The extraction of uranyl ion from aqueous nitrate, perchlorate and thi
ocyanate medium with 2-thenoyl trifluoroacetone (HTTA) and N,N-disecbu
tyl pentanamide (DBPA) has been studied to know the extracted U(VI) sp
ecies. It is established that the U(VI) species responsible for synerg
ism is UO2(TTA)2.DBPA when aqueous medium is nitric acid. With aqueous
thiocyanate medium, the predominant U(VI) species extracted is UO2(NC
S) (TTA).2DBPA. The synergic extraction of U(VI) from aqueous perchlor
ate medium using HTTA in combination with a bifunctional neutral organ
ophosphorus extractant, DBDECMP has also been studied. The U(VI) speci
es responsible for the synergism is found to be UO2(TTA)2.DBDECMP. Equ
ilibrium constant values for the various extraction equilibria involve
d are calculated.