Catalytic activity of Mn(III) and Fe(III) porphyrins supported onto multi-walled carbon nanotubes in the green oxidation of organic dyes with hydrogen peroxide: a comparative study

Oxidation of organic dyes with hydrogen peroxide (H2O2) catalyzed by carbon nanotube supported iron(III) and manganese(III) complexes of meso-tetrakis(4-caroxyphenyl)porphyrin has been reported. The solid catalysts were characterized by transmission electron microscopy, thermal analysis, UV–Vis, atomic absorption and FT-IR spectroscopy. The influence of some important factors in the catalytic activity such as initial pH of the dye solution, reaction time, temperature and concentration of the oxidant and imidazole as co-catalyst were evaluated. The results show that catalytic activity of the manganese catalyst for oxidation of different dyes in aqueous media over a wide pH range at ambient temperature is higher than the iron one. Moreover, the solid catalysts can be reused several times under similar conditions.