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Application and refinement of COSMO-RS-ES for calculating phase equilibria of electrolyte systems at high concentrations in mixed and non-aqueous solvents
Citation Link: https://doi.org/10.15480/882.2994
Publikationstyp
Doctoral Thesis
Date Issued
2020-08
Sprache
English
Author(s)
Advisor
Referee
Title Granting Institution
Technische Universität Hamburg
Place of Title Granting Institution
Hamburg
Examination Date
2020-08-07
Institut
TORE-DOI
TORE-URI
Citation
Technische Universität Hamburg (2020)
For an efficient process design to save resources and time or for a first estimation during the beginning phase of the development, predictive thermodynamic models are a key tool. COSMO RS is an efficient method that allows prediction of thermodynamic properties without the need for binary interaction parameters which in many cases have to be adjusted to experimental data. The electrolyte extension of this model, namely COSMO RS ES, has been shown to be a very versatile model being capable of predicting very diverse phase equilibria in electrolyte systems. The model employs an especially modified COSMO RS model to describe the short-range interactions of the different species combined with the Pitzer-Debye-Hückel model to describe the long-range ionic interactions.
In this work, the model was successfully extended to be able to calculate solubilities of inorganic solvents in mixed-solvent and completely non-aqueous systems. Some systematic deviations could be found, which could be attributed to the short-range or the long-range part of the model respectively.
By including Gibbs free energies of transfer of ions into the training set of the model, the short-range description of the ionic interactions was improved, allowing for a better prediction of salt solubilities in a wide range of solvents. To also improve the long-range interactions of the model, the influence of using the solution properties such as permittivity and density was assessed leading to several important observations for this part of the model. As other models include a Born term to describe the ion solvation better, which so far is not considered within the COSMO RS ES model, this possibility is investigated. Furthermore, the model is enhanced to explicitly describe the effect of ion-pairing which becomes prominent for systems with a very low permittivity. With these developments, the predictive capabilities of the model are greatly advanced.
Two completely non-aqueous liquid-liquid equilibrium systems and four solid-liquid equilibria are measured and modelled with COSMO RS ES leading to a better understanding of how the model works for these complex systems.
Finally, the model is reparametrized from the ground up to allow prediction of pKa values, applying the model to free solvation energies for the first time.
In this work, the model was successfully extended to be able to calculate solubilities of inorganic solvents in mixed-solvent and completely non-aqueous systems. Some systematic deviations could be found, which could be attributed to the short-range or the long-range part of the model respectively.
By including Gibbs free energies of transfer of ions into the training set of the model, the short-range description of the ionic interactions was improved, allowing for a better prediction of salt solubilities in a wide range of solvents. To also improve the long-range interactions of the model, the influence of using the solution properties such as permittivity and density was assessed leading to several important observations for this part of the model. As other models include a Born term to describe the ion solvation better, which so far is not considered within the COSMO RS ES model, this possibility is investigated. Furthermore, the model is enhanced to explicitly describe the effect of ion-pairing which becomes prominent for systems with a very low permittivity. With these developments, the predictive capabilities of the model are greatly advanced.
Two completely non-aqueous liquid-liquid equilibrium systems and four solid-liquid equilibria are measured and modelled with COSMO RS ES leading to a better understanding of how the model works for these complex systems.
Finally, the model is reparametrized from the ground up to allow prediction of pKa values, applying the model to free solvation energies for the first time.
Subjects
Electrolyte thermodynamics
Predictive model
Non-aqueous systems
COSMO-RS
COSMO-RS-ES
Solubility
LLE
SLE
Gibbs free energies of transfer
DDC Class
620: Ingenieurwissenschaften
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Name
Dissertation.Simon.Mueller.Application.and.Refinement.of.COSMO-RS-ES.pdf
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