Modifier Effects in the Supercritical Fluid Extraction of Solutes from Clay, Soil, and Plant Materials

The effect of polar modifiers on matrix swelling has been examined under supercritical conditions. Plant materials and clays which would typically be used in supercritical fluid extraction have been examined. The extent of swelling of modifiersaturated plant and clay matrices was observed via a high-pressure sapphire view cell. Extractions of radiolabeled solutes from these matrices were conducted separately. The relationship between the extractability and the swelling in these materials was determined. A correlation based on these results suggested a mechanism to explain the interaction between the supercritical fluid, the modifier, and the matrix.