Oxidation of Ferrous Ions by Hydroxyl Radicals

Abstract

Hydroxyl radicals have been found by pulse radiolysis to oxidize hydrated ferrous to ferric ions with a rate constant of (2.3 ± 0.2)× 108 M–1 s–1. The corresponding reaction of OD radicals in D2O solution has a rate constant of (9.4 ± 0.8)× 107 M–1 s–1. OD radicals oxidize ferrocyanide in D2O solution with (9.7 ± 1.0)× 109 M–1 s–1. The mechanism of the oxidation of ferrous ions is though to consist of simple electron transfer, and the difference in rate between H2O and D2O solution is attributed to differences between free energies of hydration in the two solvents.