Oxidative degradation of norfloxacin by water soluble colloidal MnO₂ in the presence of cationic surfactant

Abstract

The oxidative degradation of norfloxacin (NOR) by water soluble colloidal MnO₂ in alkaline medium has been studied spectrophotometrically in the absence and presence of cationic surfactant, cetyltrimethylammonium bromide (CTAB) at 298 K. The rate of reaction has been followed under pseudo-first order condition with respect to [MnO₂]. Positive fractional order and negative fractional order are observed with respect to [NOR] and [NaOH] respectively in both aqueous and micellar media. The rate constant increases with decreasing dielectric constant of the medium in both the systems. The retardation effect observed by CTAB is discussed by well known Berezin’s model and from this model micelle binding constant has been computed. Using the Arrhenius equation, thermodynamic activation parameters have also been evaluated in both the media. On the basis of experimental results suitable mechanism and rate law are proposed.