Investigating the Extraction of Lead and Zinc from the Zinc Processing Residue Using the Enhanced Electrokinetic Process

Abstract

Heavy metal contamination in soil has already become a global problem, increasingly endangering the environment and human health. Various methods are known for the reclamation of soils contaminated with heavy metals and can typically be performed on-site or off-site. Electrokinetic (EK) remediation is a promising remediation technology for soils contaminated with inorganic, organic, and mixed pollutants. Electrokinetic remediation is a technique for soil, sediment, and groundwater purification based on a direct current electric field applied to a contaminated matrix to extract contaminants through a combined mechanism of electroosmosis, electromigration, and electrophoresis. Among the various available treatment techniques, electrokinetic remediation is considered particularly suitable for the treatment of fine-grained soils with low hydraulic conductivity and high specific surface area. However, the effectiveness of this technique can be influenced by various effects caused by the adsorption of pollutants on the soil particle surface and by the hydrogen ions and hydroxide ions produced at the electrodes. In this study, electrokinetic technology was applied to mainly remove the heavy metals (Pb, Zn) in real contaminated soil. For this purpose, the effects of EDTA, citric acid, nitric acid, and distilled water were investigated. An EK remediation reactor (24 cm in length) equipped with a DC electric current (maximum value of 24 V) was used. Graphite electrodes were used for both the anode and cathode and were set up for 1 week of operation. As a result, only 33% of Pb and 55% of Zn were removed from the soil section without pH control.