Microscopic study and modeling of thermodiffusion in binary associating mixtures

Area of Science:

• Thermodynamics
• Physical Chemistry
• Non-equilibrium systems

Background:

• Thermodiffusion in associating mixtures is complex due to concentration-dependent molecular structures.
• Understanding species separation mechanisms in these mixtures is crucial.

Purpose of the Study:

• To elucidate the phenomenon of thermodiffusion in binary associating mixtures.
• To propose a qualitative mechanism for species separation.
• To develop and validate a predictive model for the thermal diffusion factor.

Main Methods:

• Modification of a dynamic model based on the Drickamer nonequilibrium thermodynamic approach.
• Establishing a correlation between thermal diffusion factor sign changes and mixture properties (molecular structure, viscosity, excess entropy of mixing).
• Comparing the predictive power of proposed expressions against experimental data and existing models.

Main Results:

• A correlation was established between the thermal diffusion factor's sign change and alterations in molecular structure, viscosity, and excess entropy of mixing.
• Modified theoretical expressions were proposed for estimating the thermal diffusion factor in binary associating mixtures.
• The proposed expressions accurately predict the sign change in the thermal diffusion factor.

Conclusions:

• The study provides a mechanistic understanding of thermodiffusion in associating mixtures.
• The developed model offers a self-contained method for predicting thermal diffusion behavior using only viscosity data.
• This work advances the understanding and prediction of thermodiffusion in complex fluid mixtures.