Potential application of persulfate and simulated sunlight radiation on azithromycin removal

Abstract

Azithromycin (AZT) is a macrolide antibiotic whose presence in different bodies of water has been reported. This implies that conventional treatment systems are not able for AZT removal. This paper presents the main results regarding the potential use of simulated sunlight and persulfate (PS) on the removal of AZT. The effects of the solution pH and the concentration of PS were evaluated considering a face centered, central composite experimental design. Under optimized experimental conditions, it was possible to reach an AZT elimination around 70.0%, and ~30.0% reduction of the total organic matter after 120 min of reaction. Additionally, it was established that basic pH conditions favor AZT removal, and high doses of PS could have an inhibitory effect on the reaction due to a radical scavenging phenomenon. The roles of SO4-• and OH• radicals on the reaction were evaluated by conducting tests under the presence of ethanol and tert-Butyl alcohol. In this manner, OH• radicals seem to be the main oxidizing species of AZT. Finally, the evaluation of the effect of the initial pollutant concentration allowed to establish that a pseudo first-order reaction kinetics model can be used to describe the AZT elimination under the evaluated experimental conditions.