EFFECTS OF ELECTRIC FIELD DIRECTIONS ON SURFACTANT ENHANCED ELECTROKINETIC REMEDIATION OF DIESEL-CONTAMINATED SAND COLUMN

摘要

The removal of diesel from a sandy soil column was conducted by surfactant enhanced electrokinetic remediation process to study the effects of the electric field direction on the diesel removal efficiency. Anionic surfactant SDS (sodium dodecyl sulfate) was fed to one of the electrode chambers driven by electrokinetics and/or a pump. When an electric current was applied while SDS was fed to anode chamber at a constant rate by pump, an effluent flowrate higher than the feeding rate was obtained at cathode side because the directions of electroosmosis and pumped convective flow were identical. Meanwhile, when SDS was fed to cathode chamber by pump in the presence of an electric current, a lowered effluent flowrate was obtained, where the directions of electrosmosis and pumped flow were opposite. In this case, however, the diesel removal rate and total recovered amount of diesel were substantially increased compared to the case that SDS was fed to anode side. Results implied in SDS transport through the soil column that the electrophoretic transport of SDS anion towards anode was dominant over the retardation of SDS transport by the electroosmosis flowing towards cathode. The diesel mobilization would be achieved by solubilization of diesel components into SDS micelles and thus by transporting of SDS-diesel complexes together convectively and electrophoretically towards anode side.