Equilibrium sedimentation profiles of charged colloidal suspensions

TL;DR

This paper studies the sedimentation equilibrium of charged colloids at low ionic strength, demonstrating that the effective mass derived from density profiles matches the actual particle mass, challenging prior assumptions.

Contribution

It provides a theoretical analysis showing the effective mass from sedimentation profiles equals the true particle mass, using a Poisson-Boltzmann approach.

Findings

Effective mass matches actual colloid mass

Density profiles follow a barometric law

Contradicts previous studies' assumptions

Abstract

We investigate the sedimentation equilibrium of a charge stabilized colloidal suspension in the regime of low ionic strength. We analyze the asymptotic behaviour of the density profiles on the basis of a simple Poisson--Boltzmann theory and show that the effective mass we can deduce from the barometric law corresponds to the actual mass of the colloidal particles, contrary to previous studies.