Study of Uncatalyzed and Micellar‐Catalyzed Oxidative Degradation of Amoxicillin by Colloidal MnO ₂ : Experimental Optimization and Mechanistic Aspects

Herein, the oxidative degradation of amoxicillin (AMX) by water‐soluble colloidal MnO 2 is investigated spectrophotometrically at 298 K in both uncatalyzed and nonionic micellar‐catalyzed media (Triton X‐100 and Brij‐35). A 1:1 stoichiometric ratio between AMX and MnO 2 in acidic medium is observed, and two primary oxidation products are identified and characterized by gas chromatography–mass spectrometry analysis. The reaction exhibits first‐order kinetics with respect to the concentration of AMX in aqueous media, and a fractional‐order dependence in micellar media. Similarly, first‐order and fractional‐order dependences are observed with respect to the concentrations of MnO 2 and H 2 SO 4 , respectively, in both phases. The effects of experimental parameters, including ionic strength, dielectric constant, and the concentrations of Mn(II), KBr, KCl, and Na 2 SO 4 , are thoroughly investigated. Significant catalytic effects are observed for the nonionic surfactants Triton X‐100 and Brij‐35, which are explained using an appropriate mathematical model. A reaction mechanism and corresponding rate law consistent with the experimental data are proposed for both uncatalyzed and micellar‐catalyzed systems, and the thermodynamic activation parameters are evaluated using the Arrhenius equation.