Investigation of the effect of surfactant on the electrokinetic treatment of PFOA contaminated soil

Abstract

Perfluorooctanoic acid (PFOA) is a persistent, nonbiodegradable environmental pollutant progressively becoming more problematic. Due to its ubiquitous use, PFOA is one of the PFAS chemicals frequently detected in the environment. This study assessed electrokinetic (EK) technology as an in-situ remediation procedure to remove PFOA from kaolinite as a model soil. In this study, a 100 mg/kg of PFOA/kaolinite mixture was used, and the effectiveness of the unenhanced EK was compared with the surfactant-enhanced EK experiments with SDS, NaC, and Tween80. 5% (w/w) surfactants were added to the cathode in the EK experiments of one and two weeks long. The study evaluated the impacts of processing time and electric current on the EK performance. Electroosmosis and electromigration mechanisms affected PFOA transport in soil, causing PFOA to accumulate in the middle of the soil. However, the minimal accumulation of PFOA in the cathode region suggests that electromigration was the main transport mechanism. In a one-week EK experiment, the PFOA removal efficiency in the unenhanced EK process was 14.49% at 10 mA and 19.00% at 20 mA, while in surfactant enhanced EK, it was 17.67% at 10 mA and reached 32.66% at 20 mA. The PFOA removal in surfactant enhanced EK reached 75.58% in the two weeks EK experiments carried out at 20 mA. The NaC-EK experiment exhibited the highest PFOA removal, followed by the SDS-EK experiment and TW80-EK experiment. The outcomes show the feasibility of removing PFAS from contaminated soil using the surfactant-enhanced EK technique. • Enhanced EK for the removal of PFOA from kaolinite soil using three types of surfactants. • PFOA removal from kaolinite doubled by increasing the EK duration from 1 to 2 weeks. • PFOA removal is in the following order EK-NaC > EK-SDS > EK > EK-TW80. • NaC-EK tests achieved 75% PFOA removal, the highest among all surfactant-EK tests.