Abstract:

The regeneration of Fe²⁺ can have a marked effect on·OH production in Fenton system. Hydroxylamine hydrochloride, hydroquinone, p-benzoquinone and sodium sulfite were used as typical additives. Different regeneration mechanisms of Fe²⁺ were revealed by analysis of Fe²⁺ concentration, H₂O₂ concentration and oxidation-reduction potential (ORP) as well. Furthermore, reactions between additives and H₂O₂ and·OH were also explored. Results demonstrated that Fe²⁺ was regenerated by hydroxylamine quickly, but concentration of Fe²⁺ gradually decreased with the consumption of hydroxylamine. Hydroquinone and p-benzoquinone exerted similar effect on Fenton system, resulting in enhanced regeneration of Fe²⁺. Quinone cycle could be built once they were added to Fenton system. Therefore, the concentration of Fe²⁺ could maintain a relatively high level in a long period. Quinone cycle can be established by one of the two substances or their mixture. Sodium sulfite reacted with·OH and H₂O₂, which contributed to a poor performance on Fe³⁺ reduction.

Key words: Fenton, regeneration of ferrous ion, radical, Rhodamine B, reduction, aqueous solution

摘要：

Fe²⁺的再生直接决定Fenton体系产生的能力。选取羟胺、对苯二酚、对苯醌、亚硫酸钠4种典型添加剂，通过分析不同改性Fenton体系中Fe²⁺浓度、H₂O₂浓度、氧化还原电极电位（ORP），揭示了Fe²⁺再生机制的差异，并进一步分析了不同添加剂与体系中H₂O₂及·OH的反应情况。结果表明：NH₂OH能快速使Fe²⁺再生，但伴随其消耗，Fe²⁺浓度不断降低。对苯二酚、对苯醌具有相似效果，两者均可大大强化Fe²⁺的再生。与NH₂OH不同，两者在体系中可迅速建立醌循环，持续还原Fe³⁺，且以两种物质或其组合均可建立循环。与上述机理均不同，Na₂SO₃会先与·OH及H₂O₂反应，因而不能有效还原Fe³⁺。实验还发现添加剂均存在与·OH的反应，其中Na₂SO₃还会消耗H₂O₂。

关键词: Fenton, Fe²⁺再生, 自由基, 罗丹明B, 还原, 水溶液