Soret Motion of a Charged Spherical Colloid

TL;DR

This paper presents a theoretical study of the thermophoretic motion of charged colloids, combining analytical and numerical methods to explore effects of charge, potential, and fluid dynamics, aligning well with recent experimental data.

Contribution

It introduces a comprehensive theoretical framework for Soret motion of charged colloids, including analytical solutions for weak charges and numerical analysis for high charges, considering complex electrokinetic effects.

Findings

Analytical Soret drift velocity for weakly charged colloids.

Numerical solutions for highly charged colloids considering nonlinear effects.

Good agreement with recent experimental observations.

Abstract

The thermophoretic motion of a charged spherical colloidal particle and its accompanying cloud of counterions and co-ions in a temperature gradient is studied theoretically. Using the Debye-Huckel approximation, the Soret drift velocity of a weakly charged colloid is calculated analytically. For highly charged colloids, the nonlinear system of electrokinetic equations is solved numerically, and the effects of high surface potential, dielectrophoresis, and convection are examined. Our results are in good agreement with some of the recent experiments on highly charged colloids without using adjustable parameters.