KINETICS AND THERMODYNAMIC STUDY OF ALKALINE FADING OF MALACHITE GREEN IN AQUEOUS SOLUTION

Abstract

Kinetic and thermodynamic study of alkaline fading of malachite green in aqueous solution       via pseudo-first order kinetics at 618nm is reported using UV-1800 Shimadzu Spectrophotometer. The reaction revealed first order dependence with respect to malachite green  concentration  and first order dependence to hydroxyl ion concentration. Michaelis-Menten plot showed the presence of an intermediate complex and the reaction is dependent on ionic strength of the solution. Activation energy(Ea) and activation parameters like ΔH‡, ΔS‡ and ΔG‡ were obtained from Arrhenius plot and Erying’s equation .  A mechanism is postulated based on the kinetic and spectroscopic studies.