Stabilization of iron-catalysed hydrogen peroxide decomposition by magnesium

Catalytic decomposition of alkaline hydrogen peroxide by iron can be retarded by introduction of magnesium ions. This effect has been studied to evaluate the possibility of stabilization via formation of an iron–magnesium complex species. Under alkaline conditions, magnesium reacts with initial hydrolysis products of Fe3+ to produce a colourless complex species, in which the metal centres are probably linked through oxy or hydroxy bridges. This species is produced when the Mg:Fe molar ratio exceeds 6:1, and this ratio is also significant when magnesium is introduced during peroxide decomposition experiments. The evidence suggests that complex formation is an important factor in producing stabilization, and cannot be disregarded in favour of an alternative explanation where superoxide radicals combine with Mg2+ to produce magnesium dioxide. Keywords: hydrogen peroxide, kinetics, iron, magnesium, stabilization.