Kinetics and mechanism of the carbonate ion inhibited aqueous ozone decomposition

Attila Nemes, I. Fábián, Rudi Van Eldik

Research output: Contribution to journalArticle

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Abstract

The carbonate ion inhibited aqueous decomposition of ozone was studied by the stopped-flow method at 25.0 ± 0.1 °C in 0.5 M NaClO 4. It was shown that the rate of decomposition sharply decreases and reaches a limiting value by increasing the carbonate ion concentration. A detailed kinetic model was developed for the interpretation of the results. The corresponding set of rate constants was calculated by simultaneously fitting kinetic traces obtained at the absorption maxima of O 3 (: 260 nm, O 3 - (430 nm), and CO 3 - (600 nm). It was confirmed that the inhibition is mainly due to the removal of two dominant chain carrier radicals, OH and O 3 -, via the following reaction steps: CO 3 2- + OH → CO 3 - + OH -, k = 1.0 ± 0.1 × 10 8 M -1 s -1, and CO 3 - + O 3 - → CO 3 2- + O 3, k = 5.5 ± 0.5 × 10 7 M -1 s -1. The kinetically less significant reactions of other transient species are also discussed in detail. The mechanism gives proper description of ozone decay, the formation and subsequent disappearance of ozonide ion and carbonate ion radicals, as well as the concentration change of other intermediates over the pH range 10.7-12.8. The model predicts that ozone decomposition occurs in a simple first-order process at high CO 3 2- concentration, in agreement with the experimental data.

Original languageEnglish
Pages (from-to)7995-8000
Number of pages6
JournalJournal of Physical Chemistry A
Volume104
Issue number34
Publication statusPublished - Aug 31 2000

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Ozone
Carbonates
Carbon Monoxide
ozone
carbonates
Ions
Decomposition
decomposition
Kinetics
kinetics
ozonides
ions
ion concentration
decay
Rate constants

ASJC Scopus subject areas

  • Physical and Theoretical Chemistry

Cite this

Kinetics and mechanism of the carbonate ion inhibited aqueous ozone decomposition. / Nemes, Attila; Fábián, I.; Van Eldik, Rudi.

In: Journal of Physical Chemistry A, Vol. 104, No. 34, 31.08.2000, p. 7995-8000.

Research output: Contribution to journalArticle

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