Understanding the adsorption sites on nitrogen- and oxygen-doped carbon nanotubes for iodine uptake

The effective capture and storage of radioactive iodine is of great significance to the safe use of nuclear energy. In this study, nitrogen- and oxygen-doped carbon nanotubes acted as effective iodine capture agents in a low concentration of iodine solution of approximately 100 mg L−1. The iodine uptake capacity is proportionate to hydroxy-functional groups as oxygen species and graphitic nitrogen as nitrogen species, respectively, rather than defects and the specific surface area of carbon nanotubes. The essential adsorption activity of oxygen-doped carbon nanotubes is more than 2.5 times that of nitrogen-doped carbon nanotubes, indicating oxygen-doped carbon nanotubes as a potential carbon material in practical applications for the adsorption of iodine. Theoretical study further deepened the understanding of the iodine adsorption sites on carbon nanotubes. This work provided a new method for the design and synthesis of high-performance radioactive iodine solid adsorbents in the future.