The formation of dithionate during the iron(III)-catalysed autoxidation of sulfur(IV)-oxides

The iron(III)-catalyzed autoxidation of sulfur(IV)-oxides results in the formation of two different oxidation products of sulfur(IV): dithionate, S2O62−, and sulfate, SO42−. The yield of these reaction products depends on the experimental conditions. Under the studied conditions ([Fe(III)] : [SIV)] = 1:10, pH = 2–4) dithionate is the minor reaction product. The formation of dithionate is influenced by the initial pH but not by the initial O2 concentration. The presence of CO2+, Mn2+, and Ni2+ have no influence on the yield of dithionate, whereas in the presence of Cr3+ less and, in the presence of Cu2+, no dithionate is formed.