Fe0／H2O2类Fenton体系降解水中对氯硝基苯

Degradation of para-chloronitrobenzene by Fe0／H2O2 Fenton-like

摘要:

为解决传统Fenton过程中Fe³⁺返回Fe²⁺速率慢致使反应过程中铁离子循环受阻的瓶颈问题,对Fe⁰／H₂O₂-类Fenton降解对氯硝基苯(pCNB)的效果与机理进行研究．考察H₂O₂和铁的投加量、初始pH值等因素对pCNB降解效果的影响,对体系TOC和Cl-、NO₃-浓度以及一些中间产物进行鉴定和分析．当pH值为5,铁、H₂O₂、pCNB初始投量分别为200、3.5、20 mg／L,反应20 min时,Fe⁰／H₂O₂类Fenton体系能将pCNB去除73％．在相同pH值、铁和H₂O₂投加量情况下,Fe⁰／H₂O₂-类Fenton法对pCNB的降解效率比传统Fenton法高20％～30％,pH值在3.5～7.0内,该体系对pCNB都具有很好的降解去除作用．pCNB在降解过程中没有被完全矿化,苯环上的—Cl和—NO₂也没有完全转化为无机离子,主要中间产物为草酸、羟基乙酸、乙酸、马来酸、对硝基酚、对氯酚、2-氯-5-硝基酚、5-氯-2-硝基酚等．

Abstract:

Para-chloronitrobenzene degradation by Fenton-like with zero-valent iron and hydrogen peroxide was studied in depth for the purpose to solve the circulation of iron ions suffocated caused by the slow rate of Fe³⁺ returns Fe²⁺ in the traditional Fenton reaction. Different effects of hydrogen peroxide and iron dose, initial pH value and others factors were investigated. Para-chloronitrobenzene removal efficiency of 73％ was achieved under optimal reaction conditions of pH value 5, with dosage of 200 mg／L zero-valent iron, and 3.5 mg／L of hydrogen peroxide after 20 min. The Removal efficiency of para-chloronitrobenzene by Fe⁰／H₂O₂ Fenton-like increased 20％-30％ than the traditional Fenton reaction under the same dosage of iron and hydrogen peroxide, and the same of pH value. And in 3-7 range of the pH value, para-chrornitrobenzene degradation effects were obvious by Fe⁰／H₂O₂ Fenton-like. The choro-(—Cl) and nitro-(—NO₂) on the phenyl were transformed inorganic ions incomplete. The main intermediates were oxalic acid, glycolic acid, acetic acid, maleic acid, p-nitrophenol, p-chlorophenol, 2-chloro-5-nitrophenol, 5-chloro-2-nitrophenol. An degradation pathway of the para-chloronitrobenzene was also proposed.