Voltammetric and chronoamperometric study of omnipaque electrooxidation at Ti/RuO2 electrode

Abstract

Electrochemical methods have shown their effectiveness in the prevention and resolution of wastewater contamination problems. However, before the electrolysis of an organic pollutant (Omnipaque: OMP) by this method, it is necessary to know the electrochemical behavior of this pollutant. Thus, the objective of this work is to contribute to the understanding of the electrochemical phenomena occurring at the electrode/electrolyte interface during the electrooxidation of omnipaque. The study was carried out using voltammetry and chronoamperometry. In this study, Ti/RuO₂ electrode was prepared on titanium (Ti) substrate by thermal decomposition techniques at 400 °C. The prepared electrode was characterized by scanning electron microscopy (SEM) and electrochemistry. These characterizations showed the presence of RuO₂ on the electrode surface. The electrochemical study has shown that the oxidation of omnipaque is done following a direct electronic transfer on the surface of the electrode by an adsorption-diffusion coupling of the electroactive species on the surface of the electrode. OMP electrooxidation includes the exchange of three protons and five electrons in acidic media and two protons and one electron exchanged in basic media. We note the activation of several active sites on RuO₂ surface as well as the intervention of hydroxyl radicals in the catalytic electrooxidation process of OMP with increasing temperature. The values of activation energy and catalytic rate constant were estimated as 7.895 kJ/mol and 82.2 M^-1 s^-1, respectively.