LIQUID-LIQUID-EXTRACTION OF YTTRIUM(III) FROM THIOCYANATE SOLUTIONS WITH SULFOXIDES AND THEIR MIXTURES - COMPUTER-AIDED ANALYSIS

The extraction of yttrium(III) from thiocyanate solutions by alkyl and aryl sulphoxides and tri-n-octyl phosphine oxide and their mixtures in benzene has been studied. Synergistic effects have been observed with a mixture of extractants which are ascribed to the formation of mixed ligand complexes. These extraction data have been analysed theoretically by taking into account aqueous-phase speciation and all plausible complexes extracted into the organic phase. The extraction behaviour of yttrium(III) has also been compared with that of some lanthanides. It was observed that yttrium(III) behaves like a lighter rare earth in thiocyanate solutions during extraction with dialkyl sulphoxides. Separation factors have also been evaluated. The influence of metal ion concentration and of the diluent on the extraction of yttrium(III) has also been investigated.