State‐of‐the‐art on the supercritical extraction of organics from hazardous wastes

Influence of water on the supercritical fluid extraction of naphthalene from soil

Supercritical fluid extraction (SFE) is an innovative soil remediation technology. To aid system evaluation and design, thermodynamic and kinetic parameters have been measured using a naphthalene contaminated, loamy sand at various water contents. The experimental results show that supercritical carbon dioxide can easily extract naphthalene from soil when the water content is below 10%. At low water contents, mass transfer is rapid and the equilibrium partition coefficient is independent of the soil's water content. However, the overall mass transfer coefficient, (kova), decreases by at least a factor of 200 as the water content increases from 10 to 20%.

Directly coupled supercritical fluid extraction-gas chromatographic analysis of polycyclic aromatic hydrocarbons and polychlorinated biphenyls from environmental solids

A method has been developed for the direct coupling of supercritical fluid extractions with gas chromatography (SFE-GC) that yields good chromatographic peak shapes and quantitative recovery of analytes from environmental solids with a total extraction and analysis time of less than one hour. Maximum sensitivity is achieved and analyte degradation or loss is minimized since the extracted species are quantitatively transferred into a fused-silica capillary gas chromatographic column for cryogenic focusing followed by normal GC analysis using flame ionization, electron-capture, or mass spectrometric (MS) detection. Coupled SFE-GC-MS determinations of polycyclic aromatic hydrocarbons from National Bureau of Standards urban dust (SRM 1649) gave excellent agreement with certified values.