Degradation of ciprofloxacin by hydrogen peroxide activated with pyrite under simulated sunlight

Abstract

Ciprofloxacin (CIP) residues in the environment pose risks to both human health and ecosystems. In this study, we explored the effect of hydrogen peroxide (H₂O₂) on CIP degradation, activated by pyrite (FeS₂) under simulated sunlight. XRD, XRF, EDS, XSP, DRS, and PL tests confirmed the high purity of FeS₂ and its photocatalytic properties. With [CIP] = 30 μM, [FeS₂] = 0.2 g/L, [H₂O₂] = 0.2 mM, CIP removal reached 87.6 %. The removal rate of TOC reached 55.3 % after 60 min of light exposure, and hydroxyl radicals (OH) contributed 72.7 % to the process. H₂O₂ utilization was 67.5 %, and the system operated effectively across a pH range of 2.00 to 8.00. CIP removal in river water reached 87.9 % after 3 h of light exposure, though the degradation was slower than in ultrapure water. Cl⁻, SO₄²⁻, and NO₃⁻ had little effect on degradation, whereas H₂PO₄⁻, CO₃²⁻, and HCO₃⁻ significantly inhibited the process as their concentrations increased. In livestock wastewater, the simulated sunlight-FeS₂/H₂O₂ system was less effective, but after diluting the wastewater 100 times, CIP removal reached 87.6 % after 60 min. The degraded solutions showed no significant toxicity. These findings suggest that FeS₂, combined with simulated sunlight, can effectively catalyze low concentrations of H₂O₂ to produce OH radicals, removing antibiotics from livestock wastewater.