Development of a Zeolite Modified by an Ion Exchange and Impregnation Process for the Recovery of Uranium from Aqueous Effluent

In this study, adsorbent materials were developed by surface modification of zeolite NaX, using two processes, namely ion exchange and saline impregnation with MnCl₂ with the aim of improving the adsorption capacity uranyl ions in aqueous solutions. The synthesized and modified Faujasite X zeolite was characterized by X-ray diffraction, thermogravimetric analysis, Fourier transform infrared spectroscopy, laser particle size analyzer and nitrogen adsorption-desorption analysis. The textural properties, kinetics, adsorption equilibria and desorption cycle of NaX, NaX-exchanged and NaX-impregnated zeolites were studied to evaluate their potential in uranium adsorption. The experimental results show that the adsorption capacity of uranium by the zeolite NaX 24 mg/g was improved following the modification treatments. It is 30 mg/g and 45 mg/g for the NaX-impregnated and Na-X-exchanged materials respectively. The kinetic study showed that the uranyl ion recovery process is controlled by the pseudo-second order model and the equilibrium data of uranyl ion adsorption was best fitted by the Langmuir model for the three materials. Desorption with HNO₃ at 0.1N revealed the recovery of 80% of uranyl ions after one treatment cycle. The adsorption yields of uranyl ions by the NaX, exchanged NaX and NaX materials impregnated with a real solution titrating 114.9 mg/L in uranium, under optimal conditions, are 81.28%, 87.25% and 90 .73% respectively.