MD simulations of diffusivities in methanol-n-hexane mixtures near the liquid-liquid phase splitting region

Abstract

Molecular Dynamics (MD) simulations have been carried out to determine the self-diffusivities in binary mixtures of methanol and n-hexane with varying compositions at four different temperatures of 303.15Κ , 307.7Κ , 310.7Κ , and 313.15Κ . The Darken relation was used to determine both the Fick diffusivity and the Maxwell-Stefan diffusivity. The values of the Fick diffusivity obtained from the simulations are in very good agreement with published experimental data of Clark and Rowley [17]. These diffusivities approach zero near composition regions where liquid-liquid phase splitting occurs. On the other hand, the Maxwell-Stefan diffusivity is well-behaved and appears to be practically insensitive to the complex thermodynamics.