Effect of Different Organic Acids for Heavy Metal Extraction from Pb, Zn and Cd Contaminated Soil

Abstract

The aim of this work was to select organic aids with most obvious activation to Pb, Zn and Cd compound in contaminated soil in order to assist phytoremediation. Five kinds of low-molecular organic acid were used to leach the soils, and then heavy metal contents in the filtrate were measured. The effect of organic acids was evaluated in mobilization of heavy metals and their impacts on soil pH were discussed. With increasing concentrations of organic acids, the activation effect increased while soil pH had negative correlation. Citric acid had the most obvious activation compared with the other four organic acids. The maximum extraction rate of Cd, Zn of citric acid was shown at concentration of 50 mmol·kg-1, and that of Pb was at 40 mmol·kg-1. The extraction rates were 7.36%, 28.79%, 0.56%, respectively. The activation effects of heavy metals in soil were Zn>Cd>Pb.