Roles of surfactant, oxidant and activator on enhanced electrokinetic-persulfate technique for the removal of hydrophobic organic compounds in soil: A review

Researchers have explored electrokinetic remediation (EKR) for two decades due to its applicability, cost-effectiveness, flexibility, and wider scope for the soil remediation of organic and inorganic contaminants. The integration of the EKR technique with persulfate-based advanced oxidation has received considerable attention recently. Persulfate (PS) can degrade into strong oxidants, such as sulfate (SO4•−) and hydroxyl radicals (•OH), which can degrade most of the hydrophobic organic contaminants (HOCs) in soil. Various studies have discussed the efficiency, synergistic effects, and futuristic scope of the EKR-PS technique. However, research on the challenges and limitations of the EKR-PS technique is limited. This review summarizes bench-scale studies of EKR-PS techniques, where new knowledge and insights have emerged, particularly regarding the role of surfactants, oxidants, and activators in the effective degradation of HOCs in low-permeability soils. We emphasize that it is essential to update our understanding of the enhanced EKR-PS technique in order to apply it to the remediation HOCs at the field level. Future research directions are also discussed.