Comparison of the cadmium and lead removal from three soils by electrokinetic remediation

Abstract

Abstract The use of citric acid and ethylenediaminetetraacetic acid disodium as electrolytes on the removal of lead and cadmium from three soils were investigated for the first time by electrokinetic remediation. The experimental results showed that: under the voltage gradient of 2 V/cm and remediation time of 4 d, the best electrolyte for brown soil (ZR) was EDTA, and the removal rates of Cd and Pb were 17.8% and 13.2%, which were lower than those of red soil (HR)and black soil (BR). It seemed that electrokinetic remediation was less effective for ZR due to the high soil pH, and could combined with other remediation techniques to improve the efficiency. For HR, extending the remediation time to 10 d, the Cd removal rate reached 91.1% when the electrolyte was citric acid, and the Pb removal rate reached 63.2% when the electrolyte was EDTA. For BR, it was more sensitive to electrokinetic remediation technology, and the focusing phenomenon was serious. The removal rate of Cd in S1 of BR1 was 99%, and the focusing phenomenon occurs in S4 and S5 zones, resulting in an average removal rate of 22%, which could be improved by cathodic control; the removal rate of Pb in S5 of BR2 was 84.8%, and the focusing phenomenon occurred in S1, which could be improved by anodic control.