Alumina surface chemistry at 25, 40, and 60[degrees]C

Journal Article · Tue Feb 01 04:00:00 EST 1994 · Geochimica et Cosmochimica Acta; (United States)

DOI:https://doi.org/10.1016/0016-7037(94)90586-X· OSTI ID:7101993

Brady, P V ^[1]

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1. Sandia National Laboratories, Albuquerque, NM (United States)

Potentiometric titrations and metal adsorption measurements on [gamma]-Al[sub 2]O[sub 3] at 25, 40 and 60[degrees]C indicate that alumina surface chemistry is temperature-sensitive. The pH[sub zpc] of [gamma]-Al[sub 2]O[sub 3] decreases slightly, if at all, from pH 6.45 at 25[degrees]C to 6.32 at 60[degrees]C. Metal binding constants for Cd[sup ++] and Pb[sup ++], calculated with a constant capacitance model, increase up to 1.5 orders of magnitude between 25[degrees]C and 60[degrees]C. Enthalpies of unidentate PB and Cd binding are 21.3 and 81.8 kj/mol, respectively; these are similar in sign and magnitude to the enthalpies of metal hydrolysis. Because temperature favors the latter, surface coordination is favored by increasing temperature (i.e., and increasing depth in the crust).

• OSTI ID: 7101993
• Journal Information: Geochimica et Cosmochimica Acta; (United States), Journal Name: Geochimica et Cosmochimica Acta; (United States) Vol. 58:3; ISSN GCACAK; ISSN 0016-7037
• Country of Publication: United States
• Language: English

Related Subjects

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY
400201* -- Chemical & Physicochemical Properties
58 GEOSCIENCES
580000 -- Geosciences
ALUMINIUM COMPOUNDS
ALUMINIUM OXIDES
CADMIUM
CHALCOGENIDES
CHEMICAL REACTIONS
ELEMENTS
LEAD
METALS
OXIDES
OXYGEN COMPOUNDS
SORPTIVE PROPERTIES
SURFACE PROPERTIES
TEMPERATURE DEPENDENCE