ИСТИНА

The separation of the minor actinides (MA) after the reprocessing of nuclear fuel is one of the more formidable challenges associated with the design of the advanced fuel cycle. The selective extraction of MA is complicated by the high concentration of the trivalent lanthanides that have similar chemical properties. Figure 1. Molecular structure of the extractants In this work we synthesized and characterized three types of new polydentate ligands (Figure 1) consisting of two distinct functional units: pyridine-based moiety with soft nitrogen donors and two functional groups with hard-oxygen donors (amide and/or phosphineoxide) as well as series of their complexes with trivalent 4f-element ions. The chemical stoichiometry of Ln3+ complexes with all types of ligands is determined to be 1:1 using X-ray crystallography and mass-spectrometry (MALDI-TOF). Extraction experiment were performed for Am3+/Eu3+ pair in nitric acid solution (1-5M). Nitrobenzene was used as diluent. Bis-phosphineoxides L-1 exhibit low solubility (up to 5*10-3 M) and moderate selectivity toward americium over europium (separation factor values don’t exceed 2.5). Mixed-group ligands L-2 demonstrate acceptable solubility in the diluent and show quantitative extraction of f-elements from highly acidic solutions. However, ligands of this type are characterized as nonselective extractants. Solubility of the ligands L-3 reaches 0.05M and more. Extraction experiments for these compounds are in progress.