Removal of hazardous contaminants from soils by supercritical fluid extraction

Experimental data and a mathematical model are presented for the desorption of pure naphthalene and 1,2,4 trimethylbenzene from soil with supercritical CO2 as solvent. The linear driving force concept was employed to incorporate intraparticle diffusion as well external mass transfer. The experimental data was approached as a concentration history of solute desorption at different flow rates. A simulation has been performed using an equilibrium desorption model where the rate of desorption is controlled by external and intraparticle mass transfer and solved using software. This model has been proved to be accurate in predicting the desorption profiles from organic contaminants over a range of operating conditions. From the experimental data, adsorption equilibrium constants and overall mass transfer coefficients are obtained using the model. The results indicate that external mass transfer was significant at very low now rates, and intraparticle diffusion resistance was found to be significant for the particle size studied.