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 degrees 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 Fe-0/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.