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Li M, Lv L, Fang T, Hao L, Li S, Dong S, Wu Y, Dong X, Liu H. Self-Consistent Implementation of a Solvation Free Energy Framework to Predict the Salt Solubilities of Six Alkali Halides. J Chem Theory Comput 2023; 19:5586-5601. [PMID: 37471389 DOI: 10.1021/acs.jctc.3c00083] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 07/22/2023]
Abstract
To assess the salt solubilities of six alkali halides in aqueous systems, we proposed a thermodynamic cycle and an efficient molecular modeling methodology. The Gibbs free energy changes for vaporization, dissociation, and dissolution were calculated using the experimental data of ionic thermodynamic properties obtained from the NBS tables. Additionally, the Marcus' and Tissandier's solvation free energy data for Li+, Na+, K+, Cl-, and Br- ions were compared with the conventional solvation free energies by substituting into our self-consistent thermodynamic cycle. Furthermore, Tissandier's absolute solvation free energy data were used as the training set to refit the Lennard-Jones parameters of OPLS-AA force field for ions. To predict salt solubilities, an assumption of a pseudo-solvent was proposed to characterize the coupling work of a solute with its environment from infinitely diluted to saturated solutions, indicating that the Gibbs energy change of solvation process is a function of ionic strength. Following the self-consistency of the cycle, the newly derived formulas were used to determine the salt solubilities by interpolating the intersection of Gibbs free energy of dissolution and the zero free energy line. The refined ion parameters can also predict the structure and thermodynamic properties of aqueous electrolyte solutions, such as densities, pair correlation functions, hydration numbers, mean activity coefficients, vapor pressures, and the radial dependences of the net charge at 298.15 K and 1 bar. Our method can be used to characterize the solid-liquid equilibria of ions or charged particles in aqueous systems. Furthermore, for highly concentrated strong electrolyte systems, it is essential to introduce accurate water models and polarizable force fields.
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Affiliation(s)
- Miyi Li
- School of Chemistry and Chemical Engineering, Beijing Institute of Technology, Beijing 10081, China
| | - Liqiang Lv
- College of Chemical Engineering, Shijiazhuang University, Hebei, Shijiazhuang 050035, China
| | - Tao Fang
- Beijing Institute of Aerospace Testing Technology, Beijing 100074, China
| | - Long Hao
- Beijing Institute of Aerospace Testing Technology, Beijing 100074, China
| | - Shenhui Li
- School of Chemistry and Chemical Engineering, Beijing Institute of Technology, Beijing 10081, China
| | - Shoulong Dong
- School of Chemistry and Chemical Engineering, Beijing Institute of Technology, Beijing 10081, China
| | - Yufeng Wu
- School of Chemistry and Chemical Engineering, Beijing Institute of Technology, Beijing 10081, China
| | - Xiao Dong
- School of Chemistry and Chemical Engineering, Beijing Institute of Technology, Beijing 10081, China
| | - Helei Liu
- School of Chemistry and Chemical Engineering, Beijing Institute of Technology, Beijing 10081, China
- Key Laboratory of Low-Carbon Conversion Science & Engineering, Shanghai Advanced Research Institute, Chinese Academy of Sciences (Shanghai Advanced Research Institute, Chinese Academy of Sciences), Shanghai 201210, China
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Martínez-Jiménez M, Benavides AL. The liquidus temperature curve of aqueous methanol mixtures: a numerical simulation study. J Chem Phys 2022; 157:104502. [DOI: 10.1063/5.0099751] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
Abstract
The liquidus temperature curve that characterizes the boundary between the liquid methanol/water mixture and its coexistence with ice Ih is determined using the direct-coexistence method. Several methanol concentrations and pressures of 0.1 MPa, 50 MPa, and 100 MPa are considered. In this study, we used the TIP4P/Ice model for water and two different models for methanol: OPLS and OPLS/2016, using the geometric rule for the Lennard-Jones cross interactions. We compared our simulation results with available experimental data and found that this combination of models reproduces reasonably well the liquidus curve for methanol mole fractions up to xm=0.3 at p=0.1 MPa. The freezing point depression of these mixtures is calculated and compared to experimental results. We also analyzed the effect of pressure on the liquidus curve, and we found that both models also reproduce qualitatively well the experimental decreasing of the liquidus temperatures as the pressure increases.
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Affiliation(s)
| | - Ana Laura Benavides
- Ingeniería Física, Universidad de Guanajuato División de Ciencias e Ingenierías Campus León, Mexico
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Lamas CP, Vega C, Noya EG. Freezing point depression of salt aqueous solutions using the Madrid-2019 model. J Chem Phys 2022; 156:134503. [PMID: 35395902 DOI: 10.1063/5.0085051] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Salt aqueous solutions are relevant in many fields, ranging from biological systems to seawater. Thus, the availability of a force-field that is able to reproduce the thermodynamic and dynamic behavior of salt aqueous solutions would be of great interest. Unfortunately, this has been proven challenging, and most of the existing force-fields fail to reproduce much of their behavior. In particular, the diffusion of water or the salt solubility are often not well reproduced by most of the existing force-fields. Recently, the Madrid-2019 model was proposed, and it was shown that this force-field, which uses the TIP4P/2005 model for water and non-integer charges for the ions, provides a good description of a large number of properties, including the solution densities, viscosities, and the diffusion of water. In this work, we assess the performance of this force-field on the evaluation of the freezing point depression. Although the freezing point depression is a colligative property that at low salt concentrations depends solely on properties of pure water, a good model for the electrolytes is needed to accurately predict the freezing point depression at moderate and high salt concentrations. The coexistence line between ice and several salt aqueous solutions (NaCl, KCl, LiCl, MgCl2, and Li2SO4) up to the eutectic point is estimated from direct coexistence molecular dynamics simulations. Our results show that this force-field reproduces fairly well the experimentally measured freezing point depression with respect to pure water freezing for all the salts and at all the compositions considered.
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Affiliation(s)
- Cintia P Lamas
- Departamento de Química-Física I (Unidad de I+D+i Asociada al CSIC), Facultad de Ciencias Químicas, Universidad Complutense de Madrid, 28040 Madrid, Spain
| | - Carlos Vega
- Departamento de Química-Física I (Unidad de I+D+i Asociada al CSIC), Facultad de Ciencias Químicas, Universidad Complutense de Madrid, 28040 Madrid, Spain
| | - Eva G Noya
- Instituto de Química Física Rocasolano, CSIC, C/ Serrano 119, 28006 Madrid, Spain
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