Speaker
Description
Deep eutectic solvents (DESs), a novel class of environmentally benign solvents, have emerged as a key focus in the field of metal ion separation. DESs are eutectic mixtures formed by combining hydrogen bond donors (HBDs) and hydrogen bond acceptors (HBAs) in specific molar ratios, resulting in melting points significantly lower than those of the individual components and often rendering them liquid at room temperature. DESs have exhibited excellent dissolution capacity for certain metal oxides. Lanthanide elements account for approximately 35–40% of the total mass of fission products in spent nuclear fuel (SNF). As strong neutron absorbers (neutron poisons), they impair reactor operational efficiency; meanwhile, they possess considerable economic value due to their recoverability and recyclability. Nevertheless, separating and recovering rare earth elements from spent nuclear fuel presents significant challenges due to the similar chemical properties between lanthanides and actinides.
This study employed a deep eutectic solvent (DES) composed of betaine (BET) and lactic acid (LA) to investigate its separation behavior toward lanthanides in simulated spent nuclear fuel. Key parameters influencing dissolution—including water content in the DES, temperature, solid-to-liquid ratio, and reaction time—were systematically examined. Based on these findings, optimal conditions for the BET-LA system were established, enabling the selective dissolution and separation of Ln2O3 from the simulated fuel. Under the optimized conditions, the removal efficiency of Ln2O3 (La, Nd, Eu, and Gd) reached 90 %, while the dissolution of UO2 was merely 1.5 %. This remarkable selectivity enables the effective recovery of UO₂ powder with an overall yield of approximately 98%. Meanwhile, the separation mechanism was elucidated with the help of UV–Vis, FT-IR and mass spectrometry. These results demonstrate the potential feasibility of separating Ln2O3 from spent nuclear fuel via selective dissolution. It should be noted that this study was conducted using simulated spent nuclear fuel, which inherently imposes certain limitations on the generalizability of its findings. Nevertheless, the BET-LA DES offers advantages including low production cost, biodegradability, and low toxicity, suggesting its potential applicability for the separation of Ln in nuclear fuel reprocessing. Beyond nuclear applications, this DES also holds significant potential for the sustainable recovery of rare earth elements from other secondary resources.