Effects of Amorphous Iron on Extraction of Lead-Contaminated Soil with EDTA
Publication: Practice Periodical of Hazardous, Toxic, and Radioactive Waste Management
Volume 4, Issue 1
Abstract
Ethylenediaminetetraacetic acid (EDTA) is one of the more common chelating agents used in the extraction of heavy metals from soil. For soil extraction processes to be economically competitive with other remedial technologies, the amount of EDTA applied for extraction should be optimized; that is, extraction of metals should be maximized with a minimum amount of EDTA used. Generally, the molar amount of EDTA used is several times higher than the molar amount of the target metal present in the soil. This is to ensure there will be sufficient EDTA to extract the target heavy metals from the soil, since a host of non-target metals such as iron and calcium may compete for EDTA ligand sites. Bench-scale experiments using artificially prepared lead-contaminated soils were conducted to investigate the effects of amorphous iron and the different types of lead species on lead extraction. Three different lead species—lead sulfate, lead carbonate, and lead phosphate—were used. The extraction efficiency of lead was found to be a function of EDTA:Pb molar ratio, pH, lead species, and amorphous iron concentration. Experimental results showed that for a pH less than 6.0, amorphous iron in soil was found to strongly compete with lead for EDTA ligand sites. The extent of competition was dependent not only on the solution pH but also on the lead species present and the EDTA:Pb molar ratio. Amorphous iron was found to affect lead sulfate-contaminated soil the most, while lead carbonate-contaminated soil was the least affected. For EDTA:Pb molar ratios of less than 2, a solution pH between 6.5 and 8.5 must be maintained to optimize extraction of lead from lead sulfate- and lead phosphate-contaminated soil, if amorphous iron is present. The degree of difficulty of extraction of various lead species using EDTA:Pb molar ratios of less than 2 and in the presence of amorphous iron was: lead sulfate > lead phosphate > lead carbonate.
Get full access to this article
View all available purchase options and get full access to this article.
References
1.
Adhikari, M., Majumdar, M. K., and Nayek, A. K. (1985). “Nature of extractable iron and aluminum in some terai and teesta alluvial soils of north Bengal and their fate on potash fertilization.” Clay Res., 4(2), 87–91.
2.
Ainsworth, C. C., Pilon, J. L., Gassman, P. L., and Van Der Sluys, W. G. (1994). “Cobalt, cadmium, and lead sorption to hydrous iron oxide: residence time effect.” Soil Sci. Soc. Am. J., 58(6), 1615–1623.
3.
Bowers, A. R., and Huang, C. P. (1987). “Role of Fe(III) in metal complex adsorption by hydrous solids.” Water Res., 31(7), 757–764.
4.
Clevenger, T. E., Salwan, C., and Koirtyohann, S. R. (1991). “Lead speciation of particles on air filters collected in the vicinity of a lead smelter.” Envir. Sci. and Technol., 25(6), 1128–1133.
5.
Cline, S. R., and Reed, B. E. (1995). “Lead removal from soils via bench-scale soil washing techniques.”J. Envir. Engrg., ASCE, 121(10), 700–705.
6.
Davis, A., Drexler, J. W., Ruby, M. V., and Nicholson, A. (1993). “Micromineralogy of mine wastes in relation to lead bioavailability, Butte, Montana.” Envir. Sci. and Technol., 27(7), 1415–1425.
7.
Elliot, H. A., Linn, J. H., and Shields, G. A. (1989). “Role of Fe in extractive decontamination of Pb-polluted soils.” Hazardous Waste and Hazardous Mat., 6, 223–229.
8.
Follett, E. A. C. (1965). “The retention of amorphous colloidal ferric hydride by kaolinites.” J. Soil Sci., 16(2), 334–341.
9.
Gad, M. A., and LeRichie, H. H. (1966). “A method for separating the detrital and nondetrital fraction of trace elements in reduced sediments.” Geochim. Cosmochim. Acta, 30, 841–846.
10.
Lindsay, W. L. (1979). Chemical equilibria in soil. Wiley, New York.
11.
McKeague, J. A., and Day, J. H. (1966). “Dithionite- and oxalate-extractable Fe and Al as aids in differentiating various classes of soils.” Can. J. Soil Sci., Ottawa, 46(1), 13–22.
12.
MINTEQA2/PRODEFA2, a geochemical assessment model for environmental systems, version 3.0 user's manual. U.S. Environmental Protection Agency, Washington, D.C.
13.
Neale, D., Nelson, C., Bricka, R. M., and Chao, A. C. (1997). “Evaluating acids and chelating agents for removing heavy metals from contaminated soils.” Envir. Progress, 16(4), 274–280.
14.
Peters, R. W., and Shem, L. ( 1992). “Use of chelating agents for remediation of heavy metal contaminated soil.” Environmental remediation, G. F. Vandergrift et al., eds. American Chemical Society, Washington, D.C.
15.
Raghavan, R., Coles, E., and Dietz, D. (1989). “Cleaning excavated soil using extraction agents: a state-of-the-art review.” EPA/600/2-89/034, U.S. EPA Risk Reduction Engineering Laboratory, Cincinnati, Ohio.
16.
Royer, M. D., Selvakumar, A., and Gaire, R. (1992). “Control technologies for remediation of contaminated soil and waste deposits at Superfund lead battery recycling sites.” J. Air Waste Mgmt. Assoc., 42(7), 970–980.
17.
Schwertmann, U., and Cornell, R. M. (1991). Iron oxides in the laboratory: preparation and characterization. VCH Publishers, Inc., New York.
18.
Schwertmann, U., and Fischer, W. R. (1973). “Natural amorphous ferric hydroxide.” Geoderma, 10(3), 237–247.
19.
Sommers, L. E., and Lindsay, W. L. (1979). “Effects of pH and redox on predicted heavy metal-chelate equilibria in soils.” Soil Sci. Soc. Am. J., 43(1), 39–47.
20.
Superfund engineering issue: treatment of lead-contaminated soils. (1991). U.S. Environmental Protection Agency, Washington, D.C.
21.
Swallow, K. C., Hume, D. N., and Morel, F. M. M. (1980). “Sorption of copper and lead by hydrous ferric oxide.” Envir. Sci. and Technol., 14(11), 1326–1331.
22.
Test methods for evaluating solid waste. Volume 1A: Laboratory manual physical/chemical methods. (1986). 3rd Ed., U.S. Environmental Protection Agency, Washington, D.C.
23.
Van Benshoten, J. E., Reed, B. E., Matsumoto, M. R., and McGarvey, P. J. (1994). “Metal removal by soil washing for an iron oxide coated sand soil.” Water Envir. Res., 66(2), 168–175.
Information & Authors
Information
Published In
Practice Periodical of Hazardous, Toxic, and Radioactive Waste Management
Volume 4 • Issue 1 • January 2000
Pages: 16 - 23
History
Received: May 27, 1997
Published online: Jan 1, 2000
Published in print: Jan 2000
Authors
Metrics & Citations
Metrics
Citations
Download citation
If you have the appropriate software installed, you can download article citation data to the citation manager of your choice. Simply select your manager software from the list below and click Download.