https://doi.org/10.1140/epje/s10189-021-00134-6
Regular Article – Flowing Matter
The Soret coefficients of the ternary system water/ethanol/triethylene glycol and its corresponding binary mixtures
1
Physikalisches Institut, Universität Bayreuth, 95440, Bayreuth, Germany
2
Universite de Pau et des Pays de l’Adour, E2S UPPA, CNRS, TotalEnergies, LFCR UMR5150, Anglet, France
3
Mondragon Unibertsitatea, 20500, Arrasate-Mondragon, Spain
4
MRC, CP 165/62, Université libre de Bruxelles (ULB), 50, Ave. F.D. Roosevelt, B-1050, Brussels, Belgium
5
BRGM, Orléans, France
6
Ikerbasque, Basque Foundation for Science, Bilbao, Spain
m
werner.koehler@uni-bayreuth.de
Received:
22
July
2021
Accepted:
2
October
2021
Published online:
18
October
2021
Thermodiffusion in ternary mixtures is considered prototypic for the Soret effect of truly multicomponent systems. We discuss ground-based measurements of the Soret coefficient along the binary borders of the Gibbs triangle of the highly polar and hydrogen bonding ternary DCMIX3-system water/ethanol/triethylene glycol. All three Soret coefficients decay with increasing concentration, irrespective of the choice of the independent component, and show a characteristic sign change as a function of temperature and/or composition. With the exception of triethylene glycol/ethanol at high temperatures, the minority component always migrates toward the cold side. All three binaries exhibit temperature-independent fixed points of the Soret coefficient. The decay of the Soret coefficient with concentration can be related to negative excess volumes of mixing. The sign changes of the Soret coefficients of the binaries allow to draw far-reaching conclusions about the signs of the Soret coefficients of the corresponding ternary mixtures. In particular, we show that at least one ternary composition must exist, where all three Soret coefficients vanish simultaneously and no steady-state separation is observable.
© The Author(s) 2021
Open Access This article is licensed under a Creative Commons Attribution 4.0 International License, which permits use, sharing, adaptation, distribution and reproduction in any medium or format, as long as you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons licence, and indicate if changes were made. The images or other third party material in this article are included in the article’s Creative Commons licence, unless indicated otherwise in a credit line to the material. If material is not included in the article’s Creative Commons licence and your intended use is not permitted by statutory regulation or exceeds the permitted use, you will need to obtain permission directly from the copyright holder. To view a copy of this licence, visit http://creativecommons.org/licenses/by/4.0/.