Title

Surface Speciation Modeling Of Heavy Metals In Kaolin: Implications For Electrokinetic Soil Remediation Processes

Keywords

Electrokinetic remediation; Electrophoresis experiments; Electrostatic adsorption models; Equilibrium constants; Kaolin

Abstract

The driving mechanisms for flux occur at interface between the soil particles and solution during electrokinetic soil remediation and the nature of this interface affects the electrokinetic response of the system. The pH-dependent adsorption of heavy metal contaminants by kaolin and the sensitivity of kaolin zeta potential to the aqueous phase properties are two important aspects that complicate the metal movement during electrokinteic soil remediation. This paper addresses these aspects and presents an electrostatic adsorption model that describes the behavior of kaolin surface for Cr(VI), Cr(III), Ni(II), and Cd(II) under various chemical conditions. This study showed that the aqueous properties: pH, ionic strength and the presence of the heavy metals Cr(VI), Cr(III), Ni(II), and Cd(II) in the system affect the zeta potential of kaolin surface. The zeta potential of kaolin shifts to a more negative value if the system pH increases. However, it shifts to a more positive value if the system ionic strength or metal concentration increases. It was found that the amount of the heavy metal adsorbed by kaolin has a pronounced sensitivity to the pH. As a result of the adsorption modeling, the constant capacitance protonation-dissociation intrinsic constants of kaolin are: pK +int = -3.8 ± 0.5 and pK_int = 9.4 ± 0.5. The ion-kaolin surface complexation constants (pK int) of Cr(VI), Cr(III), Ni(II), and Cd(II) are: -12.5± 0.5, -5.0± 1.0, 2.6± 0.6, and 3.3± 1.0, respectively. © 2005 Springer Science + Business Media, Inc.

Publication Date

11-1-2005

Publication Title

Adsorption

Volume

11

Issue

5-6

Number of Pages

529-546

Document Type

Article

Personal Identifier

scopus

DOI Link

https://doi.org/10.1007/s10450-005-5611-6

Socpus ID

29144536112 (Scopus)

Source API URL

https://api.elsevier.com/content/abstract/scopus_id/29144536112

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