Diffusion coefficients of ethers in supercritical carbon dioxide

The Taylor-Aris tracer response method was applied to measure binary diffusion coefficients, D-12, in supercritical carbon dioxide under quasi-infinite-dilution conditions, by means of the Giddings and Seager chromatographic technique. Diethyl ether, diisopropyl ether, and tetrahydrofuran have been studied at 40, 50, and 60 degrees C in the pressure range 80-160 atm. The resulting binary diffusion coefficients are on the order of 10(-4) cm(2)/s. The influence of molecular weight, temperature, pressure, carbon dioxide density, and viscosity on the D-12 values is extensively examined. The applicability of the Wilke-Chang and Tyn-Calus hydrodynamic correlations, the free-volume diffusion model of Dymond, the Catchpole and King correlation, and the Lennard-Jones model of Liu-Silva-Macedo is also evaluated.