Synthesis of Nanocontainer Chabazites from Fly Ash with a Template- and Fluoride-Free Process for Cesium Ion Adsorption

Chabazite (CHA)-type zeolites were prepared using three different types of fly ashes in this investigation. The demonstrated universal synthetic strategy, which was template- and fluoride-free, consisted of fusion and hydrothermal reaction. The adsorption properties of cesium ions on prepared CHA were then investigated in static adsorption experiments combined with thermodynamic analysis. As-synthesized CHA, with typical CHA crystal structures, exhibited walnut-like particles in morphology. In the case of physical adsorption analysis, the as-synthesized sample showed pore blockage under N 2 flow, whereas the CO 2 isotherm revealed its considerable specific surface area of 336 m 2 /g, which, in return, ensured its notable properties for adsorption of ions. The removal efficiencies of cesium ions onto the CHA samples were as high as 99% in dilute solution. Furthermore, the obtained CHA-type zeolite maintained high adsorption capacities within a wide temperature range, thus demonstrating that it could be employed as a nanocontainer in radioactive wastewater management.