Optimal Extraction and Separation of Europium and Samarium from Nitrate Medium Using Binary Mixture of Cyanex 572 and Tertiary Amine Extractants

Abstract

ABSTRACT Extraction and separation of rare-earth elements (Eu(III) and Sm(III)) from nitrate solutions were studied using Cyanex 572 and Alamine 336 type extractants, as well as their binary mixtures in kerosene. Separate studies were carried out on the parameters that influence the extraction process. According to the slope analysis method, the composition of extracted species in the organic phase is [MNO3A2(HA)2][R3NH.NO3]2(Org). The mixture loading capacity towards Eu(III) and Sm(III), as well as the stripping of their loads from the organic phases, were also tested. After being treated with a NaOH solution, the stripped binary mixture was regenerated. The FT-IR spectra of the binary mixture organic phase, the organic phase loaded with metals, the stripped organic phase, and the regenerated organic phase were identified and compared. The separation method is based on a combined reduction-precipitation process in which europium is reduced to its bivalent state by commercial zinc metal, followed by the precipitation of its sparingly soluble europous sulphate. The developed method was used to separate a synthetic mixture of Eu(III) and Sm(III) from an analogous solution in nitrate medium to that expected from spent nuclear fuel leach liquor. Extraction and separation processes for Eu(III) and Sm(III) were detailed in a flowchart.