Unraveling the phase diagram-ion transport relationship in aqueous electrolyte solutions and correlating conductivity with concentration and temperature by semi-empirical modeling

Hilal Al-Salih; Elena A Baranova; Yaser Abu-Lebdeh

doi:10.1038/s42004-023-00993-4

Unraveling the phase diagram-ion transport relationship in aqueous electrolyte solutions and correlating conductivity with concentration and temperature by semi-empirical modeling

Commun Chem. 2023 Sep 12;6(1):195. doi: 10.1038/s42004-023-00993-4.

Authors

Hilal Al-Salih^{1

2

3}, Elena A Baranova^{1

2}, Yaser Abu-Lebdeh⁴

Affiliations

¹ Department of Chemical and Biological Engineering, Centre for Catalysis Research and Innovation, University of Ottawa, 161 Louis-Pasteur, Ottawa, ON, K1N 6N5, Canada.
² Nexus for Quantum Technologies (NexQT), University of Ottawa, Ottawa, ON, K1N 6N5, Canada.
³ Energy, Mining, and Environment Research Centre, National Research Council of Canada, 1200 Montreal Road, Ottawa, ON, K1A 0R6, Canada.
⁴ Energy, Mining, and Environment Research Centre, National Research Council of Canada, 1200 Montreal Road, Ottawa, ON, K1A 0R6, Canada. Yaser.Abu-Lebdeh@nrc-cnrc.gc.ca.

Abstract

The relationship between structure and ion transport in liquid electrolyte solutions is not well understood over the whole concentration and temperature ranges. In this work, we have studied the ionic conductivity (κ) as a function of molar fraction (x) and Temperature (T) for aqueous solutions of salts with nitrate anion and different cations (proton, lithium, calcium, and ammonium) along with their liquid-solid phase diagrams. The connection between the known features in the phase diagrams and the ionic conductivity isotherms is established with an insight on the conductivity mechanism. Also, known isothermal (κ vs.. x) and iso-compositional (κ vs.. T) equations along with a proposed two variables semi-empirical model (κ = f (x, T)) were fitted to the collected data to validate their accuracy. The role of activation energy and free volume in controlling ionic conductivity is discussed. This work brings us closer to the development of a phenomenological model to describe the structure and transport in liquid electrolyte solutions.