Solid-Liquid Extraction of Rare Earth Elements Ce(IV), Pr(III), Er(III), and Y(III) from Concentrated Phosphoric Acid Solutions Using Strongly Acidic Cation Exchange Resin (SQS-6)

SQS-6 as a cationic exchange resin was originally used for production of enriched nitrogen and separation of ultrapure N-14. Based on the literature, the application of such resin is very limited. Therefore, it is interesting to test its ability to extract and separate some of the rare earth ions from aqueous media like phosphoric acid solution. In this work, solid-liquid extraction of some rare earth metal ions namely; Ce(IV), Pr(III), Er(III) and Y(III) from 8.0 M phosphoric acid was studied using batch and column techniques with a strongly acidic cation exchange resin (SQS-6). Batch investigations data indicated that the amount of adsorbed metal ions studied decreased with increasing the phosphoric acid concentration. Thermodynamic results obtained from the study of the temperature effect on metal ions sorption showed that the process is endothermic and spontaneous associated with increasing the randomness of the system. The sorption isotherm was favorable and obeys Langmuir isotherm model based on a comparison between experimental and calculated sorption capacity. The experimental sorption capacity were found 5.2, 12.6, 8.8, and 3.8 mg/g for Ce(IV), Pr(III), Y(III), and Er(III), respectively. Column investigations were carried out in terms of the breakthrough curves of the metal ions under study. The breakthrough data obtained for the lanthanide metal ions proved that the experimental sorption capacity and the time required for 50% adsorbate breakthrough (tau) are close to that calculated from Thomas and Yoon-Nelson models. Possible separations of those metal ions were studied and assessed at different sorption conditions.