CHARACTERIZATION OF THE LANTHANUM(III) AND EUROPIUM(III) TRICHLOROACETATE COMPLEXES EXTRACTED WITH 18-CROWN-6

Extraction of lanthanide(III) ions with 18-crown-6 (18C6) and trichloroacetate (tea) has been studied. The composition, hydration, and structure of the La(III) and Eu(III) complexes extracted into 1,2-dichloroethane were investigated by using several methods such as the liquid-liquid distribution technique, conductimetry, Karl Fisher titration, laser luminescence spectroscopy, and 1 H NMR. The La(III) complex was found to be a monohydrate, La(tca) 3 (18C6)(H 2 O), while that of Eu(III) was a mixture of a monohydrate and a dihydrate, i.e., Eu(tca) 3 (18C6)(H 2 0) and Eu(tca) 3 (18C6)(H 2 0) 2 - The origin of the selectivity by 18C6 which gives much higher extractability of La(III) than of Eu(III) is explained by considering the hydration and probable structure of their complexes.