Abstract
Third phase formation in the extraction of HCl by tri-n-butyl phosphate (TBP) in n-octane has been investigated. The extraction of the acid is accompanied by the simultaneous extraction of large amounts of water and brings about organic phase splitting when the equilibrium HCl concentration in the aqueous phase is higher than 7.6 M. For a description of mechanism and energetics of these phenomena, a combination of coordination chemistry and concepts and techniques that are typical of colloid chemistry is needed. SANS data for organic phases loaded with progressive amounts of HCl and water have been interpreted using the Baxter model for hard spheres with surface adhesion. According to this model, the increase in scattering intensity in the low Q range observed when increasing amounts of solutes are extracted into the organic phase, arises from van der Waals interactions between reverse micelles containing up to seven TBP molecules. At the onset of third phase formation, the potential energy of attraction between micelles is about twice the average thermal energy. The results obtained for HCl extraction are compared with those reported previously for the extraction of metal nitrates under the same conditions.
| Original language | English |
|---|---|
| Pages (from-to) | 125-148 |
| Number of pages | 24 |
| Journal | Solvent Extraction and Ion Exchange |
| Volume | 24 |
| Issue number | 2 |
| DOIs | |
| State | Published - 2006 |
| Externally published | Yes |
Funding
Keywords: HCl extraction, tri-n-butyl phosphate, n-octane, third phase formation, SANS data Received 4 August 2005, Accepted 17 October 2005 Work performed under the auspices of the U.S. Department of Energy, Office of Basic Energy Science, Division of Chemical Sciences, Biosciences and Geosciences (for the part performed at the Chemistry Division of ANL) and Division of Material Science (for the part performed at INPS), under contract No. W-31-109-ENG-38. We thank Dr. Zdenek Kolarik for some of the HCl distribution measurements, the personnel of the Analytical Chemistry Division of ANL for the water analyses, and Denis Wozniak (IPNS) for help provided during the SANS measurements. This work was funded by the U.S. Department of Energy, Office of Basic Energy Science, Division of Chemical Sciences, Biosciences and Geosciences (for the part performed at the Chemistry Division of ANL) and Division of Material Science (for the part performed at IPNS). The submitted manuscript has been created by the University of Chicago as Operator of Argonne National Laboratory (“Argonne”) under Contract No. W-31-109-ENG-38 with the U.S. Department of Energy. The U.S. Government retains for itself, and others acting on its behalf, a paid-up, nonexclusive, irrevocable worldwide license in said article to reproduce, prepare derivative works, distribute copies to the public, and perform publicly and display publicly, by or on behalf of the Government.
| Funders | Funder number |
|---|---|
| Division of Material Science | |
| Office of Basic Energy Science | |
| University of Chicago as Operator of Argonne National Laboratory | |
| U.S. Department of Energy | |
| Argonne National Laboratory | |
| Chemical Sciences, Geosciences, and Biosciences Division |
Keywords
- HCl extraction
- N-octane
- SANS data
- Third phase formation
- Tri-n-butyl phosphate