Removal of heavy metals from a contaminated calcareous soil using oxalic and acetic acids as chelating agents

Abstract

Extraction of heavy metals by organic acids is likely to be representative of a available fraction to plants. Oxalic and acetic acids commonly are known as moderate and week chelating agents, respectively. In this research the potential of these two organic acids to decontaminate a calcareous soil (with a total heavy metal concentration of 80.6 mmol kg-1) from the zinc-lead smelting plant area in Zanjan province-Iran was investigated. This was carried out via 12 times successive washing experiments with concentration of 0.01 M. Results showed that oxalic acid extracted greater Zn than Cd and the reverse occurred for acetic acid. This may be due to the formation of calcium oxalate which removed oxalate from the solution and decreased its extraction power. The results of our study indicate that no general efficiency order for chelating agents could be distinguished