Ion-pair extraction of uranium(VI) using N-cinnamoyl-o-tolyl hydroxylamine in presence of tri-n-octyl phosphine oxide in chloroform and hexafluorophosphoric acid

N-cinnamoyl-o-tolylhydroxylamine (CT0HA.HL) forms extractable binary complex with uranium. The extracted complex, UO2L2(0), when shaken with tri-n-octylphosphine oxide (TOPO.R) in chloroform, is gradually back-extracted into aqueous phase due to formation of the cationic complex, UO2LR+. The gradual substitution has been followed spectrophotometrically by the decrease in absorbance of UO2L2(0). Uranium (VI) can be extracted into the chloroform phase by formation of ion-pair [UO2LR+.PF6-]0 of UO2LR+ with the anion hexafluorophosphate. Extraction of the ion-pair complex is followed by enhanced absorbance values. The substitution constant Ks and ion-pair constant, KI, have been evaluated to be 0.075 and 2.05x103 respectively. (author)