Electrokinetic Remediation Coupled with CaMnO ₃ -Catalyzed Peroxydisulfate Activation for Polychlorinated Biphenyls–Contaminated Soils

The electrokinetic remediation (EKR) of organic contaminants has recently attracted interest due to its applicability in low-permeability soils and its suitability for large-scale applications. Polychlorinated biphenyls (PCBs) were once used as dielectric fluids in electrical equipment, such as transformers and capacitors. Due to their persistence and hydrophobicity, PCBs have been detected in all environmental matrices, including air, water, soil, sediment, and biological samples. In response to the mounting evidence of bioaccumulation and adverse health effects, the production and use of PCBs were discontinued. Despite bans and regulations, PCB levels remain high in the soils of developing countries. Hence, remediation of contaminated sites is paramount. Recently, electrokinetic remediation (EKR) has emerged as a promising technique, particularly in soils with low permeability. However, the EKR-persulfate technique for the remediation of PCB-contaminated soils poses challenges due to PCBs’ recalcitrant and hydrophobic properties. The present study used a bench-scale reactor to investigate the effect of CaMnO3 and the surfactant Tween 80 as enhancing agents for the EKR of PCB-contaminated soils. The batch experiments identified 3% Tween 80 and 10% peroxydisulfate activated by 0.625 g of CaMnO3 as optimal PCB extraction and removal dosages. Under optimized conditions, the PCB removal efficiency increased with the electroosmotic flow (EOF). The peroxydisulfate activation led to the generation of SO4∙− and •OH radicals, which have a higher potential for PCBs degradation. The results showed a significant removal of PCBs from the soil, with the highest removal efficiency of 64% (mean value for six PCB congeners). The low-cost and eco-friendly Ca- and Mn-containing materials have promising applications in the remediation of PCB-contaminated soils. The findings of this study showed that surfactant-assisted EKR can be an effective solution for PCB-contaminated soils.