Extraction of Zirconium Nitrate by TBP in n-Octane:  Influence of Cation Type on Third Phase Formation According to the “Sticky Spheres” Model

Abstract

Small-angle neutron scattering (SANS) data for the tri-n-butyl phosphate (TBP)-n-octane, HNO(3)-Zr(NO(3))(4) solvent extraction system, obtained under a variety of experimental conditions, have been interpreted using the Baxter model for hard spheres with surface adhesion. The increase in scattering intensity in the low Q range observed when increasing amounts of Zr(NO(3))(4) were extracted into the organic phase was interpreted as arising from interactions between small reverse micelle-like particles containing two to three TBP molecules. Upon extraction of Zr(NO(3))(4), the particles interact through attractive forces between their polar cores with a potential energy that exceeds 2 k(B)T. The interparticle attraction, under suitable conditions, leads to third phase formation. A linear relationship exists between the derivative of the potential energy of attraction with respect to the concentration of nitrate ions in the organic phase and the ionization potential or the hydration enthalpy of the extracted metal cations.

Spectroscopic and structural characterization of pure and FeCl3-containing tri-n-butyl phosphate

“…The presence of the phosphate functional group allowing specific ligand properties and the overall physico-chemical properties make TBP an excellent industrial solvent extensively employed as extractant and complexing agent [4].…”

Characterization of the Species Formed during the Extraction of Thorium Employing Tri-n-Butyl Phosphate and N,N-Dihexyl Octanamide as Extractants by Laser Desorption/Ionization Time-of-Flight Mass Spectrometry

“…These techniques have helped in identifying the physical/chemical parameters (for example, aggregation, nature and concentration of acids, diluents) responsible for third-phase formation and also identifying species formed in the heavier organic phases. [3][4][5][6][7]27,[32][33][34][35] SANS measurements on TBP solutions loaded with only HNO 3 or with increasing amounts of U(VI) or Th(IV) revealed the presence of ellipsoidal aggregates (reverse micelle type) before phase splitting. The presence of smaller aggregates in the light organic phase upon third-phase formation was observed, while the heavy organic phase contained pockets of diluent.…”

“…Similar observations were made during the extraction of Zr(IV) from nitric acid medium by TBP/n-octane. 35 Third-phase formation has been attributed to interactions between small reverse micelle-like metal solvates in the organic phases. The particles interact through attractive forces between their polar cores leading to the third-phase formation.…”

Liquid-liquid extraction of iron (III) from Ouenza iron ore leach liquor by tributylphosphate

“…Tributylphosphate (TBP) is an organophosphate compound (C 12 H 27 O 4 P) characterized by low solubility in water, exceptional chemical resistance, high polarity and very low vapor pressure [12][13][14].…”

“…Nouioua et al J Fundam Appl Sci. 2017, 9(3), 1473-1484 1475 The presence of the phosphate functional group allowing specific ligand properties and the overall physicochemical properties make TBP an excellent industrial solvent widely used as an extractant and complexing agent [12].…”