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Habibi P, Polat HM, Blazquez S, Vega C, Dey P, Vlugt TJH, Moultos OA. Accurate Free Energies of Aqueous Electrolyte Solutions from Molecular Simulations with Non-polarizable Force Fields. J Phys Chem Lett 2024; 15:4477-4485. [PMID: 38634502 PMCID: PMC11057036 DOI: 10.1021/acs.jpclett.4c00428] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2024] [Revised: 04/11/2024] [Accepted: 04/12/2024] [Indexed: 04/19/2024]
Abstract
Non-polarizable force fields fail to accurately predict free energies of aqueous electrolytes without compromising the predictive ability for densities and transport properties. A new approach is presented in which (1) TIP4P/2005 water and scaled charge force fields are used to describe the interactions in the liquid phase and (2) an additional Effective Charge Surface (ECS) is used to compute free energies at zero additional computational expense. The ECS is obtained using a single temperature-independent charge scaling parameter per species. Thereby, the chemical potential of water and the free energies of hydration of various aqueous salts (e.g., NaCl and LiCl) are accurately described (deviations less than 5% from experiments), in sharp contrast to calculations where the ECS is omitted (deviations larger than 20%). This approach enables accurate predictions of free energies of aqueous electrolyte solutions using non-polarizable force fields, without compromising liquid-phase properties.
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Affiliation(s)
- Parsa Habibi
- Engineering
Thermodynamics, Process & Energy Department, Faculty of Mechanical
Engineering, Delft University of Technology, Leeghwaterstraat 39, 2628 CB Delft, Netherlands
- Department
of Materials Science and Engineering, Faculty of Mechanical Engineering, Delft University of Technology, Mekelweg 2, 2628 CD Delft, Netherlands
| | - H. Mert Polat
- Engineering
Thermodynamics, Process & Energy Department, Faculty of Mechanical
Engineering, Delft University of Technology, Leeghwaterstraat 39, 2628 CB Delft, Netherlands
| | - Samuel Blazquez
- Departamento
de Química Física, Facultad de Ciencias Químicas, Universidad Complutense de Madrid, 28040 Madrid, Spain
| | - Carlos Vega
- Departamento
de Química Física, Facultad de Ciencias Químicas, Universidad Complutense de Madrid, 28040 Madrid, Spain
| | - Poulumi Dey
- Department
of Materials Science and Engineering, Faculty of Mechanical Engineering, Delft University of Technology, Mekelweg 2, 2628 CD Delft, Netherlands
| | - Thijs J. H. Vlugt
- Engineering
Thermodynamics, Process & Energy Department, Faculty of Mechanical
Engineering, Delft University of Technology, Leeghwaterstraat 39, 2628 CB Delft, Netherlands
| | - Othonas A. Moultos
- Engineering
Thermodynamics, Process & Energy Department, Faculty of Mechanical
Engineering, Delft University of Technology, Leeghwaterstraat 39, 2628 CB Delft, Netherlands
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Naseri Boroujeni S, Maribo-Mogensen B, Liang X, Kontogeorgis GM. Theoretical and practical investigation of ion-ion association in electrolyte solutions. J Chem Phys 2024; 160:154509. [PMID: 38639315 DOI: 10.1063/5.0198308] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2024] [Accepted: 03/26/2024] [Indexed: 04/20/2024] Open
Abstract
In this study, we present a new equation of state for electrolyte solutions, integrating the statistical associating fluid theory for variable range interactions utilizing the generic Mie form and binding Debye-Hückel theories. This equation of state underscores the pivotal role of ion-ion association in determining the properties of electrolyte solutions. We propose a unified framework that simultaneously examines the thermodynamic properties of electrolyte solutions and their electrical conductivity, given the profound impact of ion pairing on this transport property. Using this equation of state, we predict the liquid density, mean ionic activity coefficient, and osmotic coefficient for binary NaCl, Na2SO4, and MgSO4 aqueous solutions at 298.15 K. Additionally, we evaluate the molar conductivity of these systems by considering the fraction of free ions derived from our equation of state in conjunction with two advanced electrical conductivity models. Our results reveal that, while ion-ion association has a minimal influence on the modification of the predicted properties of sodium chloride solutions, their impact on sodium and magnesium sulfate solutions is considerably more noticeable.
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Affiliation(s)
- Saman Naseri Boroujeni
- Center for Energy Resources Engineering, Department of Chemical and Biochemical Engineering, Technical University of Denmark (DTU), Søltofts Plads, Building 229, 2800 Kgs. Lyngby, Denmark
| | - B Maribo-Mogensen
- Hafnium Labs ApS., Vestergade 16, 3rd floor, 1456 Copenhagen, Denmark
| | - X Liang
- Center for Energy Resources Engineering, Department of Chemical and Biochemical Engineering, Technical University of Denmark (DTU), Søltofts Plads, Building 229, 2800 Kgs. Lyngby, Denmark
| | - G M Kontogeorgis
- Center for Energy Resources Engineering, Department of Chemical and Biochemical Engineering, Technical University of Denmark (DTU), Søltofts Plads, Building 229, 2800 Kgs. Lyngby, Denmark
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Naseri Boroujeni S, Maribo-Mogensen B, Liang X, Kontogeorgis GM. Novel Model for Predicting the Electrical Conductivity of Multisalt Electrolyte Solutions. J Phys Chem B 2024; 128:536-550. [PMID: 38175818 DOI: 10.1021/acs.jpcb.3c05718] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2024]
Abstract
This study presents a novel model to predict the electrical conductivity of multisalt electrolyte solutions by incorporating corrections to the ideal behavior due to relaxation and electrophoretic effects. The performance of the model is evaluated by comparing its predictions with the experimental data of 24 multisalt aqueous solutions. The comparison reveals good agreement for solutions with an ionic strength below 1 mol/L without adjusting any parameter to fit to the experimental data. However, the model tends to overestimate the molar conductivity at higher ionic strengths. The discrepancy is attributed to the neglect of the solvent structure and the formation of ion pairs. It has been speculated how the accuracy of the developed model could be improved in relation to these limitations. Furthermore, the performance of the model is rigorously tested in systems with ion complex formation. It has been demonstrated that when the distribution of ion complexes is calculated from a thermodynamic model and then used to predict the electrical conductivity with the developed model, a satisfactory level of accuracy is attained for these systems.
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Affiliation(s)
- Saman Naseri Boroujeni
- Center for Energy Resources Engineering, Department of Chemical and Biochemical Engineering, Technical University of Denmark (DTU), Søltofts Plads, Building 229, 2800 Kgs. Lyngby, Denmark
| | | | - Xiaodong Liang
- Center for Energy Resources Engineering, Department of Chemical and Biochemical Engineering, Technical University of Denmark (DTU), Søltofts Plads, Building 229, 2800 Kgs. Lyngby, Denmark
| | - Georgios M Kontogeorgis
- Center for Energy Resources Engineering, Department of Chemical and Biochemical Engineering, Technical University of Denmark (DTU), Søltofts Plads, Building 229, 2800 Kgs. Lyngby, Denmark
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