One-Step Arc-Produced Amino-Functionalized Graphite-Encapsulated Magnetic Nanoparticles for the Efficient Removal of Radionuclides

Graphite-encapsulated magnetic nanoparticles (GEMNPs) modified with highly concentrated nitrogen-containing species were synthesized via a one-step arc discharge. The NH3 added in the arc atmosphere dissociated H radicals to etch the graphite shells and incorporated four types of nitrogen-containing components into the surface networks (i.e., quaternary, pyrrolic, amino, and pyridinic N). The optimal amount of −NH2 distributed on the surface of each nanoparticle was 8.62 × 1016 of amino groups (discharging condition: 0.1% of NH3 at 80 Torr). With a batch sorption technique, radionuclides could be efficiently captured by functionalized GEMNPs with sorption capabilities of 47.28 mg/g for U(VI), 45.48 mg/g for Th(IV), and 32.21 mg/g for Eu(III), respectively. The sorption capacities exhibited an excellent positive linearity with the number of nitrogen-containing species. Functionalized GEMNPs could also be recycled and used well even after five cycles of regeneration, exhibiting favorable potentials for the uptake of radionuclides in real management.