Solvent extraction of trivalent lanthanoid ions with N,N′-dimethyl-N,N′-diphenyl-3-oxapentanediamide

The extraction of trivalent lanthanoid ions from nitric acid and hydrochloric acid solutions by N,N'-dimethyl-N,N'-diphenyl-3-oxapentanediamide, DMDPhOPDA, was investigated. The distribution ratios in the nitric acid system were much higher than those in the hydrochloric acid system. In the nitric acid system, the dependencies of the distribution ratios on nitric acid and DMDPhOPDA concentrations showed a difference between lighter and heavier lanthanoid ions. The plots of the number of DMDPhOPDA molecules in the extracted species obtained from slope analysis in 4 mol dm(-3) nitric acid versus the ionic radius of trivalent lanthanoid ions exhibited a significant change around the middle of the lanthanoids (S-shape). The distribution ratios in the nitric acid system increased with an increase in the atomic number, while those in the HCl system decreased.