OsO(IV) catalyzed oxidative decolorization of azo dye metanil yellow by bromamine –B in alkaline medium: Spectrophotmetric, kinetic and mechanistic approach

Abstract

The kinetics of oxidative decolorization of metanil yellow (MY) by Bromamine -B in NaOH medium in presence of OsO(IV) has been investigated spectrophotometrically (λmax = 414 nm) at 298 K. Kinetic studies were performed under pseudo first-order conditions of [BAB]o>> [MY]o. The reactions show first-order dependence each on [BAB]o, [MY] and [OsO(IV)], a fractional-order dependence on [NaOH]. Stoichiometry of the reaction was found to be 1:3 and the oxidation products were identified by spectral analysis. The reaction was studied at different temperatures and various activation parameters have been computed. Effects of benzenesulfonamide, ionic strength and dielectric constant of the medium have been studied. Reaction mixture fails to induce polymerization with acrylonitrile. Probable mechanism and relevant rate law have been deliberated for the observed kinetic results.