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09:26
Synthesis and Characterization of Supramolecular Colloids
Published on: April 22, 2016
Smoluchowski equation and the colloidal charge reversal
1Departamento de Física, Universidade Federal do Ceará, Caixa Postal 6030, CEP 60455-760 Fortaleza, Ceará, Brazil. diehl@fisica.ufc.br
The Journal of Chemical Physics
|September 1, 2006
Summary
Electrophoretic mobility reversal occurs in colloids when zeta potential changes sign due to multivalent electrolytes. This phenomenon depends on surface charge density and electrolyte concentration, even with small ions.
Area of Science:
- Colloid and Surface Science
- Physical Chemistry
Background:
- Electrophoretic mobility is crucial for understanding colloid behavior.
- Zeta potential, the diffuse potential at the shear plane, governs electrophoretic mobility.
- The precise location of the shear plane is critical for accurate zeta potential determination.
Purpose of the Study:
- To investigate the conditions leading to electrophoretic mobility reversal.
- To analyze the role of zeta potential in mobility reversal.
- To determine the influence of ion size, surface charge, and electrolyte concentration on this phenomenon.
Main Methods:
- Utilizing the Smoluchowski equation for theoretical analysis.
- Employing Monte Carlo simulations for empirical validation.
- Modeling the diffuse layer potential at a shear plane located one ionic diameter from the surface.
Main Results:
- Zeta potential can invert sign with increasing multivalent electrolyte concentration for strongly charged colloids.
- Electrophoretic mobility reversal is observed under these conditions.
- This reversal is achievable even with small ions (4 Å diameter) given sufficient surface charge density and low 1:1 electrolyte concentration.
Conclusions:
- The study elucidates the mechanism of electrophoretic mobility reversal.
- Zeta potential inversion is a key factor, influenced by electrolyte type and concentration.
- The findings have implications for controlling colloidal dispersion stability and behavior.
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