Tracer diffusion coefficients of citral and d-limonene in supercritical carbon dioxide

Binary diffusion coefficients for infinitely diluted solutions of citral and d-limonene in supercritical CO2 were measured at 313.15, 323.15 and 333.15 K and pressures ranging from 12 to 20 MPa using the Taylor–Aris dispersion technique. The dependency on pressure, temperature and carbon dioxide density is examined, as well as the hydrodynamic behaviour. The applicability of the following models is evaluated: Dymond, Wilke–Chang, Tyn–Calus, Catchpole–King, Liu–Silva–Macedo, He–Yu–Su, Funazukuri and co-workers. The one-parameter correlation of Liu–Silva–Macedo achieves the best representation; He–Yu–Su is the best purely predictive model.