Electrokinetic Removal of Cd and Cu from Mine Tailing: EDTA Enhancement and Voltage Intensity Effects

Abstract

This study investigated electrokinetic removal of cadmium and copper from contaminated soil of the Koushk mine tailing dam. The effect of ethylenediaminetetraacetic acid (EDTA) 0.1 M as catholyte and NaOH 0.1 M as an anolyte was investigated. Two voltage gradients, 1 and 2 V/cm, were used in the study. Therefore, six sets of tests were conducted, five 10-day tests and one 13-day test. The study measured pH, electroosmosis flow, electric current, and the concentration of the target metals. The energy expenditure of each test was calculated based on the measured electrical current. The results indicate that usage of EDTA as the catholyte along with distilled water as anolyte did not enhance the cadmium and copper removal. This could be due to antagonistically affected results from competition between metal cations and the EDTA. Application of NaOH instead of distilled water as an anolyte incorporated with EDTA as catholyte showed better remediation results, which might be due to facilitating metal–EDTA movement and formation. A study on the voltage intensity revealed that higher voltage applications can improve metal removal. The final 13-day test showed better removal efficiency compared with similar 10-day test.