Colloid and Polymer Science

, Volume 273, Issue 12, pp 1186–1192 | Cite as

Residual changes in the surface charge of TiO2 (anatase) suspensions as a result of exposure to a 44 MHz radiofrequency electric field

  • K. W. Busch
  • M. A. Busch
  • S. Gopalakrishnan
  • E. Chibowski
Original Contribution

Abstract

Potentiometric titrations of TiO2 (anatase) suspensions in solutions of 10−2, 10−3, and 10−4 M NaCl prior to treatment with a radiofrequency (RF) electric field gave values of pHpzc and pHiep of 5.75±0.1 and 5.85±0.1, respectively, within the range of literature values. Surface charge plots versus pH for untreated samples gave curves with a common intersection point, indicating that NaCl acts as an indifferent electrolyte. Identical suspensions of anatase were then exposed for 30 min to an RF electric field with a peak-to-peak, no-load amplitude of 34V and a frequency of 44 MHz. Portions of the treated suspension were titrated after different time periods following removal of the field (2, 15, 30, and 45 min). At 2 min, the pHpzc had shifted to 6.50±0.1, and at 15, 30 and 45 min, the curves for the three NaCl concentrations were found to lack a common intersection point, an effect which became more pronounced with time. It is proposed that RF treatment results in the formation of a porous gel layer of hydrous titanium dioxide on the surface of the anatase particles that subsequently undergoes a slow ion-exchange reaction involving ions of the supporting electrolyte.

Key words

Anatase radiofrequency electric field surface charge hydrous titanium dioxide ion exchange 

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Copyright information

© Steinkopff Verlag 1995

Authors and Affiliations

  • K. W. Busch
    • 1
  • M. A. Busch
    • 1
  • S. Gopalakrishnan
    • 1
  • E. Chibowski
    • 2
  1. 1.Department of ChemistryBaylor UniversityWacoU.S.A.
  2. 2.Department of Physical ChemistryMaria Curie-Skŀodowska UniversityLublinPoland

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