The main objective of this research is to exploit the possibility of using an ex situ solvent extraction technique for the remediation of
soils contaminated with semi-volatile petroleum hydrocarbons. The composition of the organic phase was chosen in order to form a single
phase mixture with an aqueous phase and simultaneously not being disturbed (forming stable emulsions) by the soil particles hauling the
contaminants. It should also permit a regeneration of the organic solvent phase.
As first, we studied the miscibility domain of the chosen ternary systems constituted by ethyl acetate–acetone–water. This system proved
to satisfy the previous requirements allowing for the formation of a single liquid phase mixture within a large spectrum of compositions, and
also allowing for an intimate contact with the soil.
Contaminants in the diesel range within different functional groups were selected: xylene, naphthalene and hexadecane. The analytical
control was done by gas chromatography with FID detector.
The kinetics of the extractions proved to be fast, leading to equilibrium after 10 min. The effect of the solid–liquid ratio on the extraction
efficiency was studied. Lower S/L ratios (1:8, w/v) proved to be more efficient, reaching recoveries in the order of 95%. The option of
extraction in multiple contacts did not improve the recovery in relation to a single contact. The solvent can be regenerated by distillation with
a loss around 10%. The contaminants are not evaporated and they remain in the non-volatile phase.
The global results show that the ex situ solvent extraction is technically a feasible option for the remediation of semi-volatile aromatic,
polyaromatic and linear hydrocarbons
