Distribution coefficients of lanthanide elements and some separations on layered hydrous titanium dioxide

Distribution coefficients /K_d/ of lanthanide elements on layered hydrous titanium dioxide, H₂Ti₄O₉.nH₂O /where n=1.2–1.3/, have been determined as a function of the pH of the aqueous phase. The plots of 1g K_d vs. pH gave straight lines with slopes equal to +3 except for the data for heavier lanthanides, suggesting ideal ion-exchange equilibria between tervalent cations in the aqueous phase and hydrogen ions in the hydrous oxide. Mutual separations of La–Cs and La–Ba have been achieved on a column of this material on the basis of large differences in affinities between the metal ion pairs.