Croatica Chemica Acta, Vol. 80 No. 3-4, 2007.
Original scientific paper
Stability of Surface Complexes Formed at the TiO2/Water Interface
Ariel D. Weisz
; Unidad de Actividad Química, Centro Atómico Constituyentes, Comisión Nacional de Energía Atómica, San Martín, Argentina
Alberto E. Regazzoni
; Unidad de Actividad Química, Centro Atómico Constituyentes, Comisión Nacional de Energía Atómica, San Martín, Argentina; Instituto Sábato, Universidad Nacional de General San Martín, San Martín, Argentina
Miguel A. Blesa
; Unidad de Actividad Química, Centro Atómico Constituyentes, Comisión Nacional de Energía Atómica, San Martín, Argentina; Escuela de Posgrado, Universidad Nacional de General San Martín, San Martín, Argentina
Abstract
TiO2 surface complexation by bidentate organic ligands is analysed in terms of the ligand Brønstead and Lewis basicities. The complexation and basicity constants comply with linear Gibbs Energy relationships (LGERs). For dicarboxylic acids, the surface chelate bond makes an approximately constant contribution to the stability. The proton transfer to the surface modulates the pH dependence of stability. A correlation exists between the surface complexation constant of the neutral acid H2L and the ligand first acidity constant. On the other hand, the surface complexation constants of dianions L2- of cathecols and aminophenols are positively correlated with the ligand second acidity constant. Apparent stability is determined by the competition of H+ and surface metal ions for the ligand. Stability trends are strongly influenced by the Brønstead acid base reaction between the acid ligands H2L and the surface, whereas the stability of the surface chelate contributes to the overall stability.
Keywords
adsorption; surface complexation; titanium dioxide; carboxylic acids; affinity trends
Hrčak ID:
18257
URI
Publication date:
30.11.2007.
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