Degradation of sulfanilamide in aqueous solution by ionizing radiation: Performance and mechanism.

Sulfonamide (SA) is an emerging contaminants and the efficient treatment of SA containing wastewater remains a challenge. Herein, SA degradation by gamma irradiation has been systematacially studied. SA (10 mg/L) could be totally removed with 1.5 kGy irradiation. Quenching experiments demonstrated that •OH and e aq ⁻ were the predominant for SA degradation. SA degradation was reduced with initial concentration increasing, and the removal was faster with pH increasing in the range of 3.1–10.8. The coexisting matters affected SA degradation through changing reactive species, and the introduction of SO 4 ²⁻ and Cl⁻ enhanced SA degradation, while CO 3 ²⁻ had a negative impact on SA degradation, and the degradation was insignificantly affected when adding humic acid. Gamma irradiation could remain effective in real water matrixes. In conjunction with LC-MS analysis and DFT calculation, possible degradation pathways for SA were proposed. Gamma irradiation could reduce the toxicity of SA, while several byproducts with more toxic were also formed. Furthermore, gamma/priodate (PI) process was promising to enhance SA degradation and mineralization. k value increased by 1.85 times, and mineralization rate increased from 19.51% to 79.19% when adding PI. This study suggested that ionizing radiation was efficient to eliminate SA in wastewater. [Display omitted] • Ionizing irradiation was efficient for sulfanilamide degradation. • •OH and e aq ⁻ were the predominant in degradation by gamma irradiation. • Degradation pathways for sulfanilamide were proposed. • Periodate could improve sulfanilamide degradation by gamma irradiation. [ABSTRACT FROM AUTHOR]