Characterization and Modeling of the Al-Oxide/Aqueous Solution Interface: I. Measurement of Electrostatic Potential at the Origin of the Diffuse Layer Using Negative Adsorption of Na+ Ions
✍ Scribed by Z.Z. Zhang; Donald L. Sparks; Noel C. Scrivner
- Publisher
- Elsevier Science
- Year
- 1994
- Tongue
- English
- Weight
- 585 KB
- Volume
- 162
- Category
- Article
- ISSN
- 0021-9797
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✦ Synopsis
A method of measuring electrostatic potential at the origin of the diffuse layer, (\psi_{\mathrm{d}}), from co-ion negative adsorption experiments was described and used for an amphoteric Al-oxide. It was found that the magnitude of (\psi_{\mathrm{d}}) for the Al-oxide decreased with increasing electrolyte concentration. Our data showed that the zeta potential, (\zeta), differed from (\psi_{\mathrm{d}}) for the (\wedge \mathrm{I})-oxide. Therefore, the generally accepted assumption that (\psi_{\mathrm{d}} \approx \zeta) should be further examined. We modeled our experimental data using the triple layer model. It was shown that both the surface charge density, (\sigma_{0}), mcasured from acid-base titration and (\psi_{\mathrm{d}}), determined from co-ion negative adsorption experiments, can be quantitatively described by the triple layer model using a self consistent set of parameters. A major criterion of a desired surface complexation model should be its ability to account for various properties of the interface with a self consistent set of parameters as demonstrated by describing or modeling different experimental data. Hence, further characterization of the physical and chemical nature and properties of the colloidal systems is needed to provide the additional data base for developing, testing, and modifying models. *it 19944 A s:ademic lress, Inc.