted well to the pseudo first-order kinetics.The observed reaction rate constant（Kobs） values were 0.0165 h^-1 and 0.0046 h^-1,respectively.The ratio of initial adsorption of TCP on the nanometer-to micrometer-sized Fe0 was 2.9,which was close to that of Kobs（3.6）.Therefore,it could be concluded that the differences in degradation and adsorption efficiency between the two kinds of zero-valent iron were attributed to the variation of surface site activity from micrometer to nanometer size.In addition,in the case of the TCP degradation by Fe0,the effects of two sites of Fe0 surface could be distinguished in the TCP adsorption and degradation processes.Initially,adsorption mostly induced by non-reactive sites was more important than degradation induced by reactive sites,and subsequently the degradation was dominative.The pH values increased from 5.7 to 10.5 and 8.2 in the reaction with nanometer-and micrometer-sized Fe^0,respectively.Comparatively,the rate of TCP degradation was enhanced in the low pH.The surface oxidation on Fe0（nano） was also increased during the degradation,and a large portion of oxide was deposited on particle surface,while few ionic Fe was dissolved in the suspension.

关 键 词：2 4 6-三氯酚 纳米级Fe0 微米级Fe0 动力学 

分 类 号：X131.2[环境科学与工程—环境科学]