Application of Ti-based mixed metal oxide electrodes towards electrochemical mineralization of Metronidazole: Evaluation of influencing factors and removal by-products

Abstract

BackgroundThe treatment of Metronidazole (MTZ) as a persistent pharmaceutical waste in the water is a significant challenge. To reduce the adverse effect of MTZ in water, we tested a novel SiO2-incorporated MMO-Ti/IrO2-Ta2O5 electrode via the electrochemical oxidation (EO) method. MethodsThe electrode was characterized by scanning electron microscopy, energy dispersive spectrum, atomic force microscopy, and cyclic voltammetry analyses. Structural characterization results were represented high resistance, compact surface, and better electrocatalytic properties for Ti/IrO2-Ta2O5-SiO2 electrode. The influence of critical operational parameters, including applied current density, initial pH, initial concentration of MTZ, and electrolysis time, was detected on electrocatalytic removal efficiency. Significant findingsIt was recognized that the high electrocatalytic power of SiO2-incorporated MMO-Ti/IrO2-Ta2O5 electrode gives a high amount of •OH during the removal process. At optimum conditions (pH = 7, J = 200 mA/cm2, [MTZ]0 = 40 mg/L, t = 80 min), 98.76% MTZ removal efficiency was achieved. Besides, comparison analysis was performed with SiO2-incorporated MMO-Ti/IrO2-Ta2O5 electrode and Ti/IrO2-Ta2O5, so results point out the higher total organic carbon removal of about 78.90% and 54.30% with SiO2-incorporated MMO-Ti/IrO2-Ta2O5 than Ti/IrO2-Ta2O5, respectively. Furthermore, MTZ removal intermediates formed during the electrocatalytic oxidation process were identified by the gas chromatography–mass spectrometry technique.