Catalytic Activity of Thallium on Electrochemical Degradation of Metronidazole from Aqueous Solutions

Abstract

The platinum/thallium electrode was prepared by thallium electrodeposition on platinum substrate in order to use it for the increase of the electrochemical degradation rate of some drugs, such as, in our study, metronidazole (MNZ). The platinum/thallium electrode was characterized by chronoamperometry, electrochemical impedance spectroscopy (EIS), and scanning electron microscopy coupled with energy-dispersive X-ray spectroscopy. 2D progressive nucleation mechanism of thallium layer development was found by chronoamperometry. The value of charge transfer resistance of 537.2 Ω cm2 and the double-layer capacitance value of 2.9 mF cm−2 were deduced by EIS. The scanning electron microscopy showed a relatively fine-grained structure and the uniform distribution of the thallium granules. The electrochemical degradation of metronidazole has been performed using galvanostatic technique associated with UV-Vis spectrophotometry. The degradation degree of metronidazole reached a higher level on platinum/thallium electrode than that on platinum plate, indicating its improved performance and electrocatalytic activity of thallium coating. Moreover, the electrochemical degradation mechanism of this drug was proposed, the best way to fit the experimental data being the kinetics model of the first-order reactions.