Production of Hydroxyl Radical via the Activation of Hydrogen Peroxide by Hydroxylamine.
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.
College of Biology and the Environment, Nanjing Forestry University , Nanjing 210037, China.
Liwei
L
Chen
School of Environmental Science and Engineering, Zhejiang Gongshang University , Hangzhou 310018, China.
Xuchun
X
Li
College of Architecture and Environment, Sichuan University , Chengdu 610065, China.
Jing
J
Zhang
School of Environmental Science and Engineering, Sun Yat-sen University , Guangzhou 510275, China.
Jingyun
J
Fang
College of Biology and the Environment, Nanjing Forestry University , Nanjing 210037, China.
Yanmin
Y
Huang
College of Biology and the Environment, Nanjing Forestry University , Nanjing 210037, China.
Ping
P
Wang
State Key Laboratory of Urban Water Resource and Environment, Harbin Institute of Technology , Harbin 150090, China.
Jun
J
Ma
D003497:Cyclic N-Oxides / Q000737:chemistry; D004578:Electron Spin Resonance Spectroscopy; D005297:Ferrozine / Q000737:chemistry; D006861:Hydrogen Peroxide / Q000737:chemistry*; D006863:Hydrogen-Ion Concentration; D017665:Hydroxyl Radical / Q000737:chemistry*; D019811:Hydroxylamine / Q000737:chemistry*; D007202:Indicators and Reagents; D007502:Iron Chelating Agents / Q000737:chemistry; D013113:Spin Labels; D028561:Transition Elements
D003497:Cyclic N-Oxides; D007202:Indicators and Reagents; D007502:Iron Chelating Agents; D013113:Spin Labels; D028561:Transition Elements; D005297:Ferrozine; D019811:Hydroxylamine; D017665:Hydroxyl Radical; D006861:Hydrogen Peroxide