Mechanistic analysis and environmental impact assessment of ferrate degradation of sulfonamide antibiotics

The widespread use of sulfonamide antibiotics and the absence of efficient treatment methods have led to increasing environmental contamination. This research explores the degradation of sulfamethoxazole (SMX) and sulfamethazine (SMT) in water using potassium ferrate (Fe(VI)) as a green oxidant. Various factors influencing degradation efficiency, including mass ratio, pH, temperature, coexisting ions, and humic acid (HA), were systematically investigated. A higher mass ratio significantly improved removal efficiency, achieving complete degradation of SMX within 40 and 20 min at 15:1 and 20:1 ratios, respectively, and SMT within 35 and 15 min. Acidic conditions (pH 5-7) favored SMT removal, while alkaline conditions (pH 8-9) enhanced SMX degradation. Temperature elevation had a more pronounced effect on SMT removal. NO 2- initially promoted but subsequently inhibited degradation, whereas HCO3- enhanced SMT removal and hindered SMX degradation. Fe3+ and Cu2+ strongly inhibited the degradation of both pollutants. Mass spectrometry and DFT simulations elucidated oxidation pathways involving ring-opening, hydroxylation, and desulfurization. Fe(VI) treatment markedly reduced the toxicity of both compounds, demonstrating promising results in real water samples. This research provides valuable insights into the application of Fe(VI) for antibiotic degradation, offering a novel approach for the efficient removal of pollutants from water bodies.