UO22+Sorption in Natural Mexican Erionite and Y Zeolite

The use of Y zeolite and erionite to remove UO2 2+ ions from aqueous solutions has been investigated. The effect of temperature, the concentration of UO2 2+ uptake, the diffusion coefficients, and the ion-exchange isotherms were also studied. X-ray diffraction, thermal analyses, and transmission electron microsocopy were used to characterize the solids. The UO2 2+ content was determined by neutron activation analysis. The diffusion coefficients are not clearly affected by temperature or concentration. They definitely depend on the structure of each zeolite. The UO2 2+ exchange capacities were 0.2037 and 0.7345 meq UO2 2+/g for erionite and Y zeolite, respectively. It was found that UO2 2+ is exchanged with the cations of the large cavity in Y zeolite. In the case of erionite, UO2 2+ is exchanged with the cations localized in sites where the charge densities are very high.