Degradation of ciprofloxacin and sulfamethoxazole in water using an ozonation/persulfate system under solar irradiation

Pharmaceutical contaminants such as ciprofloxacin (CIP) and sulfamethoxazole (SMX) pose global risks due to their inadequate removal by conventional wastewater treatment plants. This study evaluates their degradation using O₃/PS AOPs under solar irradiation in a 15 L reactor. Key operational parameters were systematically evaluated. Ozonation achieved 98% CIP degradation at an ozone dosage of 65.04 mg L⁻¹, following pseudo-first-order kinetics with apparent rate constant (Kapp = 0.06362 min⁻¹). Degradation efficiencies decreased with increasing pollutant concentration and under acidic conditions: 10 mg L⁻¹ CIP achieved 99% degradation, whereas 20 mg L⁻¹ resulted in 93%, while 15 mg L⁻¹ SMX achieved 94% and 60 mg L⁻¹ achieved 83% degradation. At pH 2, CIP and SMX degradation declined to 73% and 65%, respectively. The addition of 0.045 mmol L⁻¹ PS enhanced performance, achieving 90% CIP degradation within 15 min, eliminating the fluorescence signal of CIP. The combined O₃/PS system exhibited a higher rate constant (Kapp = 0.08615 min⁻¹) than either oxidant alone. Radical scavenging experiments identified hydroxyl and sulfate radicals as the dominant species. A preliminary cost analysis estimated a chemical cost of $0.0009 L⁻¹. Overall, the O₃/PS system demonstrated high efficiency and adaptability for solar-assisted antibiotic removal in water treatment.