The decomposition of peroxomonosulfate induced by manganese(II) in acid solution

Abstract

The rate law for the manganese(II)-induced decomposition of peroxomonosulfate ion, HOOSO 3 −, is ▪ with rate constants k Mn = (5.1±0.3)×10 −3 and (9.7±0.2)×10 −3 M − 1 2 s −1 at 50 °C in H 2SO 4 and HClO 4 media, respectively. The rate constant is sensitive to the nature and concentration of the anion. The values of Δ H ‡ and Δ S ‡ are 31±2 kJ mol −1 and −194±5 J mol −1 K −1, respectively, in 1 M H 2SO 4. The presence of manganese(III) as an intermediate and as a minor product is confirmed. Peroxodisulfate, a minor product presumably from chain termination, has been used to estimate the chain length. On the basis of all the data, a mechanism quite different from most metal-induced peroxomonosulfate decompositions is postulated and some consequences and complications are elaborated.