Well-Designed a Novel Phosphomolybdic-Acid@PCN-224 Composite with Efficient Simultaneously Capture Towards Rubidium and Cesium Ions

Enrichment high value-added rubidium (Rb) and cesium (Cs) from aqueous solutions is a greatly challenge owing to its trace concentration and restricted selectivity. A series of novel phosphomolybdic acid (PMA) promoted PCN-224 composites were designed and prepared by one pot hydrothermal synthesis technique. The Rb+ and Cs+ captured abilities from aqueous solution were systemically evaluated. The XRD, thermos gravimetric analysis, scanning electron microscopy, transform infrared spectra, and N2 adsorption were explored to prove the existence of PMA in the structure of mesoporous PCN-224. The Lewis acid-base interaction played a decisive sole for high uptakes of Rb+ and Cs+ onto the PMA@PCN-224, whose is even outstanding to some adsorbents in literature. The adsorption kinetics of PCN-224 and PMA@PCN-224 were quite fitted to the pseudo-second order kinetic model, demonstrating that the chemisorption possessed an important role during the adsorption process. Importantly, the saturated PMA@PCN-224 could be easily recollected by washing with an ammonium nitrate solution. The uptake of Rb+ and Cs+ could be maintained more than 90% even after fifth cycle. Overall, the novel PMA@PCN-224 could be capable of capturing Rb+ and Cs+ from aqueous solutions. We believe that the PMA@PCN-224 would be potential applied on a large scale if enough engineering data supported in the future.