SEPARATION OF RARE EARTH ELEMENTS BY THE ANION-EXCHANGE CHROMATOGRAPHY USING 2-ETHYLHEXYL-2-ETHYLHEXYL-PHOSPHONATE-KEROSENE AS ELUANT

170Tm, 152,154En, 147Pmand141Ce are separated on the anion exchange resin column by gradient elution using organic extractant HEHEHP-kerosene as eluant. The equilibrium distribution ratios of these rare earth elements between the ion-exchange resin and extractant phases are determined. Both the dependence of lg D to lg H+ and that of lg D to lg (HEHEHP)2 are linear; with a slope of about -2 and +2 respectively.