Mengwei Li a b, Guangli Xiu a b, Wei Zhang a b

DOI: 10.1016/j.cej.2025.172132

https://doi.org/10.1016/j.cej.2025.172132

Abstract

       The effectiveness of different types of humic substances (HS) in electrokinetic remediation combined permeable reactive barrier (EK-PRB) technique for remediating PFOA-contaminated soil and their impact on soil pore structure remain unclear. This study explored the distinct mechanisms by which various HS regulate PFOA removal during EK-PRB remediation. Fulvic acid (FA), due to its higher solubility and stronger electron acceptor capacity, moderately enhanced the electric field conditions and soil properties, achieving a removal efficiency of 96.18 % after 21 d. Additionally, FA-treated soil exhibited higher porosity (52.05 %) and a stable micropore structure, which facilitated more efficient PFOA transport and removal. In contrast, humic acid (HA) induced significant changes in soil pore structure, particularly under acidic conditions, forming aggregates that hindered PFOA migration and retention. The removal efficiency for HA was 93.35 %, which was lower than the control group (94.87 %). Density functional theory analysis further confirmed FA's stronger electric field responsiveness and enhanced PFOA migration under an applied electric field. Furthermore, multidimensional analysis revealed that “electrochemical driving + pore structure regulation” was the core synergistic mechanism for PFOA removal in EK-PRB remediation. These findings provide theoretical support and practical guidance for the application of EK-PRB remediation in the remediation of PFOA-contaminated soils.

Graphical abstract