Fenton处理对氯酚过程中间产物对Fe^(3+)的还原作用

Reduction of Fe^(3+) by intermediates during Fenton oxidation of p-chlor ophenol

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1minFe2+的浓度急剧下降到10%.研究结果表明:H2O2、·OH、HO2·与O2-·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.

To understand the pathways of Fe^2＋ regeneration during the Fenton oxidation of p-chlorophenol （4-CP）, the change of the concentration of Fe^2＋ and the reduction of Fe^3＋ by the intermediates were studied. Fe^2＋ remained almost unchanged during the oxidation of 4-CP by the Fenton process. But in the presence of 1-propanol, the scavenger of · OH, Fe^2＋ sharply decreased to 10% at the end of the first minute. Analysis of the rate constants of Fe^2＋ and Fe^2＋ with H2O2, ·OH, HO2 · and O2^- suggested that the net contribution of these radicals to Fe^2＋ regeneration was small and the reduction of Fe^3＋ by the intermediates of 4-CP oxidation was the main pathway of Fe^2＋ regeneration. Hydroquinone and benzoquinone were identified as the intermediates by HPLC. Hydroquinone could reduce Fe^3＋ quickly but benzoquinone could hardly reduce Fe^3＋. Hydroquinone was oxidized to form benzoquinone by Fe^3＋ and the ratio of hydroquinone to Fe^3＋ was 1 ： 2. This study is helpful to better understand the regeneration of Fe^2＋ in the Fenton process.