Decomposition of Pinacyanol Chloride Dye Using Several Manganese Oxide Catalysts

The decomposition of the cyanine dye, pinacyanol chloride, has been studied using hydrogen peroxide and several mixed valent manganese oxide catalysts in aqueous, alkaline solution at room temperature. These catalysts belong to a class of porous manganese oxides known as octahedral molecular sieves (OMS). The most active catalysts were those of Fe 3+ -, Cr 3+ -, and Co 2+ -doped OMS-2. Rates of reaction were found to be first-order with respect to the dye. The highest reaction rates were observed when no H 2 O 2 was present. Reactions were studied at pH = 6−11, which caused variations in the catalytic activity. The decomposition of the dye was examined using varying amounts of the catalysts, which showed the dye decomposing activity to be proportional to the amount of catalyst. X-ray diffraction studies showed that no changes in the catalyst structure occurred, implying that these reactions are surface controlled.