###### Abstract  
Electrokinetic (EK) remediation methods can remove heavy metals from the soil, but the removal efficiency is generally low. In this paper, indoor remediation experiments of simulated copper-contaminated clay under four different types of electrolyte conditions (KCI, HAc, AC, and PASP (polyaspartic acid)) are carried out to validate the theory of an electrodynamically coupled steel slag permeability reactive wall (PRB). By comparison with EK remediation, it has been shown that the EK-PRB coupled remediation method can promote the removal of heavy metal copper in the soil, especially in the removal of reducible copper and exchangeable copper. The method can effectively avoid the increase in soil pH value and reduce the accumulation range of heavy metals while reducing the accumulation amount of heavy metals. This method has better energy utilization efficiency, and the unit energy consumption is smaller than the single electric remediation test. Electrokinetic remediation; steel slag; permeable reactive barrier; electrolytes; Cu-contaminated clay 202220220221 July 202220221 July 20220220222 July 20222022 July 202222 July 202222 July 202222 July 202222 July 202222 July 202222 July 2022222 July 2022222 July 2022222 July 2022222 July 20222222  
pollutants to migrate to the end of the soil column by electromigration, electroosmotic flow, electrophoresis, and diffusion [10]. Compared with other technologies, electrokinetic remediation can be performed in situ, even in low permeability soil, and is characterized by stability, high efficiency, and low cost [11]. The pH of the soil is one of the important factors affecting the efficiency of electrokinetic remediation, which can change the existing form of heavy metals in soil, and affect the process of heavy metal adsorption-desorption, and precipitation-dissolution. Generally, in the process of remediation, the electric current value increases with the increase in voltage, and it also consumes more energy. At the same time, when the voltage increases, the removal rate of heavy metals also increases significantly. Studies have shown that adding complexing agents can effectively improve the efficiency of electrokinetic remediation. As an electrolyte, the complexing agent can neutralize the OH\({}^{-}\) generated by water electrolysis and effectively control the pH value of the soil. The complexing agents can react with heavy metal ions to form metal complexes, which enhance the solubility of heavy metals. Many studies have explored the remediation effects of EK on contaminated soil, in which sulfuric acid, KCl, and acetic acid have been used as electrolytes to remediation Cu-contaminated soil. It has been reported that no obvious removal is observed when sulfuric acid is used, and the removal efficiency reaches 15-31% and 18-30%, respectively, when KCl and acetic acid are used [12; 13; 14]. In order to enhance the electrokinetic remediation effect, chelating and complexing agent solutions are applied that can combine with toxic metals and convert them into soluble metal-chelating complexes and coordination complexes to improve the desorption efficiency of metals in soil. Common chelating and complexing agents include EDTA (Ethylene Diamine Tetraacetic Acid), NTA (Network Terminal Appliance), DTTPA (Diethylenetiaminepentaacetic acid), EGTA (Ethylenebis (oxyethylenemitrilio) tetraacetic acid), CA (Chemical Abstracts), and PASP (polyasparatic acid), etc. [15]. The first four species are expensive and will cause secondary pollution to the environment that can increase the potential toxicity to plants, so they are not suitable for application in practical soil remediation [16]. However, CA and PASP are non-toxic, chemically stable, and have strong ionic complexation ability because they include multiple-COOH groups that can form M-complexes. Therefore, they are environmentally friendly and economical complexing agents [17; 18; 19].