Non-Uniform Electrokinetic Removal of Heavy Metals from Contaminated Soil with Permeable Reactive Composite Electrodes

Abstract

A hexagonal unit cell for non-uniform electrokinetic (EK) remediation was constructed and the electric field distribution of the cell was simulated using MATLAB software. The changes of soil pH and residues of heavy metals in different parts of the cell during the permeable reactive composite electrode electrokinetic (PRCE-EK) remediation were also studied. The results showed that, the changes of soil pH, the removal of heavy metals and the distribution of the non-uniform electric field in the cell were closely related to one another during the PRCE-EK remediation. Simulation of electric field distribution could help to predict the changes of soil pH of different parts of the cell, and then help to optimize the EK remediation process. The results also showed that an acidic migration band, which could prevent premature precipitation of heavy metals to a certain extent and promote EK removal of heavy metals, was formed in the whole hexagonal cell when the cathode used PRCE during the non-uniform EK remediation of cationic metallic ions, Cd2+ and Pb2+. After 480 hours of remediation, the total removal efficiency of Cd and Pb were 89.9% and 69.3%, respectively. Further prolonging remediation and constantly replacing electrodes with new ones could obtain better remediation results.