INQUIMAE   12526
INSTITUTO DE QUIMICA, FISICA DE LOS MATERIALES, MEDIOAMBIENTE Y ENERGIA
Unidad Ejecutora - UE
artículos
Título:
Hydrotalcite dissolution in aqueous media
Autor/es:
MATÍAS JOBBÁGY; ALBERTO E. REGAZZONI
Revista:
APPLIED CLAY SCIENCE
Editorial:
ELSEVIER SCIENCE BV
Referencias:
Lugar: Amsterdam; Año: 2011 vol. 51 p. 366 - 366
ISSN:
0169-1317
Resumen:
Aqueous dissolution of a synthetic chloride-containing Mg2+-Al3+ layered double hydroxide was studied at 298 K as a function of pH. Mild acidification (final pH 9 -5) results in incongruent dissolution of Mg2+, exclusively. Formation of an amorphous Al(OH)3 passive layer prevents further Mg2+ leaching, thus dissolved Mg2+ amounts for only 20% of the solid. At lower pH values, massive dissolution readily takes place in a congruent fashion. Congruent dissolution profiles are accounted for by a contracting volume kinetic law. The pH dependence of the observed rate constant shows that the kinetic order on proton concentration is 0.41, indicating that dissolution is surface controlled. The implications of these findings are discussed.