Am(III) AND Eu(III) EXTRACTION BY ALIQUAT-336 AND BENZYL SUBSTITUTED QUATERNARY AMMONIUM SALTS FROM NITRATE AND THIOCYANATE SOLUTIONS*

The extraction of Am(III) and Eu(III) from HN03 - L1NO3 or from HCOOH -NH4SCN solutions by different quaternary ammonium salts dissolved in o-xylene was investigated as function of the aqueous phase composition. As extractants, the nitrate or thiocyanate salts of Aliquat*336, tridodecylmethylammonium, benzyl-dimethyldodecylammonium, p-methoxybenzyldimethyldodecylammonium and p-trifluoromethylbenzyldimethyldodecylammonium were used. The extraction data obtained with the thiocyanate - formic acid aqueous solutions were quantitatively interpreted by a reaction scheme that takes into account the aqueous metal complexation and the competition of formic acid and metal species for the extractant reaction center. The effect of the benzyl group (whether substituted or not) on the metal and acid extraction by the different quaternary ammonium salts was interpreted on the basis of the inductive effect of the substituents. In the thiocyanate system, Aliquat*336 provided the highest Am/Eu separation factors.