Calmagite dye oxidation using in situ generated hydrogen peroxide catalysed by manganese(II) ions.

Hydrogen peroxide (H(2)O(2)) generated from the manganese(II) catalysed reduction of dioxygen has been shown to efficiently oxidize Calmagite (3-hydroxy-4-(2-hydroxy-5-methylphenylazo)naphthalene-1-sulfonic acid) in aqueous solution at pH 8.0 and 20 +/- 1 degrees C with de-protonated Tiron (1,2-dihydroxybenzene-3,5-disulfonate, disodium salt) acting as an essential co-ligand.