Thermodiffusion Coefficients of Water/Ethanol Mixtures for Low Water Mass Fractions

Abstract

The difficulty of measuring the thermodiffusion coefficients by optical properties of water-ethanol binary mixtures of approximately 20 wt % of water has been highlighted by several authors in recent years. This is because the concentration derivative of the refractive index (∂ n/∂ c) p,T is near zero at this concentration. For this reason, we measured the thermodiffusion coefficients by means of density analysis using the thermogravitational column technique from 5 wt % to 50 wt % at 25∘C. In addition, we measured the thermophysical properties such as density, dynamic viscosity, thermal expansion and mass expansion.