Degradation of sulfamethoxazole by ozonation combined with ionizing radiation.

In this study, the degradation and mineralization of sulfamethoxazole (SMX) by ozonation and ionizing radiation were investigated respectively, and the performance of the combined process of ozonation and ionizing radiation was evaluated. Results showed that complete degradation of SMX could be obtained by ozonation in 12 min or by ionizing radiation with the absorbed dose of 1.5 kGy. However, the mineralization of SMX was very limited in ozonation and ionizing radiation system, TOC removal efficiency was less than 15% and 27% in single-ozonation and single-radiation process, respectively. The combination of ozonation and radiation process obviously enhanced the mineralization of SMX, TOC removal efficiency increased to 65.7%. Moreover, the ozonation-radiation process also exhibited good performance in the mineralization of sulfamethazine (SMT) and sulfanilamide (SM), suggesting a good application prospect of the combined process in treating wastewater contaminated with antibiotics. In addition, some different intermediate products were identified during SMX degradation in ozonation process and ionizing radiation process by a high-performance liquid chromatography-mass spectrometry (LC-MS), and possible pathways of SMX degradation by ozonation and radiation were proposed.