Decolorisation of azo dyes with hydrogen peroxide catalysed by manganese protoporphyrins

Abstract

Manganese protoporphyrin or mesoporphyrin derivatives catalysed the decolorisation of azo dyes by hydrogen peroxide under mild conditions, pH 8.0 and 25°C. The decolorisation rate was increased by the presence of manganese protoporphyrin or mesoporphyrin derivatives and was dependent upon the structures of the porphyrins and of the azo dyes. The rate was found to depend upon the concentration of ligands. Kinetic studies of the decolorisation rate by hydrogen peroxide catalysed by a poly(ethylene glycol)-linked manganese mesoporphyrin derivative showed how the structures of the porphyrin and the azo dye affect the rate.