Application of the Theoretical 1-pK Approach to Analyzing Proton Adsorption Isotherm Derivatives on Heterogeneous Oxide Surfaces

Abstract

The theory based on the complexation model has been used to derive the adsorption isotherm equation describing proton adsorption at the solid/electrolyte interface. The present equation applies to the 1-pK theory developed by Hiemstra and co-workers to describe oxide/electrolyte interfaces. Development has also been performed to take into account the local surface heterogeneity (i.e., the local pK distribution). It has then been shown that whatever the assumption, all the equations degenerate into a single derivative isotherm equation as the local surface potential and the heterogeneity parameters merge into one parameter. The obtained derivative equation has been used to model experimental high-resolution titration curves realized on anatase and goethite by using the titration derivative isotherm summation (TDIS) method proposed by Prelot and co-workers. The comparison between the fits obtained with this model and the Bragg-Williams-Temkin model shows that very similar quantitative results (peak position, adsorbed amounts) can be obtained. The present approach is, however, considered to be more realistic from a physical point of view.

Monte Carlo modeling of ion adsorption at the energetically heterogeneous metal oxide/electrolyte interface: Micro- and macroscopic correlations between adsorption energies

“…Moreover, this suggests that the degree of surface heterogeneity depends on the kind of interactions presented in the system. In our previous papers [39,40], we showed that the surface heterogeneity and electrostatics can be treated together, that is, using one common parameter describing both effects. Recently, Piasecki [41] showed that the distinction between the surface heterogeneity effects and the electrostatic effects can be problematic for the metal oxide/electrolyte interface.…”

Adsorption of cobalt species on the interface, which is developed between aqueous solution and metal oxides used for the preparation of supported catalysts: a critical review

“…However, this approach does not take into account the predominant contribution of the double layer to the potentiometric titration data. Recently, an attempt has been reported to use the aforementioned methodology, but taking into account the contribution of the double layer for determining the abovementioned parameters of TiO 2 [72]. However, even in this case, the parameters determined differ markedly from those predicted by crystallographic considerations that had been fitted with potentiometric titration data [73].…”

On derivatives of surface charge curves of minerals

“…A recent paper [12] dealt with a procedure similar to that of Schwarz and co-workers [13,14]. The present author has some reservations about the tentative derivation of pK values of surface functional groups based on potentiometric titration curves.…”

“…This, however, strongly contradicts the bulk of oxide titration curves at different background electrolyte concentrations. In the more recent attempt to extract proton affinities from titration data [12], only one ionic strength was considered. Also the titration curves, in particular at higher ionic strength, tend to be linear curves when they are plotted as surface charge versus pH.…”

“…Goethite is also used because experimental data on goethite have recently been used for derivative analysis [12]. Since the published derivative curves [12] could not be generated from any of the published goethite models, a generic model (based on realistic parameters) was used to generate those features.…”