EXTRACTION OF TRIVALENT RARE-EARTH-METAL NITRATES BY SOLUTIONS OF TRIBUTYL-PHOSPHATE AND DIISOOCTYLMETHYLPHOSPHONATE IN KEROSENE

Isotherms of extraction of trivalent rare-earth metal nitrates in the series lanthanum-lutetium, yttrium by 0.5-2.5 M solutions of tri-n-but yl phosphate and diisooctyl methylphosphonate in kerosene at 298.15 K, pH 2 are presented. The influence of the ionic strength of aqueous ph ase and extractant concentration on the concentration extraction const ants in the case of formation of metal(III) trisolvates in organic pha se is given by equation log K-ex(0)(I,C-TBP) = log K-ex(0,0) + Delta Z (2)F(I) + theta I + lambda C-TBP, where theta and lambda are empirical parameters. The former factor is independent of the nature of metal, whereas the latter is influenced by it. The values of log K-ex(0,0), t heta, and lambda are presented.