Promising results for many anomalous properties of pure water have been obtained in our group so far [1] [2] by the implementation of the two-state (TS) theory with the PC-SAFT equation of state (EOS). However, there are still some deviations from the experimental data for the properties, especially for the derivative ones, such as the speed of sound and heat capacities.
Alternatively, using the SAFT-VR Mie model might result in lower deviations because it employs the more general Mie potential instead of Lennard-Jones potential, and researchers have found that it represents the derivative properties of fluids more accurately compared to traditional SAFT-type EOSs.
Therefore, it is worth investigating whether successful overall representations of the anomalous properties of both pure water and solutions can be obtained using the TS theory within the SAFT-VR Mie model. Moreover, if this new approach proves its ability to capture the thermophysical properties of water, it also offers an opportunity to predict the phase behavior of aqueous mixtures, especially electrolyte solutions.
In the second phase of the project, it will be tested to capture the properties related to the ion-water interactions, such as the temperature dependency of activity coefficients of water-salts and individual ion activity coefficients, as well as the ion effects on the water structure.
Overall, throughout the project, the aim is to prove the validity of the debated theory stating that water molecules exist in two distinct phases with different densities. A better understanding of the nature of water might be crucial for the design of future processes involving water or aqueous mixtures.
This project is funded by the Independent Research Fund Denmark | Natural Sciences.
[1] Novak, N., Liang, X., & Kontogeorgis, G. M. (2024). Prediction of water anomalous properties by introducing the two-state theory in saft. The Journal of Chemical Physics, 160(10). https://doi.org/10.1063/5.0186752
[2] Novak, N., Liang, X., & Kontogeorgis, G. M. (2025). PC-SAFT-TS-CAF: A revised two state model for pure water and binary aqueous mixtures. Fluid Phase Equilibria, 598, 114475. https://doi.org/10.1016/j.fluid.2025.114475
Main supervisor:
Prof. Georgios M. Kontogeorgis
Co- supervisors:
Assoc. Prof. Xiaodong Liang
Dr. Nefeli Novak