Role of various extractants in removing group-IIB elements of soils incubated with EDTA

This paper presents the results of an experimental investigation undertaken to evaluate different extractant solutions viz. HCl, Mg(NO3)2, and DTPA with the range of concentration from 0.001 to 0.1N after incubation with group-IIB metals (Zn, Cd, and Hg) and EDTA to understand the capability to remove Zn, Cd, and Hg from soils. Two noncontaminated soils, one acidic (GHL) and the other alkaline (KAP), in reaction were taken from an agricultural field of West Bengal, India for this investigation. Experiments were conducted on these two soils spiked with ZnII, CdII, and HgII in concentrations of 612, 321, and 215 mg/kg for soil GHL and 778, 298, and 157 mg/kg for soil KAP, respectively, which simulate typical electroplating waste contamination. The removal of Zn, Cd, and Hg in soil GHL within the range of HCl concentrations was 8.2-16.5, 12.2-19.1, and 4.3-6.9 whereas these were 6.5-7.6, 8.5-14.1, and 3.2-5.2 in soil KAP. The removal of Zn, Cd, and Hg in soil GHL within the range of Mg(NO3)2 concentrations were 12.2-28.5, 19.1-24.6, and 18.2-19.1 whereas these were 9.1-12.1, 8.3-12.1, and 10.6-48.1 in soil KAP. For DTPA extractant, the percent removal of metal was found to be significantly higher than the other two extractants, which corroborates that DTPA is a better extractant for soil cleaning.