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Bulletin of the Korean Chemical Society (BKCS)

ISSN 0253-2964(Print)
ISSN 1229-5949(Online)
Volume 27, Number 11
BKCSDE 27(11)
November 20, 2006 

Determination of Hydroperoxyl/superoxide Anion Radical (HO2/O2ㆍ-) Concentration in the Decomposition of Ozone Using a Kinetic Method
Bum Gun Kwon, Jai H. Lee*
Hydroperoxyl radical, Superoxide anion radical, Ozone, Fenton-like, Hydroxyl radical
A novel kinetic method for determination of HO2·/O2·- in ozone decomposition in water is described. In this study, potential interferences of O3 and the hydroxyl radicals, ·OH(O3), are suppressed by HSO3-/SO32-. HO2·/O2·- formed in ozone decomposition reduces Fe3+-EDTA into Fe2+-EDTA and subsequently the well-known Fenton-like (FL) reaction of H2O2 and Fe2+-EDTA produces the hydroxyl radicals, ·OH(FL). Benzoic acid (BA) scavenges ·OH(FL) to produce OHBA, which are analyzed by fluorescence detection (λex = 320 nm and λem = 400 nm). The concentration of HO2·/O2·- in ozone decomposition has been determined by the novel kinetic method using the experimentally determined half-life (t1/2). The steady-state concentration of HO2·/O2·- is proportional to the O3 concentration at a given pH. However, the steady-state concentration of HO2·/O2·- in ozone decomposition is inversely proportional to pH values. This pH dependence is due to significant loss of O2·- by O3 at higher pH conditions. The steady-state concentrations of HO2·/O2·- are in the range of 2.49 (± 0.10) × 10-9 M (pH = 4.17) ~ 3.01 (± 0.07) × 10-10 M (pH = 7.59) at [O3]o = 60 μM.
1785 - 1790
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