The Confinement Effect of “Ion Lock” for Highly Selective Cesium(I) Capture and Recovery by a 3D Microporous Metal Oxalatophosphate

Abstract

AbstractThe highly selective capture of 137Cs+ from complex solutions is still challenging because of its high solubility, easy mobility, and the influence of interfering ions. Here, a reliable strategy is demonstrated for specific Cs+ ion recognition and separation through constructing the confined space as an “ion lock” in the microporous framework. A new 3D microporous indium oxalatophosphate with the highly selective Cs+ capture, namely [Me2NH2]1.5[In2(PO4)0.5(H2PO4)(HPO4)1.5(C2O4)] (FJSM‐NINPC) is prepared. FJSM‐NINPC with excellent radiation resistance shows ultra‐fast kinetics (high removal rate of 97.63% within 1 min) and high adsorption capacity of 268.12 mg g−1 for Cs+. It can highly selectively capture Cs+ under excessive competitive ions and even in environmental water samples. Furthermore, the ion exchange column filled with FJSM‐NINPC can quickly separate and recover Cs+ from mixed Cs+ and Sr2+ solution (separation factor SFCs/Sr = 249.17). Moreover, single crystal structure analysis combined with density functional theory calculations confirms that Cs+ ions are “encapsulated” in channels of FJSM‐NINPC by the suitable spatial confinement and with strong Cs···O interactions. This work not only provides an unprecedented microporous metal oxalatophosphate with high Cs+ selectivity but clearly reveals the Cs+ capture mechanism and structure‐function relationship of microporous materials for radionuclides remediation.