SYNERGISTIC ION-PAIR EXTRACTION OF LANTHANIDE(III) WITH THENOYLTRIFLUOROACETONE AND CROWN-ETHER INTO 1,2-DICHLOROETHANE

Synergistic extraction of trivalent lanthanides(ln) was investigated using thenoyltrifluoroacetone(HTTA) and crown ether(CE). Characteristic ion-pair extraction of the lighter Ln(III) was observed with 1,2-dichloroethane containing HTTA and 18-crown-6 or dicychlohexano-18-crown-6, in which the cationic complex, Ln(TTA)(2)CE(+), was formed and extracted. Remarkable increases of an extractability and a selectivity were attained in the synergistic ion-pair extraction of the lighter Ln ions, which could be elucidated on the basis of size-fitting effect in the complex formation of the lighter Ln ions with CE.