Influence of variable chemical conditions on EDTA-enhanced transport of metal ions in mildly acidic groundwater

Environmental Pollution
By: , and 

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Abstract

Adsorption of Ni and Pb on aquifer sediments from Cape Cod, Massachusetts, USA increased with increasing pH and metal-ion concentration. Adsorption could be described quantitatively using a semi-mechanistic surface complexation model (SCM), in which adsorption is described using chemical reactions between metal ions and adsorption sites. Equilibrium reactive transport simulations incorporating the SCMs, formation of metal-ion-EDTA complexes, and either Fe(III)-oxyhydroxide solubility or Zn desorption from sediments identified important factors responsible for trends observed during transport experiments conducted with EDTA complexes of Ni, Zn, and Pb in the Cape Cod aquifer. Dissociation of Pb-EDTA by Fe(III) is more favorable than Ni-EDTA because of differences in Ni- and Pb-adsorption to the sediments. Dissociation of Ni-EDTA becomes more favorable with decreasing Ni-EDTA concentration and decreasing pH. In contrast to Ni, Pb-EDTA can be dissociated by Zn desorbed from the aquifer sediments. Variability in adsorbed Zn concentrations has a large impact on Pb-EDTA dissociation.

Additional publication details

Publication type Article
Publication Subtype Journal Article
Title Influence of variable chemical conditions on EDTA-enhanced transport of metal ions in mildly acidic groundwater
Series title Environmental Pollution
DOI 10.1016/j.envpol.2007.11.022
Volume 153
Issue 1
Year Published 2008
Language English
Publisher Elsevier
Contributing office(s) Toxic Substances Hydrology Program
Description 9 p.
First page 44
Last page 52
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