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Production of Hydroxyl Radical via the Activation of Hydrogen Peroxide by Hydroxylamine

2015; American Chemical Society; Volume: 49; Issue: 17 Linguagem: Inglês

10.1021/acs.est.5b00483

1520-5851

Liwei Chen, Xuchun Li, Jing Zhang, Jingyun Fang, Yanmin Huang, Ping Wang, Jun Ma,

Electrochemical Analysis and Applications

The production of the hydroxyl radical (HO·) is important in environmental chemistry. This study reports a new source of HO· generated solely from hydrogen peroxide (H2O2) activated by hydroxylamine (HA). Electron paramagnetic resonance analysis and the oxidation of a HO· probe, benzoic acid, were used to confirm the production of HO·. The production of HO· increased with increasing concentrations of either HA or H2O2 as well as decreasing pH. The second-order rate constant for the reaction was (2.2 ± 0.2) × 10–4 M–1 s–1. HO· was probably produced in two steps: the activation of H2O2 by protonated HA and then reaction between the H2O2 and the intermediate protonated aminoxyl radical generated in the first step. Such a two-step oxidation can possibly be ascribed to the ionizable hydroxyl moiety in the molecular structure of HA, as is suggested by comparing the reactivity of a series of HA derivatives in HO· production. The results shed light on a previously unknown source of HO· formation, which broadens the understanding of its role in environmental processes.