Kinetic evidence for the redox cycling of manganese(II,III) in the presence of –ON(NO)SO3– in aqueous media
Abstract
Redox cycling of MnII/III in the presence of –ON(NO)SO3– in the absence and presence of oxygen was studied by following the increase and decrease of MnIII spectrophotometrically as a function of [–ON(NO)SO3–], [MnIII], [MnII] and pH. The autoxidation reaction exhibits typical autocatalytic behaviour in which the induction period depends on the concentrations of MnIII and –ON(NO)SO3–. Under acidic conditions the reaction does not take place in the absence of MnIII or O2. The concentrations of O2, MnII and –ON(NO)SO3– determine whether only oxidation of MnII to MnIII, or reduction of MnIII to MnII, or both in one or two redox cycles is observed. Preliminary simulations of some of the observed kinetic traces are presented.