Study of the effect of dealumination and desilication on the structural properties of ZSM-5 zeolite. Application in the adsorption of uranium from aqueous effluents

In this study, adsorbent materials were developed by post-synthesis modification of ZSM-5 zeolite using two processes, namely desilication and dealumination, to improve the adsorption capacity of uranyl ions in aqueous solutions. The synthesized and modified ZSM-5 zeolite was characterized by X-ray diffraction, Fourier transform infrared spectroscopy, scanning electron microscope, and nitrogen adsorption-desorption analysis. The experimental adsorption capacities were found to be 6, 2.5, and 9 mg g ^-1 for ZSM-5, ZSM-5 Dealuminated, and ZSM-5 Desilicated materials, respectively, in the concentration range of 10–300 mg L ^-1 . ZSM-5 Desilicated zeolite showed better adsorption compared to the other two materials due to the formation of silanol groups. The equilibrium adsorption isotherms of uranium (VI) on the three adsorbents are in perfect agreement with the Langmuir model and the adsorption kinetics follow the pseudo-second order model. The adsorption efficiencies of uranyl ions are of the order of 66, 89, and 33% on the ZSM-5, ZSM-5 Desilicated and ZSM-5 Dealuminated materials respectively with a real solution titrating in the range of 108.69 mg/L in uranium.