Construction of nitrogen-rich groups @ zirconium-based metal-organic frameworks for efficient iodine capture

Efficient capture of radioactive iodine serves as an inevitable demand for secure utilization of nuclear energy, environmental conservation, and human health. In this contribution, a series of iodine adsorbent materials Im@UiO-66 were fabricated by encapsulating imidazole (Im) molecules into the pore of a classical zirconium-based metal-organic frameworks UiO-66, employing a simple and feasible vapor-diffusion strategy. Compared with original UiO-66, the resulting composites achieved a significant enhancement in iodine capture performance. Particularly, Im@UiO-66-3 demonstrated outstanding iodine adsorption performance with capacities of 4.66 g g(-1) for vapor and 915 mg g(-1) for solution, which were 3.5 and 9.2 times of the original UiO-66, respectively. Moreover, the introduction of nitrogen through ligand encapsulation provided additional sites for iodine immobilization. The primary mechanism underlying this remarkable performance was identified as charge transfer between iodine and imidazole (Im) molecules. The research offers valuable insights for the design of high-efficiency iodine adsorbents.