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Titre du document / Document title

Surface chemistry and surface charge formation for an alumina powder in ethanol with the addition of HCl and KOH

Auteur(s) / Author(s)

VAN TASSEL J. (1) ; RANDALL C. A. (1) ;

Affiliation(s) du ou des auteurs / Author(s) Affiliation(s)

(1) Particulate Materials Center, Materials Research Laboratory, Pennsylvania State University, University Park, Pennsylvania 16802, ETATS-UNIS

Résumé / Abstract

Surface charge and surface adsorption on an alpha-alumina powder were investigated in a 99.5/0.5 wt% ethanol/water suspension. A model is proposed in which ethanol molecules are dissociatively adsorbed as ethoxide ions and protons to Lewis acid and base sites on the surface. These ions can then desorb separately from the surface. The surface, therefore, acts as a catalyst for the autoprotolysis of the solvent and creates its own ionic atmosphere which cannot be predicted directly from chemistry in the bulk of the solvent. 3.5 μmol/m2 of HCl is reversibly adsorbed to the surface by replacement of ethoxide ions adsorbed to surface acid sites by chloride ions. 2.4 μmol/m2 of KOH is adsorbed to the surface by replacement of surface adsorbed protons with potassium ions. More rapid desorption of negative ions from the surface leaves the particles with a net positive surface charge except when the concentration of negative ions in solution is sufficient to supress this desorption and net surface charge goes to zero. Surface charge is found to be a function only of the activity of the negative ions in solution at the surface. No significant negative surface charge was measured under any conditions here. Equilibrium constants for surface adsorption and charge density as a function of surface activity of ethoxide and chloride ions are calculated. No effect of adsorbed potassium ions on the surface potential was found.

Revue / Journal Title

Journal of colloid and interface science    ISSN  0021-9797   CODEN JCISA5 

Source / Source

2001, vol. 241, no2, pp. 302-316 (18 ref.)

Langue / Language

Anglais

Editeur / Publisher

Elsevier, Amsterdam, PAYS-BAS  (1966) (Revue)

Mots-clés anglais / English Keywords

Surface properties

;

Hydration

;

Primary alcohol

;

Potassium hydroxide

;

Electrophoretic deposition

;

Hydrochloric acid

;

Electrokinetic potential

;

Surface charge

;

Liquid solid adsorption

;

Particle suspension

;

Aqueous solution

;

Ethanol

;

Powder

;

Aluminium Oxides

;

Experimental study

;

Mots-clés français / French Keywords

Propriété surface

;

Hydratation

;

Alcool primaire

;

Potassium hydroxyde

;

Dépôt électrophorétique

;

Chlorhydrique acide

;

Potentiel électrocinétique

;

Charge superficielle

;

Adsorption liquide solide

;

Suspension particule

;

Solution aqueuse

;

Ethanol

;

Poudre

;

Aluminium Oxyde

;

Etude expérimentale

;

Mots-clés espagnols / Spanish Keywords

Propiedad superficie

;

Hidratación

;

Alcohol primario

;

Potasio hidróxido

;

Depósito electroforético

;

Ácido chlorhídrico

;

Potencial electrocinético

;

Carga superficial

;

Adsorción líquido sólido

;

Suspensión partícula

;

Solución acuosa

;

Etanol

;

Polvo

;

Aluminio Óxido

;

Estudio experimental

;

Localisation / Location

INIST-CNRS, Cote INIST : 4124, 35400009950040.0020

Nº notice refdoc (ud4) : 14092801



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