零价铁/过二硫酸盐去除水中硝基苯的还原与氧化机理

Reduction and oxidation reaction mechanism of nitrobenzene removal by zero-valent iron and persulfate

探讨了零价铁(Fe0)/过二硫酸盐(PS)去除水中硝基苯(NB)体系中还原反应和氧化反应之间的相互影响机制.实验表明,采用依次投加Fe0和PS的方式去除NB,随着PS投加时间的推后,Fe0还原NB产生更多的苯胺(AN),加入PS后,氧化去除AN更彻底;在NB/Fe0/PS的反应体系中,当NB和AN同时存在,SO-·4易和AN反应,而基本不去除NB.酸性条件和增加Fe0投加量,利于Fe0还原NB产生更多的AN,增加PS投加量利于AN的氧化去除.投加PS后AN的去除可能主要是发生了Fe2+催化PS的类Fenton氧化反应.

This paper discussed the interaction between reduction and oxidation in the process of nitrobenzene （NB） removal by zero-valent iron （Fe~ ）/persulfate （PS） system. The results showed four trends. Firstly, when sequential additions of Fe0 and PS were adopted, the longer the delay of PS addition, the more aniline （AN） was produced by the reduction of NB by Fe0, and the more thorough oxidation of AN by adding PS seemed to occur. Secondly, in the system of NB/Fe~/PS where AN and NB both existed, sulfate radicals （SO4-1） tended to oxidize AN and little NB was oxidized. Thirdly, the initial pH and the dosage of Fe~ mainly influenced the reduction of NB by Fe~. Acidic environment and more Fe~ were conducive to the reduction of NB. Finally, the removal of AN in the system after introduction of PS seemed to be a Fenton-like reaction resulting from the catalyzed decomposition of PS by Fe2~ and the production of S04-