Photocatalytic oxidation of ciprofloxacin by UV/ α-Fe2O3/sulfite: mechanism, kinetic, degradation pathway

ABSTRACT

This study was aimed to investigate the synergistic effect of sulfite reducing agent on the UV/hematite (α-Fe₂O₃) photocatalytic process performance in the removal of ciprofloxacin from the aqueous solutions. For this purpose, influence of the operation parameters including initial antibiotic concentration, pH, sulfite to hematite molar ratio and the reaction time on the UV/hematite/sulfite (UHS) performance was evaluated. UV alone, UV/hematite (α-Fe₂O₃) (UH) and UV/sulfite (US) processes indicated to have little influence on the ciprofloxacin degradation. The simultaneous presence of hematite and sulfite in the reaction environment was significantly improved the degradation efficiency, as UHS process indicated an increase of 89%, 64% and 59% in the removal performance than that of UV alone, UH and US processes, respectively. Under the selected condition (pH of 7.0 and sulfite/hematite molar ratio of 1:3), 94% of ciprofloxacin (CFX) was degraded after 5 min of reaction. In addition, r_{obs (}mg L⁻¹ min) value for UHS process was 25.26, 6 and 4.8 times that of UV alone, UH and US processes, respectively. The EEO and TCS values for UV alone, US, UH and UHS processes were (44.21 kWh/m⁻³ and 2.08 $ m⁻³), (10.5 kWh/m⁻³ and 1.1 $ m⁻³), (4.8 kWh/m⁻³ and 1.04 $ m⁻³) and (1.75 kWh/m⁻³ and 0.85 $ m⁻³), respectively. In addition, the study of the reaction mechanism showed hydroxyl and sulfate radicals play a vital role in the degradation of CFX by UHS process.

Graphical Abstract

KEYWORDS:

• Advanced oxidation process
• ciprofloxacin
• halogenated antibiotics
• hematite
• sulfite

Acknowledgments

This study is based on the projects done in the Khoy University of Medical Sciences. The authors would like to express their gratitude to the Khoy University of Medical Sciences for their financial support of this study (project number: 98000014 (Ethical code: IR.KHOY.REC.1399.008).

Disclosure statement

No potential conflict of interest was reported by the author(s).

Additional information

Funding

This work was supported by the khoy university of medical sciences [project number: 98000014].