Abstract
Charging of particles in aqueous suspensions is primarily related to potential determining ions, such as silver and iodide ions at silver halide particle surfaces. Proton is considered as a (secondary) potential determining ion at hydrated metal oxide surfaces. Indifferent electrolytes neutralize at increased concentration the surface charge but do not reverse it. However, in the presence of a non-Coulombic interaction the surface charge may be enhanced or reversed at increased ionic strength. Such interaction is denoted specific which may be due to enhanced van der Waals dipolar, Lewis acid-base, solvation (Hofmeister) and/or Born solvation effects. Alternatively, these interactions have been characterized in terms of (semi) empirical ion and surface properties, such as hard-soft acid-base (HSAB) interaction. Within the Stern layer closest to the particle surface truly specific effects are related to the inner Helmholtz plane (IHP) in order to distinguish them from the charge and solvation related effects occurring within the outer Helmholtz plane (OHP). We review some recent observations on the particular influence of ions on the charging of titania particles in aqueous 1:1, 2:1, 1:2 and mixed electrolyte suspensions.
| Original language | English |
|---|---|
| Pages (from-to) | 51-67 |
| Number of pages | 17 |
| Journal | Advances in Colloid and Interface Science |
| Volume | 179-182 |
| DOIs | |
| Publication status | Published - 1 Nov 2012 |
| MoE publication type | A2 Review article in a scientific journal |
Keywords
- ζ-Potential
- 1:1, 2:1, 1:2 and mixed electrolytes
- Common intersection points
- DLVO model
- Isoelectric points
- Multisite complexation model
- Partial charge model
- Schultze-Hardy model
- Settling
- Stern layer adsorption
- Titania suspensions
- Viscosimetry
- Yield stress