Fenton处理对氯酚过程中间产物对Fe3+的还原作用

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.

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

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.