ELECTROOSMOTIC REMOVAL OF GASOLINE HYDROCARBONS AND TCE FROM CLAY

This laboratory study examines the application of electroosmosis (EO) for removal of hydrocarbons from clay. EO mobilization is conducted in 7.62-cm inside diameter (id) glass columns containing 30.48 cm of clay and tap water electrolyte. Iron electrodes are used to impress a 0.4-volt/cm DC electrical gradient. Destructive sampling of columns following various periods of EO treatment results in breakthrough curves describing relative hydrocarbon contaminant mobilization. EO flushing of dissolved organic chemicals in fine-grained soils can be predicted using traditional contaminant-transport equations, which incorporate advection, dispersion, and adsorption. Chemicals with relatively high water solubilities and low distribution coefficients (i.e., benzene, toluene, trichloroethylene (TCE), and m-xylene) are easily removed from Kaolin by EO. Chemicals with a low water solubility and high distribution coefficient (i.e., hexane and isooctane) are transported from the clay at a slower rate. EO has the potential to remove hydrocarbons from fine-grained soils. Additional laboratory- and bench-scale studies will be needed before the feasibility of the technique in field applications can be determined.