Kinetics of Methyl Green Fading in the Presence of TX-100, DTAB and SDS

Abstract

The rate constant of alkaline fading of methyl green (ME 2+ ) was measured in the presence of non ionic (TX100), cationic (DTAB) and anionic (SDS) surfactants. ME 2+ hydrolyses and fades in neutral water and in this work we search the effects of surfactants on its fading rate. The rate of reaction showed remarkable dependence on the electrical charge of the used surfactants. It was observed that the reaction rate constant decreased in the presence of DTAB and SDS and increased in the presence of TX-100. Binding constants of ME 2+ to TX-100, DTAB and SDS and the related thermodynamic parameters were obtained by classical (or stoichiometric) model. The results show that binding of ME 2+ to TX-100 and DTAB are two-region and that of SDS is threeregion. Also, the binding constants of ME 2+ to surfactant molecules in DTAB/TX-100 and SDS/TX-100 mixed