Activity Coefficients and Solubility of CaCl2 from Molecular Simulations

Jeffrey M. Young, Christopher Tietz, Athanassios Z. Panagiotopoulos

Research output: Contribution to journalArticle

Abstract

We obtain the activity coefficients and lower bounds to the solubility of CaCl2 in aqueous solutions at temperatures between 298.15 and 473.15 K using molecular simulations with three previously developed nonpolarizable force fields. We find that a scaled-charge force field gives incorrect activity coefficients at low concentration and has a different absolute chemical potential than experiments, but still predicts an accurate solubility for the calcium chloride dihydrate. The two full-charge models have chemical potentials and activity coefficients closer to experiments, but there is considerable variation between them, with the chemical potentials differing by over 100 kJ·mol-1. The slow dynamics of the full-charge models at high concentrations are unrealistic and require advanced sampling methods to obtain the activity coefficients. We find that development of polarizable models is likely necessary to accurately represent both thermodynamic and transport properties of divalent electrolyte solutions.

Original languageEnglish (US)
JournalJournal of Chemical and Engineering Data
DOIs
StateAccepted/In press - Jan 1 2019

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Activity coefficients
Chemical potential
Solubility
Calcium Chloride
Calcium chloride
Transport properties
Electrolytes
Thermodynamic properties
Experiments
Sampling
Temperature

All Science Journal Classification (ASJC) codes

  • Chemical Engineering(all)
  • Chemistry(all)

Cite this

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abstract = "We obtain the activity coefficients and lower bounds to the solubility of CaCl2 in aqueous solutions at temperatures between 298.15 and 473.15 K using molecular simulations with three previously developed nonpolarizable force fields. We find that a scaled-charge force field gives incorrect activity coefficients at low concentration and has a different absolute chemical potential than experiments, but still predicts an accurate solubility for the calcium chloride dihydrate. The two full-charge models have chemical potentials and activity coefficients closer to experiments, but there is considerable variation between them, with the chemical potentials differing by over 100 kJ·mol-1. The slow dynamics of the full-charge models at high concentrations are unrealistic and require advanced sampling methods to obtain the activity coefficients. We find that development of polarizable models is likely necessary to accurately represent both thermodynamic and transport properties of divalent electrolyte solutions.",
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Activity Coefficients and Solubility of CaCl2 from Molecular Simulations. / Young, Jeffrey M.; Tietz, Christopher; Panagiotopoulos, Athanassios Z.

In: Journal of Chemical and Engineering Data, 01.01.2019.

Research output: Contribution to journalArticle

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