Comparison of the crude oil removal effects of different surfactants in electrokinetic remediation of low-permeability soil

Comparison of the crude oil removal effects of different surfactants in electrokinetic remediation of low-permeability soil

Crude oil

Surfactant

Soil remediation

EK remediation

Low-permeability soil

Remediation

Petroleum transportation

Leakage (fluid)

Soil pollution

Soils

Sulfur compounds

Sodium dodecyl sulfate

Nonionic surfactants

Micelles

Soil conservation

Electroosmosis

Crude oil leakage during production, transportation and storage has polluted large soil areas. If improperly treated, this could seriously threaten human health. In this study, low-permeability soil was selected as the contaminated target because it has been proven to be hardly treated with common technologies. Spiked soil was treated in an EK cell at 1V/cm for 15 days with different surfactants, including an anionic surfactant, sodium dodecyl sulfate (SDS), biosurfactant, rhamnolipid (Rham) and nonionic surfactant, Tween 80. Experimental dependent variables, including current, electroosmotic flow (EOF), gas volume, residual crude oil concentration and components in the restored soil were monitored and analyzed. The results indicated that the produced gas and current followed the sequence of SDS > Rham > Tween 80, but the overall efficiency of the surfactants regarding crude oil removal from soil followed the order of Tween 80 > Rham > SDS, corresponding to 18.05%, 14.06%, and 9.35%, respectively, agreeing with the EOF sequence. It is proposed that the EOF is closely related to pollutant removal, and the relatively low SDS and Rham removal levels were mainly related to the electromigration/electrophoresis reduction in micelles. Furthermore, experimental result analysis revealed that the light oil phase proportion in the surfactant-treated samples decreased, while the heavy component proportion increased, regardless of the surfactant type. Hence, surfactant-enhanced EK remediation may be unsuitable for low-permeability soil with a high heavy oil proportion, which may be a notable limitation of this technology.

Journal of Environmental Chemical Engineering

2021

2021-02-11

Li, Yunlong

Jiang, Liguo

journalArticle

2213-3437

10.1016/j.jece.2021.105190

https://www.sciencedirect.com/science/article/pii/S2213343721001676