THE EFFECT OF SOLVENTS ON THE EXTRACTION OF LANTHANOIDS WITH 18-CROWN-6 AND TRICHLOROACETATE

The effect of solvents on the extraction of lanthanoids with 18-crown-6 and trichloroacetic acid was investigated for the solvents, 1,1,-dichloroethane, 1,2-dichloroethane, 1,1, 2,2- tetrachloroethane, chloroform, di-2-chloroethyl ether, and methylene chloride. Distribution coefficients (25-degrees-C) normalized to the water solubility (wt./vol.) in thc solvents correlated to the polarizability index (pi*) for La3+, Ce3+, Pr3+, and Nd3+ with r values = 0.93, 0.93, 0.95, and 0.98, respectively. The distribution coefficients for Nd3+ also correlated with the Hildebrand solubility parameter (sigma) (r=0.98). These correlations agree with the literature that for large ions, the extraction thermodynamic properties correlate with the polarizability index and Hildebrand solubility parameter.