Degradation of an Antibiotic from the Fluoroquinolone Group by Photocatalysis with a New Carbon Nitride Compound

Ofloxacin (OFL), a fluoroquinolone, is an antibiotic found in hospital wastewater, groundwater, and other water bodies. Its occurrence in water results in several environmental problems, such as the emergence of antibiotic-resistant bacteria. This research is focused on determining the viability of removing and mineralizing OFL by photocatalysis under visible radiation with a graphitic carbon nitride photocatalyst (GCNP) synthesized from the pyrolysis of urea and calcium oxalate at 600°C. The photocatalyst was characterized by X-ray diffraction (XRD) and scanning electron microscopy (SEM). Moreover, the point of zero charge (PZC) of the photocatalyst was determined, and the adsorption isotherms were obtained. The photocatalytic activity of this new material was tested with a synthetic aqueous solution of OFL (20 mg/L) exposed to visible radiation. Three pH values (5, 7, and 10) and three doses of H2O2 (41.7, 83.3, and 333.2 mg/L) were considered. The achieved mineralization was evaluated through the decrease in the content of total organic carbon (TOC). The highest degradation of OFL was 23.9% after 40 min, with an initial concentration of H2O2 of 83.3 mg/L and a pH value of 10. It was confirmed that the reaction follows a kinetics of pseudo-first order.