Effect of chelating agents on heavy metal extraction from contaminated soils

In the present study shacking and incubation experiments were carried out in order to evaluate the changes in heavy metal solubility in the studied soils by addition of different concentration of Ethylene dinitrilo tetra acetic acid (EDTA), Diethylene triamine penta acetic acid (DTPA), and Nitrilo tri acetic acid (NTA). The effects of EDTA, DTPA and NTA application on solubility of Copper (Cu), Lead(Pb), Cadmium(Cd) and Chromium(Cr) in soil were evaluated. In shacking experiment, maximum Cu, Pb, Cd and Cr were solubilized by DTPA extractant. It was found that with increasing chelating agent doses metals availability was increased and 5.0 mM doses of EDTA, DTPA and NTA was noticed the best optimum dose for further experiments. For shacking time significant results were obtained at 120 hours by applying EDTA and NTA where as DTPA behaved well at 24 hours. In incubation experiments more Cu and Cd were extracted by DTPA 6.65 and 6.67 ppm respectively. EDTA was proved good extracting solution for Pb which has solubilized maximum concentration of Pb (22.816 ppm). Maximum concentration of Cr (1.335 ppm) was solubilized by NTA as compared to EDTA and DTPA. For incubation experiment day 20-30 were more suitable for solubilzation of metals. Chelats has potential for the remediation of heavy metalcontaminated soils either as on-site soil washing agents or for in situ remediation. These findings can be used to develop a predictive tool for the target metals contaminants and for assessing chelation remediation efficiency based on chelates dose and contact time test results. Index termChelating agents, contaminated soils, heavy metals, extraction, and remediation ——————————  ——————————