Experiment study and mechanism analysis of chelating agent enhanced on electrokinetic removal of copper and lead from loess

The rapid development of western China has resulted in a growing problem of heavy metal pollution in the land. Electrokinetic remediation has gained attention due to its great maneuverability. However, certain factors such as polarization phenomena and precipitation of heavy metals near the cathode have lead to a decrease in the efficiency of electrokinetic remediation. Therefore, this article focuses on studying copper-lead contaminated loess as the subject of research. It combines the technology of chelating agent coupling electric remediation with the addition of catholyte, and investigates the effects of tartaric acid, citric acid, and EDTA as cathode electrode liquid on the removal efficiency of copper and lead metals in loess. The article also aims to explore the influence of these substances on the removal efficiency and understand the underlying removal mechanism. The results indicate that tartaric acid, citric acid and EDTA can enhance the migration ability of copper and lead through complexation, thereby improving the removal efficiency of these metals to varying estents. The improvement in the removal efficiency of copper and lead metals is particularly noticeable in the vicinity of the cathode. Among the three chelating agents, EDTA exhibits strong chelating ability and can react with copper and lead metals across different pH ranges, resulting in the formation of a more stable complex and enhancing the removal efficiency. Compared with the control group, EDTA forms a stable complex by coordinating with heavy metals through six atoms, converting them into exchangeable states with enhanced migration capabilities, and making them easier to remove. As a result, the overall removal efficiency of copper and lead increased to 55.4% and 27.2%, respectively.