The effect of solvents on the extraction of lanthanoids with 18-crown-6 and trichloroacetate

The effect of solvent 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 deg C) normalized to the water solubility (wt./vol.) in the solvents correlated to the polarizability index (π*) 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 corralated with the Hildebrand solubility parameter (σ) (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. (author) 12 refs.; 3 figs.; 1 tab