Evaluation of antibiotic oxytetracycline removal in water using a gas phase dielectric barrier discharge plasma

Abstract

Degradation of oxytetracycline (OTC), a primary member of antibiotics in water, was performed by a gas phase dielectric barrier discharge (GPDBD) plasma reactor. The influences of operation conditions including applied voltages, air bubbling rates, initial OTC concentrations and initial pH values on OTC abatement were investigated respectively. The results showed that the decontamination process can be fitted by first order kinetics, and the removal ratio and rate were affected obviously by those parameters. After 20 min of discharge treatment, approximately 93.4% of OTC was removed under the experimental conditions: applied voltage of 7.5 kV, air flow rate of 1.0 L/min, initial OTC concentration of 100 mg/L, and initial pH of 5.0. In addition, TOC and COD removal efficiency reached 43.0% and 73.7% at the original pH 9.3, respectively. Furthermore, the amounts of hydrogen peroxide and ozone in aqueous were quantitatively measured to evaluate their roles during antibiotic removal, and the main function of hydroxyl radicals was demonstrated by the radicals scavenger test. At last, the analyses of UV–Vis spectra and HPLC-MS were employed to study the OTC elimination mechanism, and the possible decomposition pathway was proposed based on the speculated intermediates.