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Reduction of Fe3+ by intermediates during Fenton oxidation of p-chlorophenol

DU Yingxun;ZHOU Minghua;LEI Lecheng

  

  • Online:2005-10-25 Published:2005-10-25

Fenton处理对氯酚过程中间产物对Fe3+的还原作用

杜瑛珣;周明华;雷乐成   

  1. 浙江大学环境工程研究所,浙江 杭州 310027

Abstract: To understand the pathways of Fe2+ regeneration during the Fenton oxidation of p-chlorophenol(4-CP), the change of the concentration of Fe2+ and the reduction of Fe3+ by the intermediates were studied.Fe2+ remained almost unchanged during the oxidation of 4-CP by the Fenton process.But in the presence of 1-propanol,the scavenger of •OH, Fe2+ sharply decreased to 10% at the end of the first minute. Analysis of the rate constants of Fe2+ and Fe3+ with H2O2, •OH, HO2• and O-2• suggested that the net contribution of these radicals to Fe2+ regeneration was small and the reduction of Fe3+ by the intermediates of 4-CP oxidation was the main pathway of Fe2+ regeneration. Hydroquinone and benzoquinone were identified as the intermediates by HPLC. Hydroquinone could reduce Fe3+ quickly but benzoquinone could hardly reduce Fe3+.Hydroquinone was oxidized to form benzoquinone by Fe3+ and the ratio of hydroquinone to Fe3+ was 1∶2.This study is helpful to better understand the regeneration of Fe2+ in the Fenton process.

摘要: 为探明Fenton处理对氯酚(4-CP)过程中Fe2+再生的途径,考察了反应过程Fe2+的浓度变化,同时对4-CP降解中间产物和Fe3+之间的氧化还原反应进行了研究.Fenton氧化对氯酚过程中Fe2+的浓度基本不变;而在•OH捕获剂丙醇的存在下,反应开始后1 min Fe2+的浓度急剧下降到10%.研究结果表明:H2O2•OH、HO2•与O-2•等自由基对Fe2+的再生净贡献较小,4-CP降解的中间产物对Fe3+的还原是Fe2+再生的主要途径.Fenton处理4-CP产生的中间产物有对苯二酚和对苯醌.对苯二酚能够快速还原Fe3+,使Fe2+得到再生;而对苯醌还原Fe3+的作用很微弱.这一研究有助于更好地了解Fenton氧化过程中Fe2+的再生.