Extraction of heavy metals from contaminated soils using EDTA and HCl

Abstract

The present study examines the extraction of lead (Pb), cadmium (Cd) and nickel (Ni) from   a contaminated soil by washing process. Ethylenediaminetetraacetic acid disodium salt (Na₂EDTA) and hydrochloric acid (HCl) solution were used as extractants.  Soil washing is one of the most suitable in-situ/ ex-situ remediation method in removing heavy metals. Soil was artificially contaminated with 500 mg/kg (Pb , Cd and Ni ).  A set of batch experiments were carried out at different conditions of  extractant concentration , contact time, pH and agitation speed. The results  showed  that the  maximum removal efficiencies  of (Cd, Pb  and Ni ) were (97, 88 and 24 )  % respectively using ( 0.1 M) Na₂EDTA.  While the maximum removal efficiencies using (1M)  HCl were (98, 94 and 55)% respectively. The experimental data of batch extraction were applied in four kinetic models; first order, parabolic diffusion, two constant and Elovich model. The parabolic diffusion was the most fitted to the experimental data.