SUPERCRITICAL CARBON-DIOXIDE EXTRACTION OF ORGANICS FROM SOIL

The adsorption isotherms for naphthalene, phenanthrene, hexachlorobenz ene, and pentachlorophenol on soil were determined in the presence Of liquid and supercritical carbon dioxide. The adsorption isotherms for naphthalene, phenanthrene, and hexachlorobenzene are linear, whereas f or pentachlorophenol, a slight deviation from linearity was observed. The heats of adsorption of naphthalene, phenanthrene, hexachlorobenzen e, and pentachlorophenol on soil at 308 K were found to be in the rang e of 1-5 kcal/mol, indicating physical adsorption. The desorptive beha vior of these organics from soil using supercritical carbon dioxide wa s also investigated, and local equilibrium theory was found to predict the desorption profiles fairly accurately.