Synergistic effects of UV irradiation and hydrogen peroxide in the degradation of chloramphenicol: Mechanism and identification of reaction byproducts and intermediates

The growing accessibility of antibiotics in aquatic environments caused by their widespread use poses significant risks including the possible development of bacterial resistance. Chloramphenicol (CHP) is a strong broad-spectrum antibiotic commonly used in aquaculture operations, which contributes to their environmental propagation. The removal of CHP from wastewater using conventional treatment methods is ineffective especially when it is in trace concentrations. In this context, this research investigates the competitiveness of a photon-driven technology to degrade CHP by exploiting the synergies between hydrogen peroxide (H2O2) and UV irradiation. The impact of operational parameters on treatment efficacy was explored through experimental design by considering the effects of H2O2 dose, UV irradiance intensity, pH of the solution, and CHP initial concentration. The findings demonstrate that this process yields almost 100 % degradation for 50 mg/L CHP solution within optimal conditions of 25 mM of H2O2 under 1240 μW/cm2 of UV radiation at pH 6.2. Furthermore, the identification of main transformation by-products allowed the description of a degradation pathway of CHP under H2O2/UV treatment. This study emphasizes the potential of the investigated low-cost treatment as an effective method for reducing antibiotic contamination in aquatic ecosystems, providing important insights for future solar-driven large-scale applications in wastewater treatment.