MODELING OF SUPERCRITICAL EXTRACTION OF ORGANICS FROM SOLID MATRICES

The desorption profiles of various organics from soil and activated ca rbon using dense liquid and supercritical carbon dioxide were modeled. The model accounts for effective diffusion of the organics in the sol id pores, axial dispersion in the fluid phase, and external mass trans fer to the fluid phase from the particle surface. This model, involvin g partial differential equations, is solved using the orthogonal collo cation on finite elements. The model is able to predict the experiment al data quite well without any adjustable parameters. The importance o f each parameter depended on the system, although adsorption equilibri um and the effective pore diffusion of the organic were the most signi ficant parameters in all the systems investigated.