Removal of Tetracycline via Ultraviolet-Activated Peroxyacetic Acid: Performance and Mechanism

To address the worsening environmental pollution caused by the large-scale release of tetracycline (TC) into the environment, this study developed an advanced oxidation system utilizing ultraviolet (UV)-activated peroxyacetic acid (PAA) for the removal of TC. The results showed that the UV/PAA system exhibited markedly enhanced performance compared to individual treatments. Under identical conditions (1.0 mM PAA, 400 W UV irradiation), the TC removal rates by PAA alone and UV irradiation alone were 25.80% and 55.05%, respectively. In contrast, the combined UV/PAA system achieved a significantly higher degradation efficiency of 79.77%, which was 3.09 times and 1.45 times higher than that of PAA and UV processes alone. This superior performance is attributed to the generation of highly reactive species within the system. The degradation process followed pseudo-first-order kinetics. An increase in TC concentration led to a decrease in degradation efficiency, whereas elevating the PAA dosage or light intensity increased the concentration of radicals in the system, thereby enhancing removal performance. Overall degradation efficiency was slightly higher under alkaline conditions compared to acidic conditions, while neutral conditions resulted in slower degradation rates. Among coexisting anions, HCO₃^- and H₂PO₄^- inhibited TC degradation, SO₄^2- and Cl^- exhibited negligible effects, and NO₃^- promoted the degradation of TC. Radical quenching experiments confirmed that hydroxyl radicals (·OH) were the dominant reactive species, working together with superoxide anion radicals (O₂·^-) and singlet oxygen (¹O₂) to drive TC degradation in the UV-activated PAA system. Experiments conducted in real water matrices demonstrated that the system could effectively degrade TC in ultrapure water, tap water, and campus lake water, highlighting its strong environmental adaptability. These findings provide both technical support and a theoretical foundation for the treatment of antibiotic pollutants.