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Coordination of acetate to Al(III) in aqueous solution and at the water-aluminum hydroxide interface: A potentiometric and attenuated total reflectance FTIR study

Persson, Per LU ; Karlsson, M. and Ohman, L. O. (1998) In Geochimica et Cosmochimica Acta 62. p.3657-3668
Abstract
Attenuated total reflectance FTIR spectroscopy was used to characterize Al(III)-acetate complexation at 25 degrees C, in homogeneous aqueous solution and at the water-aluminum hydroxide interface. The data collected in aqueous solution, at [Al](tot) = 0.080 M, [OAc](tot) = 0.040 M, and pH < 4.3, indicate the presence of only one dominating complex which, by spectral analysis, is shown not to involve monodentate acetate coordination but rather a syn-syn bridging geometry. In quantitative terms, the data strongly support the appearance of a binuclear mixed-hydroxo species [Al-2(OH)(2)OAc](3+) which, in view of the above, probably consists of a dihydroxo-bridged Al-2(mu-OH)(2)-unit to which the acetate ion bridges via the apices of the two... (More)
Attenuated total reflectance FTIR spectroscopy was used to characterize Al(III)-acetate complexation at 25 degrees C, in homogeneous aqueous solution and at the water-aluminum hydroxide interface. The data collected in aqueous solution, at [Al](tot) = 0.080 M, [OAc](tot) = 0.040 M, and pH < 4.3, indicate the presence of only one dominating complex which, by spectral analysis, is shown not to involve monodentate acetate coordination but rather a syn-syn bridging geometry. In quantitative terms, the data strongly support the appearance of a binuclear mixed-hydroxo species [Al-2(OH)(2)OAc](3+) which, in view of the above, probably consists of a dihydroxo-bridged Al-2(mu-OH)(2)-unit to which the acetate ion bridges via the apices of the two Al(III) octahedra. Also at the water-aluminum hydroxide interface, only one dominating surface complex is indicated. Zn contrast to the aqueous species this complex is a weak mononuclear outer-sphere complex, and it is speculated that, due to a lack of structural flexibility of the surface Al(III) octahedra, the formation of a bridging inner-sphere complex is prohibited. Based on the concept of surface complexation, and utilizing the extended constant capacitance model to account for contributions from electrostatic forces, an equilibrium model, which quantitatively describes these interactions in an ionic medium of 0.1 M NaCl, is presented. Copyright (C) 1998 Elsevier Science Ltd. (Less)
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author
publishing date
type
Contribution to journal
publication status
published
subject
in
Geochimica et Cosmochimica Acta
volume
62
pages
3657 - 3668
publisher
Elsevier
external identifiers
  • scopus:0032461899
ISSN
0016-7037
DOI
10.1016/S0016-7037(98)00260-9
language
English
LU publication?
no
id
0725a8f0-81e4-433e-b67e-aafcf6f75280 (old id 4332642)
date added to LUP
2014-03-04 09:43:41
date last changed
2017-03-05 03:34:13
@article{0725a8f0-81e4-433e-b67e-aafcf6f75280,
  abstract     = {Attenuated total reflectance FTIR spectroscopy was used to characterize Al(III)-acetate complexation at 25 degrees C, in homogeneous aqueous solution and at the water-aluminum hydroxide interface. The data collected in aqueous solution, at [Al](tot) = 0.080 M, [OAc](tot) = 0.040 M, and pH &lt; 4.3, indicate the presence of only one dominating complex which, by spectral analysis, is shown not to involve monodentate acetate coordination but rather a syn-syn bridging geometry. In quantitative terms, the data strongly support the appearance of a binuclear mixed-hydroxo species [Al-2(OH)(2)OAc](3+) which, in view of the above, probably consists of a dihydroxo-bridged Al-2(mu-OH)(2)-unit to which the acetate ion bridges via the apices of the two Al(III) octahedra. Also at the water-aluminum hydroxide interface, only one dominating surface complex is indicated. Zn contrast to the aqueous species this complex is a weak mononuclear outer-sphere complex, and it is speculated that, due to a lack of structural flexibility of the surface Al(III) octahedra, the formation of a bridging inner-sphere complex is prohibited. Based on the concept of surface complexation, and utilizing the extended constant capacitance model to account for contributions from electrostatic forces, an equilibrium model, which quantitatively describes these interactions in an ionic medium of 0.1 M NaCl, is presented. Copyright (C) 1998 Elsevier Science Ltd.},
  author       = {Persson, Per and Karlsson, M. and Ohman, L. O.},
  issn         = {0016-7037},
  language     = {eng},
  pages        = {3657--3668},
  publisher    = {Elsevier},
  series       = {Geochimica et Cosmochimica Acta},
  title        = {Coordination of acetate to Al(III) in aqueous solution and at the water-aluminum hydroxide interface: A potentiometric and attenuated total reflectance FTIR study},
  url          = {http://dx.doi.org/10.1016/S0016-7037(98)00260-9},
  volume       = {62},
  year         = {1998},
}