Kinetics of the extraction of pyrene using carbon dioxide in dense phase

Bath extraction experiments of pyrene from two spiked soils with different textural composition (sandy, sandy-clay) were performed with near-critical and supercritical CO2 at different pressures (7.5, 15, 20, 25 MPa) and temperatures (40, 50, 60 °C) in order to obtain mass transfer rate data. An empirical equation whose parameters depend on type of soil but are independent of pressure and temperature is proposed. The comparison between individual mass transfer coefficients shows that the extraction is controlled by the resistance within the particle. Effective diffusivities between 0.4 and 6.0 × 10−10 m2/s are deduced.