Kinetics and mechanism of the oxidation of aqueous hydrogen sulfide by peroxymonosulfate

Eric Betterton, M. R. Hoffmann

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The stoichiometry and mechanism of the oxidation of aqueous S(-II) by HSO5- is similar to the oxidation of S(-II) by H2O2, but the rate of oxidation by HSO5- is 3-4 orders of magnitude faster than the corresponding reaction with H2O2. A two-term rate law of the following form is found to be valid for the pH range of 2.0-6.3: -d[S(-II)]/dt = k1[H2S][HSO5-] + k2K(a)1[H2S][HSO5-]/[H+], where k1 = 1.98 x 101 M-1 s-1, k2 = 1.22 x 104 M-1 s-1, and K(a)1 = [H+][HS-]/[H2S] = 2.84 x 10-8 M at 4.9 °C, μ = 0.2 M, and [S(-II)] = [H2S] + [HS-] + [S2-]. At high pH and high [HSO5-]/[S(-II)] ratios SO42- and H+ formation are favored, whereas at low pH and low [HSO5-]/[S(-II)] ratios elemental sulfur (S8) is favored as the principal reaction product. Peroxymonosulfate is a monosubstituted derivative of hydrogen peroxide that is thermodynamically more powerful as an oxidant than H2O2 and kinetically more reactive. These properties make HSO5- a potentially important oxidant in natural systems such as remote tropospheric clouds and also a viable alternative to H2O2 for the control of malodorous sulfur compounds and for the control of sulfide-induced corrosion in concrete sewers.

Original languageEnglish (US)
Pages (from-to)1819-1824
Number of pages6
JournalEnvironmental Science and Technology
Issue number12
Publication statusPublished - Dec 1990


ASJC Scopus subject areas

  • Environmental Engineering
  • Environmental Science(all)
  • Environmental Chemistry

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