On the Extraction of Trivalent f-Elements from High-Level Waste Containing Derivatives of (2-Carbamoylethyl) Diphenylphosphine Oxides

Extraction of f-elements from model solutions of high-level waste (HLW) was studied in order to identify the possibility of group separation of lanthanides and other components of this waste in the extraction process using a series of (2-carbamoylethyl) diphenylphosphine oxides (CEPO). As a result it was shown that CEPO class compounds extract trivalent lanthanide cations in nitric acid media selectively and effectively. The separation factor in the pair sum Ln3+/sum of the salt background cations of the model solution of HLW reaches 6 × 104 for compounds III–IV, while for compounds I and V it turns out to be significantly smaller—about 200. Re-extraction of the sum Ln3+ from the saturated organic phase occurs quantitatively using a sodium carbonate solution in contrast to aqueous reextraction.