Sorption and separation of Er and Y from phosphoric acid using commercial cation exchange resin; Amberlite IR-120

Rare earth elements (REE) are found in low amounts (hundreds of ppm) in phosphoric acid solutions. Due to the strong acidity and complex nature of phosphoric acid, the development of a particularly cost-effective method for the selective recovery and separation of REEs is necessary. Extraction of REEs with commercial chelating ion exchange resins may be considered a promising alternative to the traditional but costly and pollutant solvent extraction technique. In this work, the possibility of extracting erbium(III) and yttrium(III) from phosphoric acid using a commercial cation exchange resin (Amberlite IR-120) has been investigated. In a batch system, several factors such as acid concentration, contact time, initial metal ion concentration, V/m ratio, and temperature that may affect the sorption of these metal ions were separately examined. The changes in standard thermodynamic quantities were calculated, and the outcomes indicated that the sorption of both studied metal ions is endothermic, spontaneous, and connected with an increase in the randomness of the system. During the full concentration range under study, the adsorption adhered to the Langmuir isotherm model. Desorption with 1.0 mol/L citric acid followed by 1.0 mol/L sodium sulfate (1.0 mol/L) allowed separation of Er(III) and Y(III) and recovery with 79.0% and 65.9%, respectively.