Supercritical carbon dioxide extraction of Sm+3 and Nd+3 from solid matrix using Cyanex 921

The goal of this research was to investigate the feasibility of removing samarium and neodymium ions from solid matrix using Cyanex 921 in supercritical CO₂. The effect of various parameters such as pressure, temperature, extraction time, and stoichiometry of the complexation reaction was studied and optimized. It was found that optimal parameters are, respectively, 9 and 11 MPa, 45°C, 30 min, and 1: 3 (metal: ligand) for both samarium and neodymium. The conditional formation constant for the complexation reaction of samarium and neodymium with Cyanex 921 in the supercritical fluid phase was calculated as log K _d = 1.51 and log K _d = 1.08, respectively.