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Structure and bonding of Cu(II)-glutamate complexes at the gamma-Al2O3-water interface

Fitts, J. P.; Persson, Per LU ; Brown, G. E. and Parks, G. A. (1999) In Journal of Colloid and Interface Science 220. p.133-147
Abstract
The composition and mode of attachment of Cu(II) complexes at the gamma-Al2O3-water interface in suspensions containing a simple amino acid (glutamate) were characterized with EXAFS and FTIR spectroscopies. The spectroscopic results indicate that two types of Cu(II)-glutamate-alumina interactions are primarily responsible for Cu(II) and glutamate uptake between pH 4 and 9. In acidic suspensions of alumina, glutamate forms a bridge between Cu(II) ions and the (hydr)oxide surface (Type B complex). In this Type B surface complex, Cu(II) is bonded to amino acid headgroups (i.e., +H3NCHRCOO-) of two glutamate molecules. Spectroscopic and ionic strength dependent uptake results are combined to propose that the nonbonded side chain carboxylate... (More)
The composition and mode of attachment of Cu(II) complexes at the gamma-Al2O3-water interface in suspensions containing a simple amino acid (glutamate) were characterized with EXAFS and FTIR spectroscopies. The spectroscopic results indicate that two types of Cu(II)-glutamate-alumina interactions are primarily responsible for Cu(II) and glutamate uptake between pH 4 and 9. In acidic suspensions of alumina, glutamate forms a bridge between Cu(II) ions and the (hydr)oxide surface (Type B complex). In this Type B surface complex, Cu(II) is bonded to amino acid headgroups (i.e., +H3NCHRCOO-) of two glutamate molecules. Spectroscopic and ionic strength dependent uptake results are combined to propose that the nonbonded side chain carboxylate groups of this complex are attracted to the oxide surface through long-range forces, leading to enhanced Cu(II) uptake relative to the glutamate-free system. In alkaline suspensions the relative amount of surface-bound Cu(II) complexed by glutamate decreases, and a direct Cu(II)-surface bond becomes the dominant mode of attachment (Type A complex). These surface complexes differ markedly from the species found in the alumina-fi ee Cu(II)glutamate aqueous system under similar solution conditions, where Cu(H2O)(6)(2+) and Cu(glutamate)(2)(2-) are the dominant species in acidic and alkaline solutions, respectively. Based on these spectroscopic results, surface complexation reactions are proposed for the Cu(II) and glutamate ternary interactions with the alumina surface in this system. Similarities between the results of this study and Cu(II) uptake behavior and complexation in the presence of natural organic material (NOM) indicate that Cu(II)-glutamate interactions mimic those in more complex Cu(II)-NOM-mineral-water systems, (C) 1999 Academic Press. (Less)
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author
publishing date
type
Contribution to journal
publication status
published
subject
in
Journal of Colloid and Interface Science
volume
220
pages
133 - 147
publisher
Elsevier
external identifiers
  • scopus:0033485929
ISSN
1095-7103
DOI
10.1006/jcis.1999.6521
language
English
LU publication?
no
id
8102ac5a-26e2-4a73-9f7f-6c3b1df3438b (old id 4332626)
date added to LUP
2014-03-04 09:43:19
date last changed
2017-08-13 03:29:28
@article{8102ac5a-26e2-4a73-9f7f-6c3b1df3438b,
  abstract     = {The composition and mode of attachment of Cu(II) complexes at the gamma-Al2O3-water interface in suspensions containing a simple amino acid (glutamate) were characterized with EXAFS and FTIR spectroscopies. The spectroscopic results indicate that two types of Cu(II)-glutamate-alumina interactions are primarily responsible for Cu(II) and glutamate uptake between pH 4 and 9. In acidic suspensions of alumina, glutamate forms a bridge between Cu(II) ions and the (hydr)oxide surface (Type B complex). In this Type B surface complex, Cu(II) is bonded to amino acid headgroups (i.e., +H3NCHRCOO-) of two glutamate molecules. Spectroscopic and ionic strength dependent uptake results are combined to propose that the nonbonded side chain carboxylate groups of this complex are attracted to the oxide surface through long-range forces, leading to enhanced Cu(II) uptake relative to the glutamate-free system. In alkaline suspensions the relative amount of surface-bound Cu(II) complexed by glutamate decreases, and a direct Cu(II)-surface bond becomes the dominant mode of attachment (Type A complex). These surface complexes differ markedly from the species found in the alumina-fi ee Cu(II)glutamate aqueous system under similar solution conditions, where Cu(H2O)(6)(2+) and Cu(glutamate)(2)(2-) are the dominant species in acidic and alkaline solutions, respectively. Based on these spectroscopic results, surface complexation reactions are proposed for the Cu(II) and glutamate ternary interactions with the alumina surface in this system. Similarities between the results of this study and Cu(II) uptake behavior and complexation in the presence of natural organic material (NOM) indicate that Cu(II)-glutamate interactions mimic those in more complex Cu(II)-NOM-mineral-water systems, (C) 1999 Academic Press.},
  author       = {Fitts, J. P. and Persson, Per and Brown, G. E. and Parks, G. A.},
  issn         = {1095-7103},
  language     = {eng},
  pages        = {133--147},
  publisher    = {Elsevier},
  series       = {Journal of Colloid and Interface Science},
  title        = {Structure and bonding of Cu(II)-glutamate complexes at the gamma-Al2O3-water interface},
  url          = {http://dx.doi.org/10.1006/jcis.1999.6521},
  volume       = {220},
  year         = {1999},
}