Extraction Behaviors of Rare Earth Elements in Solvent Extraction with Single and Mixed Extractant Systems. Extraction of rare earths by phosphoric acid esters containing bulky alkyl groups. II.

Abstract

Solvent extraction of rare earths with phosphoric acid esters has been carried out to elucidate the structural effect of the phosphates on the extraction behaviors of thirteen rare earth elements. The results indicate that the position of the side chain in the alkyl group of the phosphates is important to control the extraction behaviors, and the alkyl side chain in the vicinity of PO (OH) group increases the separation factors of the elements. It is also suggested that the effect of the side chain on the extraction is related to dimerization of the phosphates. In the case of mixed phosphate systems, a heterodimer consisting of two different phosphates forms to afford the synergistic enhancement of the extraction. The formation of the heterodimer was assessed by use of fast atom bombardment mass spectrometry