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:
CreatorsEmailORCIDORCID Put Code
Sehnem, Andre LuizUNSPECIFIEDUNSPECIFIEDUNSPECIFIED
Niether, DoreenUNSPECIFIEDorcid.org/0000-0002-8496-4215UNSPECIFIED
Wiegand, SimoneUNSPECIFIEDorcid.org/0000-0001-6333-1956UNSPECIFIED
Figueiredo Neto, Antonio MartinsUNSPECIFIEDUNSPECIFIEDUNSPECIFIED
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: Unspecified
Divisions: Unspecified
Subjects: no entry
Uncontrolled Keywords:
KeywordsLanguage
FORCED RAYLEIGH-SCATTERING; THERMAL-DIFFUSION; AQUEOUS-SOLUTIONS; TEMPERATURE-DEPENDENCE; SORET COEFFICIENT; CHARGED COLLOIDS; TETRAALKYLAMMONIUM HALIDES; POLYMER-SOLUTIONS; TRANSPORT; IONSMultiple languages
Chemistry, PhysicalMultiple languages
Refereed: Yes
URI: http://kups.ub.uni-koeln.de/id/eprint/18940

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