Polyethylene glycol (PEG)-linked manganese halogenated porphyrins (Chart ) catalyzed oxidation of azo dyes (Chart ) by H2O2 under mild conditions such as pH 8.0 at 25 °C especially when imidazole was present, causing the decoloration of azo dyes. The decoloration of azo dyes by synthetic manganese porphyrins under mild conditions was first reported. The decoloration rate depended on the structures of the porphyrins, in which the largest rate was observed in the presence of PEG−MnDCPP. The decoloration may be contributed by radical species rather than electrophilic species, consistent with the side-chain oxidation of toluene. Kinetics on polyethylene glycol-linked manganese porphyrin-catalyzed decoloration of C.I. Acid Orange 7 by hydrogen peroxide revealed that the decoloration was contributed at the oxidation process by manganese porphyrins with hydrogen peroxide in the polymer domain rather than the complex-formation process between manganese porphyrins and azo dyes.

Water-soluble manganese porphyrins are catalysts for the decoloration of azo dyes by hydrogen peroxide under mild conditions (pH 8.0 and 25°C). The decoloration rate depends on the structure of the manganese porphyrin and the added ligands.

The effect of three surfactants, dodecylbenzenesulfonate (DBS), n-hexadecyltrimethylammonium bromide (HTAB), and polyethylene glycol mono-p-octylphenyl ether (PEOPE), on the decoloration rates of C.I. Acid Orange 7, C.I. Basic Green 4, and C.I. Basic Orange 33 by peroxide bleaching agents such as sodium percarbonate and hydrogen peroxide is examined. The decoloration rate of Acid Orange 7 by peroxide bleaching agents accelerates in the presence of DBS, HTAB and PEOPE, especially near the cmc, with the maximum rate being observed in the presence of HTAB. However, the decoloration rate of Basic Orange 33 by hydrogen peroxide accelerates only when DBS is present near the cmc. There is no or less enhanced decoloration in the presence of HTAB or PEOPE. Interestingly, the decoloration rate of Basic Green 4 by hydrogen peroxide accelerates with increasing HTAB concentration, and in contrast, the rate decreases when DBS is present. These results indicate that decoloration rates by peroxide bleaching agents largely depend on interactions between the dyes and surfactants.

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.