A semi-empirical molecular statistical thermodynamic model for calculating standard molar Gibbs energies of aqueous species above and below the critical point of water

Journal Article · Fri Feb 02 00:00:00 EST 2018 · Journal of Molecular Liquids

DOI:https://doi.org/10.1016/j.molliq.2018.01.074· OSTI ID:1509715

Lvov, Serguei N. ^[1]; Hall, Derek M. ^[1]; Bandura, Andrei V. ^[2]; Gamwo, Isaac K. ^[3]

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1. Pennsylvania State Univ., University Park, PA (United States)
2. St. Petersburg State Univ., St. Petersburg (Russia)
3. National Energy Technology Lab. (NETL), Pittsburgh, PA, (United States)

An increasing number of industrial applications rely on controlling solutes in water above and below its critical point. Processes such as hydrothermal synthesis, steam power generation and ultra-high enthalpy geothermal power are all influenced by factors such as mineral precipitation, pH and solute speciation. Here, the supercritical point of water is remarkable in that slight changes in temperature and pressure can cause dramatic changes in some solute properties. Here, it was found that our approach reliant on molecular statistical thermodynamic expressions for hard sphere (HS), ion-dipole and dipole-dipole interactions via mean spherical approximation (MSA) provided excellent agreement to available experimental data. In addition to model parameters having some physical meaning, this approach used less adjustable parameters than the well-known Helgeson-Kirkham-Flowers (HKF) model. Furthermore, the model was used to obtain standard thermodynamic values for HCl⁰(aq), KCl⁰(aq) and NaOH⁰(aq) ion pairs. In total, modeling parameters for 10 different aqueous species were obtained to demonstrate the capabilities of the approach.

• Research Organization: National Energy Technology Lab. (NETL), Pittsburgh, PA, (United States)
• Sponsoring Organization: FE; USDOE
• OSTI ID: 1509715
• Report Number(s): NETL-PUB-21649
• Journal Information: Journal of Molecular Liquids, Vol. 270, Issue C; ISSN 0167-7322
• Publisher: Elsevier
• Country of Publication: United States
• Language: English

Related Subjects

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY
critical point of water
aqueous species
standard Gibbs energy of formation
high temperature
mean spherical approximation
molecular statistical thermodynamics