Combining potassium chloride leaching with vertical electrokinetics to remediate cadmium-contaminated soils

• Published in: Environmental geochemistry and health Vol. 41; no. 5; pp. 2081 - 2091
• Main Authors: Ma, Qiang, Li, Jun, Lee, Charles C. C., Long, Xinxian, Liu, Yongmao, Wu, Qi-Tang
• Format: Journal Article
• Language: English
• Published: Dordrecht Springer Netherlands 01-10-2019; Springer Nature B.V
• Subjects: Cadmium; Cadmium - analysis; Cadmium - chemistry; Cadmium - isolation & purification; Copper; Earth and Environmental Science; Electrochemical Techniques; Electrokinetics; Environment; Environmental Chemistry; Environmental Health; Environmental Pollution - prevention & control; Environmental Restoration and Remediation - methods; Feasibility studies; Geochemistry; Heavy metals; Leaching; Lead; Metals; Metals, Heavy - analysis; Metals, Heavy - chemistry; Metals, Heavy - isolation & purification; Original Paper; Potassium; Potassium chloride; Potassium Chloride - chemistry; Public Health; Removal; Soil; Soil - chemistry; Soil contamination; Soil Pollutants - analysis; Soil Pollutants - chemistry; Soil Pollutants - isolation & purification; Soil pollution; Soil remediation; Soil Science & Conservation; Soil surfaces; Subsoils; Terrestrial Pollution; Topsoil; Zinc; Contaminated soil; Removal efficiency; KCl; Leaching; Heavy metals; Vertical electrokinetics
• ISSN: 0269-4042; 1573-2983
• DOI: 10.1007/s10653-019-00259-w

This study evaluated the feasibility of combining potassium chloride (KCl) leaching and electrokinetic (EK) treatment for the remediation of cadmium (Cd) and other metals from contaminated soils. KCl leaching was compared at three concentrations (0.2%, 0.5%, and 1% KCl). EK treatment was conducted separately to migrate the metals in the topsoil to the subsoil. The combined approach using KCl leaching before or after EK treatment was compared. For the single vertical EK treatment, the removal of Cd, lead (Pb), copper (Cu) and zinc (Zn) from the topsoil (0–20 cm) was 9.38%, 4.80%, 0.95%, and 10.81%, respectively. KCl leaching at 1% KCl removed 84.06% Cd, 9.95% Pb, 4.34% Cu, and 19.93% Zn from the topsoil, with higher removal efficiency than that of the 0.2% and 0.5% KCl leaching treatments. By combining the KCl leaching and EK treatment, the removal efficiency of heavy metals improved, in particular for the 1% KCl + EK treatment, where the removal rate of Cd, Pb, Cu, and Zn from the upper surface soil reached 97.79%, 17.69%, 14.37%, and 41.96%, respectively. Correspondingly, the soil Cd content decreased from 4 to 0.21 mg/kg, and was below the Chinese standard limit of 0.3 mg/kg soil. These results indicate that 1% KCl + EK treatment is a good combination technique to mitigate Cd pollution from contaminated soils used for growing rice and leafy vegetables.