Identification of reactive species and functional groups determining the selective oxidation of organic contaminants in Bismuth ferrate/peroxymonosulfate system

The reactive species and functional groups determining the major reactive species contributing to the degradation of organic pollutants were identified in the Bi₂Fe₄O₉/PMS (BFO/PMS) system. Competitive degradation, radical quenching experiments of organic contaminants, PMSO₂ generation, Raman spectroscopy, ¹⁸O isotope labeling experiments and the comparison of sulfadiazine degradation intermediates suggest the generation of both free radical and high-valent iron in BFO/PMS system. The groups determining the high-valent iron oxidation pathways for different organic contaminants were identified respectively (acetaminophen: -OH, sulfadiazine: -NH₂, diclofenac: -NH-, ciprofloxacin: -NH- and N-R3). The linear relationship between Hammett's constants and the contribution of high-valent iron oxidation to the degradation of homologues under neutral condition was established. This study provides a novel insight into heterogeneous activation mechanisms of PMS and helps predict the fate of various organic pollutants carrying different functional groups during environmental remediation by the activation of PMS by iron-based catalysts.