Micellar Effects of Cetyl Trimethyl Ammonium Bromide (CTAB) and Sodium Dodecyl Sulphate (SDS) on Oxidation of Indigo Carmine with Potassium Peroxy Diphosphate

The oxidation of indigo carmine with potassium peroxy diphosphate in absence and presence of cationic CTAB and anionic SDS micelles is investigated. The kinetic study is investigated in an aqueous sulphuric acid medium by maintaining the ionic strength at 3.0 moldm-3 using sodium sulphate. The reaction stoichiometry is reported as 1:1. The pseudo zero order constant is determined from the linear plots of absorbance versus time under the conditions [IC] < [PDP]. The reaction obeys zero order kinetics w.r.t varying [IC], first order kinetics w.r.t varying [H+] and [PDP] in absence and in presence of micelles. The reaction rate is accelerated with varying [CTAB] and [SDS] and reached a limiting value. The rate [surfactant]-profile has limiting nature so that the reaction is unimolecular on the surface of the micelle. The binding constant of peroxy diphosphate is determined with CTAB and SDS micelles by applying Berezin treatment for the kinetic pattern.