Improvement of the electrokinetic fluxes by tall fescue: Alleviation of ion attenuation and maintainability of soil colloidal properties

In this study, we aimed to address the attenuation of electrokinetic fluxes that occur during plant (tall fescue)-based electrokinetic remediation of oil-contaminated soil. Following 60 days of treatment, the concentration of water-soluble cations and anions in the electrokinetics-assisted phytoremediation treatment (EK-P) were 20.03 mg/kg and 15.7 mg/kg higher than that in the electrokinetic (EK) treatment, respectively. At the electrode, plants were able to alleviate the ion aggregation effect caused by the electrokinetics, reduce the conversion of soluble ions to insoluble ones, and reduce the decay of water-soluble ions. In addition, the zeta potential of EK-P was 5.05 mV lower than that of EK. Plants maintained the stability of the soil colloid and reduced the movement of the peak of colloidal particle size from small to large particles, thereby reducing the amount of colloidal deposition. Finally, the EK-P current was 22.49% higher than that in EK while the electrokinetic effect was maintained. Meanwhile, electrokinetics increased plant biomass by 20.21%. Electrokinetics was found to create a synergy with the plants, an effect that eventually enhanced the rate of oil degradation.