Development of novel assisting agents for the electrokinetic remediation of heavy metal-contaminated kaolin

•A novel assisting agent (CA + CaCl2) is developed in EK removal of multi-metals.•The influence of CA and CaCl2 concentration are investigated in EK remediation.•The CA + CaCl2 treatment exhibits high removal efficiencies for multi-heavy metals.•The CA + CaCl2 treatment poses lower power consumption and lesser environmental risk

A novel assisting agent (citric acid + calcium chloride, CA + CaCl2), combined the advantages of two diffenrent compositions, has been investigated for the electrokinetic (EK) remediation of multi-metals (Cd, Cu, Ni, Pb, Zn) contaminated kaolin simultaneously. The result shows that CA and CaCl2 concentration significant affect the removal efficiency of heavy metals. The optimum concentration is obtained at the 0.2 mol/L CA mixed with 0.05 mol/L CaCl2 in this study, and the removal efficiencies of Cd, Cu, Ni, Pb, and Zn were 98.19%, 95.24%, 98.95%, 86.21%, and 99.01%, respectively, with the consuming of 124.8 KWh/m3 electric energy. Compared to traditional CA and HCl treatment, the CA + CaCl2 poses the advantages of cost-efficient, eco-friendly, high removel efficiency for multi-heavy metals, may promote the progress toward commercial application.