Electro-oxidation of tetracycline in ethanol-water mixture using DSA-Cl anode and stimulating/monitoring the formation of organic radicals.

Recent studies reported a new strategy of electro-oxidation of organic compounds using methanol as solvent. Considering its well-known toxicity, this work sought to evaluate the use of ethanol as an alternative solvent for pollutants degradation. Therefore, thorough analyses were performed in order to evaluate tetracycline (TC) electro-oxidation using DSA-Cl anode in ethanol-HO solutions. The effects of solvent mixture, pH and current density on the degradation efficiency were evaluated. TC degradation in methanol-water and ethanol-water media resulted in very close removals of 95% and 90%, respectively, after 15 min of electrolysis at 10 mA cm. In ethanol medium, the increase in current densities from 10 to 25 mA cm did not lead to significant changes in removal efficiency. The variation of the initial pH of the solution showed that the best removal efficiencies were obtained at neutral pH resulting in TC removals up to 90%, which is actually related to the molecular structure of TC. Through analysis using electron paramagnetic resonance (EPR), the formation of radicals such as hydroxyethyl (CHCHOH), hydroxyl (OH) and ethoxy (CHCHO) were detected, which effectively contributed toward the pollutant oxidation.