Degradation of azo dye with dirhodium(II) caprolactamate as heterogeneous catalyst

The kinetics of the oxidative degradation of an azo dye Metanil Yellow (MY) was investigated in aqueous solution using dirhodium(II) caprolactamate, Rh₂(cap)₄, as a catalyst in the presence of H₂O₂ as oxidizing agent. The reaction process was followed by UV/Vis spectrophotometer. The decolorization and degradation kinetics were investigated and both followed a pseudo-first-order kinetic with respect to the [MY]. The effects of various parameters such as H₂O₂ and dye concentrations, the amount of catalyst and temperature have been studied. The studies show that Rh₂(cap)₄ is a very effective catalyst for the formation of hydroxyl radicals HO^• which oxidized and degraded about 92% of MY into CO₂ and H₂O after 24 h as measured by total carbon analyzer.