W. Janusz et al., The electrical interfacial layer at the TiO2 (anatase)/electrolyte interface - Adsorption of Zn(II) and Cd(II) ions, J DISP SCI, 21(6), 2000, pp. 739-759
Mechanism of adsorption of Zn(II) and Cd(II) ions at the TiO2 (anatase)/ele
ctrolyte interface has been studied by different experimental techniques (p
otentiometric titration, microelectrophoresis and adsorption measurements o
f zinc and cadmium species). It was found that the point of zero charge (pz
c) of anatase (pH = 5.8) was shifted to the lower pH values with increasing
concentrations of Zn(II) or Cd(II) ions. The surface charge of anatase in
the presence of Zn(II) and Cd(II) for pH > pH(pzc) was higher than that obs
erved for original sample in NaClO4 solutions only. Due to low coverage of
anatase surface with Zn(II) or Cd(II) species almost no shift of the isoele
ctric point (iep) or charge reversal were observed. Adsorption density vs.
pH plots for both Zn(II) or Cd(II) showed, typical for multivalent ions, pr
esence of ,,adsorption edge."