Diffusiophoresis of a moderately charged spherical colloidal particle

Area of Science:

• Colloid and Surface Science
• Physical Chemistry
• Electrochemistry

Background:

• Diffusiophoresis describes particle movement in electrolyte gradients.
• Existing models for diffusiophoretic mobility have limitations in accuracy and applicability.
• Understanding particle behavior is crucial for applications in nanotechnology and materials science.

Purpose of the Study:

• To derive a more accurate analytic expression for the diffusiophoretic mobility of charged spherical colloidal particles.
• To extend the applicability of mobility formulas to a wider range of zeta potentials and electrical double-layer thicknesses.
• To provide a simpler approximate mobility expression for practical applications.

Main Methods:

• Derivation of an analytic expression using perturbation theory.
• Expansion of the expression to the third order of the particle zeta potential.
• Analysis of the contribution of the electrophoresis component to diffusiophoresis.

Main Results:

• An analytic expression for diffusiophoretic mobility, accurate to the third order of zeta potential, was obtained.
• The new expression is valid for low and moderate zeta potentials and arbitrary electrical double-layer thicknesses.
• A simpler approximate mobility expression, avoiding exponential integrals, was also derived.

Conclusions:

• The derived third-order expression improves upon previous second-order models.
• The findings are significant for accurately predicting colloidal particle behavior in electrolyte solutions.
• The simplified expression offers a practical alternative for computational and experimental studies.