Use of complexones for the extraction separation of rare earth and transplutonium elements with amines

The extraction distribution and separation of rare earth elements and americium from the concentrated lithium nitrate solution with solutions of tertiary amines in organic solvents has been studied as a function of the composition and structure of complexones of the polyaminepolyacetic acid series by a radioactive tracer method. It has been found that diethylenetriaminepentaacetic acid is suitable for the separation of REE from americium(III). The apparent stability constants for the lanthanide complexes with EDTA and DTPA in concentrated litium nitrate solutions have been obtained by extraction, pH-metric titration and solubility. Using these constants, the optimum conditions of separation have been found and the separation factors of REE calculated. The calculated and experimental values are in good agreement. The optimum conditions for the separation of americium(III) from REE in a wide range of lanthanide and complexone concentrations (10⁻¹–10⁻⁶ M) have been determined.