PhD Defence by Saman Naseri Boroujeni

Principal supervisor
Professor Georgios M. Kontogeorgis

Co-supervisors
Associate Professor Xiaodong Liang
DTU Chemical Engineering

Founder and CTO Bjørn Maribo-Mogensen
Hafnium Labs, Denmark

Examiners
Professor Nicolas von Solms
DTU Chemical Engineering

Senior Engineer Daniel Eriksen
Aker Carbon Capture, Denmark

Professor Jean-Charles de Hemptinne
IFP-Centre for Energy and Processes, France

Chairperson at Defence
Senior Researcher Michael Bache
DTU Chemical Engineering

Popular Summary

This Ph.D. thesis explores the captivating realm of electrolyte solutions, providing new insights into the prediction of their properties. This study follows two distinct paths that eventually come together to form a unified framework. Initially, it investigates electrical conductivity and then examines ion pairing from a thermodynamic perspective.

Primary attention is given to electrical conductivity, a significant property that is affected by the formation of ion pairs in electrolytes. After examining existing research, two new models are proposed, intended for single-salt and multi-salt electrolytes. These models, based on Smoluchowski dynamics and Debye-Hückel-Onsager theory, are remarkably precise when complete dissociation is assumed, as confirmed through thorough comparisons with experimental data.

The dissertation then changes focus to consider ion pairing from a thermodynamic perspective. Four equations of state are studied, leading to the development of a new model, the Binding Debye-Hückel model, for charged hard sphere fluids. This model, which is based on a variety of theoretical concepts, is tested against Monte Carlo simulations to demonstrate its accuracy in predicting essential thermodynamic properties.

The true power of this research is revealed when the two approaches are combined. The models for electrical conductivity, which have been verified under the presumption of full dissociation, are joined with the Binding Debye-Hückel model that is designed for ion pairing effects. This integration allows for the prediction of properties in a variety of electrolyte solutions, from aqueous to mixed-solvent and ionic liquid-co-solvent systems, using an implicit solvent model.

The culmination of the research is the development of a novel electrolyte equation of state, known as Binding eSAFT-VR-Mie, and the introduction of a unified framework for modeling electrolyte solutions. This framework is tested across a range of electrolytes, demonstrating its ability to accurately predict properties for solutions with varying levels of ion pairing.