Supercritical fluid extraction of polycyclic aromatic hydrocarbons (PAH) from native soil and fly ash with pure and modified carbon dioxide and dimethylether

Polycyclic aromatic hydrocarbons (PAH) and alkyl-PAH in the lower mg/kg range were extracted from soil and fly ash. Extraction yields were measured for toluene Soxhlet, supercritical carbon dioxide, toluene modified carbon dioxide, and toluene modified dimethylether (DME) extractions. Pure DME similarly to toluene Soxhlet extraction enhances extraction 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 DME (50 mg/kg) yield much better extraction yields than Soxhlet (32 mg/kg) or pure supercritical fluid extractions. Received: 19 July 1996 / Revised: 23 September 1996 / Accepted: 22 October 1996