Theory of Soret coefficients in binary organic solvents

Area of Science:

• Thermodynamics
• Statistical Mechanics
• Physical Chemistry

Background:

• Thermodiffusion, or thermal diffusion, is crucial for understanding mass transport in liquid mixtures.
• Existing models often simplify intermolecular interactions, limiting predictive accuracy.

Purpose of the Study:

• To develop and apply a nonequilibrium thermodynamic model for thermodiffusion in binary molecular liquids.
• To quantify the contribution of orientation-dependent interactions to thermodiffusion.
• To compare theoretical predictions with experimental data for organic solvent solutions.

Main Methods:

• Utilized a nonequilibrium thermodynamic framework.
• Calculated thermodynamic parameters via statistical mechanics.
• Quantified thermodiffusion using chemical potential variations with temperature and concentration.
• Incorporated orientation-dependent Keezom interactions, averaged using Boltzmann weighting.

Main Results:

• The model successfully predicts enthalpies of evaporation, showing good agreement with literature values.
• A measurable contribution from orientation-dependent Keezom interactions was identified.
• Calculated energetic parameters for material transport were significantly higher than those from literature simulations.

Conclusions:

• The developed model provides a robust framework for studying thermodiffusion in binary molecular liquids.
• Orientation-dependent interactions play a key role in thermodiffusion phenomena.
• Further refinement of energetic parameter calculations in transport simulations is warranted.