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

This study was aimed to investigate the synergistic effect of sulfite reducing agent on the UV/hematite (alpha-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 (alpha-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.

Automated summary

This study aimed to investigate the synergistic effect of a sulfite reducing agent on the performance of the UV/hematite photocatalytic process in removing ciprofloxacin from aqueous solutions. The results showed that the simultaneous presence of hematite and sulfite significantly improved the degradation efficiency of ciprofloxacin, with a degradation increase of 89%, 64%, and 59% compared to UV alone, UV/hematite, and UV/sulfite processes, respectively. Additionally, under the selected conditions, 94% of ciprofloxacin was degraded after 5 minutes of reaction.