Electrokinetic remediation of chromium-contaminated soils: The potential for advanced materials in three-dimensional EKR approaches

Chromium (Cr) contamination in soils presents significant environmental and human health risks, necessitating the development of efficient and sustainable remediation strategies. Electrokinetic remediation (EKR) has emerged as a promising technique for heavy metal removal; however, its conventional application is hindered by challenges such as soil heterogeneity, poor electric field distribution, pH imbalances, and high energy consumption. The study begins by exploring chromium-soil interactions, highlighting the chemical behavior of Cr in soil matrices and the complexities associated with its remediation. It then discusses the limitations of conventional EKR, particularly regarding soil properties, poor electric field distribution, pH imbalances, and energy consumption. A key focus is the integration of advanced materials-including nanomaterials, biochar, conductive polymers, biopolymers, and aerogels-into EKR systems to enhance their performance. These materials facilitate charge transfer, increase ionic conductivity, and act as electrochemical catalysts, improving electrode reactions and electroosmotic flow. Specifically, they function as reactive barriers, auxiliary electrodes, and mobility enhancers, enhancing contaminant desorption, redox transformations, and targeted Cr migration. Special attention is also given to three-dimensional electrokinetic remediation (3D-EKR) approach, which leverages these materials to generate a more uniform and intensified electric field, buffer pH fluctuations through redox-active surfaces, and increase contaminant removal efficiency by enabling selective ion transport and enhanced electrochemical interactions. The review concludes with perspectives on future research directions to optimize material-assisted EKR for sustainable soil remediation and the role of interdisciplinary approaches in advancing this technology.