LIQUID-LIQUID-EXTRACTION OF CERIUM(III) FROM THIOCYANATE MEDIA WITH MIXTURES OF ORGANOPHOSPHORUS EXTRACTANTS

The extraction of Ce(III) from thiocyanate solutions with mixtures of 2-ethylhexylphosphonic acid mono-2-ethylhexyl ester (EHPNA) and di(2-e thylhexyl)-phosphoric acid (DEHPA) or tri-n-butyl phosphate (TBP) in b enzene has been studied systematically over a wide range of conditions . A relatively small synergistic enhancement has been observed with mi xtures of acidic organophosphorus extractants (EHPNA + DEHPA) and also with mixtures of acidic and neutral organophosphorus extractants (EHP NA + TBP). These extraction data have been analysed theoretically, tak ing into account complexation of the metal in the aqueous phase by ino rganic ligands and plausible complexation in the organic phase.