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Formation of Ternary Metal-Oxalate Surface Complexes on alpha-FeOOH Particles

Simanova, Anna A.; Loring, John S. and Persson, Per LU (2011) In Journal of Physical Chemistry C 115. p.21191-21198
Abstract
Processes at the aqueous interfaces of metal (hydr)oxide particles greatly influence the mobility, bioavailability, and reactivity of metal ions and ligands. Here we investigated the time-dependent reactions of oxalate or Me(C(2)O(4))(3)(3-) (Me = Fe(III), Al(III), Ga(III), Co(III)) with goethite in aqueous suspension at pH 4 using attenuated total reflectance infrared (ATR-IR) and extended X-ray absorption fine structure (EXAFS) spectroscopy. The data indicate four coordination modes for oxalate and Fe(C(2)O(4))(3)(3-) adsorbed at the goethite surface: (1) outer-spherically with a hydration shell similar to aqueous ligand; (2) outer-spherically but hydrogen bonded to a surface site; (3) inner-spherically to surface iron; (4)... (More)
Processes at the aqueous interfaces of metal (hydr)oxide particles greatly influence the mobility, bioavailability, and reactivity of metal ions and ligands. Here we investigated the time-dependent reactions of oxalate or Me(C(2)O(4))(3)(3-) (Me = Fe(III), Al(III), Ga(III), Co(III)) with goethite in aqueous suspension at pH 4 using attenuated total reflectance infrared (ATR-IR) and extended X-ray absorption fine structure (EXAFS) spectroscopy. The data indicate four coordination modes for oxalate and Fe(C(2)O(4))(3)(3-) adsorbed at the goethite surface: (1) outer-spherically with a hydration shell similar to aqueous ligand; (2) outer-spherically but hydrogen bonded to a surface site; (3) inner-spherically to surface iron; (4) inner-spherically within a ternary type A surface complex. In the presence of oxalate, the two outer-sphere complexes form rapidly, but with time these species are partially consumed and the ternary inner-sphere complex is formed as a result of a dissolution-readsorption process. We propose that iron in these ternary complexes is more labile than iron that is mostly embedded in the lattice. Thus, ternary complexation may play an important role in iron bioavailabilty in the environment. For goethite reacted with Al(C(2)O(4))(3)(3-) or Ga(C(2)O(4))(3)(3-), these four surface complexes are accompanied by an additional Al(III) or Ga(III) ternary oxalate surface complex. (Less)
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author
publishing date
type
Contribution to journal
publication status
published
subject
in
Journal of Physical Chemistry C
volume
115
pages
21191 - 21198
publisher
The American Chemical Society
external identifiers
  • scopus:80055031886
ISSN
1932-7447
DOI
10.1021/jp2058707
language
English
LU publication?
no
id
e4adbe52-72b2-41d7-886a-cf15e5db1c62 (old id 4332284)
date added to LUP
2014-03-04 09:45:47
date last changed
2017-09-24 03:22:34
@article{e4adbe52-72b2-41d7-886a-cf15e5db1c62,
  abstract     = {Processes at the aqueous interfaces of metal (hydr)oxide particles greatly influence the mobility, bioavailability, and reactivity of metal ions and ligands. Here we investigated the time-dependent reactions of oxalate or Me(C(2)O(4))(3)(3-) (Me = Fe(III), Al(III), Ga(III), Co(III)) with goethite in aqueous suspension at pH 4 using attenuated total reflectance infrared (ATR-IR) and extended X-ray absorption fine structure (EXAFS) spectroscopy. The data indicate four coordination modes for oxalate and Fe(C(2)O(4))(3)(3-) adsorbed at the goethite surface: (1) outer-spherically with a hydration shell similar to aqueous ligand; (2) outer-spherically but hydrogen bonded to a surface site; (3) inner-spherically to surface iron; (4) inner-spherically within a ternary type A surface complex. In the presence of oxalate, the two outer-sphere complexes form rapidly, but with time these species are partially consumed and the ternary inner-sphere complex is formed as a result of a dissolution-readsorption process. We propose that iron in these ternary complexes is more labile than iron that is mostly embedded in the lattice. Thus, ternary complexation may play an important role in iron bioavailabilty in the environment. For goethite reacted with Al(C(2)O(4))(3)(3-) or Ga(C(2)O(4))(3)(3-), these four surface complexes are accompanied by an additional Al(III) or Ga(III) ternary oxalate surface complex.},
  author       = {Simanova, Anna A. and Loring, John S. and Persson, Per},
  issn         = {1932-7447},
  language     = {eng},
  pages        = {21191--21198},
  publisher    = {The American Chemical Society},
  series       = {Journal of Physical Chemistry C},
  title        = {Formation of Ternary Metal-Oxalate Surface Complexes on alpha-FeOOH Particles},
  url          = {http://dx.doi.org/10.1021/jp2058707},
  volume       = {115},
  year         = {2011},
}