PEDOT derived S-doped porous carbon/Fe₇S₈ stimulates peroxymonosulfate to degrade phenazopyridine hydrochloride from industrial wastewater

The S-doped carbon/Fe₇S₈ catalyst (S-C/Fe₇S₈) was prepared with 3,4-ethylenedioxythiophene (EDOT) as sulfur source through one-pot methods. In this work, the S-C/Fe₇S₈ was utilized as heterogeneous catalyst for peroxymonosulfate (PMS) activation to degrade phenazopyridine hydrochloride (PhP). The effects of catalyst dosage, PMS concentration, solution pH and inorganic ions on PhP degradation were discussed. The S-C/Fe₇S₈ could remove 97.8% PhP (20 mg/L) within 6 min, which exhibited the selective degradation performance for the PhP among the TZ, OTC, DH and TC. Moreover, the CR, MY, RhB, MO, MB and the mixed solution can be respectively degraded by S-C/Fe₇S₈/PMS over the full pH range within 6 min. The ¹O₂, O₂^·−, h⁺ and electron-transfer were confirmed as the main contributors to PhP degradation. The possible degradation mechanism and degradation pathway were proposed. The Fe species, and S^2– were active sites to activate PMS. This work might provide a facile method to prepare sulfur-containing photocatalyst for environmental remediation.