Browsing by Author "Duplouy, Lucie"

Found together in nature, the isolation of rare earth elements (REEs) has always been challenging. Their separation usually involves processes including solvent extraction, precipitation and ion exchange. Zeolites are well-known for their ion exchange capabilities that would be potentially applicable for the REEs separation. This study primarily investigated the ion exchange behavior of REEs onto several types of zeolites, namely the Ferrierite, the Faujasite and the Linde Type L. These zeolites were chosen because of their altered framework type and controllable charge density through synthesis. The commercially available zeolites were systematically characterized by means of X-Ray Diffraction (XRD), Energy Dispersive X-ray spectroscopy (EDX) and Attenuated Total Reflectance Fourier Transform Infrared spectroscopy (ATR-FTIR). Lanthanum was chosen as the model REE. The pH-uptake behavior of La on zeolites was studied extensively. Results showed that among all our selected zeolites, only LTL gave reasonable amount of La ion exchange capacity (0.16 mmol/g at pH 3). Subsequently, the ion exchange isotherm of La on LTL was described at pH 3. The isotherm followed Langmuir type with a maximum capacity of 0.25 mmol/g. An equimolar ternary mixture of lanthanum, neodymium and dysprosium was used to test the selectivity of LTL zeolite towards different REEs. Results suggested that the uptake sequence followed La > Nd > Dy, which indicated the decrease of capacity with increased atomic number. Almost all the REEs could be leached off from the REE loaded zeolites with a pH 1.51 nitric acid solution.