Oxygen-rich microporous carbons with exceptionally high adsorption of iodine

The effective adsorption of radioactive iodine from nuclear waste using porous carbons remains significantly challenging, which currently appears to have an upper limit for their uptake capacity. Here, to overcome this upper limit, we explore the potential of oxygen-rich microporous carbons derived from cellulose diacetate via a general hydrothermal carbonization and KOH activation route. These activated carbons show exceptionally high adsorption of radioactive iodine due to the combined effect of their high surface area, large pore volume and intrinsic oxygen-rich nature. Our results indicate that these activated carbons have large surface areas of 1829–2997.7 m2 g−1, large pore volumes of 0.88–1.40 cm3 g−1 and high oxygen contents of 19.32–26.14%. They possess high iodine adsorption capacities of up to 6.44 g g−1 in dry conditions and 2.44 g g−1 even at high humidity (74.0 ± 0.9%). Further DFT calculations reveal that the oxygen-rich nature of activated carbon enhances its interaction with iodine molecules, resulting in a high pore accessibility. Also, the porous carbon shows good iodine retention and good reusability for practical applications. These results have fundamental implications for understanding the iodine uptake of oxygen-rich porous carbon and designing materials to handle radioactive iodine emission.