羟胺/EDTA协同强化芬顿反应的机理与动力学

经典芬顿反应(Fe²⁺/H₂O₂)在实际水处理中存在pH响应范围窄、亚铁盐投加量大和铁泥产量高等技术瓶颈问题。改用乙二胺四乙酸(EDTA)络合的亚铁离子(Fe²⁺-EDTA)做引发剂后，pH响应范围明显扩大，然而也引入了有机二次污染，同时提高了溶解铁的去除难度。在Fe²⁺-EDTA/H₂O₂体系中投加还原性的羟胺(HA)，可将失活的Fe³⁺-EDTA转化成具有活性的Fe²⁺-EDTA，从而实现低铁投加量/低EDTA投加量条件下有机污染物的消除。结果表明：以伊文思蓝为模型污染物，HA/EDTA/芬顿体系的pH范围可扩大至7.0~9.0；铁离子和EDTA的最佳投料比为1∶1，H₂O₂的最佳投加量为0.5 mmol∙L⁻¹，HA的最佳投加量为0.1 mmol∙L⁻¹； HA/EDTA/芬顿体系中主要的活性物质为羟基自由基(·OH)；苯基甲基亚砜(PMSO)的降解路径分析则证明了新体系中高价铁(Fe^IV)几乎不起任何作用。以上结果表明，将羟胺引入EDTA/芬顿体系后可同步降低铁离子与络合剂的使用量，故此体系改变了络合剂强化的芬顿反应中药剂投加量过大与后续铁离子不好处置的问题，可为进一步拓展芬顿反应的应用范围提供参考。

Enhanced Fenton process by a synergistic effect of EDTA and hydroxylamine: Mechanism and kinetics

Traditional Fenton processes (Fe2+/H2O2) have long suffered from the impractically narrow pH range (around pH 3.0), the addition of ferrous salt and production of a large mass of iron precipitates after neutralization. The employment of ethylene diamine tetraacetic acid (EDTA) for chelating Fe2+ as an initiator (Fe2+-EDTA) of Fenton process can extend the pH range, but it also causes secondary contamination and increases the difficulty on the subsequent removal of dissolved iron. In this study, hydroxylamine was employed for accelerating regeneration of Fe2+-EDTA from Fe3+-EDTA, resulting in continuous degradation of organic contaminants with low dosage of iron salt and EDTA. Using Evans Blue as radical probe, HA/EDTA/Fenton system could output oxidation ability at the pH range of 7.0-9.0; the optimal ratio of iron ions and EDTA was 1:1; taking the cost and efficiency into consideration, the optimal dosages of H2O2 and HA were 0.5 mmol∙L−1 and 0.1 mmol∙L−1, respectively. Quenching experiments, electron spin resonance analysis revealed hydroxyl radical (·OH) as main reactive oxygen species, while degradation analysis of Phenyl methyl sulfoxide (PMSO) excluded the role of iron-oxo (FeIV) in the system. The simultaneous addition of EDTA and HA could reduce the dosage of iron salt and chelating agents, further avoiding the subsequent problem such as larger doses of reagents and the downstream treatment of Fe3+-EDTA. The research can provide a reference for the extension of Fenton process application range.