Spectroscopic studies on the oxidative decomposition of malachite green using ozone

Spectroscopic studies on the oxidative decomposition of Malachite Green (MG) using ozone were investigated. Parameters such as color removal, initial dye concentration, COD reduction, reaction temperature and pH were studied to determine optimum conditions for complete MG decomposition. Complete removal of MG color was achieved within 10 min of reaction with ozone. The ozone oxidation reaction time increased as concentration of MG increases, inferring, there would be increase in MG removal as concentration decreases. COD reduction was observed as reaction time increases and the rate of reaction monotonically increased as temperature increases. From the spectroscopic analysis of the intermediates and the by-products of MG reaction with ozone, a tentative mechanistic approach of MG decomposition was postulated. It was also observed that after five minutes of ozone oxidation, color removal rate in the wastewater containing Malachite Green obtained from a small scale local dyeing industry reached almost 90%.