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

Strontium-90 (⁹⁰Sr) has a long half-life (t_1/2 = 28.8 years) and high β⁻ decay energy (decay energy = 0.546 MeV), making it a hazardous radioactive pollutant. Various methods to remove ⁹⁰Sr²⁺ 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.