Anion Exchange Resins for the Selective Separation of Technetium from Uranium in Carbonate Solutions

In alkaline carbonate solutions both technetium and uranium exist as anionic species, TcO₄^– and UO₂(CO₃)₃^4–, which makes separating Tc and U from each other more challenging compared to acidic PUREX type solutions where uranium forms neutral or cationic complexes. We tested the batch separation of ⁹⁹Tc, ²³⁸U, and ²³⁹Pu from carbonate solutions using anion exchange resins with different properties, including Purolite A530E, Reillex HPQ, and Dowex Marathon WBA. Overall, the highest K_d values for pertechnetate were achieved using the strong base resins in solutions of the lowest carbonate concentration. Pretreating the resins in higher carbonate concentrations before use was shown to increase the K_d values for pertechnetate. The measured K_d values for uranium generally were low, resulting in high selectivity for the separation of pertechnetate from uranium in carbonate solutions.