Surface charge of variable porosity Al2O3(s) and SiO2(s) adsorbents

Keith W. Goyne, Andrew R. Zimmerman, Bharat L. Newalkar, Sridhar Komarneni, Susan L. Brantley, Jon Chorover

Research output: Contribution to journalArticle

66 Citations (Scopus)

Abstract

The surface charge properties of two SiO2 and three Al2O3 mineral adsorbents with varying degrees of framework porosity were investigated using discontinuous titration and ion adsorption methodologies. Points of zero net change (p.z.n.c.) for porous SiO2 were <2.82 and for Al2O3 minerals ranged from 6.47-6.87. Silica surfaces possessed very slight negative charge in the acid pH range (pH ≤ 7) and significant dissociation of silanol groups occurred at pH ≥7. Variation of surface charge density with aqueous proton concentration was nearly identical within a mineral type (i.e., SiO2 or Al2O3) irrespective of the degree of framework porosity, indicating that the densities of dissociable surface sites are equivalent, when normalized to surface area. The results suggest that the use of titration methods alone may be insufficient for thorough surface charge characterization, particularly at low and high pH. Proton titrations should be coupled with concurrent ion adsorption measurements to confirm surfaced charge development. Discontinuous proton titration and ion adsorption data, which were in agreement in the slightly acidic through slightly basic pH range, both indicated that p.z.n.p.c. was equal to the point of zero net proton charge (p.z.n.p.c.) for the variable charge minerals investigated.

Original languageEnglish (US)
Pages (from-to)243-256
Number of pages14
JournalJournal of Porous Materials
Volume9
Issue number4
DOIs
StatePublished - Dec 2002

Fingerprint

Surface charge
adsorbents
Adsorbents
Protons
Titration
Porosity
Minerals
porosity
titration
minerals
protons
Ions
Adsorption
adsorption
ions
Charge density
Silicon Dioxide
Density (specific gravity)
Silica
Acids

Keywords

  • Alumina
  • Ion-adsorption
  • P.z.n.p.c.
  • Proton adsorption
  • Silica
  • Surface charge

ASJC Scopus subject areas

  • Catalysis
  • Chemistry (miscellaneous)
  • Physical and Theoretical Chemistry
  • Materials Science(all)

Cite this

Goyne, K. W., Zimmerman, A. R., Newalkar, B. L., Komarneni, S., Brantley, S. L., & Chorover, J. (2002). Surface charge of variable porosity Al2O3(s) and SiO2(s) adsorbents. Journal of Porous Materials, 9(4), 243-256. https://doi.org/10.1023/A:1021631827398

Surface charge of variable porosity Al2O3(s) and SiO2(s) adsorbents. / Goyne, Keith W.; Zimmerman, Andrew R.; Newalkar, Bharat L.; Komarneni, Sridhar; Brantley, Susan L.; Chorover, Jon.

In: Journal of Porous Materials, Vol. 9, No. 4, 12.2002, p. 243-256.

Research output: Contribution to journalArticle

Goyne, KW, Zimmerman, AR, Newalkar, BL, Komarneni, S, Brantley, SL & Chorover, J 2002, 'Surface charge of variable porosity Al2O3(s) and SiO2(s) adsorbents', Journal of Porous Materials, vol. 9, no. 4, pp. 243-256. https://doi.org/10.1023/A:1021631827398
Goyne, Keith W. ; Zimmerman, Andrew R. ; Newalkar, Bharat L. ; Komarneni, Sridhar ; Brantley, Susan L. ; Chorover, Jon. / Surface charge of variable porosity Al2O3(s) and SiO2(s) adsorbents. In: Journal of Porous Materials. 2002 ; Vol. 9, No. 4. pp. 243-256.
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