A MICROEMULSIFICATION APPROACH FOR REMOVING ORGANOLEAD AND GASOLINE FROM CONTAMINATED SOIL

Remediation of soils contaminated with leaded gasoline due to leakage, spillage, and inappropriate disposal is an important environmental co nsideration. Columns of a loam soil initially saturated with saline so lution (aqueous 0.01 M NaCl) were contaminated with 48 ml of leaded ga soline. The contaminated soil columns were then flushed sequentially w ith saline and surfactant/cosurfactant/water (S/CoS/W) solutions in or der to investigate removal efficiencies for residual tetraethyl lead ( TEL) and gasoline components. As expected, the saline solution immisci bly displaced only limited amounts of mobile gasoline and associated T EL (dissolving in gasoline) components from the soil columns. However, immobile or residual gasoline and associated TEL entrapped in the soi l pores were removed primarily as the S/CoS/W solution produced leaded -gasoline-in-water (LG/W) microemulsions. The S/CoS/W solution removed 95% of the immobile gasoline and 90% of the immobile Pb from the soil columns when the initial saturation of leaded gasoline was approximat ely 30% (or 48 ml) in the soil columns. Mass balance analysis shows th at one gram of surfactant (sodium lauryl sulfate) removed 0.6 g of imm obile gasoline and 2 mg of immobile Pb from the soil. These immobile g asoline and immobile Pb were not removable by NaCl solution.