MEASUREMENT AND CORRELATION OF BINARY DIFFUSION-COEFFICIENTS IN NEAR-CRITICAL FLUIDS

The binary diffusion coefficients of benzoic acid, oleic acid, alpha-t ocopherol, and glycerol trioleate were measured in near critical carbo n dioxide over the temperature range 298-318 K and pressure range 71-2 51 bar. A correlation based on an extensive literature database was de veloped which can be used to estimate both self and binary diffusion c oefficients in a range of near critical solvents over the solvent redu ced density range 1-2.5, with an average error of +/- 10%. The correla tion is not suitable for estimating binary diffusion coefficients at t he binary mixture critical point. The only input data required for the correlation are the solvent molecular weight, reduced temperature, an d density, the solute molecular weight, and an estimate of the solute critical volume.