Measurement of isothermal diffusion coefficients in ternary mixtures using counter flow diffusion cell

A new diffusion cell and an interferometer have been developed for determination of isothermal diffusion coefficients in ternary mixtures. Two interferometer schemes have been proposed and tested for the measurements. The classical Mach–Zehnder interferometer can be reconfigured into a common-path interferometer to resolve high gradients of the refractive index that are typical of diffusion experiments. Formulations, methodology and algorithms for data extraction are presented for the example of a ternary mixture with an equal mass fraction of all components (1:1:1) in the system of tetralin–isobutylbenzene–dodecane. The selection of the fitting procedure is very important for obtaining reliable results.