摘要
The release and dispersion of uranium during mining activities and fuel/waste management processes in nuclear power plants pose serious environmental risks, particularly in aqueous systems. In such environments, uranium exhibits high solubility and strong mobility, leading to severe radioactive contamination of groundwater, soil, and ecosystems. Therefore, remediating uranium-contaminated environments remains a significant scientific and technological challenge. To address this issue, the present study exploits the high specific surface area and tunable pore architectures/functional sites of metal-organic frameworks (MOFs). Using a controlled synthesis strategy, a core-shell (Fe-Ni) galvanic cell structure was constructed and integrated with MIL-100(Fe) to fabricate the Ni-Fe-MIL-100(Fe) composite, enabling highly efficient and synergistic removal of U(VI) via an “adsorption-reduction-complexation” mechanism. Experimental results demonstrate that the maximum uranium uptake capacity reached 3038.19 mg·g −1 at 303 K and pH = 5, with a significantly enhanced removal efficiency. The kinetic analysis indicates that the uranium adsorption process is well described by the pseudo-second-order model. Combined with density functional theory (DFT) calculations, the electronic transfer channels of the structure were elucidated, revealing that they drive the reduction of U(VI) and facilitate its coordination and immobilization at multi-metal and oxygen-containing sites. These findings confirm that U(VI) removal by the composite material proceeds via a coupled chemical reduction and complexation process, thereby clarifying the underlying adsorption mechanism. Moreover, in mixed-ion solutions and real seawater, the composite maintains high adsorption capacity and excellent selectivity, demonstrating strong potential for uranium immobilization and recovery in the remediation of radioactive wastewater.
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