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(Reference retrieved automatically from Web of Science through information on FAPESP grant and its corresponding number as mentioned in the publication by the authors.)

Thermodiffusion of Monovalent Organic Salts in Water

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Author(s):
Sehnem, Andre Luiz [1] ; Niether, Doreen [2] ; Wiegand, Simone [2, 3] ; Figueiredo Neto, Antonio Martins [1]
Total Authors: 4
Affiliation:
[1] Univ Sao Paulo, Inst Phys, Sao Paulo - Brazil
[2] Forschungszentrum Julich GmbH, ICS Soft Condensed Matter 3, D-52428 Julich - Germany
[3] Univ Cologne, Dept Chem Phys Chem, D-50939 Cologne - Germany
Total Affiliations: 3
Document type: Journal article
Source: Journal of Physical Chemistry B; v. 122, n. 14, p. 4093-4100, APR 12 2018.
Web of Science Citations: 4
Abstract

The ionic Soret effect induced by temperature gradients is investigated in organic electrolytes (tetramethylammonium and tetrabutylammonium hydroxides) dispersed in water using a holographic grating experiment. We report the influences of temperature and salt concentrations on the Soret, diffusion, and thermal diffusion coefficients. Experimental results to the thermal diffusion coefficient are compared with a theoretical description for thermodiffusion of Brownian particles in liquids based in the thermal expansion of the liquid solution. It is observed that the obtained thermal diffusion coefficients for the organic electrolytes present a similar temperature dependence as the theoretical prediction. Comparing the experimental results for the organic and common inorganic salts it is proposed an additional physical mechanism as the cause to the different thermal diffusion coefficients in both types of salt. We propose that the temperature dependence of hydration free energy gives rise to a force term that also leads to ion migration in a temperature gradient. We describe the thermal diffusion results as a competition between thermal expansion and hydration effects. The specific structure each type of ion cause in water molecules is considered in the heat of transport theory to describe thermal diffusion of electrolytes. A qualitative agreement is seen between our results and the classical heat of transport theory. (AU)

FAPESP's process: 14/50983-3 - INCT 2014: complex fluids
Grantee:Antonio Martins Figueiredo Neto
Support Opportunities: Research Projects - Thematic Grants