Extraction of REE(III) and Am(III) from a nitric acid solution with Fe(III) and Mn(II) compounds with dibutyl phosphoric acid

The behavior of a number of REE and Am(III) during their extraction from nitric acid solutions with iron and manganese compounds with dibutyl phosphoric acid (HDBP) in various solvents was studied. It was shown for the first time that, with an increase in the concentration of iron and manganese in the organic phase, an increase in the REE distribution coefficients and, in some cases, a noticeable change in the element separation factors are observed. There is a significant difference in the element separation factors in different solvents. The increase in the separation factors of pairs of elements can reach significant values. For example, the Er/Dy separation factor in toluene increases by a factor of 5, and the Dy/Tb separation factor in chloroform, by 7. The use of decalin as a solvent leads in most cases to a maximum increase in the REE distribution coefficients. In the system with an o-nitrotoluene (ONT) solvent, at a certain ratio of HDBP to Fe(III), the separation factors of americium and REE (except cerium) are high enough to allow their separation. The influence of the transition metal and solvent on the distribution and separation of REE is discussed.