Catalytic Mechanism of the “Noncatalytic” Autooxidation of Sulfite

Iron ions are shown to play a special role among transition metal ions in the oxidation of sulfite by oxygen. The thermodynamically favorable formation of chain carriers S\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document} $$\operatorname{so} _3^{\dot - }$$ \end{document} : FeOH2++ HSO3–→ Fe2++ H2O + \documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document} $$\operatorname{so} _3^{\dot - }$$ \end{document}, ΔHr2980≤ –250 kJ/mol accompanied by the regeneration of the active Fe(III) form in the reactions of Fe(II) with \documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document} $$\operatorname{so} _{3 - 5}^{\dot - }$$ \end{document} and HSO5–provides the efficient catalytic mechanism for sulfite consumption even at [Fe]0≥ 10–8mol/l. Any aqueous solution contains iron ions in this amounts. Thus, the “noncatalytic” oxidation of sulfite is in fact the catalytic reaction involving unavoidable microadmixtures of iron ions. Other transition metal ions (Mn2+, Co2+, etc.) can only enhance the catalytic effect of iron admixture.