(204t) Measurement of Diffusion Coefficients of Chromium(III) Acetylacetonate in Supercritical Carbon Dioxide at High Temperatures
In this work, diffusion coefficients of chromium(III) acetylacetonate, Cr(acac)3, together with retention factors were measured above 70 Â°C using the chromatographic impulse response method, which is a kind of transient response methods and two parameters: diffusion coefficient and retention factor are simultaneously determined . Validating a hydrodynamic equation  as a predictive correlation for determined diffusion coefficients of Cr(acac)3, average absolute relative deviation (AARD) increased with increasing temperature. The diffusion coefficients at higher temperatures deviate from the reference values in low temperature scCO2. It is implied that the hydrodynamic equation based on the Stokes-Einstein equation, derived from those in liquid phases, is no longer valid in supercritical fluids at high temperatures and low pressures. Moreover, solubilities of the solutes in scCO2 can be estimated using an Ekartâs equation  from retention factors determined. The estimated solubilities provided high accuracies with AARD < 10% at all temperatures.
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