Boosting the Iodine Adsorption and Radioresistance of Th-UiO-66 MOFs via Aromatic Substitution

Effective capture of radioactive iodine is of paramount importance for the safe and long-term storage of fission products in the nuclear fuel cycle. Herein, a series of functionalized Th-UiO-66 MOFs was employed as a model to investigate the effects of substituents on iodine adsorption in both solution and vapor states. Sorption studies revealed that the electro-donating amino group exhibits the most positive role on increasing the removal rate of iodine from cyclohexane and the uptake capacity of iodine vapor. Particularly, the disubstituted Th-UiO-66-(NH₂)₂ can effectively remove 91.9 % of iodine (300 mg L⁻¹) from cyclohexane and capture 969 mg g⁻¹ iodine vapor, significantly higher than 59.6 % and 334 mg g⁻¹ of untagged Th-UiO-66, respectively. In addition, the substituent effect on the radiolytic stability of MOFs was for the first time investigated, leading to the unearthing of one of the most radioresistant MOFs Th-UiO-66-NH₂ reported to date.