Determination of Binary Diffusion Coefficients of Benzene, Phenol, Naphthalene and Caffeine in Supercritical CO₂ between 308 and 933 K in the Pressure Range 90 to 160 gar with Supercritical Fluid Chromatography (SFC)

Abstract

Abstract Binary diffusion coefficients D12 have been determined for benzene, phenol, naphthalene and caffeine in supercritical CO2 at 40°C between 80 and 160 bar using the chrpmatographic peak-broadening method (CPB). The observed diffusion coefficients are of the order of 10−4 cm2/s and decrease by about 50% for a pressure rise from 80 to 160 bar. For naphthalene in CO2 the effect of temperature on D12 was investigated between 35 and 60°C at a constant C02 density of 0.6 g/cm3; the energy of activation was found to be 4.7 kJ/mol, With increasing molecular size and polarity of the diffusing compound, adsorption effects are observed which can lead to serious errors.