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Environmental Engineering Research 1997;2(4): 251-260.
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Combined Supercritical Fluid Extraction with Carbon Adsorption and Counterflow Oxidative Regeneration for Contaminated Soil |
Keon Sang Ryoo† |
Department of Chemistry, Andong National University, Andong, Kyongbuk 760-749, Korea |
Corresponding Author:
Keon Sang Ryoo , |
Received: May 10, 1997; Accepted: November 11, 1997. |
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ABSTRACT |
An comprehensive technique for supercritical fluid extraction (SFE) and adsorption by activated carbon, following cxninterflow oxidative regeneration (COR) was examined for both extraction and destruction of contaminated organic compounds in soil This approach was based on the laboratory bench scale Supercritical fluid extraction was performed to evaluate extraction efficiencies for a variety of analytes such as chlorinated phenols (CPs) and polychlorinated biphenyls (PCBs). Extraction efficiency up to 83% for PCBs was obtained with supercritical CO2 fluid at 0.75g/ml (177atm, 323K) and a marked improvement was brought about by introduction of MeOH (2% w/w) as a polar modifier. Activated carbon was used as a trapping material for adsorption of chlorinated aromatics after SFE. Average adsorption efficiencies ranged between 92% and 97% for chlorinated aromatics, and nearly all of the aromatics adsorbed were completely destroyed, while a small portion of carbon was consumed, by a counterflow oxidative regeneration. Furthermore, adsorptive capacity of the craitarninated carbon was largely recovered after regeneration, and any toxic chemicals such as polychlorinated dibenzo-p-dioxins (PCDDs) or polychlorinated dibaizofurans (PCDFs) over GC/MS detection level of ppb were not found in the regenerated carbon or effluent gases. |
Keywords:
SFE | COR | Modifier | Chlorinated Aromatics | PCBs/PCDDs/PCDFs |
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