Efficient Cs⁺-Sr²⁺ Separation over a Microporous Silver Selenidostannate Synthesized in Deep Eutectic Solvent

Area of Science:

• Materials Science
• Inorganic Chemistry
• Nuclear Chemistry

Background:

• Efficient separation of cesium (Cs+) and strontium (Sr2+) is crucial for radionuclide recovery in medical, industrial, and nuclear waste management applications.
• Existing separation methods often face challenges with selectivity, stability, and environmental impact.
• Microporous materials offer potential for selective ion exchange due to their tunable pore structures.

Purpose of the Study:

• To develop a novel material for highly efficient and selective separation of Cs+ from Sr2+.
• To investigate the ion exchange properties and stability of the new material for practical applications.
• To evaluate the potential of the material in radionuclide recovery and nuclear waste treatment.

Main Methods:

• Synthesis of a novel microporous silver selenidostannate, [NH3CH3]0.5[NH2(CH3)2]0.25Ag1.25SnSe3 (AgSnSe-1), in a deep eutectic solvent (DES).
• Ion exchange experiments to determine selectivity and capacity for Cs+ over Sr2+.
• Column studies to evaluate continuous flow separation performance and stability under radiation and varying pH conditions.

Main Results:

• AgSnSe-1 demonstrated exceptional Cs+/Sr2+ separation with a high separation factor (SF ≈ 121.4) and distribution coefficients (KdCs = 1.06 × 104 mL g-1, KdSr = 87.7 mL g-1).
• Continuous flow separation achieved >99.9% Cs+ removal and negligible Sr2+ removal over 10,000 bed volumes.
• The material exhibits excellent radiation resistance (β and γ), broad pH stability (1-12), and low Se leaching, with performance unaffected by common cations.

Conclusions:

• The novel microporous silver selenidostannate, AgSnSe-1, is a highly effective material for selective Cs+ and Sr2+ separation via ion exchange.
• Its robust chemical and radiation stability, coupled with efficient separation performance, makes it suitable for nuclear waste treatment and radionuclide recovery.
• The facile elution of Cs+-laden AgSnSe-1Cs allows for material recycling, highlighting the potential of open framework metal selenides in sustainable nuclear technologies.