Capture of Iodine Species in MIL-53(Al), MIL-120(Al), and HKUST-1(Cu) Periodic DFT and Ab-Initio Molecular Dynamics Studies

The potential use of three metal–organic frameworks (MIL-53(Al), MIL-120(Al) and HKUST-1(Cu)) to adsorb iodine species (I 2 and ICH 3 ), which can be released during a severe nuclear accident, is investigated using periodic dispersion density functional theory for the first time. Competitive adsorption of iodine in the presence of water molecules is also characterized for the hydrophilic HKUST-1(Cu). In the first step, we have found that the absolute values of interaction energies of I 2 and ICH 3 are higher in the hydrated form of HKUST-1(Cu) than in the dehydrated one, which is of very high interest for iodine trapping. In a second stage, iodine species are strongly adsorbed in MIL-53(Al) than in MIL-120(Al) and HKUST-1(Cu) MOFs and therefore this material could potentially trap iodine compounds. Moreover, we study the influence of the functionalization of the MIL-53(Al) organic linkers on the adsorption behavior of iodine and it turns out that the substitutions does not present a significant effect for this purpose. The factors governing the interaction energies between iodine (I 2 and ICH 3 ) and MOF structures are analyzed and the important role of van der Waals interactions in these materials is highlighted.