Selective Sr²⁺ capture in an In³⁺-based anionic metal-organic framework

Strontium-90 (Sr-90) has a long half-life (t1/2 = 28.8 years) and high beta(-) decay energy (decay energy = 0.546 MeV), making it a hazardous radioactive pollutant. Various methods to remove Sr-90(2+) from radioactive wastewater have been developed. Among them, the ion-exchange method has gained significant attention owing to its high capacity, simplicity, and cost-effectiveness. In this study, we synthesize a water-stable, anionic metal-organic framework, DGIST-12, assembled from In3+ and partially deprotonated 4,6-dihydroxy-1,3-benzenedicarboxylic acid. Furthermore, we evaluate the potential of DGIST-12 as a promising Sr2+ sorbent, highlighting its high porosity and a negatively charged In8 cluster. DGIST-12 effectively exchanges its counter cations, dimethylammonium, with Sr2+. Our findings suggest that the maximum Sr2+ uptake capacity of DGIST-12 is reached within 30 min of exposure, and this capacity is maintained across a broad pH range of 4-11. Importantly, DGIST-12 selectively adsorbs Sr2+ in the presence of various competing ions. Furthermore, the viability test performed on yeast cells exposed to Sr2+-containing media treated with DGIST-12 reveals that DGIST-12 can mitigate the harmful effects of Sr2+ toxicity on living organisms. These results underscore the promising prospects for creating innovative sorbent materials designed for the effective and discriminative removal of radioactive contaminants.