Electroviscous effect of moderately concentrated colloidal suspensions: Stern-layer influence

Area of Science:

• Colloid and Surface Science
• Rheology of Suspensions
• Electrochemistry

Background:

• Previous models for suspension viscosity did not fully account for complex interfacial phenomena.
• The dynamic Stern layer (DSL) contributes significant surface conductance, affecting electrokinetic properties.
• Understanding these effects is crucial for accurate modeling of fluid dynamics in colloidal systems.

Purpose of the Study:

• To extend a prior model for the viscosity of moderately concentrated suspensions.
• To incorporate the influence of a dynamic Stern layer (DSL) on surface conductance.
• To investigate the impact of DSL on energy dissipation during laminar flow.

Main Methods:

• Theoretical extension of a previous viscosity model.
• Application of Happel's cell model with Simha's boundary conditions for hydrodynamics.
• Integration of a dynamic Stern-layer model for ionic conduction on particle surfaces.

Main Results:

• The extended model provides predictions valid for arbitrary zeta potentials and double-layer thicknesses.
• Significant new behaviors were identified due to the inclusion of DSL.
• Comparison reveals a substantial influence of DSL on energy dissipation compared to models without additional surface conductance.

Conclusions:

• The dynamic Stern layer plays a critical role in the energy dissipation of flowing suspensions.
• Accurate prediction of suspension viscosity requires the inclusion of DSL effects.
• The enhanced model offers improved agreement with experimental observations for electrolyte-particle systems.