Diffusiophoresis of a cylindrical colloidal particle oriented parallel to an electrolyte concentration gradient field

Area of Science:

• Colloid and Surface Science
• Physical Chemistry
• Electrokinetics

Background:

• Diffusiophoresis is a key electrokinetic phenomenon driving particle motion in response to chemical gradients.
• Understanding particle mobility is crucial for applications in microfluidics, drug delivery, and separation technologies.
• Existing models often rely on approximations for particle zeta potential and electrical double-layer thickness.

Purpose of the Study:

• To derive a general analytical expression for the diffusiophoretic mobility of a cylindrical particle.
• To validate the accuracy of the derived expression for a wide range of conditions.
• To assess the validity of the low zeta potential approximation.

Main Methods:

• Derivation of the general diffusiophoretic mobility expression for a cylindrical particle parallel to a concentration gradient.
• Integration with an approximate analytical solution for the electric potential distribution around the cylinder.
• Validation against known approximations and theoretical limits.

Main Results:

• A general analytical expression for diffusiophoretic mobility was obtained.
• The expression is valid for arbitrary zeta potentials and electrical double-layer thicknesses.
• The low zeta potential approximation was confirmed as accurate for low-to-moderate zeta potentials.

Conclusions:

• The derived mobility expression offers a more accurate and versatile tool for predicting diffusiophoretic behavior.
• This work provides a refined understanding of particle dynamics in non-uniform electrolyte solutions.
• The findings have implications for designing and optimizing systems utilizing diffusiophoresis.