INFLUENCE OF MIXED SULFUR-NITROGEN OXIDES ON THE REDOX KINETICS OF IRON IONS IN AQUEOUS-SOLUTION

The influence of mixed sulfur-nitrogen oxides on the redox chemistry o f iron-(III) and -(II) species in aqueous solution was studied kinetic ally as a function of various concentrations. Two oxides, viz. HONH(SO 3)(-) and HON(SO3)(2)(2-), were found to reduce Fe-III to Fe-II, where by these oxides undergo an iron(III)-induced hydrolysis reaction. The hydrolysis products were analysed by ion chromatography. These redox r eactions can in principle account for the inhibiting effect of sulfur- nitrogen oxides on the metal-catalysed autoxidation of sulfur(Iv) oxid es. Possible reaction mechanisms are suggested.