1
|
Wilson AD, Foo ZH, Jayasinghe AS, Stetson C, Lee H, Rollins HW, Deshmukh A, Lienhard JH. Modeling Henry's law and phase separations of water-NaCl-organic mixtures with solvation and ion-pairing. Phys Chem Chem Phys 2024; 26:749-759. [PMID: 37800279 DOI: 10.1039/d3cp02003g] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/07/2023]
Abstract
Empirical measurements of solution vapor pressure of ternary acetonitrile (MeCN) H2O-NaCl-MeCN mixtures were recorded, with NaCl concentrations ranging from zero to the saturation limit, and MeCN concentrations ranging from zero to an absolute mole fraction of 0.64. After accounting for speciation, the variability of the Henry's law coefficient at vapor-liquid equilibrium (VLE) of MeCN ternary mixtures decreased from 107% to 5.1%. Solute speciation was modeled using a mass action solution model that incorporates solute solvation and ion-pairing phenomena. Two empirically determined equilibrium constants corresponding to solute dissociation and ion pairing were utilized for each solute. When speciation effects were considered, the solid-liquid equilibrium of H2O-NaCl-MeCN mixtures appear to be governed by a simple saturation equilibrium constant that is consistent with the binary H2O-NaCl saturation coefficient. Further, our results indicate that the precipitation of NaCl in the MeCN ternary mixtures was not governed by changes in the dielectric constant. Our model indicates that the compositions of the salt-induced liquid-liquid equilibrium (LLE) boundary of the H2O-NaCl-MeCN mixture correspond to the binary plateau activity of MeCN, a range of concentrations over which the activity remains largely invariant in the binary water-MeCN system. Broader comparisons with other ternary miscible organic solvent (MOS) mixtures suggest that salt-induced liquid-liquid equilibrium exists if: (1) the solution displays a positive deviation from the ideal limits governed by Raoult's law; and (2) the minimum of the mixing free energy profile for the binary water-MOS system is organic-rich. This work is one of the first applications of speciation-based solution models to a ternary system, and the first that includes an organic solute.
Collapse
Affiliation(s)
- Aaron D Wilson
- Chemical Separations Group, Idaho National Laboratory, Idaho Falls, ID 83415-2208, USA.
| | - Zi Hao Foo
- Department of Mechanical Engineering, Massachusetts Institute of Technology, Cambridge, MA 02139-4307, USA
| | - Ashini S Jayasinghe
- Analytical Chemistry Group, Idaho National Laboratory, Idaho Falls, ID 83415-2208, USA
| | - Caleb Stetson
- Chemical Separations Group, Idaho National Laboratory, Idaho Falls, ID 83415-2208, USA.
| | - Hyeonseok Lee
- Chemical Separations Group, Idaho National Laboratory, Idaho Falls, ID 83415-2208, USA.
| | - Harry W Rollins
- Chemical Separations Group, Idaho National Laboratory, Idaho Falls, ID 83415-2208, USA.
| | - Akshay Deshmukh
- Department of Mechanical Engineering, Massachusetts Institute of Technology, Cambridge, MA 02139-4307, USA
| | - John H Lienhard
- Department of Mechanical Engineering, Massachusetts Institute of Technology, Cambridge, MA 02139-4307, USA
| |
Collapse
|
2
|
Reynolds JG, Nienhuis ET, Mergelsberg ST, Pearce CI, Rosso KM. The Apparent Reversal of the Law of Mass Action in Concentrated Multicomponent Aqueous Solutions. J Mol Liq 2023. [DOI: 10.1016/j.molliq.2023.121470] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/27/2023]
|
3
|
Wilson AD, Lee H, Stetson C. Local stress within a granular molecular solvent matrix, a mechanism for individual ion hydration. J Mol Liq 2022. [DOI: 10.1016/j.molliq.2022.119544] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
|
4
|
Reynolds JG, Graham TR, Pearce CI. Extending Zavitsas’ hydration model to the thermodynamics of solute mixtures in water. J Mol Liq 2022. [DOI: 10.1016/j.molliq.2021.118309] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
|