CHELATING EXTRACTION OF LEAD AND COPPER FROM AN AUTHENTIC CONTAMINATED SOIL USING N-(2-ACETAMIDO)IMINODIACETIC ACID AND S-CARBOXYMETHYL-L-CYSTEINE

Heavy metal contamination of soil is common at many hazardous waste sites in many industrialized nations. Lead, chromium, cadmium, copper, zinc, and mercury are most often encountered at elevated concentrations. The extraction of heavy metals using selected chelating agents is seen as a remediation technique. In this study, we examined the chelating extraction and recovery of lead and copper from an authentic contaminated soil using S-carboxymethyl-L-cysteine (SCMC) and N-(2-acetamido)iminodiacetic acid (ADA) as a function of contact time, pH, ligand concentration, soil suspension, and number of consecutive runs. The results suggested that the chelators effectively extracted lead and copper from the contaminated soil, with ADA particularly effective for lead, the major contaminant of the soil. The chelators were recovered and reused over consecutive runs with no loss in performance. The extraction effectiveness depended on chelator concentration but not on pH or solid contents of the suspension. Major findings from this study of an authentic soil were consistent with our previous efforts in the extraction of heavy metals from spiked soils.