Catalytic Effect of Polyoxyethylene t-octylphenol (Triton X-100) Surfactant on the Oxidation of EDTA by Chromic Acid
Abstract:The effect of nonionic Triton X-100 (TX-100) micelles on the pseudo-first order rate constants (kΨ) for the oxidation of EDTA by chromic acid has been studied at different perchloric acid concentrations. The micellar-mediated reaction was independent of chromic acid concentration whereas first- and complex-order dependence on [EDTA] and [HClO4], respectively, were observed. Increase in the total concentration of TX-100 from 0.0 to 60.0×10−3 mol dm−3 caused the kΨ to increase by nearly 4-fold at constant temperature and [HClO4]. The observed catalytic effect has been explained on the basis of pseudo-phase kinetic and Piszkiewicz models. The higher rate of EDTA oxidation in the micellar pseudo-phase is attributed to association of the reactants with the nonionic micellar head groups through hydrogen bonding. A mechanism is proposed in accordance with the experimental results obtained.
Document Type: Research Article
Publication date: January 1, 2002