On the Measurement of Positive Soret Coefficients

Dutrieux, J. F.; Platten, J. K.; Chavepeyer, G.; Bou-Ali, M. Mounir

doi:10.1021/jp013945r

Cited by 100 publications

(121 citation statements)

References 17 publications

Supporting

Mentioning

115

Contrasting

Order By: Relevance

“…The time dependence of the diffracted signal intensity is analyzed and gives the diffusion coefficient D, the thermal diffusion coefficient D T and the Soret coefficient S T . In the benchmark test it was demonstrated that the classical TDFRS method gives reliable results for organic mixtures and also the data obtained for simple aqueous systems compare well with other experimental techniques [11][12][13][14] . However, recent studies on the surfactant hexaethylene glycol monododecyl ether (C 12 E 6 ) in water with the classical TDFRS showed, that the small amount of dye added to create a temperature grating, leads to an unexpected second mode in the concentration part of the classical TDFRS signal 15,16 .…”

Section: Introductionmentioning

confidence: 56%

Investigation of the Soret effect in aqueous and non-aqueous mixtures by the thermal lens technique

Polyakov

Wiegand

2009

Phys. Chem. Chem. Phys.

View full text Add to dashboard Cite

In the present work we investigate the thermal diffusion behavior of three different binary mixtures with a thermal lens (TL) setup. In the setup used in this study we avoid the addition of a dye for systems, such as aqueous mixtures, with a weak absorption band at a wavelength of 980 nm. In some aqueous systems with a complex phase behavior the addition of dye significantly affects the apparent measured thermal diffusion properties. The studied systems are dimethylsulfoxide (DMSO) in water, the ionic liquid 1-ethyl-3-methylimidazolium ethylsulfate (EMIES) in butanol and a non-ionic surfactant hexaethylene glycol monododecyl ether (C 12 E 6 ) in water. The Soret coefficients of the selected systems cover a range of two orders of magnitude. For DMSO in water with a very low Soret coefficient of the order of S T ∼ 10 −3 K −1 we find for a low DMSO content (c = 0.33) a reasonable agreement with previous measurements, while the weak thermal lens signal for the DMSO-rich mixture (c = 0.87) leads to 20% too large Soret coefficients with an uncertainty of more than 30%. Secondly we studied a liquid salt 1-ethyl-3-methylimidazolium ethylsulfate (EMIES) in butanol with a roughly ten times higher Soret coefficient of S T ∼ 10 −2 K −1 .For this system we performed additional measurements with another experimental technique, the classical thermal diffusion forced Rayleigh scattering (TDFRS), which requires the addition of a small amount of dye to increase the absorption. In the entire investigated concentration range the results obtained with the TL and classical TDFRS technique agree within the error bars. As a third system we studied a non-ionic surfactant hexaethylene glycol monododecyl ether (C 12 E 6 ) in water with a Soret coefficient of the order of S T ∼ 10 −1 K −1 . For this system we find good agreement with previous measurements. We conclude that the TL technique is a reliable method for systems with a strong optical contrast and fairly large Soret coefficient of the order of S T ∼ 10 −2 K −1 .

show abstract

Section: Introductionmentioning

confidence: 56%

Investigation of the Soret effect in aqueous and non-aqueous mixtures by the thermal lens technique

Polyakov

Wiegand

2009

Phys. Chem. Chem. Phys.

View full text Add to dashboard Cite

show abstract

“…In the recent years it was also demonstrated that the TDFRS method gives reliable results for aqueous systems and compares well with other experimental techniques 10,[13][14][15] . But recent studies on a non-ionic surfactant by the TDFRS technique showed, that the small amount of dye, which is added to convert light into heat energy, can influence the thermal diffusion behavior of the surfactant system 16,17 .…”

Section: Introductionmentioning

confidence: 60%

Systematic study of the thermal diffusion in associated mixtures

Polyakov

Wiegand

2008

The Journal of Chemical Physics

View full text Add to dashboard Cite

We performed systematic temperature and concentration dependent measurements of the Soret coefficient in different associated binary mixtures of water, deuterated water, dimethyl sulfoxide (DMSO), methanol, ethanol, acetone, methanol, 1-propanol, 2-propanol, propionaldehyde using the so called thermal diffusion forced Rayleigh scattering method. For some of the associating binary mixtures such as ethanol/water, acetone/water and DMSO/water the concentration x ± w at which the Soret coefficient changes its sign does not depend on temperature and is equal to the concentration x × w where the Soret coefficient isotherms intersect. While for others such as 1-propanol/water, 2-propanol/water and ethanol/DMSO the sign change concentration is temperature dependent, which is the typical behavior observed for non-associating mixtures. For systems with x ± w = x × w we found that x ± w depends linearly on the ratio of the vaporization enthalpies of the pure components. Probably due to the similarity of methanol and DMSO we do not observe a sign change for this mixture. The obtained results are related to structural changes in the fluid observed by nuclear magnetic resonance, mass specrometric and X-ray experiments in the literature. Furthermore we discuss the influence of hydrophilic and hydrophobic interactions and the solubility on thermal diffusion behavior.

show abstract

“…5 In the past the thermal diffusion behavior of simple fluid mixtures has been studied extensively. [6][7][8][9][10][11][12][13] Organic liquid mixtures have been used in a benchmark test, to establish reference data. 14 Recently, special focus has been on the dependence of S T on parameters such as mass and moment of inertia.…”

Section: Introductionmentioning

confidence: 99%