A negatively-charged supramolecular trap for precisely catching strontium ion

Area of Science:

• Environmental Science
• Materials Science
• Radiochemistry

Background:

• Separating radioactive strontium (Sr²⁺) from aqueous environments is challenging due to similar properties of alkali and alkaline earth metals.
• Existing methods for environmental radioactivity remediation face limitations in accuracy and efficiency.

Purpose of the Study:

• To develop a highly selective adsorbent for precise Sr²⁺ capture.
• To investigate a supramolecular framework for efficient removal of radioactive strontium from groundwater and seawater.

Main Methods:

• Construction of an anionic crown ether-based metal-organic framework (ZJU-X99) mimicking crown-ether carboxylic acids.
• Utilizing synergistic electrostatic interactions and supramolecular host-guest recognition for Sr²⁺ binding.
• Conducting adsorption kinetics, capacity, and selectivity experiments, including dynamic column and radioactive decontamination trials.

Main Results:

• ZJU-X99 demonstrated rapid adsorption kinetics (1 min) and a high adsorption capacity (263 mg/g) for Sr²⁺.
• Exceptional selectivity for Sr²⁺ was observed, even in the presence of 1000-fold excess of Na⁺, K⁺, and Cs⁺.
• The framework exhibited strong binding affinity for Sr²⁺ with minimal structural changes, validated by dynamic column experiments and radioactive ⁹⁰Sr decontamination.

Conclusions:

• The designed supramolecular framework (ZJU-X99) offers an effective strategy for targeted Sr²⁺ removal.
• Findings provide insights into designing advanced materials with tailored binding sites for specific ion capture in environmental remediation.
• The study highlights the potential of ZJU-X99 for practical applications in decontaminating radioactive strontium from water sources.