Effect of the formation of EDTA complexes on the diffusion of metal ions in water

Kenji Furukawa, Yoshio Takahashi, Haruo Sato

Research output: Contribution to journalArticle

21 Citations (Scopus)

Abstract

The diffusion coefficients of aquo metal ions (Mz+) and their EDTA complexes (M-EDTA(z-4)+) were compared to understand the effect of EDTA complexation on the diffusion of metal ions by the diffusion cell method for Co2+, Ga3+, Rb+, Sr2+, Ag+, Cd2+, Cs+, Th4+, UO2 2 +, and trivalent lanthanides. Most studies about ionic diffusion in water have dealt with free ion (hydrated ion). In many cases, however, polyvalent ions are dissolved as complexed species in natural waters. Hence, we need to study the diffusion behavior of complexes in order to understand the diffusion phenomenon in natural aquifer and to measure speciation by diffusive gradient in thin films (DGT), which requires the diffusion coefficients of the species examined. For many ions, the diffusion coefficients of M-EDTA(z-4)+ are smaller than those of hydrated ions, but the diffusion coefficients of M-EDTA(z-4)+ are larger than those of hydrated ions for ions with high ionic potentials (Ga3+ and Th4+). As a result, the diffusion coefficients of EDTA complexes are similar among various metal ions. In other words, the diffusion of each ion loses its characteristics by the complexation with EDTA. Although the difference is subtle, it was also found that the diffusion coefficients of EDTA complexes increase as the ionic potential increases, which can be explained by the size of the EDTA complex of each metal ion.

Original languageEnglish
Pages (from-to)4416-4424
Number of pages9
JournalGeochimica et Cosmochimica Acta
Volume71
Issue number18
DOIs
Publication statusPublished - Sep 15 2007
Externally publishedYes

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EDTA
Edetic Acid
Metal ions
ion
Water
metal
Ions
water
Complexation
complexation
effect
Lanthanoid Series Elements
Aquifers
rare earth element
aquifer
Thin films

ASJC Scopus subject areas

  • Geochemistry and Petrology

Cite this

Effect of the formation of EDTA complexes on the diffusion of metal ions in water. / Furukawa, Kenji; Takahashi, Yoshio; Sato, Haruo.

In: Geochimica et Cosmochimica Acta, Vol. 71, No. 18, 15.09.2007, p. 4416-4424.

Research output: Contribution to journalArticle

Furukawa, Kenji ; Takahashi, Yoshio ; Sato, Haruo. / Effect of the formation of EDTA complexes on the diffusion of metal ions in water. In: Geochimica et Cosmochimica Acta. 2007 ; Vol. 71, No. 18. pp. 4416-4424.
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