Microcrystalline cellulose-based, nitrogen-doped carbon nanoflakes for adsorption of uranium and thorium†

Nitrogen-doped carbon nanoflakes (N-CNFs) were synthesized via a simple acid-assisted carbonization process using microcrystalline cellulose (MCC) and urea. The as-synthesized N-CNFs were used for the adsorption of simulated radioactive nuclides such as uranium [U(VI)] and thorium [Th(IV)]. Under optimized experimental conditions, N-CNFs removed ≈45.6 and ≈48.7 ppm of U(VI) and Th(IV), respectively. U(VI) and Th(IV) adsorption followed the Langmuir and pseudo-second-order kinetic models. The effect of pH, concentration, and loading capacity was also explored. Furthermore, adsorption–desorption studies were conducted to evaluate the recyclability of N-CNFs as an adsorbent, which demonstrated good recyclability efficiency for four cycles.