Photodegradation of the antibiotic sulphamethoxazole in water with UV/H₂O₂ advanced oxidation process

Abstract

Photodegradation of the antibiotic sulphamethoxazole (SMX) in water using a medium‐pressure UV lamp combined with H₂O₂ (UV/H₂O₂) was used to generate the advanced oxidation process (AOP). The photodegradation process was steadily improved with addition of H₂O₂ at relatively low to moderate concentrations (5 to 50 mg L⁻¹). However, the addition of H₂O₂ to the photolysis process at higher concentrations (50 to 150 mg L⁻¹) did not improve the degradation rate of SMX (in comparison with 50 mg L⁻¹ H₂O₂). Addition of H₂O₂ to the UV photolysis process resulted in several processes occurring concurrently as follows: (a) formation of HO· radicals which contributed to the SMX degradation, (b) decrease in the available light for direct UV photolysis of SMX, and (c) scavenging of the HO· radicals by H₂O₂, which was highly dominant at moderate to high concentrations of H₂O₂. It is clear that these factors, separately and synergistically, and possibly others such as by‐product formation, affect the overall difference in SMX degradation in the AOP process at different H₂O₂ concentrations.

Keywords:

• advanced oxidation process
• medium‐pressure UV lamp
• hydroxyl radicals
• photolysis
• antibiotic residues

Acknowledgements

The authors gratefully acknowledge Mr. Igal Gozlan, researcher at IMI Tami, Institute for R&D Ltd., Israel for his assistance in the chemical aspects of this research.