Kinetic investigations on the fading reaction between MX and SDS at concentrations below and above the critical micellar concentration

Murexide (MX), the ammonium salt of purpuric acid, was found to significantly fade in the presence of sodium dodecyl sulfate (SDS) within 2 hours. Herein, the fading reaction kinetics data between MX and SDS at concentrations below and above the critical micellar concentration were studied using a UV-Visible spectrophotometer equipped with a temperature control system. By establishing a kinetic model and analysing the data, the influences of micelle and temperature on reaction orders and rate constants were determined. These results indicate that micelle formation can influence the reaction mechanism, lead to a decrease in reaction rate constants (k) and a shift in the partial order (β) from positive to negative. These results demonstrate that the formation of micelles have a substantial impact on the rate of the MX fading reaction, providing a new approach for studying the role of micelles in dye fading mechanisms.