INFINITE-DILUTION DIFFUSION-COEFFICIENTS IN SUPERCRITICAL FLUIDS

A predictive equation, based on the rough-hard-sphere theory, was deve loped for: the determination of infinite-dilution molecular diffusion coefficients in supercritical fluids. The equation parameters were det ermined from molecular dynamics simulations and from experimental data on 1-octene diffusion in supercritical ethane, propane, and hexane ov er a wide range of temperatures and pressures for supercritical fluid densities in the range of 69.9-500.2 kg/m(3). An extensive database on diffusion in supercritical fluids was collected through the literatur e in order to evaluate the proposed equation and to determine the accu racy of the predictions with no additional parameter adjustment. The p redictions were very good, with an average absolute deviation of 15.08 % over 1548 data points. For systems where actual data on the critical constants were available, the average error of the predictions reduce s to 9.61% over 939 points.