Eur. Phys. J. E (2004) 15: 255-263
https://doi.org/10.1140/epje/i2004-10065-5

Particle thermophoresis in liquids

¹ INFM and Dipartimento di Fisica e Matematica, Università dell’Insubria, Via Valleggio 11, 22100, Como, Italy
² INFM and Dipartimento di Ingegneria Nucleare, Politecnico di Milano, via Ponzio 34/3, 20133, Milano, Italy

^* e-mail: parola@mi.infm.it

Received: 5 September 2004
Accepted: 21 October 2004
Published online: 16 November 2004

Abstract

We present a microscopic description of thermophoretic phenomena in dilute suspensions of spherical colloids. The specific particle/solvent interfacial interactions generate a force density field on the surrounding fluid which in turn gives rise to an “effective force” on the colloid. In our approach, such a force turns out to be solely related to the non-conservative anisotropic contribution to brought forth by the thermal gradient. By adopting a Smoluchowski picture of colloid motion, we find a general expression for the Soret coefficient S_T, which we apply to the specific cases of neutral colloids in pure solvent and of Debye-Hückel systems. For the latter, our result for S_T agrees with those obtained by previous hydrodynamic approaches.