INFIQC   05475
INSTITUTO DE INVESTIGACIONES EN FISICO- QUIMICA DE CORDOBA
Unidad Ejecutora - UE
artículos
Título:
Influence of carbonate intercalation in the surface-charging behavior of ZnCr layered double hydroxides"
Autor/es:
R. ROJAS; C. BARRIGA; C. P. DE PAULI; M. J. AVENA
Revista:
MATERIALS CHEMISTRY AND PHYSICS
Editorial:
ELSEVIER SCIENCE SA
Referencias:
Año: 2009 vol. 119 p. 303 - 308
ISSN:
0254-0584
Resumen:
The influence of interlayer composition in the surface charge and reactivity of layered double hydroxides
(LDHs) has been explored. With this purpose, a chloride-intercalated ZnCr-LDH has been synthesized by
the constant pH coprecipitation method and afterwards exchanged with carbonate to obtain solids with
different Cl−/CO3
2− ratios. The solids structure has been characterized by elemental chemical analysis,
powder X-ray diffraction and infrared spectroscopy, while its surface-charging behavior and reactivity
have been studied by acidbase potentiometric titrations and electrophoretic mobility determinations.
The chloride-intercalated sample shows an increasing hydroxyl adsorption with increasing pH and
decreasing support electrolyte concentration and the particles present positive electrophoretic mobility
in the measured pH range. As carbonate content increases in the samples, the total OH− uptake diminishes
and the samples show an isoelectric point at pH around 10. When the gallery is totally occupied by
carbonate anions, the OH uptake vs. pH curves registered at different electrolyte concentrations merge at
around pH 10. A LDHwater interface model has been used to give an interpretation to the experimental
data. The model indicates that as carbonate content increases, the sample behavior becomes similar to
that of a metal (hydr)oxide and that surface (bi)carbonate anions undergo acidbase reactions.−/CO3
2− ratios. The solids structure has been characterized by elemental chemical analysis,
powder X-ray diffraction and infrared spectroscopy, while its surface-charging behavior and reactivity
have been studied by acidbase potentiometric titrations and electrophoretic mobility determinations.
The chloride-intercalated sample shows an increasing hydroxyl adsorption with increasing pH and
decreasing support electrolyte concentration and the particles present positive electrophoretic mobility
in the measured pH range. As carbonate content increases in the samples, the total OH− uptake diminishes
and the samples show an isoelectric point at pH around 10. When the gallery is totally occupied by
carbonate anions, the OH uptake vs. pH curves registered at different electrolyte concentrations merge at
around pH 10. A LDHwater interface model has been used to give an interpretation to the experimental
data. The model indicates that as carbonate content increases, the sample behavior becomes similar to
that of a metal (hydr)oxide and that surface (bi)carbonate anions undergo acidbase reactions.− ratios. The solids structure has been characterized by elemental chemical analysis,
powder X-ray diffraction and infrared spectroscopy, while its surface-charging behavior and reactivity
have been studied by acidbase potentiometric titrations and electrophoretic mobility determinations.
The chloride-intercalated sample shows an increasing hydroxyl adsorption with increasing pH and
decreasing support electrolyte concentration and the particles present positive electrophoretic mobility
in the measured pH range. As carbonate content increases in the samples, the total OH− uptake diminishes
and the samples show an isoelectric point at pH around 10. When the gallery is totally occupied by
carbonate anions, the OH uptake vs. pH curves registered at different electrolyte concentrations merge at
around pH 10. A LDHwater interface model has been used to give an interpretation to the experimental
data. The model indicates that as carbonate content increases, the sample behavior becomes similar to
that of a metal (hydr)oxide and that surface (bi)carbonate anions undergo acidbase reactions.− uptake diminishes
and the samples show an isoelectric point at pH around 10. When the gallery is totally occupied by
carbonate anions, the OH uptake vs. pH curves registered at different electrolyte concentrations merge at
around pH 10. A LDHwater interface model has been used to give an interpretation to the experimental
data. The model indicates that as carbonate content increases, the sample behavior becomes similar to
that of a metal (hydr)oxide and that surface (bi)carbonate anions undergo acidbase reactions.