AQUEOUS S(IV) OXIDATION .1. CATALYTIC EFFECTS OF SOME METAL-IONS

Catalytic effect of metal ions [Fe(III), Mn(II), Cu(II), Pb(II) and Zn(II)] on the oxidation of S(IV) in aqueous solution at concentrations of metal ions and S(IV) as found in an urban atmosphere were studied under controlled experimental conditions (T, pH, air flow rate, mixing, concentration of reactant, etc.). The following rate expressions were obtained: -r(s)(IV) = k [Fe(III)] [S(IV)], -r(s)(IV) = k [Mn(II)] [S(IV)]0.65, -r(s)(IV) = k [Cu(II)] [S(IV)]2. The activation energy equals 104 kJ mol-1 for Fe(III), 63.3 kJ mol-1 for Mn(II), and 116.8 kJ mol-1 for Cu(II) catalysed S(IV) oxidation.