Third Phase Formation in the Extraction of Th(NO3)4 by Tri-n-Butyl Phosphate and Tri-iso-Amyl Phosphate in n-Dodecane and n-Tetradecane from Nitric Acid Media

Abstract

Binary solutions of tri-n-butyl phosphate (TBP) or tri-iso-amyl phosphate (TiAP) in n-dodecane or n-tetradecane (1.1 M) as diluents have been investigated for third phase formation in the extraction of Th(NO3)4 from its solutions with 1 M or 5 M HNO3 as a function of equilibrium aqueous phase Th(IV) concentration ([Th(IV)]aq,eq) at 303 K. Extraction isotherms for the extraction of Th(IV) and HNO3 have been generated with respect to [Th(IV)]aq,eq. The difference in density between the third phase and the diluent-rich phase as well as the diluent-rich phase and the pure diluent, ratio of volume of the diluent-rich phase to that of the third phase have also been determined over a wide range of [Th(IV)]aq,eq in the triphasic region. An attempt has also been made to determine the extractant concentrations in the third phase and the diluent-rich phase in the extraction of Th(NO3)4 by the above solvents from its saturated solutions with 1 M and 5 M HNO3.