Highly Efficient Sequestration of (Radio) Iodine from Water via Isostructural ionic Metal-Organic Frameworks

Abstract

Large-scale production of radioactive iodine isotopes (129I and 131I) in nuclear reactors is a serious environmental and health hazard in fallout situations, which requires the synthesis of highly effective iodine sequestration materials. This study utilized two isostructural ionic metal-organic frameworks (MOFs) iMOF-3C and IPM-201 with different counter anions for the selective removal of I2/I3- species. Both MOFs had fast kinetics, with capture efficiencies of over 99% within the initial 5 minutes of exposure. These results illustrate an adequate and stable method of the fast sequestration of radioactive iodine, with implications for their use in nuclear waste treatment. Both the MOFs are stable and porous for a wide range of pH as well as varied conditions of water. They therefore are highly efficient in charge- and size-selective entrapment of iodine via an ion-exchange process. The highest capacities of iMOF-3C and IPM-201 for iodine uptake in the vapor phase are 4.44 g g⁻¹ and 4.21 g g⁻¹, while in the aqueous phase, they are 3.28 g g⁻¹ and 2.54 g g⁻¹, respectively.