RADIOCHEMICAL EXTRACTION OF LANTHANIDE THIOCYANATE COMPLEXES WITH BIS-2-ETHYLHEXYL SULFOXIDE

The extraction of lanthanides (Ln) such as Nd(III), Eu(III) and Er(III ) from thiocyanate solutions by bis-2-ethylhexyl sulphoxide (B2EHSO) i n benzene has been studied by tracer techniques. For comparison, extra ction studies have been carried out with di-n-octyl sulphoxide (DOSO) and tri-octyl phosphine oxide (TOPO). Extraction studies have also bee n carried out with mixtures of B2EHSO and DOSO or TOPO. A relatively s mall synergistic enhancement has been observed with a mixture of extra ctants, which may be due to the formation of more stable mixed-ligand complexes. The extraction data have been analysed by both graphical an d theoretical methods taking into account aqueous phase speciation and all plausible complexes extracted into the organic phase. The equilib rium constants of the extracted species were determined by non-linear regression analysis.