Iron-modified biochar from fermented grain residues for enhanced oxytetracycline degradation via periodate activation

The frequent presence of antibiotics like oxytetracycline (OTC) in aquatic environments has raised significant concerns owing to their potential to cause antibiotic resistance genes and ecological risks, demanding efficient and sustainable remediation methods. This study developed a novel iron-modified biochar (4MBC800) derived from fermented grain residues to activate periodate (PI) for OTC degradation. The biochar was prepared via pyrolysis and characterized by various instruments, revealing a well-developed porous structure and high specific surface area. Under operating conditions (OTC = 20.4 mg/L, 4MBC800 = 1.1 g/L, PI = 3.3 g/L, t = 150 min), 92.1% of OTC was effectively removed. Radical quenching experiments and HPLC-MS analysis identified ^•OH, ^•O₂⁻, and ¹O₂ as the dominant reactive species driving OTC degradation through three distinct pathways. The 4MBC800/PI system demonstrated robust catalytic performance, reusability, and adaptability across different water matrices without generating toxic byproducts. This work provides new insights into the design of waste-derived catalysts for periodate-based advanced oxidation processes in antibiotic-contaminated water treatment.