Iron-Based Biochar for Efficient Persulfate Activation and Sulfamethoxazole Degradation

In this study, we investigated the performance of iron-loaded biochar (Fe-BC) derived from mulberry branches in activating persulfate (PS) for the efficient degradation of sulfamethoxazole (SMX). The Fe-BC/PS system exhibited superior catalytic activity towards SMX degradation, achieving 97% removal within 60 min. The degradation efficiency was found to be highly dependent on preparation conditions, including calcination temperature, the type of iron salt, and biomass feedstock. Reactive species such as hydroxyl radicals (^•OH), sulfate radicals (SO₄^•-), and iron (IV) (Fe(IV)) were identified as key contributors to SMX degradation, with Fe(IV) playing a dominant role. The influence of water quality parameters, such as inorganic ions, pH, and natural organic matter (NOM), on the degradation of SMX was also examined. Proposed degradation pathways revealed the stepwise oxidation of SMX into smaller intermediates, ultimately leading to mineralization. Our findings highlight the potential of Fe-BC/PS systems as a sustainable and effective approach for the remediation of sulfonamide antibiotics in aquatic environments.