Surfactants for Electrokinetic Remediation of Hydrophobic Organic Contaminants in Soil–Water Systems

Hydrophobic organic compounds (HOCs) in water–soil systems pose persistent risks to pore water quality and groundwater safety because of their low aqueous solubility and strong soil sorption affinity. Electrokinetic remediation has emerged as a promising technology for controlling HOCs in contaminated water–soil systems, as it can regulate pore water movement, ionic migration, and contaminant transport under an applied electric field. However, the limited transfer of HOCs from soil into the aqueous phase restricts their electrokinetic removal efficiency, necessitating the use of surfactants to overcome these technical bottlenecks. This review elucidates the mechanistic basis of surfactant-enhanced electrokinetic remediation, with particular emphasis on micellar solubilization in pore water, contaminant desorption from soil matrices, and electrically driven transport across water–soil interfaces. Building on this mechanistic framework, the applications and performance of nonionic, anionic, cationic, biosurfactant, and mixed surfactants are summarized. Furthermore, the key factors governing surfactant efficacy are analyzed, including soil properties, contaminant characteristics, remediation objectives, operational parameters, environmental safety, and economic feasibility. By integrating mechanistic insights with environmental considerations, this review establishes a science-based framework for surfactant selection in electrokinetic remediation. This work provides a reference for enhancing contaminant transfer from soil matrices to the aqueous phase, reducing secondary risks to pore water and groundwater, and advancing the theoretical development and implementation of surfactant-enhanced electrokinetic remediation in environmental management.