Photodegradation performances and transformation mechanism of sulfamethoxazole with CeO2/CN heterojunction as photocatalyst

[Display omitted] •Heterojunction of 5CeO2/CN benefited the separation of photogenerated carriers.•Higher SA and the photoinduced carriers enhanced the performance of 5CeO2/CN.•SMX pathways included bond break, substitution, hydroxylation and oxidation. Sulfamethoxazole (SMX) is a ubiquitous sulfonamides in aquatic environment which is difficult to be removed by traditional wastewater treatment technologies. Herein, heterogenous nanocomposites of CeO2 and graphite carbon nitride (CN) were prepared and applied to photodegrade SMX under visible light irradiation. With the optimized mass ratios, the photocatalyst 5CeO2/CN (CeO2, 5% mass ratio) showed robust ability in absorbing visible light and promoting separation efficiency of photoinduced electrons and holes. Consequently, the removal efficiency of SMX with 5CeO2/CN reached 99.2% after irradiation for an hour, 7.56% and 91.83% higher than that with pure CN and CeO2. OH, O2− and h+ were proved to be the active species towards SMX photodegradation, and O2− was the dominant one. The intermediate products were identified and the possible pathways of SMX by photocatalysis were proposed in this study.