Capture and immobilization of gaseous ruthenium tetroxide RuO 4 in the UiO-66-NH 2 metal–organic framework

106 Ru is a radioactive isotope usually generated by the nuclear industry within power plant reactors. During a nuclear accident, 106 Ru reacts with oxygen, leading to the production of highly volatile ruthenium tetroxide RuO 4 . The combination of volatility and radioactivity makes 106 RuO 4 , one of the most radiotoxic species and justifies the development of a specific setup for its capture and immobilization. In this study, we report for the first time the capture and immobilization of gaseous RuO 4 within a porous metal–organic framework (UiO-66-NH 2 ). We used specific installation for the production of gaseous RuO 4 as well as for the quantification of this gas trapped within the filtering medium. We proved that UiO-66-NH 2 has remarkable affinity for RuO 4 capture, as this MOF exhibited the worldwide highest RuO 4 decontamination factor (DF of 5745), hundreds of times higher than the DF values of sorbents daily used by the nuclear industry (zeolites or activated charcoal). The efficiency of UiO-66-NH 2 can be explained by its pore diameters well adapted to the capture and immobilization of RuO 4 as well as its conversion into stable RuO 2 within the pores. This conversion corresponds to the reactivity of RuO 4 with the MOF organic sub-network, leading to the oxidation of terephthalate ligands. As proved by powder X-ray diffraction and NMR techniques, these modifications did not decompose the MOF structure.