Article ID | Journal | Published Year | Pages | File Type |
---|---|---|---|---|
6477746 | The Journal of Supercritical Fluids | 2017 | 9 Pages |
â¢A solute-induced effect on the density enhancement of near-critical fluids is weak.â¢Weak local density change indicates no formation of distinct cluster structure.â¢High/low density region near the solute is from the fluctuation of neat solvent.â¢Solute selects its surroundings depending on the extent of the attractive forces.â¢Pre-existent density fluctuation amplifies the effect of short-range interactions.
Molecular Dynamics (MD) simulations were performed to understand the solvation structure and the mechanistic nature of the divergence of partial molar volume (vË2â) near the critical point. Isothermal-isobaric (NpT) simulations were carried out at Tr = 1.03 from pr = 0.87 to pr = 3.72 with the truncated and shifted Lennard-Jones and the Weeks-Chandler-Andersen (WCA) potentials. A statistical analysis on the structural characters was carried out to investigate the origin of the divergent vË2â near the critical point. The result suggested that no distinct cluster structure exists. Rather, a solute enters the pre-existent high-density and/or low-density domain and its preference depends on the magnitude of the solute/solvent attractive interaction. The influence of the attractive forces is propagated via the density fluctuation throughout the entire system. Thus, the interplay between the solute/solvent attraction and the pre-existent density fluctuation is the mechanistic origin of the divergence of vË2â near the critical point.
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