Oxidation of H2S in Seawater as a Function of Temperature, pH, and Ionic Strength

Frank J. Millero, Scott Hubinger, Marino Fernandez, Stephen Garnett

Research output: Contribution to journalArticlepeer-review

198 Scopus citations


The rates of oxidation of H2S in air-saturated water, seawater, and NaCl solutions have been measured as a function of temperature (5–65 °C), pH (1–12), and ionic strength (0–6 M). At pH 8.0, the overall rate constant (k, kg of H20 in = can be determined from log k = 11.78 - (3.0 × 103)/T + 0.4471/2 (a = 0.18 in log k). The energy of activation for water and seawater is 57 ± 4 kJ mol-1. The effect of pH in water at 55 °C was found to be given by k = (k0+ where k0 = 80 ± 17 kg of H20 mol-1 h_1for the oxidation of H2S and k1 = 344 ± 7 kg of H20 mol-1 h-1for the oxidation of HS-. At 25 °C our results give t1/2 = 50 ± 16 h in water and 26 ± 9 h in seawater (pH 8), which are in good agreement with the results of Chen and Morris and O’Brien and Birkner. The faster half-times (2–3 h) obtained by the electromotive force (emf) technique appear to be an artifact of the method.

Original languageEnglish (US)
Pages (from-to)439-443
Number of pages5
JournalEnvironmental Science and Technology
Issue number5
StatePublished - Jan 1 1987

ASJC Scopus subject areas

  • Chemistry(all)
  • Environmental Chemistry


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