Oxidation of aqueous SO2 by peroxymonosulfate

Eric A. Betterton, Michael R. Hoffmann

Research output: Contribution to journalArticlepeer-review

77 Scopus citations

Abstract

Recent model calculations suggest that peroxymonosulfate may constitute a significant fraction of the total sulfur budget in remote tropospheric water droplets such as cloud, fog, and rain. However, little is known about the oxidation of dissolved SO2 by peroxymonosulfate (HSO5-). We have found in aqueous solution that the rate of S(IV) oxidation is comparable to the rate of oxidation of S(IV) by hydrogen peroxide and that HSO4- is the only detectable oxidation product. We propose a mechanism in which the rate-determining step involves the acid-catalyzed decomposition of a peroxide-bisulfite intermediate to disulfate ion, S2O72-, and ultimately to sulfuric acid. The rate equation for this mechanism is -d[HSO3-]/dt = k1(k2/k-1)Ka1{H +}[HSO5-][S(IV)]/((1 + (k2/k-1){H+})(Ka1 + {H+})), where k1 = 1.21 × 106 M-1 s-1, k2/k-1 = 5.9 M-1, k1k2/k-1 = 7.14 × 106 M-2 s-1, Ka1 = 2.64 × 10-2 M at 5°C, and μ = 0.2 M. The activation parameters are ΔHk1 = 25.74 ± 0.77 kJ mol-1 and ΔSk1 = -88.1 ± 2.7 J mol-1 K-1.

Original languageEnglish (US)
Pages (from-to)5962-5965
Number of pages4
JournalJournal of physical chemistry
Volume92
Issue number21
DOIs
StatePublished - 1988

ASJC Scopus subject areas

  • Engineering(all)
  • Physical and Theoretical Chemistry

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