Advanced

Adsorption of monocarboxylates at the water/goethite interface: The importance of hydrogen bonding

Noren, K. and Persson, Per LU (2007) In Geochimica et Cosmochimica Acta 71. p.5717-5730
Abstract
The adsorption of monocarboxylates (acetate, benzoate, and cyclohexanecarboxylate) at the water/goethite interface was studied as a function of pH and ionic strength by means of quantitative adsorption measurements and attenuated total reflectance-Fourier transform infrared (ATR-FTIR) spectroscopy. ATR-FTIR spectra were obtained of suspensions prepared in both H2O and D2O. In order to identify the number of predominating surface complexes and to improve the resolution of overlapping peaks the ATR-FTIR spectra were subjected to a 2D correlation spectroscopic analysis. The adsorption envelopes of acetate, benzoate, and cyclohexanecarboxylate are similar and depend strongly on pH and ionic strength, but the pH dependence is also correlated to... (More)
The adsorption of monocarboxylates (acetate, benzoate, and cyclohexanecarboxylate) at the water/goethite interface was studied as a function of pH and ionic strength by means of quantitative adsorption measurements and attenuated total reflectance-Fourier transform infrared (ATR-FTIR) spectroscopy. ATR-FTIR spectra were obtained of suspensions prepared in both H2O and D2O. In order to identify the number of predominating surface complexes and to improve the resolution of overlapping peaks the ATR-FTIR spectra were subjected to a 2D correlation spectroscopic analysis. The adsorption envelopes of acetate, benzoate, and cyclohexanecarboxylate are similar and depend strongly on pH and ionic strength, but the pH dependence is also correlated to the slightly different pK(a) values of the monocarboxylic acids. At the molecular level, the ATR-FTIR spectroscopic results reveal two surface complexes: one solvent-surface hydration-separated ion pair and one surface hydration-shared ion pair. The former predominates at circumneutral pH values while the latter forms mainly in the acidic pH range. We find no evidence for direct inner-sphere coordination between the carboxylic oxygens and the Fe(III) ions present at the surface. The identification of surface hydration-shared ion pairs emphasizes the importance of comparatively strong ionic hydrogen-bonding interactions for adsorption processes at the water/goethite interface. (C) 2007 Elsevier Ltd. All rights reserved. (Less)
Please use this url to cite or link to this publication:
author
publishing date
type
Contribution to journal
publication status
published
subject
keywords
transform infrared-spectroscopy, outer-sphere adsorption, mineral/water, interfaces, organic-matter, carboxylic-acids, aqueous-solution, surface, complexation, neutron-diffraction, electric-fields, atr-ftir
in
Geochimica et Cosmochimica Acta
volume
71
pages
5717 - 5730
publisher
Elsevier
external identifiers
  • scopus:36048991847
ISSN
0016-7037
DOI
10.1016/j.gca.2007.04.037
language
English
LU publication?
no
id
30f92ae7-04ee-4227-a4bb-87d326997659 (old id 4332448)
date added to LUP
2014-03-04 09:40:01
date last changed
2017-10-29 03:35:04
@article{30f92ae7-04ee-4227-a4bb-87d326997659,
  abstract     = {The adsorption of monocarboxylates (acetate, benzoate, and cyclohexanecarboxylate) at the water/goethite interface was studied as a function of pH and ionic strength by means of quantitative adsorption measurements and attenuated total reflectance-Fourier transform infrared (ATR-FTIR) spectroscopy. ATR-FTIR spectra were obtained of suspensions prepared in both H2O and D2O. In order to identify the number of predominating surface complexes and to improve the resolution of overlapping peaks the ATR-FTIR spectra were subjected to a 2D correlation spectroscopic analysis. The adsorption envelopes of acetate, benzoate, and cyclohexanecarboxylate are similar and depend strongly on pH and ionic strength, but the pH dependence is also correlated to the slightly different pK(a) values of the monocarboxylic acids. At the molecular level, the ATR-FTIR spectroscopic results reveal two surface complexes: one solvent-surface hydration-separated ion pair and one surface hydration-shared ion pair. The former predominates at circumneutral pH values while the latter forms mainly in the acidic pH range. We find no evidence for direct inner-sphere coordination between the carboxylic oxygens and the Fe(III) ions present at the surface. The identification of surface hydration-shared ion pairs emphasizes the importance of comparatively strong ionic hydrogen-bonding interactions for adsorption processes at the water/goethite interface. (C) 2007 Elsevier Ltd. All rights reserved.},
  author       = {Noren, K. and Persson, Per},
  issn         = {0016-7037},
  keyword      = {transform infrared-spectroscopy,outer-sphere adsorption,mineral/water,interfaces,organic-matter,carboxylic-acids,aqueous-solution,surface,complexation,neutron-diffraction,electric-fields,atr-ftir},
  language     = {eng},
  pages        = {5717--5730},
  publisher    = {Elsevier},
  series       = {Geochimica et Cosmochimica Acta},
  title        = {Adsorption of monocarboxylates at the water/goethite interface: The importance of hydrogen bonding},
  url          = {http://dx.doi.org/10.1016/j.gca.2007.04.037},
  volume       = {71},
  year         = {2007},
}