Development of an open source predictive equation of state for complex mixtures containing electrolytes

• Applicant: Dr.-Ing. Simon Müller
• Subject Area: Chemical and Thermal Process Engineering ; Technical Thermodynamics
• Term: since 2022
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 503327656

Electrolytes are important components in many areas of application, such as the oil and gas industry, gas hydrate systems, batteries, geothermal energy and biotechnology occurring under a wide variety of temperatures, pressures and compositions.Electrolytes have a large influence on the thermodynamic phase equilibrium. The description of these systems is particularly challenging because in solution they dissociate into highly charged ions. In the industrial application, it is often accepted that the electrolytes are either neglected or that parameter-based models are laboriously adapted with their own measurements in order to describe their effects. Electrolyte modeling is therefore one of the key competencies that industry does not yet have to the extent that it is needed.The focus of this research project is the development of an open source predictive equation of state for mixed solvent systems containing electrolytes. For this purpose, the recently published COSMO-SAC-Phi equation of state is to be further developed and expanded with the successful electrolyte model COSMO-RS-ES. This project thus covers two subject areas that still have great potential for improvement in predictive terms: the description of neutral mixed systems without binary interaction parameters and the prediction of the influence of electrolytes on these mixtures. The focus of this project is to be on the development of the electrolyte description. To achieve this goal, the new equation of state makes use of the expanded COSMO-RS theory and describes the interactions as a function of the ab-initio calculable screening charge density on the surface of the molecules.In a first step, the first open source implementation of the COSMO-SAC-Phi equation of state is to be created. This will then be validated using freely available data. The new model is initially to be expanded to include aqueous electrolyte solutions. For these systems there is a large amount of thermodynamic data that allows them to be understood and analyzed in more detail. Based on the experience and improvements for aqueous systems, the equation of state will then be extended to mixed solvent systems containing electrolytes.The equation of state developed in this project will be the first completely predictive equation of state for mixed solvent systems containing electrolytes without the need for binary interaction parameters. In the spirit of open science, all data and model developments will be made available open-source.

• DFG Programme: Research Grants