Highly Selective Radioactive ¹³⁷Cs⁺ Capture in an Open-Framework Oxysulfide Based on Supertetrahedral Cluster

Abstract

Removal of 137Cs+, one of the most hazardous radionuclides, from nuclear waste, is a challenging task because it requires simultaneously high capacity and high selectivity. Chalcogenides offer a great opportunity to design and create high-performance 137Cs+ absorbents. We report a new material (InSnOS) with facile ion-exchange properties. The anionic framework is based on corner-shared pseudo-T4 supertetrahedral oxysulfide [In8Sn12O10S34]16– clusters, resulting in the formula [In8Sn12O10S32]12–. The crystal structure features the interpenetration of two independent oxysulfide cluster frameworks which create pincer cavities based on sulfur atoms that prove highly effective for capturing Cs+ ions. The binding mode of the Cs+ ions by the material was determined by a single crystal structure refinement of a fully ion-exchanged single crystal. The structure determinations show that the small pores created by the two interpenetrating frameworks are the optimal size for capturing Cs+. This advantage makes the material very effective for the removal and recovery of 137Cs+ from aqueous solution. This framework shows not only extremely high exchange capacity (q m), 537.7 mg per g of anionic [In8Sn12O10S32]12– framework, ranking it among the best reported Cs+ sorbents, but also superior affinity and selectivity when using complex solutions simulating industrial and nuclear waste conditions.

Nearly Identical but Not Isotypic: Influence of Lanthanide Contraction on Cs2NaLn(PS4)2 (Ln = La–Nd, Sm, and Gd–Ho)

“…The stark difference between chalcogenide and oxide chemistry, which each require their own synthetic route due to their specific soft and hard acid base chemistry, has prompted researchers to seek out alternative synthesis methods in search of new chalcogenide materials that exhibit the desired properties, which cannot be readily achieved in oxide materials. − Inorganic and inorganic/organic hybrid sulfides are therefore among the most rapidly expanding and developing classes of materials, which exhibit a host of potential applications due to their unique physical properties, such as their ionic conductivity, − ion exchange, − thermoelectric, − ferroelectric, and magnetic properties . The sulfide affinity for certain elements, known as chalcophiles, allows for the formation of very stable complexes that can also be found in biological systems. , Unlike chalcophiles, which are typically very stable, other chemical elements are usually less chemically stable and are therefore more sensitive to moisture and air, making their preparation and handling challenging; their syntheses require specific precautions and controlled reaction conditions.…”

Mixed Solvothermal Synthesis of Tn Cluster-Based Indium and Gallium Sulfides Using Versatile Ammonia or Amine Structure-Directing Agents

“…Metal chalcogenide supertetrahedral T n clusters with atomically defined structures span the size gap between isolated molecular species and semiconductor nanoparticles. − They can exist in the form of discrete clusters whose dispersibility in solvents bears great importance for their solution processable applications in electrocatalysis, , photocatalysis, − photoluminescence, − and so on. In addition, these clusters can also spontaneously coassemble into extended frameworks with specific applications in solid electrolyte, solar energy conversion, ion exchange, − and so on. Generally, the complex fabrication of the solid is dominated by a structure-directing mechanism. , The structure-directing agents (SDAs) with specific size and geometry occupy the space between the clusters and interact with the clusters through electrostatic interactions, van der Waals forces, and hydrogen bonds to form a relatively stable assembly system.…”

Structural investigation of the efficient capture of Cs+ and Sr2+ by a microporous Cd–Sn–Se ion exchanger constructed from mono-lacunary supertetrahedral clusters

“…Hitherto, important progress has been obtained on the uptake of Cs + and Sr 2+ by metal sulfides, e.g. KMS-1, 35 KMS-2, 36 KTS-3, 37 FJSM-SnS, 38 ZnSnS-1, 39 InS-1, 40 InS-2, 41 KZTS, 42 NaTS, 43 SbS-1K, 44 oxysulfides as InSnOS materials, 45,46 and selenides like K 14 Cd 15 Sn 12 Se 46 , 47 CuGeSe-1, 48 and AgSnSe-1. 49 These ion exchangers exhibit fast exchange kinetics, superior capacities, excellent selectivity and good acid/base and radiation resistances.…”