Amidophosphonate ligands as cerium extractants in supercritical CO2

Publication date: Available online 1 April 2019Source: The Journal of Supercritical FluidsAuthor(s): Sofyane Bouali, Antoine Leybros, Guillaume Toquer, Antoine Leydier, Agnès Grandjean, Thomas ZembAbstractIndustrial-scale rare earth extraction is typically performed by liquid-liquid extraction with large amounts of solvents, acids and organophosphorus ligands. An alternative is to use these extractants in supercritical CO2 (SC-CO2), where the crucial operating parameter is their solubility. Different molecules with amidophosphonate backbones have been synthesized and investigated to improve their solubility in SC-CO2 and their capacity to extract cerium. The CO2-philicity of these extractants was adjusted by attaching branched or linear alkyl chains with four, six and eight carbons. Using a dynamic gravimetric setup, the solubility and cerium extraction capacity of these molecules were measured to vary from 1.56 to 2.47 47 mmolligand.molCO2-1 and 0.25 to 0.46 mmolCe.molligand-1, respectively. The two properties were correlated and in both cases the highest values were obtained with a diisobutylamine chain. Solubility measurements between 313 and 331 K and between 13 and 28 MPa shows that optimal condition is (320 K ; 28 MPa).Graphical abstract

Source: The Journal of Supercritical Fluids - April 2, 2019 Category: Chemistry Source Type: research