IL-induced formation of dynamic complex iodide anions in IL@MOF composites for efficient iodine capture

Abstract

Highly efficient capture of radioactive iodine from vapor or solvent remains a serious task for nuclear waste disposal and environmental protection, for which the development of excellent adsorbents is of great importance. Herein, a new strategy named IL-induced formation of dynamic complex iodide anions in IL@MOF composites was developed to prepare efficient iodine capture adsorbents. The IL@PCN-333(Al) composite shows record iodine adsorption capacities of 7.35 g g⁻¹ and 3.4 g g⁻¹ for iodine vapor and solution, respectively. The mechanism study reveals that complex iodide anions can be dynamically formed by the reaction of bromide ions in the IL and iodine molecules, which have strong electrostatic interactions with the imidazolium cations of the IL. Owing to the reversibility of the polyiodide formation, the IL@PCN-333(Al) also shows excellent recyclable performance. This work provides a general methodology for intensification of the interactions of neutral molecules and host materials that may find applications in various adsorption-based separation processes.