Fe3O4–decorated CeZr MOF: Magnetic adsorbent for sustainable phosphate removal from contaminated wastewater

초록

The growing prevalence of phosphate in water systems demands sorbents with strong coordination affinity, selectivity, and operational stability. A magnetically separable Fe3O4/Ce–Zr metal-organic framework (MOF) composite was synthesized by anchoring Fe3O4 nanoparticles onto a mixed-metal Cesingle bondZr MOF framework via solvothermal assembly. The composite exhibited a mesoporous structure with a surface area of 395.57 m2/g, facilitating efficient transport to reactive adsorption sites. A maximum phosphate adsorption capacity of 232 mg g−1 was achieved at neutral pH. Adsorption kinetics were best defined by the pseudo-second-order (PSO) model, while equilibrium data were well fitted by the Langmuir isotherm. FTIR and XPS analysis showed that phosphate adsorption primarily involved ligand exchange and inner-sphere complexation at the oxophilic Ce and Zr centers. The composite exhibited strong resistance to interference from coexisting anions. Thermodynamic analysis confirmed that adsorption was impulsive (ΔG = −20.07 kJ mol−1) and endothermic (ΔH = 13.88 kJ mol−1). Approximately ∼60% of its original capacity was retained after five regeneration cycles, while the anchored Fe3O4 enabled rapid magnetic recovery. These findings validate the potential of Fe3O4/Ce–Zr MOFs for engineered phosphate removal applications.

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