Experimental study on electrokinetic remediation of cadmium-contaminated clayey soil

A self-designed electrokinetic remediation device is used to carry out the soil column tests on cadmium- contaminated clayey soil. The removal mechanism of cadmium in soil is explored by analyzing the removal effects of cadmium in a soil column, the microstructural change of contaminated soil before and after remediation and the species analysis of cadmium. The results show that when the initial concentration of cadmium is relatively small, the removal rate of cadmium increases remarkably when increasing the voltage, since the unstable cadmium migrates faster at greater voltage. When the initial concentration of cadmium is relatively great, the residual content of cadmium exhibits a gradual increase trend from the anode to cathode. After the electrokinetic remediation, the appearance of soil particles changes from a spherical cohesive structure to a smooth and loose one. When the voltage is 40 V, about 95 % of the weak acid extractable and reducible cadmium is removed from the soil, and the residual cadmium in the soil column after remediation is about 60 % of the total cadmium, which effectively reduces the toxicity of the cadmium-contaminated soil.