Selective separation of uranium, iodine and pertechnetate by porous materials

The rapid development of nuclear energy demands both the continuous supply of nuclear fuel and the safe treatment of spent fuel. Efficient extraction of U(VI) is critical for nuclear fuel preparation and the nuclear fuel cycle, while the selective removal of other fission products is essential for controlling radionuclide pollution. In this mini-review, we summarize recent advances in the separation and capture of uranium, iodine, and pertechnetate using porous nanomaterials through sorption, photocatalysis, and electrocatalysis strategies. Macroscopic experimental studies, combined with advanced spectroscopic characterizations and theoretical calculations, demonstrate that U(VI) can be selectively adsorbed by specific functional groups and active sites, photocatalytically precipitated as UO₂ or (UO₂)(O₂)·4H₂O under visible light irradiation, and electrocatalytically converted into UO_2, U(IV)-containing bimetallic oxides, or Na₂O(UO₃·H₂O)_x precipitates. ⁹⁹TcO₄^- can be effectively separated through halogenation-assisted ion exchange or electrocatalytic reduction to form insoluble ⁹⁹TcO₃. Iodine separation is primarily achieved through electron transfer processes that lead to the formation of I₃^- and I₅^- species from adsorbed I₂ molecules. The separation performance depends on the structures, active sites, and functional groups of the porous materials, as well as environmental conditions such as pH, coexisting ions, and temperature. Finally, the challenges and future perspectives for the practical application of porous materials in radionuclide separation are discussed from the authors' viewpoint.