Axial Dispersion of Sedimented Colloids

Abstract

After an ensemble of identical particles has had time to settle along the y-axis to their equilibrium distribution in a field of potential energy %oS(y) by gravity, but prevented from adsorbing by double-layer repulsion, their dispersion by Poiseuille flow between two horizontal plates is predicted. The residence-time distribution of particles is obtained in terms of ⊘(y). For chromatographic peaks with long retention times, equations are obtained relating the elution volume and dispersion coefficient to ⊘(y)- From such data, two pieces of information regarding ⊘(y) can be deduced: the location of the minimum, y_m, and ⊘ (y_m). However, at the opposite extreme of very short retention times, a major portion of the profile ⊘(y) can be deduced from a single chromatogram. Such an experiment might provide the first measurement of long-range forces between a colloid particle and a flat plate.