Enhanced electrokinetic remediation of Cd and Pb spiked soil coupled with cation exchange membrane

Electrokinetic (EK) remediation is one of the popular and promising in situ remediation techniques for metal-contaminated soils, but the remediation effect is strongly affected by soil type and chemical species of contaminants; moreover, pH is very difficult to control. This paper investigates the species of cadmium (Cd) and lead (Pb) in simulating contaminated soil before and after EK remediation, and the soil is a typical silt loam soil from Shanghai. Heavy metal speciation in the soil sample was analysed through a sequential extraction procedure. Cation-exchange membrane (CEM) and conductive solution were applied to improve the remediation efficiency. Both methods help to keep acid conditions and CEM can prevent anions in the cathodic compartment from penetrating into the soil sample system. The pH of the soil specimen was acidic during the test, and Cd was quickly removed from the soil while Pb was removed more slowly. The average removal efficiencies of Cd and Pb were 68.7 and 38.7%, respectively, after 60 h of remediation.