Transport properties of n-ethylene glycol aqueous solutions with focus on triethylene glycol-water

Soret effect and diffusion in triethylene glycol (TEG)-water mixtures were investigated as a function of concentration at 25 ? by means of optical digital interferometry, with the use of a classical Soret cell. Diffusion D, thermal diffusion D-T, and Soret S-T coefficients are described for the full concentration range and an analysis is made individually for TEG-water mixture and within a series of n-ethylene glycol (n-EG) aqueous systems. All coefficients decrease with increasing the concentration of TEG and n-EG. S-T shows a change of sign with concentration, and this change is directly related to the ability of the n-EG molecule to establish hydrogen bonding with water. Diffusion and thermal diffusion coefficients present a plateau behavior with increasing concentration, showing the occurrence of changes in the preferential interactions in aqueous solution with concentration and meaning that, at high TEG composition, ether oxygens can be involved in the molecular interactions. Published under an exclusive license by AIP Publishing.

Automated summary

The Soret effect and diffusion in TEG-water mixtures were investigated using optical digital interferometry. The results showed that all coefficients, including diffusion, thermal diffusion, and Soret coefficients, decreased with increasing concentrations of TEG and n-EG. The change of sign in the Soret coefficient was directly related to the hydrogen bonding ability of the n-EG molecule with water. The diffusion and thermal diffusion coefficients exhibited a plateau behavior, indicating changes in preferential interactions in aqueous solutions with concentration.