INFIQC   05475
INSTITUTO DE INVESTIGACIONES EN FISICO- QUIMICA DE CORDOBA
Unidad Ejecutora - UE
artículos
Título:
Phosphate adsorbed on Fe(III) modified montmorillonite: Surface complexation studied by ATR-FTIR spectroscopy
Autor/es:
L. BORGNINO; C. E. GIACOMELLI; M. AVENA; C. P. DE PAULI
Revista:
COLLOIDS AND SURFACES A-PHYSICOCHEMICAL AND ENGINEERING ASPECTS
Editorial:
ELSEVIER SCIENCE BV
Referencias:
Año: 2009 vol. 353 p. 238 - 244
ISSN:
0927-7757
Resumen:
This work is aimed at determining phosphate speciation at the Fe(III)-modified montmorillonite/aqueous
solution interface by attenuated total reflectance (ATR-FTIR) spectroscopy. IR spectra are analyzed by
second derivative and Fourier self-deconvolution procedures to reveal the number and positions of overlapped
bands related to phosphate surface complexes. Experiments are conducted at pH 4.5, 7.0 and 9.0 in
order to determine the effects of changing pH on the surface speciation. The molecular view offered by the
ATR-FTIR measurements is complemented by macroscopic adsorption data, such as adsorption isotherms
and electrophoretic mobilities. The ATR-FTIR spectral analyses reveal the existence of two inner-sphere
complexes when phosphate adsorbs on modified montmorillonite, as also suggested from macroscopic
adsorption data. The complex coordination depends on the pH. At pH 4.5, both complexes present C2V2V
symmetry or lower. On the other hand, at pH 7.0 and 9.0 one of them is also C2V or lower while the other
one presents C3V symmetry. Adsorbed phosphate is not associated with montmorillonite itself but with
Fe(III) (hydr)oxides coatings. Therefore, the clay acts as a carrier or support of the Fe(III)-(hydr)oxides,
and these coatings are responsible for phosphate adsorption.2V or lower while the other
one presents C3V symmetry. Adsorbed phosphate is not associated with montmorillonite itself but with
Fe(III) (hydr)oxides coatings. Therefore, the clay acts as a carrier or support of the Fe(III)-(hydr)oxides,
and these coatings are responsible for phosphate adsorption.3V symmetry. Adsorbed phosphate is not associated with montmorillonite itself but with
Fe(III) (hydr)oxides coatings. Therefore, the clay acts as a carrier or support of the Fe(III)-(hydr)oxides,
and these coatings are responsible for phosphate adsorption.