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Effect of adsorption on the surface tensions of solid-fluid interfaces
1Thermodynamics and Kinetics Laboratory, Department of Mechanical and Industrial Engineering, University of Toronto, Toronto, Canada M5S 3G8. ward@mie.utoronto.ca
The Journal of Physical Chemistry. B
|March 29, 2007
Summary
A new method uses adsorption isotherms to calculate solid surface tensions. This approach accurately determines solid-vapor and solid-liquid surface tensions, providing a reliable material property.
Area of Science:
- Surface science
- Physical chemistry
- Materials science
Background:
- Determining surface tension in solid-liquid or solid-vapor systems is crucial for understanding material properties.
- Existing thermodynamic models often require complex experimental setups or assumptions.
- A simplified yet accurate method for surface tension determination is needed.
Purpose of the Study:
- To propose a novel method for calculating surface tensions of solids in contact with liquids or vapors.
- To develop an equilibrium adsorption isotherm relation that avoids unphysical predictions at saturation vapor pressure.
- To validate the method by determining the surface tension of solids in the absence of adsorption (gamma[1](S0)).
Main Methods:
- Integrating an equilibrium adsorption isotherm with Gibbsian thermodynamics to derive surface tension expressions.
- Formulating a new isotherm relation that behaves correctly at saturation vapor pressure.
- Testing the isotherm relation on five literature solid-vapor systems.
- Determining the solid surface tension in the absence of adsorption (gamma[1](S0)) by analyzing adsorption data from multiple vapors on the same solid.
Main Results:
- The proposed method successfully derives expressions for solid-vapor (gamma[1](SV)) and solid-liquid (gamma[1](SL)) surface tensions.
- The new isotherm relation accurately describes experimental data for five different solid-vapor systems.
- Consistent values for the solid surface tension in the absence of adsorption (gamma[1](S0)) were obtained using different vapors (benzene and n-hexane) on graphitized carbon.
Conclusions:
- The integration of adsorption isotherms with Gibbsian thermodynamics offers a robust method for surface tension determination.
- The developed isotherm relation provides a physically meaningful description of adsorption phenomena.
- The ability to determine gamma[1](S0) as a consistent material property validates the proposed thermodynamic framework.
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