A strategically designed porous magnetic N-doped Fe/Fe₃C@C matrix and its highly efficient uranium(VI) remediation

With the growing development of the nuclear industry and the peaceful utilization of nuclear energy, the safe treatment and disposal of high-level wastes in nuclear waste management is still a major challenge. Overcoming this issue requires developing highly efficient materials for capturing U(vi) from nuclear wastewater. Herein, magnetic porous microcubes with a graphitic shell and highly dispersed active cores (Fe/Fe₃C nanoparticles) are rationally designed and fabricated by simply annealing preformed polydopamine (PDA) coated Prussian blue (PB) microcubes. To assess the sorption properties, sequestration of U(vi) on N-doped metal/metal carbide nanoparticles encapsulated in a carbon matrix (N-doped Fe/Fe₃C@C) was systematically investigated using batch experiments. The sorption performance revealed that the N-doped Fe/Fe₃C@C samples exhibited highly efficient removal efficiency for U(vi), and the sample prepared at 800 °C (N-doped Fe/Fe₃C@C-800) was the best among the series with a maximum sorption capacity of 203 mg g^-1. The U(vi) adsorption and reduction by N-doped Fe/Fe₃C@C-800 were affected significantly by solution pH and concentrations of bicarbonate and calcium. The main reaction mechanism involved U(vi) reduction into insoluble U(iv) species by Fe⁰/Fe(ii) and trapping the guest U(iv) in the porous carbon matrix, which synergistically promoted U(vi) removal from solution to N-doped Fe/Fe₃C@C-800. This study demonstrated the simple synthesis of magnetic N-doped Fe/Fe₃C@C derived from metal-organic frameworks and their potential application in U(vi)-contaminated wastewater remediation. Introduction to the international collaboration In 2003, Prof. X. K. Wang and Prof. B. Grambow started their collaboration in nuclear waste management and the environmental behavior of long-lived radionuclides such as the removal of radionuclides from aqueous solutions, the microstructures and species of radionuclides at the molecular level. They have published many papers in international journals such as Environmental Science & Technology and Geochimica et Cosmochimica Acta.