Thermodiffusion, molecular diffusion and Soret coefficients of aromatic+n-alkane binary mixtures

Miren Larrañaga; M Mounir Bou-Ali; Estela Lapeira; Ion Lizarraga; Carlos Santamaría

doi:10.1063/1.4964298

Thermodiffusion, molecular diffusion and Soret coefficients of aromatic+n-alkane binary mixtures

J Chem Phys. 2016 Oct 7;145(13):134503. doi: 10.1063/1.4964298.

Authors

Miren Larrañaga¹, M Mounir Bou-Ali¹, Estela Lapeira¹, Ion Lizarraga¹, Carlos Santamaría²

Affiliations

¹ MGEP Mondragon Goi Eskola Politeknikoa, Mechanical and Industrial Manufacturing Department, Loramendi 4 Apdo. 23, Mondragon 20500, Spain.
² Department of Applied Physics II, University of Basque Country, Apdo. 644, Bilbao 48080, Spain.

PMID: 27782414
DOI: 10.1063/1.4964298

Abstract

In the present work, we have measured the thermodiffusion coefficient of 51 binary liquid mixtures at 25 ^oC. These mixtures correspond to the series of the aromatics toluene and 1-methylnaphthalene with n-alkanes nCi (i = 6, 8, 10, 12, and 14) at different mass fractions in the whole range. For that, we have used the thermogravitational technique. It is shown that the thermodiffusion coefficient is a linear function of the mass fraction in all the mixtures. Extrapolating the lines, we obtain the thermodiffusion coefficient in dilute solutions of n-alkanes for both toluene and 1-methylnaphthalene. These limiting values show a linear dependence with the inverse of the product of the molecular weights. In addition, we have measured the molecular diffusion coefficient of all the mixtures at 0.5 of mass fraction and at 25 ^oC, by the sliding symmetric tubes technique. It is observed that the product of this coefficient with the viscosity at the same concentrations takes a constant value for each of the series considered. Finally, we have also determined the Soret coefficient of the equimass mixtures by the combination of the measurements of thermodiffusion and molecular diffusion coefficients.