Journal Article

FZJ-2018-03552

http://join2-wiki.gsi.de/foswiki/pub/Main/Artwork/join2_logo100x88.png Thermodiffusion of Monovalent Organic Salts in Water

Sehnem, A. L. ; Niether, D.FZJ* ; Wiegand, S.FZJ* ; Figueiredo Neto, A. M. (Corresponding author)

2018
Soc. Washington, DC

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Please use a persistent id in citations: http://hdl.handle.net/2128/20301  doi:10.1021/acs.jpcb.8b01152

Abstract: The ionic Soret effect induced by temperaturegradients is investigated in organic electrolytes (tetramethylammoniumand tetrabutylammonium hydroxides) dispersed in waterusing a holographic grating experiment. We report the influences oftemperature and salt concentrations on the Soret, diffusion, andthermal diffusion coefficients. Experimental results to the thermaldiffusion coefficient are compared with a theoretical description forthermodiffusion of Brownian particles in liquids based in thethermal expansion of the liquid solution. It is observed that theobtained thermal diffusion coefficients for the organic electrolytespresent a similar temperature dependence as the theoretical prediction. Comparing the experimental results for the organic andcommon inorganic salts it is proposed an additional physical mechanism as the cause to the different thermal diffusioncoefficients in both types of salt. We propose that the temperature dependence of hydration free energy gives rise to a force termthat also leads to ion migration in a temperature gradient. We describe the thermal diffusion results as a competition betweenthermal expansion and hydration effects. The specific structure each type of ion cause in water molecules is considered in the heatof transport theory to describe thermal diffusion of electrolytes. A qualitative agreement is seen between our results and theclassical heat of transport theory.

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Contributing Institute(s):

1. Weiche Materie (ICS-3)

Research Program(s):

1. 551 - Functional Macromolecules and Complexes (POF3-551) (POF3-551)

Appears in the scientific report 2018

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Database coverage:
; ; Current Contents - Physical, Chemical and Earth Sciences ; Ebsco Academic Search ; IF < 5 ; JCR ; NCBI Molecular Biology Database ; SCOPUS ; Science Citation Index ; Science Citation Index Expanded ; Thomson Reuters Master Journal List ; Web of Science Core Collection

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