Achieving Effective Trap of Radioactive Cesium by an Open-Framework Silver Selenidostannate

Effective and efficient incarceration of ¹³⁷Cs⁺ ions from high-level radioactive waste liquids is of particular significance for the purpose of contaminant management and resource recovery, making it one of the hot spots in current scientific research. Herein, we detailedly evaluate the cesium ion-exchange behaviors of a microporous silver selenidostannate, namely, [CH₃NH₃]₂[H₃O]Ag₅Sn₄Se₁₂·C₂H₅OH (denoted as MSTS), under various conditions. As a new cesium scavenger, MSTS exhibits a large saturated capacity (219.08 mg/g) and rapid uptake kinetics (within 15 min). Benefiting from its suitable windows and channels, MSTS displays excellent selectivity and strong preference for low-concentration cesium even in the coexistence of interfering ions (e.g., Na⁺, K⁺, Mg²⁺, Ca²⁺, HA, and CO₃²⁻) and real water environments, in which distribution coefficient Kd values (typically more than 10⁴ mL/g) far exceed or match well with the levels of many high-performance oxide/sulfide-based competitors. More attractively, when packed into an ion-exchange column, MSTS also maintains high cesium ion removal efficiencies (98.97-99.34%) for treating continuous flow. These charming advantages, together with its broad acid/alkali resistance and good recycling stability, highlight MSTS's great potential in the effective and efficient elimination of radioactive cesium from aqueous solution.