Universität zu Köln

Sehnem, Andre Luiz, Niether, Doreen ORCID: 0000-0002-8496-4215, Wiegand, Simone ORCID: 0000-0001-6333-1956 and Figueiredo Neto, Antonio Martins (2018). Thermodiffusion of Monovalent Organic Salts in Water. J. Phys. Chem. B, 122 (14). S. 4093 - 4101. WASHINGTON: AMER CHEMICAL SOC. ISSN 1520-6106

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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.

Item Type:	Journal Article
Creators:	Creators Email ORCID ORCID Put Code Sehnem, Andre Luiz UNSPECIFIED UNSPECIFIED UNSPECIFIED Niether, Doreen UNSPECIFIED orcid.org/0000-0002-8496-4215 UNSPECIFIED Wiegand, Simone UNSPECIFIED orcid.org/0000-0001-6333-1956 UNSPECIFIED Figueiredo Neto, Antonio Martins UNSPECIFIED UNSPECIFIED UNSPECIFIED
URN:	urn:nbn:de:hbz:38-189404
DOI:	10.1021/acs.jpcb.8b01152
Journal or Publication Title:	J. Phys. Chem. B
Volume:	122
Number:	14
Page Range:	S. 4093 - 4101
Date:	2018
Publisher:	AMER CHEMICAL SOC
Place of Publication:	WASHINGTON
ISSN:	1520-6106
Language:	English
Faculty:	Faculty of Mathematics and Natural Sciences
Divisions:	Faculty of Mathematics and Natural Sciences > Department of Chemistry > Institute of Physical Chemistry
Subjects:	no entry
Uncontrolled Keywords:	Keywords Language FORCED RAYLEIGH-SCATTERING; THERMAL-DIFFUSION; AQUEOUS-SOLUTIONS; TEMPERATURE-DEPENDENCE; SORET COEFFICIENT; CHARGED COLLOIDS; TETRAALKYLAMMONIUM HALIDES; POLYMER-SOLUTIONS; TRANSPORT; IONS Multiple languages Chemistry, Physical Multiple languages
Refereed:	Yes
URI:	http://kups.ub.uni-koeln.de/id/eprint/18940