Surfactant-enhanced electrokinetic remediation of hydrocarbon-contaminated soils

Abstract

Concern over soil and groundwater contamination has created a demand for new and efficient remediation technologies. Surfactant-enhanced electrokinetic remediation is an innovative technique which has the potential to remove hydrocarbons from contaminated clay soils faster and more efficiently than conventional remediation methods. The main objectives of this research were to (1) evaluate the efficiency of using surfactant-enhanced electrokinetic remediation to remove hydrocarbons from contaminated soil columns in the laboratory; (2) identify the effect of various physical and chemical factors on the performance of electrokinetic remediation; and (3) develop equations to model surfactant-enhanced electrokinetic remediation. Research was also conducted on expanding and improving the analytical methods using the relatively new solid-phase microextraction technique for the determination of hydrocarbon concentration in water. The soil column experiments indicate surfactant-enhanced electrokinetic remediation with sodium dodecylsulfate (SDS) is dominated by electrophoretic transport of micelles. The application of a surfactant increased the current through the soil which led to increased electrolysis of water. Pore fluid flow was also significantly greater in clay columns with an applied voltage potential gradient... Surfactant-enhanced electrokinetic remediation was modelled by adapting the classical advection-dispersion-retardation equation to include a modified retardation factor and electrokinetic effects. The model results were highly dependent on the input parameters chosen. Modelling results indicate that electrophoretic transport of hydrocarbons in SDS micelles is the dominant factor influencing transport during surfactant-enhanced electrokinetic remediation. In order to utilize electroosmotic flow, the voltage potential gradient should be greater than 1 V/cm. Surfactant-enhanced electrokinetic remediation is still an emerging technology and a greater understanding of the factors involved is necessary before decontamination can be confidently applied in the field. However, this research significantly adds to the knowledge of surfactant-enhanced electrokinetic remediation.