5,5-二甲基-1-吡咯啉-N-氧化物作为自旋阱的稳定性，用于基于Fenton反应的过程中对羟基自由基的定量分析。,Water Research

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5,5-二甲基-1-吡咯啉-N-氧化物作为自旋阱的稳定性，用于基于Fenton反应的过程中对羟基自由基的定量分析。
Water Research ( IF 11.4 ) Pub Date : 2016-05-02 , DOI: 10.1016/j.watres.2016.04.053
J M Fontmorin ₁ , R C Burgos Castillo ₁ , W Z Tang ₂ , M Sillanpää ₁

Affiliation

在电子顺磁共振（EPR）分析中，使用Fenton反应在类似于AOP的条件下产生羟基自由基，其中5,5-二甲基-1-吡咯啉-N-氧化物（DMPO）作为自旋捕集剂。建立了理论动力学模型，以确定自旋加合物DMPO-OH不会被Fe（3+）和过量自由基进一步氧化的条件，因此可以准确推断出羟基自由基的浓度。基于模型设计了实验，H2O2和Fe（2+）的浓度分别从1到100 mM和0.1到10 mM变化，H2O2：Fe（2+）的恒定比率为10：1。结果证实，DMPO的浓度至少应比H2O2的浓度高20倍，比铁的浓度至少高200倍，以产生稳定的DMPO-OH EPR信号。当DMPO：H2O2的比例从1变为10时，DMPO-OH可以生成中间体，并被进一步氧化，从而导致出现另外的三重态。该信号归因于顺磁性二聚体：提出了其结构和形成机理。最后，讨论了利用亚硫酸钠和过氧化氢酶终止Fenton反应的方法。过氧化氢酶似乎与DMPO兼容。但是，应避免使用亚硫酸钠，因为它会与DMPO-OH反应形成DMPO-SO3。

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Stability of 5,5-dimethyl-1-pyrroline-N-oxide as a spin-trap for quantification of hydroxyl radicals in processes based on Fenton reaction.

Fenton reaction was used to produce hydroxyl radicals under conditions similar to AOPs with 5,5-dimethyl-1-pyrroline-N-oxide (DMPO) as a spin trap agent in electron paramagnetic resonance (EPR) analysis. A theoretical kinetics model was developed to determine conditions under which the spin-adduct DMPO-OH is not further oxidized by Fe(3+) and excessive radicals, so that hydroxyl radicals concentration could be accurately inferred. Experiments were designed based upon the model and H2O2 and Fe(2+) concentrations were varied from 1 to 100 mM and from 0.1 to 10 mM, respectively, with a constant H2O2: Fe(2+) ratio of 10:1. Results confirmed that DMPO concentration should be at least 20 times higher than the concentration of H2O2 and 200 times higher than iron concentration to produce stable DMPO-OH EPR signal. When DMPO: H2O2 ratio varied from 1 to 10, DMPO-OH could generate intermediates and be further oxidized leading to the apparition of an additional triplet. This signal was attributed to a paramagnetic dimer: its structure and a formation mechanism were proposed. Finally, the utilization of sodium sulfite and catalase to terminate Fenton reaction was discussed. Catalase appeared to be compatible with DMPO. However, sodium sulfite should be avoided since it reacted with DMPO-OH to form DMPO-SO3.

更新日期：2019-11-01

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