Henry's law, surface tension, and surface adsorption in dilute binary mixtures

Akira Onuki

doi:10.1063/1.3089709

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arXiv · 0902.1204

Henry's law, surface tension, and surface adsorption in dilute binary mixtures

Akira Onuki

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Abstract

Equilibrium properties of dilute binary fluid mixtures are studied in two-phase states on the basis of a Helmholtz free energy including the gradient free energy. The solute partitioning between gas and liquid (Henry's law) and the surface tension change $Δγ$ are discussed. A derivation of the Gibbs law $Δγ=-TΓ$ is given with $Γ$ being the surface adsorption. Calculated quantities include the derivatives $d T_c/dX$ and $d p_c/dX$ of the critical temperature and pressure with respect to the solute molar fraction $X$ and the temperature-derivative $(\p γ/\p T)_{{\rm cx},p}$ of the surface tension at fixed pressure $p$ on the coexistence surface. Here $(\p γ/\p T)_{{\rm cx},p}$ can be both positive and negative, depending on the solute molecular size and the solute-solvent interaction,and diverges on the azeptropic line. Explicit expressions are given for all these quantities in the van der Waals model.

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Akira Onuki. 2009-02-07. Henry's law, surface tension, and surface adsorption in dilute binary mixtures. https://doi.org/10.1063/1.3089709

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