Robust and Flexible Thioantimonate Materials for Cs+ Remediation with Distinctive Structural Transformation: A Clear Insight into the Ion-Exchange Mechanism

It is imperative yet challenging to efficiently sequester the Cs-137(+) ion from aqueous solutions because of its highly environmental mobility and extremely high radiotoxicity. The systematical clarification for underlying mechanism of Cs+ removal and elution at the molecular level is rare. Here, efficient Cs+ capture is achieved by a thioantimonate [MeNH3](3)Sb9S15 (FJSM-SbS) with high capacity, fast kinetics, wide pH durability, excellent beta and gamma radiation resistances, and facile elution. The Cs+ removal is not significantly impacted by coexisting Na+, K+, Ca2+, Mg2+, and Sr2+ ions which is beneficial to the remediation of Cs contaminated real waters. Importantly, the mechanism is directly illuminated by revealing an unprecedented single-crystal to single-crystal structural transformation upon Cs+ uptake and elution processes. The superior Cs+ removal results from an unusual synergy from strong affinity of soft S2- with Cs+ easily exchangeable [MeNH3](+) cations, and the flexible and robust framework of FJSM-SbS with open windows as trappers.

Automated summary

This study presents a thioantimonate material (FJSM-SbS) with high capacity, fast kinetics, wide pH durability, and excellent radiation resistances for efficient Cs+ capture. The structural transformation mechanism during Cs+ uptake and elution processes is directly illuminated, showing the superior Cs+ removal results from an unusual synergy of soft S2- with Cs+ easily exchangeable [MeNH3](+) cations and the flexible, robust framework of FJSM-SbS with open windows as trappers.