Degradation of Sulfamethoxazole in Aqueous Solution by Low-Energy X-ray Irradiation

Antibiotic resistance has been a serious health threat of widespread concern, as antibiotics are difficult to degrade effectively in the environment. In this study, sulfamethoxazole (SMZ), a common antibiotic in an aqueous solution, was irradiated by low-energy X-ray to investigate the effect of the absorption dose, initial concentration, initial pH, irradiation energy and other conditions on the degradation of SMZ, as well as the kinetic mechanism of SMZ degradation. The results showed that low-energy X-ray irradiation could effectively degrade SMZ in an aqueous solution at different initial concentrations and acid-base degrees, and the degradation effect of irradiation in the range of 60–80 keV is independent of the energy of X-rays. The degradation rate of the SMZ solution, with an initial concentration of 10.70 mg/L, was 94.6% at an absorbed dose of 890 Gray, with a pH of 3.5. Similar to other works on the degradation of antibiotics by ionizing irradiation, the degradation of SMZ solutions conformed to a pseudo-first-order kinetic mechanism.