在路径 I 中，磺胺甲噁唑的异噁唑环受到 CUF/PMS 体系中活性氧物种的攻击，生成 P1、P2 和 P3。这些分解产物 P1、P2 和 P3 分别氧化为 P4 和 P5，这被视为磺胺甲噁唑的经典氧化路径[64]。根据路径 II，P6 的形成源于异噁唑环上甲基和苯环上–NH 2 的氧化，随后因 S-N 键断裂转化为 P7 和 P8[65]。在路径 III 中，磺胺甲噁唑的 S-N 键可直接被活性氧物种断裂，矿化为 P5 和 P9。接着，TP 9 的异噁唑环因羟基化被活性氧物种攻击形成 P10，随后由于·HO 与烯烃双键之间的高反应活性进一步生成 P11[66]。 此外，生成的 P9 分别通过偶联反应和异恶唑环的亲电取代进一步转化为 P12。P13 的形成可能涉及源自 P10 的–NH 2 基团的氮中心自由基与中间产物的偶联。随后，异恶唑环发生开环反应，生成 P14，后者被活性氧物种氧化为 P15。最终，这些中间产物将进一步矿化为小分子（P16、P17 和 P18）。
Ce-UiO-66-F催化PMS降解SAs的中间产物 The intermediates of CUF/PMS system were identified by the HPLC-MS (in Figure S17), which was used to investigate the possible degradation pathway of sulfamethoxazole. As shown in Figure 13d, the degradation pathway of sulfamethoxazole could be summarized as hydroxylation, deamination, sulfonamide (S-N) cleavage and desulfonation. In pathway I, the isoxazole ring of sulfamethoxazole was attacked by ROSs in CUF/PMS to generate P1, P2 and P3. The breakdown products P1, P2 and P3 oxidized into P4 and P5, respectively, which was viewed as a classic oxidation pathway of sulfamethoxazole [64]. According to pathway II, the formation of P6 resulted from the oxidation of methyl group on the isoxazole ring and –NH2 on the benzene ring and then converted into P7 and P8 due to the broken S-N bond [65]. For pathway III, the S-N bond of sulfamethoxazole could be directly broken by ROSs to be mineralized into P5 and P9. Then, the isoxazole ring of TP 9 was attacked by ROSs to form P10 due to hydroxylation, and then further generated P11, caused by high reactivity between ·HO and olefinic double bonds [66]. In addition, the generated P9 was further converted into P12 via coupling reaction and electrophilic replacement of the isoxazole ring, respectively [67]. The formation of P13 might be involved in the coupling of N-centered radical derived from by –NH2 group of P10 and intermediate products [68]. Then, the isoxazole ring opening reaction occurred resulting in the generation of P14, which was oxidized by ROSs into P15. Finally, these intermediates would be further mineralized into small molecules (P16, P17 and P18). W. Peng, J. Liao, Y. Yan, L. Chen, C. Ge, S. Lin Enriched nitrogen-doped carbon derived from expired drug with dual active sites as effective peroxymonosulfate activator: Ultra-fast sulfamethoxazole degradation and mechanism insight Chem. Eng. J., 446 (2022), Article 137407, 10.1016/j.cej.2022.137407 View PDF View articleView in ScopusGoogle Scholar [65] Y. Chen, D. Chen, X. Bai Binary MOFs-derived Mn-Co3O4 for efficient peroxymonosulfate activation to remove sulfamethoxazole: Oxygen vacancy-assisted high-valent cobalt-oxo species generation Chem. Eng. J., 479 (2024), Article 147886, 10.1016/j.cej.2023.147886 View PDF View articleView in ScopusGoogle Scholar [66] Y. Bao, W.J. Lee, T.-T. Lim, R. Wang, X. Hu Pore-functionalized ceramic membrane with isotropically impregnated cobalt oxide for sulfamethoxazole degradation and membrane fouling elimination: Synergistic effect between catalytic oxidation and membrane separation Appl. Catal. B-Environ., 254 (2019), pp. 37-46, 10.1016/j.apcatb.2019.04.081 View PDF View articleView in ScopusGoogle Scholar [67] M. Xu, H. Zhou, Z. Wu, N. Li, Z. Xiong, G. Yao, B. Lai Efficient degradation of sulfamethoxazole by NiCo2O4 modified expanded graphite activated peroxymonosulfate: Characterization, mechanism and degradation intermediates J. Hazard. Mater., 399 (2020), Article 123103, 10.1016/j.jhazmat.2020.123103 View PDF View articleView in ScopusGoogle Scholar [68] R. Guo, Y. Wang, J. Li, X. Cheng, D.D. Dionysiou Sulfamethoxazole degradation by visible light assisted peroxymonosulfate process based on nanohybrid manganese dioxide incorporating ferric oxide Appl. Catal. B-Environ., 278 (2020), Article 119297, 10.1016/j.apcatb.2020.119297 View PDF View articleView in ScopusGoogle Scholar