Search for content and authors
 

Study of the the sorption of Cu(II) species on the "TiO2 / KNO3" interface.

Aglaia D. Georgaka ,  Nikos Spanos 

Hellenic Open University, Tsamadou 13-15 and Ag. Andreou, Patras 26223, Greece

Abstract

The present work is focused on the elucidation of the detailed mechanism of Cu(II) species on TiO2 surface, which is of paramount importance for the preparation of a composite material “Cu2+/TiO2” used as catalyst, with desired properties.

The study took place by means of potentiometric titrations, adsorption edges and adsorption isotherms of Cu2+/TiO2 suspensions at 25oC. At first, the most appropriate electrolyte was selected (KNO3) and the pH range, where Cu2+ species do not precipitate, was identified. It was illustrated that the point of zero charge (pzc) and surface charge (σo) can easily be determined by two potentiometric titration curves, one for a suspension and another for the respective blank solution. It was found that an increase in the pH value brings about an increase to the negatively charged groups of the surface, thus increasing the adsorption of the positively charged Cu2+ ions. Moreover, at relatively low pH values (pH<pzc), where the surface is positively charged, an appreciable adsorption of Cu2+ species was found. This indicates that not only electrostatic adsorption takes place, but the copper species are deposited on the TiO2 surface through coordination and hydrogen bonds as well. Furthermore, it was found that the ionic strength does not affect the adsorption. Finally, an increment at the pH value results in an increase in the adsorption constant and in a decrease in the lateral interaction energy (table 1).

pH E / J mol-1 k / mol-1 L Γm / μmol m-1
3 2554 342 0.48
4 211 1344 0.52
4.5 79 1533 0.71
5 15 1989 1.47

 

Legal notice
  • Legal notice:
 

Related papers

Presentation: Poster at E-MRS Fall Meeting 2009, Symposium I, by Aglaia D. Georgaka
See On-line Journal of E-MRS Fall Meeting 2009

Submitted: 2009-05-08 12:24
Revised:   2009-06-23 10:35