Broad-spectrum sulfonamides degradation via in-situ electrogenerated-persulfate catalyzed by co-existing Mn(II): Dominant roles of Mn(IV)-oxo and electron-mediated Mn(II/III/IV) redox cycle driven radicals mechanism

Developing efficient purification technologies for sulfonamides (SAs) is beneficial for eliminating their latent threats to public health. In this study, electrochemistry (E) was introduced to in-situ produce persulfate (E-PS) through the discharge of sulfate at anode, then E-PS was efficiently and sustainably activated by the co-existing Mn(II) via its redox cycle (Mn(II/III/IV) driven by electron-mediated reaction at cathode. 92.3% of sulfamethoxazole (SMX) was degraded by E/Na 2 SO 4 /Mn(II) system within 60 min. pH, anionic species/strength were the critical factors affecting SMX degradation. The quenching, species detection, probe tests coupled with characterization analysis demonstrated that the generated Mn(IV)-oxo and redox cycle of Mn(II/III/IV) driven radicals were the crucial mechanism. Five possible decomposition routes were recognized through intermediates identification and theory calculations, and the fifth path was the primary one with the prime intermediate of TP17. The acute/chronic toxicity level of intermediates were lower than that of SMX. E/Na 2 SO 4 /Mn(II) system was also able to achieve the broad-spectrum elimination of diverse SAs. This study offered a low cost, broad-spectrum and sustainable approach for SAs purification by directly utilizing the co-existing sulfate and Mn(II), along with realizing the detoxification of SAs.