The relationship between self-diffusion activation energy and Soret coefficient in binary liquid mixtures

Abstract

The Soret effect is an observed phenomenon in which an applied temperature gradient will induce a concentration gradient in multicomponent mixtures. The Soret coefficient is the ratio of thermally driven diffusion to mutual diffusion driven by concentration gradients. It is measured at steady state when the two driving forces are balanced, i.e. the net flux is zero. This study is designed to explore the potential relationship between the activation energy of self-diffusion of the individual components of a binary mixture and the mixture’s resulting Soret coefficient. This study found a trend of increasingly negative Soret coefficients as the difference in the mole-fraction-weighted self-diffusion activation energies of the components increased.