Enrichment of radioiodine accompanied by nuclear fission threatens the health of humans, and efficient capture of iodine has attracted wide public attention in recent years. Here we report a crystalline mesoporous nitrogen-containing covalent organic framework (TAPB-BPDA COF) as a highly efficient iodine adsorbent, which is synthesized by imine condensation reaction between 1,3,5-tris(4-aminophenyl)benzene and 4,4′-biphenyldicarboxaldehyde. The TAPB-BPDA COF possesses permanent porous structure, high BET surface area of 1082 m 2 /g, excellent chemical and thermal stability and plenty of nitrogen in the skeleton as effective sorption sites. It displays remarkable adsorption of iodine in aqueous solution up to 988.17 mg/g at room temperature . The adsorption kinetics of iodine onto TAPB-BPDA COF is followed the pseudo-second-order kinetic model , and the adsorption isotherm fits well with the Langmuir model. The TAPB-BPDA COF adsorbs iodine through the weak interaction between the benzene ring on its backbone and iodine, and the electron transfer between nitrogen atoms and iodine promotes the adsorption process . Moreover, TAPB-BPDA COF still maintains efficient adsorption performance after five cycles. These results suggest the great potential of TAPB-BPDA COF as a designable porous to address the problem of nuclear fission waste contamination that threatens human health.
The disposal of radioactive xenon and krypton generated by nuclear fission is essential for the zero emission of nuclear energy, while their efficient capture at low concentrations remains a daunting challenge. We present here a design philosophy for noble gas uptake by introducing the concept of the confinement-intensified multi-heavy-atom effect derived from the Lennard-Jones 12–6 potential, which is achieved by the construction of a previously unnoticed structural unit of a tetrahedral halogen cage arranged in a metal-organic framework (Cu(idc-I)). Record-high adsorption capacities of 128.58 and 20.83 cm 3 cm −3 for Xe and Kr, respectively, were achieved at 0.1 bar and ambient temperature, along with the highest Kr Henry coefficient (10.19 mmol cm −3 bar −1 ). The dense tandem-arrayed tetrahedral iodine cages, as powerful binding sites have been visualized by in situ single-crystal X-ray diffraction studies and theoretical simulations, endowing Cu(idc-I) with the ability to effectively capture trace Xe and Kr from mimic nuclear reprocessing off-gas.