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 hydro chloric acid solutions by N,N'-dimethyl-N,N'-diphenyl-3-oxapentanediam ide, DMDPhOPDA, was investigated. The distribution ratios in the nitri c acid system were much higher than those in the hydrochloric acid sys tem. In the nitric acid system, the dependencies of the distribution r atios on nitric acid and DMDPhOPDA concentrations showed a difference between lighter and heavier lanthanoid ions. The plots of the number o f DMDPhOPDA molecules in the extracted species obtained from slope ana lysis in 4 mol dm(-3) nitric acid versus the ionic radius of trivalent lanthanoid ions exhibited a significant change around the middle of t he lanthanoids (S-shape). The distribution ratios in the nitric acid s ystem increased with an increase in the atomic number, while those in the HCl system decreased.