Correlation of binary diffusion coefficients of organic substances in supercritical carbon dioxide based on equations of state

An easy applicable and accurate method for the correlation of the infinite dilution diffusion coefficient of organic solutes in supercritical fluids is proposed. The method is applicable to all supercritical fluids; in this work, however, only supercritical carbon dioxide is considered. The infinite dilution diffusion coefficient is calculated from the solvent viscosity by means of a modified Stokes–Einstein relation. The viscosity is calculated from an equation of state using friction theory. Here two equations of state are used, namely the short form of the Span–Wagner reference equation for carbon dioxide and the Peng–Robinson equation of state.