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I'm looking for a reference on electrical properties (specifically, conductivity) of mixtures of water / ethylene glycol. Specifically, I'm interested in

  • How does the electrical conductivity of the mixture depend on the volume fraction of the glycol? Can I use standard formulas (which I also struggle to find) for liquid mixtures? Are there such formulas?
  • If there are such formulas, is there a standard reference for the electrical properties of ethylene glycol?
  • How does the conductivity of the mixture depend on temperature? Does the rule of thumb 2%/°C that is used for water stand also for water/glycol mixtures?
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Disclaimer: I am no conductivity modelling expert so take what follows with a grain of salt. Also do not hesitate to comment this answer, and I will try to improve it accordingly.


Your question consists in six(!) questions which I will try to answer below.

1. How does the electrical conductivity of the mixture depend on the volume fraction of the glycol?

You may have a look at the figure below, from Loskutov et al.[1], for water / ethylene mixtures at 25°C.

Viscosity and conductivity of a water / glycol mixture at 25°C

2. & 3. Can I use standard formulas (which I also struggle to find) for liquid mixtures? Are there such formulas?

I must admit my lack of knowledge on this very topic, but the authors in [1] propose a formula for conductivity introducing a physical quantity they called excess electrical parameter, however noting that "excess electrical conductivity is not a universal parameter, so it is introduced for general consideration of different characteristics in a single scale".

You may also want to have a look at references [2], into which the author propose two different curve fittings (exponential and quadratic models). However, I fear that these equations are purely experimental. Furthermore, in your case (binary mixture without additional salt), this would lead to R=0 in their formula, for which their fit is not that great (probably due to the actual shape of the conductance shown in the figure above).

Additionally, although I did not find many paper on water / glycol binary mixtures, I did find quite a lot of publications on ternary mixtures, adding NaCl, CaCl$_2$, carbon nanotubes, and whatnot (see [4] for instance). In the latter cases, determinations of conductivities are also very much empiric.

4. If there are such formulas, is there a standard reference for the electrical properties of ethylene glycol?

I honestly do not know what you mean by standard reference. Do you mean a standard setup and / or procedure for measuring it? Like a set of temperature / pressure / purity / cell dimension / apparatus / frequency / voltage? Do you rather refer to the measured conductivity under such conditions / with such a procedure? Both?

5. & 6. How does the conductivity of the mixture depend on temperature? Does the rule of thumb 2%/°C that is used for water stand also for water/glycol mixtures?

Regarding the influence of temperature on said conductivity, I found nought but [3], which studies the influence of temperature on the RF conductivity (1 MHz) and dielectric constant of glycol / water mixtures.

Do you have any reference for this "rule of thumb" that you mention?


References

[1] Molecular Structure of an Ethylene Glycol–Water Solution at 298 K, Loskutov et al. (2018), DOI: 10.1134/S003602441902016X
[2] Electrical Conductivity Measurements for the Ternary Systems of Glycerol/Sodium Chloride/Water and Ethylene Glycol/Sodium Chloride/Water and Their Applications in Cryopreservation, Chen et al. (2009), DOI: 10.1089/bio.2009.0001
[3] RF Conductivity and Dielectric Relaxation Studies on an Ethylene Glycol-Water Mixture, Saha et al. (1999), DOI: 10.1088/0022-3727/32/7/011
[4] Electrical Conductivity Measurements for the Ternary Systems of Glycerol/Sodium Chloride/Water and Ethylene Glycol/Sodium Chloride/Water and Their Applications in Cryopreservation, Chen et al. (2009), DOI: 10.1089/bio.2009.0001

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  • $\begingroup$ Thanks a lot for your answer. Across sources for e.g. monoethlyene glycol I found values in disagreement with each other. Typically, they would rate the conductivity to approx $1 \mu S / cm$ but that's not always true. $\endgroup$
    – G. Gare
    Dec 4, 2023 at 12:06
  • $\begingroup$ For the "rule of thumb": en.wikipedia.org/wiki/… $\endgroup$
    – G. Gare
    Dec 4, 2023 at 12:08
  • $\begingroup$ In the reference [1], the conductivity of water is quite high (1.5 $\mu S/cm$). Could I expect a lower curve in case the conductivity of water is lower? $\endgroup$
    – G. Gare
    Dec 4, 2023 at 12:50
  • $\begingroup$ @G.Gare, the wikipedia page that you mentioned also states that "This value is broadly applicable for most salts at room temperature.", so I guess it may be quite bold of an asumption to believe that it holds for non-salt substances such as glycol. For your remark on water conductivity: the latter depends on water purity (purer water will have a lower conductivity), so I would guess your expectation is right. $\endgroup$
    – mranvick
    Dec 5, 2023 at 11:44
  • $\begingroup$ thanks for your comments. What I mean with "lower curve" is: shall I expect that the "bell effect" or the excess conductivity is also, proportionally, loweR? $\endgroup$
    – G. Gare
    Dec 6, 2023 at 7:56

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