Article ID: J23.007
The selective separation of radioactive ions is essential for reducing and cleaning radioactive wastes. Among the radioisotopes to be removed, 90Sr poses a major threat to human health and the environment. However, the removal of 90Sr from environmental wastewater is still challenging owing to the difficulty in separating 90Sr2+ from Ca2+. Here, we developed a series of isostructural lanthanide–oxalate frameworks (LOFs) comprising oxalate and eight kinds of lanthanide (Ln) ions, i.e., from samarium (Sm) to thulium (Tm), for application to the selective removal of 90Sr from wastewater using its tuned porous structure. The LOFs had ion exchangeable anionic pores, in which the pore size changed in a stepwise manner depending on the host Ln species. When Tb was the host Ln of the LOFs, the LOFs showed extremely high Sr2+ selectivity and were able to distinguish the subtle difference in ionic radius (0.2 Å) between Sr2+ and Ca2+. The Sr2+ selectivity was higher than that of conventional adsorbents. The pore size tuning of the LOFs by selecting the constituent Ln species yielded a highly ion-selective adsorbent material. This novel strategy will be useful in developing custom porous materials that are easy to prepare and applicable across various fields.
