Adsorption-coupled PMS activation over waste iron sludge-derived Fe/biochar for sulfamethoxazole degradation: A singlet oxygen-associated oxidation pathway.

Fe/biochar catalyst Fe/BC-800 from waste iron sludge and calamus biomass achieved nearly complete sulfamethoxazole removal within 60 min after PMS addition, with 67% adsorption in 120 min.

• Why it matters: Waste-derived Fe and carbon catalysts are needed to efficiently degrade antibiotics, but it remains unclear how adsorption enrichment couples with PMS activation and which reactive oxygen pathway dominates.
• What they did: The authors prepared Fe/BC via hydrothermal pretreatment and KOH-assisted pyrolysis/activation, then used phase-resolved mass balance, component controls, quenching, TEMP-EPR, H2O/D2O isotope kinetics, and electrochemical tests to probe mechanisms.
• The result: Evidence indicates a predominantly 1O2-associated oxidation pathway with auxiliary O2•−, SO4•−, and •OH, supported by Fe0/Fe2+/Fe3+ cycling and Fe-carbon interfacial electron transfer, enabling 88–95% removal of five antibiotics in hospital wastewater across regeneration cycles.

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