A new generalization of the standard electrokinetic model

Area of Science:

• Colloid and Surface Science
• Physical Chemistry
• Electrochemistry

Background:

• Standard electrokinetic models assume equilibrium ion distribution (Gouy-Chapman) in the diffuse layer around particles.
• Existing models often struggle to explain experimental data where electrophoretic mobility is unexpectedly high.

Purpose of the Study:

• To present a generalized electrokinetic model that accounts for a non-equilibrium surface layer.
• To investigate how this generalized model impacts predictions of electrophoretic mobility, particularly in relation to anomalous surface conductivity.

Main Methods:

• Developed a new model incorporating a thin surface layer with non-Gouy-Chapman ion distribution and fluid flow.
• The layer includes both free ions and fixed charges of the particle.
• Boundary conditions determine free ion density without adsorption isotherms.

Main Results:

• The generalized model yields results qualitatively different from standard models.
• Electrophoretic mobility can increase with anomalous surface conductivity, contrary to standard predictions.
• The model offers a potential explanation for experimental data exceeding standard model predictions.

Conclusions:

• The proposed generalized electrokinetic model provides a more comprehensive framework for understanding particle behavior in electric fields.
• It successfully explains phenomena like increasing electrophoretic mobility with anomalous surface conductivity.
• This model broadens the scope for interpreting experimental electrokinetic data.