Sedimentation potential in aqueous electrolytes

Abstract

The validity of the Smoluchowski treatment of the sedimentation potential (Dorn effect) is explored in relation to the recent cell-model treatment of Levine et al. which is applicable at higher volume fraction where both electrical and hydrodynamic interactions must be taken into account. An apparatus was constructed for the rapid successive measurement of the sedimentation potential gradient, the particle volume concentration, and the specific volume conductivity of the medium. Measurements on a model system of 97-p.m. glass microspheres dispersed in aqueous electrolytes showed that the Smoluchowski theory was followed below a volume fraction of 0.018 and that the potentials obtained compared to those obtained from streaming potential measurements at the glass-water interface characterized by an iep at pH 3.69. At higher volume fraction where the surface conduction correction was -1.1% the Levine cell-model theory was required to explain a -28% deviation from the linear approximation theory.

Electrokinetic study on concentrated suspensions using colloid vibration potential measurements

“…Recently, many electro-kinetic studies of concentrated suspensions have been challenged from different view points: the measurements of colloid vibration potential (CVP) of the concentrated suspension [2]; the rate of electro-osmosis at colloid occluded membranes [3]; the streaming potential on plugs of spherical polystyrene particles [4]; and the sedimentation potential on a glass microspheres [5]. The CVP method is a new and useful technique permitting direct measurements over a wide range of particle concentrations, i.e., from a diluted state overlapping microelectrophoresis, to 0 = 0.7.…”

Revisiting Zeta Potential, the Key Feature of Interfacial Phenomena, with Applications and Recent Advancements

“…The ratio of this potential to the distance between two electrodes determines the sedimentation potential. Sedimentation potential is a useful measuring technique for zeta potential analysis in colloidal suspensions and its stability [147] …”

Hydrodynamic simulations of sedimenting dilute particle suspensions under repulsive DLVO interactions

“…A number of studies [21][22][23][24] of sedimentation under both electrostatic and hydrodynamic particle-particle interactions have been performed using cellular methods to obtain the hydrodynamic component, either with the free-surface boundary condition by Happel [25] or the zero vorticity condition by Kuwabara [26]. While experimental results confirm the cell models as adequate to calculate the sedimentation potential [27], both the method by Happel and that of Kuwabara fail to correctly reproduce the sedimentation behaviour of non-interacting particles in the dilute limit found by Batchelor about 14 years after the introduction of the method [9,25,26]. Furthermore, cellular methods cannot take into account changes in the RDF of the sedimenting suspension induced by the electrostatic interactions and they assume an electrically neutral unit cell, which may be a too rough simplification if Debye layers overlap strongly [28].…”