Bidentate complexation modeling of heavy metal adsorption and competition on goethite

Document Type

Article

Publication Date

4-1-2006

Abstract

Accurate sorption modeling is critical for environmental risk assessment and development of sound remedial technologies. Adsorption to iron oxide phases is one of the important sorption processes regulating the bioavailability and toxicity of metal ions in natural systems. In this study, we used spectroscopically derived bidentate surface species to constrain surface complexation modeling in addressing Ni(II) and Zn(II) adsorption and competition on goethite surfaces. The 2-pKa triple layer model successfully predicted adsorption in single adsorbate systems. The curvature in adsorption isotherms was accurately depicted using two types of sites: high affinity and low affinity, and mononuclear bidentate surface complexes. A constrained set of parameters was found for each metal (log KL = -6.63 and log K H = -2.45 for Ni, log KL = -3.92 and log KH = 2.14 for Zn) that successfully described adsorption over a large range of experimental conditions, covering 6 to 7 orders of magnitude in concentration, ionic strength from 10-3 to 10-2, and environmentally relevant pH range between 4 and 6.5. Adsorption competition was predicted using the bidentate surface species with parameters calibrated using single adsorbate data. © 2006 American Chemical Society.

Identifier

33645781578 (Scopus)

Publication Title

Environmental Science and Technology

External Full Text Location

https://doi.org/10.1021/es051916e

ISSN

0013936X

PubMed ID

16646455

First Page

2213

Last Page

2218

Issue

7

Volume

40

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