In-situ growth of FeSx nanosheets on iron foam as three-dimensional electrode for electrokinetic remediation of copper, lead and zinc co-contaminated soil

The combined contamination of heavy metals, such as copper, lead, and zinc, in soil poses a global environmental challenge, threatening soil quality, ecosystems, and human health. A novel three-dimensional electrokinetic (3D EK) system utilizing FeSx nanosheets loaded on iron foams (FeS@IF) as the third electrode was developed to enhance the electrokinetic remediation of co-contaminated soils. The application of this system achieved significantly higher removal efficiencies for Cu (34.73% vs 15.79%), Pb (36.85% vs 26.14%), and Zn (47.79% vs 29.43%) compared to traditional two-dimensional electrokinetic remediation. Soil pH was maintained within a near-neutral range (6.37–7.34), while the stability of residual heavy metals was enhanced, increasing the proportion of Zn in the residual fraction from 50.3% to ~75.0%. The system electrolytes were reusable, and the recyclable FeS@IF electrode avoided the release of heavy metals back into the soil. The synergistic effects of high electrical conductivity, soluble iron content, and adsorption capacity of the FeS@IF electrode were key to its superior performance. Additionally, microbial community analysis revealed an increase in bacterial abundance. In conclusion, this work demonstrates an efficient and environmental-friendly 3D electrode system for soil remediation, offering a sustainable solution for reducing heavy metal pollution and protecting the environment and human health.