Abstract
The thermodynamic properties of porewater in sandstone were obtained as a function of water content and temperature by vapor pressure method. The activity, the relative partial molar Gibbs free energy (Δ HH2O), the relative partial molar enthalpy (Δ SH2O) and the relative partial molar entropy (ΔSH2O) of the porewater were determined at 298.15 K. The activity decreased with decreasing water content in the region where water content is about 1.5%, and drastically decreased in the region where water content is about 0.5%. No clear dependencies of Δ H 2O and Δ SH2O on water content were found. Synthesizing the correlations of the activity, Δ GH2O, Δ H H2O and Δ S H2O with water content and the enthalpy and entropy of fusion for ice, the porewater at the surface of the solid was found to have a low chemical potential compared with free water, and dissimilar with the structure of ice. Correlating the activity and Δ GH2 O with water content, the specific surface area of sandstone and the porosity, the porewater is deduced to be weakly affected up to a distance of approximately 3 nm from the surface of the solid. However, as the porewater approaches a distance of approximately 1.1nm from the solid surface, the effect from the solid surface abruptly becomes strong. This is deduced to be the effects of hydrogen bond at the solid surface and hydration to cations corresponding to the CEC.
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Disclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.