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

Abstract

This study investigated, for the first time, the efficacy of citric acid (CA) and ethylenediaminetetraacetic acid (EDTA) as electrolytes in electrokinetic remediation (EKR) for removing lead (Pb) and cadmium (Cd) from three distinct soils (Anthrosols soil, AT; Acrisols soil, AC; and Chernozems soil, CH). Under a voltage gradient of 2 V/cm and a remediation duration of 4 days, EDTA proved most effective for Anthrosols, achieving removal rates of 17.8% for Cd and 12.8% for Pb-lower than those observed for Acrisols and Chernozems, likely due to AT’s high pH background. These results suggest that combining EKR with other remediation techniques could enhance efficiency for such soils. For Acrisols soil, extending the remediation time to 10 days significantly improved metal removal: Cd removal reached 91.1% with CA, while Pb removal attained 62.7% with EDTA. Chernozems soil exhibited higher sensitivity to EKR, with pronounced focusing phenomena. In CH1, Cd removal in anode-proximal (S1) zone reached 99%, but accumulation in the cathode-adjacent (S4 and S5) reduced the average removal rate to 22%, indicating the potential for improvement through cathodic control. Similarly, in CH2, Pb removal in S5 achieved 84.8%, while focusing in S1 suggested the need for anodic optimisation. These findings highlight the influence of soil properties and operational parameters on EKR efficiency, providing insights for tailored remediation strategies.