Dissolution of nano-size Mg-Al-Cl hydrotalcite in aqueous media

Aqueous dissolution of a synthetic chloride-containing Mg2+-Al3+ layered double hydroxide was studied at 298K 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+ leachin...

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Detalles Bibliográficos
Autor principal: Jobbagy, Matias
Publicado: 2011
Materias:
Dissolution kinetics
Hydrotalcite
Layered double hydroxide
Amorphous al3
Aqueous dissolution
Aqueous media
Congruent dissolutions
Final pH
Hydrotalcites
Kinetic order
Layered double hydroxides
Nano-size
Passive layer
PH dependence
pH value
Proton concentrations
Volume kinetics
Aluminum
Chlorine compounds
Leaching
Rate constants
Dissolution
acidification
aluminum
aqueous solution
chloride
dissolution
hydrotalcite
hydroxide
magnesium
pH
reaction kinetics
Acceso en línea:https://bibliotecadigital.exactas.uba.ar/collection/paper/document/paper_01691317_v51_n3_p366_Jobbagy
http://hdl.handle.net/20.500.12110/paper_01691317_v51_n3_p366_Jobbagy
Aporte de:
Biblioteca Digital - Facultad de Ciencias Exactas y Naturales (UBA) de Universidad de Buenos Aires
Descripción
Sumario:Aqueous dissolution of a synthetic chloride-containing Mg2+-Al3+ layered double hydroxide was studied at 298K 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. © 2010 Elsevier B.V.

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