Oxytetracycline degradation in water by activated H2O2: The effect of iron-loaded attapulgite calcination temperature

Iron-based heterogeneous Fenton-like reactions are effective for eliminating refractory antibiotics from water, yet the fundamental understanding of how calcination temperature dictates the structure-activity relationship of iron-loaded attapulgite (ATP) remains limited. Herein, we systematically investigated this factor by fabricating a series of iron-loaded ATP catalysts (F300, F500, F700) via iron solution impregnation and calcination at 300, 500 and ­ 700 °C. Comprehensive characterization (SEM, XRD, XPS, FTIR, and BET) revealed that F300 (calcined at 300°C) possessed the highest specific surface area (91.886 m²·g −1 ) and optimal pore structure, while higher temperatures (500 and­ 700°C) induced gradual structural sintering (most severe for F700). In catalytic tests for 10 mg·L −1 oxytetracycline (OTC) degradation, F300 and F500 achieved near-complete removal (≈100 %) within 65 min under optimal conditions (pH 3.5, 0.3 g·L −1 catalyst, and 0.5 mmol·L −1 H₂O₂), significantly outperforming F700 (89.55 %). Coexisting anions (Cl - , HCO₃ - ) slightly slowed degradation kinetics, with less than 4 % efficiency loss, whereas humic acid exerted a more pronounced inhibitory effect (8.91 -­ 12.32 %). Radical quenching experiments verified that hydroxyl radicals (·OH) served as the primary reactive species, contributing more than ¹O₂ or ·O₂⁻. This work elucidates the critical influence of calcination temperature on the structure-activity relationship of iron-loaded ATP, establishing a key criterion for designing efficient clay-based catalysts for antibiotic wastewater remediation. • Iron-loaded ATP catalysts were synthesized with varied calcination temperatures (300–700 °C). • F300's high surface area and pores enabled its superior catalytic performance. • F300 achieved ≈ 100 % OTC removal in 65 min under mild acidic conditions (pH 3.5). • ·OH was identified as the dominant reactive species via quenching and mechanism analysis. • Higher temperatures induced sintering; 300 °C is optimal for structure and activity.