Keywords: disodium ethylenediamine–tetraacedtic acid, Na2EDTA, heavy metals, contaminated soil, sodium sulphide, regeneration, environmental pollution, leaching efficiency, China, soil remediation, cadmium, lead, copper, zinc
Removal of Cd, Pb, Cu and Zn from real contaminated soils with fresh and regenerated Na2EDTA
The leaching efficiencies using both fresh Na
2EDTA and regenerated Na
2EDTA on the remediation of contaminated soils from Chenzhou lead–zinc mining area located in southern Hunan Province (southern China) were investigated. The total concentrations of Cd, Pb, Cu and Zn in both contaminated soils exceeded the maximum permissible limits set by Ministry of Environmental Protection for soil. Under the optimum conditions, 35% for Cd, 64% for Pb, 25% for Cu and 14% for Zn from garden soil and 97% for Cd, 87% for Pb, 46% for Cu and 33% for Zn from paddy soil were leached with 0.05M Na
2EDTA. Removal of Cd, Pb, Cu and Zn from leaching solution containing EDTA increased with increasing Na
2S addition, while about 0.15M Na
2S solution was used to separate all metals from metal–EDTA solution. Through three times regeneration and reuse, the regenerated Na2EDTA solutions have leaching ability of Cd, Pb, Cu and Zn from both contaminated soil.