SUPERCRITICAL-FLUID EXTRACTION OF POLYCYCLIC AROMATIC-HYDROCARBONS (PAH) FROM NATIVE SOIL AND FLY-ASH WITH PURE AND MODIFIED CARBON-DIOXIDEAND DIMETHYLETHER

Polycyclic aromatic hydrocarbons (PAH) and alkyl-PAH in the lower mg/k g range were extracted from soil and fly ash. Extraction yields were m easured for toluene Soxhlet, supercritical carbon dioxide, toluene mod ified carbon dioxide, and toluene modified dimethylether (DME) extract ions. Pure DME similarly to toluene Soxhlet extraction enhances extrac tion yields (32 mg/kg) as compared to pure carbon dioxide (21 mg/kg). In particular, higher molecular weight PAH are extracted with pure DME . 5% Toluene modified carbon dioxide (43 mg/kg) and toluene modified D ME (50 mg/kg) yield much better extraction yields than Soxhlet (32 mg/ kg) or pure supercritical fluid extractions.