Ca‐induced oxygen vacancies in magnetic α ‐ FeOOH for enhanced hypochlorite activation toward EDTA ‐C

Abstract

In this study, Ca‐doped α ‐FeOOH ( α ‐FeOOH@Ca) was synthesized via a one‐step hydrothermal method and applied for EDTA‐Cu oxidative removal in NaClO systems. Under optimal conditions (initial pH 9, NaClO 5 mmol/L, catalyst dosage 0.3 g/L, 30°C), the EDTA‐Cu removal efficiency reached 99.9% within 60 min, with a pseudo‐first‐order rate constant of 0.14 min ⁻¹ . Thermodynamic results verified that the reaction is spontaneous (ΔG < 0) and endothermic (ΔH > 0), which is thermodynamically favorable. The catalyst maintained over 99% removal efficiency after four cycles with negligible Fe leaching, suggesting excellent structural stability and environmental compatibility. Ca doping may induce abundant oxygen vacancies (Ovs), which potentially accelerate interfacial electron transfer and provide sufficient active sites to promote reactive oxygen species generation and conversion. Specifically, •O ₂ ⁻ can be effectively converted to ¹ O ₂ , which presumably dominates the cleavage of amino and carboxyl coordination structures of EDTA‐Cu. The Ovs engineering strategy via Ca doping serves as the core innovation for boosting ROS conversion and catalytic performance. This study provides a feasible route for fabricating vacancy‐rich iron‐based catalysts and offers new insights into high‐efficiency removal of heavy metal–organic complexes via hypochlorite oxidation.