Determination of Soret coefficient and heat of transport in a binary liquid mixture using X-ray microscopy

With a laboratory built X-ray microscope, analysis of a thermal diffusion process in a KBr solution has been performed. A solution of a salt submitted to a constant temperature gradient gives rise to a stationary concentration gradient of the species after a few hours: this is the so called Soret effect. From the digital image of the liquid, acquired in the steady state of the process, it is easy to obtain the concentration map of the species in the solution. The average concentration profile then deduced permits to reach the value of the Soret coefficient and the heat of transport of the binary compound. X-ray radiography is an alternative powerful technique to analyse this kind of complicated phenomenon where composition matter fluxes are driven by both temperature and composition gradient