title: Acid-base properties of the alumina surface: influence of the titration procedures on the microcalorimetric results.
abstract: The enthalpy changes associated with the protonation and deprotonation of an alumina surface have been determined on the basis of microcalorimetry experiments and acid-base potentiometric titrations at 25 degrees C. It has been shown that the results may vary significantly according to the experimental procedure. In order to do so, the potentiometric and microcalorimetric titrations have been carried out first from an acidic pH to basic pH and second from a pH near the pH(zpc) of alumina to acidic or basic pH. It has been demonstrated that the pK(a) values deduced from the potentiometric titrations are the same whatever the experimental protocol whereas the only way to obtain meaningful enthalpies of proton exchange is to carry out microcalorimetric titrations by starting around the point of zero charge.
authors: Microorganismes: Génome et Environnement, UMR CNRS 6023, Université Blaise Pascal, 24 avenue des Landais, 63177 Aubière cedex, France.
authors: Jean-Pierre
authors: JP
authors: Morel
authors: Nicolas
authors: N
authors: Marmier
authors: Charlotte
authors: C
authors: Hurel
authors: Nicole
authors: N
authors: Morel-Desrosiers
mesh_terms: D000537:Aluminum Oxide / Q000737:chemistry*; D002151:Calorimetry; D006863:Hydrogen-Ion Concentration; D008832:Microchemistry; D013696:Temperature; D017186:Titrimetry
chemical_list: D000537:Aluminum Oxide