Efficient Separation of Lu from Yb Using Rext-P350@Resin: A Promising Route for No-Carrier-Added 177Lu Production

Due to the nearly identical chemical properties of Lu and Yb, the production of no-carrier-added (NCA) 177Lu faces significant challenges in their separation. Achieving efficient and streamlined separation of Lu and Yb is crucial for the production of NCA 177Lu. This study systematically investigated the separation performance of the commercial Rext-P350 extraction resin for Lu and Yb. Static adsorption experiments revealed that, at a solid–liquid ratio of 8 g/L, both Lu3+ and Yb3+ were nearly completely adsorbed, with saturation adsorption capacities of 25.8 mg/g and 21.5 mg/g, respectively. An increase in the nitric acid concentration in the aqueous phase significantly inhibited adsorption, but the separation factor for Lu3+/Yb3+ remained above 1.88. The adsorption kinetics followed a pseudo-second-order model (R2 > 0.99), with equilibrium reached within 15 min, demonstrating fast adsorption kinetics. Characterization by SEM, FT-IR, and XPS confirmed the chemical coordination between the resin and Lu3+/Yb3+. Dynamic chromatographic separation experiments showed that the Rext-P350 resin exhibited significantly better separation performance for Lu3+/Yb3+ compared to 2-ethylhexylphosphoric acid mono-2-ethylhexyl ester (P507) extraction resin. Leveraging the excellent performance of Rext-P350 resin, a two-stage continuous extraction chromatography process was designed, achieving efficient separation of 0.045 mg of Lu3+ from 200 mg of Yb3+ with a Lu3+ purity of 90.9% and a yield of 98.4%. This study provides a feasible separation technique for the purification of NCA 177Lu.