Removal of hydrocarbons from heterogenous soil using electrokinetics and surfactants

Abstract

Removal of hydrocarbons from sediments could be achieved using various techniques such as hydraulic flushing aided by surfactants, which works well for sand and gravel but not as effective for finer textured media, such as clay. Electrokinetics (EK) emerged as an effective method to remediate fine-grained soils, especially when combined with the application of surfactants. Here, we analyzed the removal efficiency of EK and a nonionic surfactant (Tween 80) when applied through a fine soil (80% clay) contaminated with n-hexadecane. The study compared the EK results with hydraulic flushing under the same surfactant concentration. After 18 days of treatment, EK removed 80%, which was significantly more efficient than hydraulic flushing which removed 52%. The investigation revealed that EK causes the surfactant to tackle the clayey soil from various directions due to the whole aquifer's electrification. This would be an advantage in field studies as it precludes the need to place numerous electrodes into the soil, as done in hydraulic flushing where multiple wells are placed to direct the surfactant's movement.