Abstract
The capture of radioiodine species during nuclear fuel reprocessing and nuclear accidents is crucial for nuclear safety, environmental protection, and public health. Previously reported emerging materials for iodine uptake cannot outperform commercial zeolites and active carbon under the practical dynamic scenario. Herein, we present a new design philosophy aiming at significantly enhanced specific host-guest interactions and obtain a nitrogen-rich covalent organic framework material by introducing a bipyridine group into the building block for the simultaneous capture of both iodine gas through enhanced electron-pair effect and organic iodide via the methylation reaction. These efforts give rise to not only an ultrahigh uptake capacity of 6.0 g g−1 for iodine gas and a record-high value of 1.45 g g−1 for methyl iodide under static sorption conditions but also, more importantly, a record-high iodine loading capability under dynamic conditions demonstrated from the breakthrough experiments.
[Display omitted]
•A new design philosophy for iodine uptake material is presented•SCU-COF-2 exhibits record-high dynamic iodine uptake amount (0.98 g g−1)•SCU-COF-2 exhibits record-high static methyl iodide uptake amount (1.45 g g−1)•Moisture has a negligible influence on iodine uptake of SCU-COF-2
The efficient capture of gaseous radioiodine species during the used nuclear fuel reprocessing and nuclear accident event has attracted much attention but remains challenging owing to the low concentration of iodine combined with harsh operational conditions including elevated temperatures, high humidity, and strong acidity. Previously reported emerging materials for iodine uptake cannot outperform commercial zeolites and active carbon under the practical dynamic scenario. We overcome the challenges by introducing a bipyridine group into the COF structure and maximization of its density to significantly enhance the interactions between the COF host and iodine species, affording the first COF showing capabilities of simultaneous capture of iodine and organic iodide under dynamic conditions and representing clear advances over commercial materials. This design philosophy can be extended to the remediation of pollutants and extraction of strategic resources in low concentrations.
A 2D dual-pore covalent organic framework (SCU-COF-2) is constructed to efficiently capture iodine gas and methyl iodide simultaneously through the incorporation of 2,2′-bipyridine group introducing exceptionally strong host-guest interactions. This gives rise to new records of static methyl iodide uptake capacity and dynamic iodine uptake capacity, both far beyond those of state-of-art silver-zeolites, MOF materials, and active carbon, showing powerful application potentials.