Supercritical carbon dioxide extraction of organics from soil

Article Abstract:

Little is known about the adsorption/desorption equilibria and thermodynamic modelling of organic pollutants in the soil when supercritical carbon dioxide (SCCO2) is present, and a recent study therefore looked at the adsorption isotherms for phenanthrene, naphthalene, pentachlorophenol and hexachlorobenze on soil where both liquid and supercritical carbon dioxide existed. The adsorption heats of these organics were recorded at 1-5 kcal/mol, showing physical adsorption. It was possible to predict the desorption profiles with reasonable accuracy using local equilibrium theory.

Industrial organic chemicals, not elsewhere classified, Analysis, Soil research

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Investigation of adsorption equilibria of volatile organics on soil by frontal analysis chromatography

Article Abstract:

Soil gas extraction has been used with some success to remove potentially toxic or explosive gases from soils, but certain engineering data need to be calculated to determine the optimum flow rate, the pressure head, proper well placement and the right amount of adsorbent. Among these is the adsorption isotherm, the relation of the gas-phase concentration of contaminant to the concentration during the soil phase. Frontal analysis chromatography on six organic contaminants revealed that adsorption was uniform over all available surface area of the soils.

Research, Soil pollution, Gas extraction, Natural gas gathering

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Mathematical modeling of adsorption and desorption of volatile contaminants from soil: influence of isotherm shape on adsorption and desorption profiles

Article Abstract:

Adsorption and desorption profiles of volatile organic compounds (VOCs) on/from dry soil are predicted using a mathematical model. Results showed that the desorption breakthrough profiles reveal a plateau section if a certain limit is exceeded by the initial soil loadings of the VOCs. This plateau is explained with the existence of a desorption hysteresis phenomena. Desorption curves obtained following the adsorption and desorption branches of the isotherm are compared to determine the effect of the desorption hysteresis.

Models

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