Mechanisms of electrokinetic technology to remediate different soils contaminated by cadmium

Five typical soils were selected as Cd-contaminated media in an electrokinetic remediation experiment, to reveal comprehensive relationships between soil physicochemical properties and electrokinetic remediation. Results showed that after 20 days of remediation, removal efficiencies of Cd from red soil, black soil, yellow brown soil, fluvo-aquic soil, and paddy soil were 80.8%, 79.3%, 78.2%, 62.7%, and 74.1%, respectively. Levels of soil pH, conductivity, cation exchange capacity in fluvo-aquic soil and paddy soil treatments were generally higher than the other three types of soils, which indicated some connections between Cd removal efficiencies and the above soil characteristics. Pearson correlation analysis showed that soil H+ concentration was significantly correlated with Cd concentration and soil cation exchange capacity, and the correlation coefficients were -0.462 and -0.457, respectively. It is confirmed that H+ concentration is one of the important factors affecting the electrokinetic remediation of soil polluted by Cd.