Efficient electrochemical oxidation of ofloxacin by IrO2 -RuO2-TiO2 /Ti anode: Parameters optimization, kinetics and degradation pathways

Abstract

Among various pharmaceutical pollutants, fluoroquinolones broad-spectrum antibiotics are major water pollutants, usually present in the aquatic environment as multicomponent mixtures with potentially deleterious effects on humans and the environment. This study used electrochemical oxidation to remove ofloxacin from aqueous solution using Ti and IrO₂–RuO₂–TiO₂/Ti electrodes as cathode and anode, respectively. We investigated the morphology and electrochemical behavior of the selected anode and analyzed the effects of operational variables on the degradation performance of OFL in detail. The results showed that the electrochemical system for degrading OFL possessed high oxidizing activity and excellent durability, and the hydroxyl and reactive chlorine radicals generated by the electrochemical reaction could effectively degrade OFL. As predicted and optimized by the PSO-SVR model, the removal of OFL could be increased to 99.011 % when the electrolyte concentration was 5.65 mM, current density was 3.9 mA/cm², initial pH was 7.12, and treatment time was 3.7 min. In addition, four possible degradation pathways, including ring opening and mineralization, were proposed based on the byproducts calculated by DFT and determined by GC-MS. More importantly, this electrochemical process can efficiently degrade various organic pollutants (ciprofloxacin, enrofloxacin, sulfamethoxazole, oxytetracycline, and chloromycetin). This study provides the theoretical basis and essential data for applying this electrochemical system in wastewater treatment.