Electroviscous Effect of Moderately Concentrated Colloidal Suspensions

Abstract

The electroviscous effect of a colloidal suspension is considered. The disagreement between the different existing theories and the experimental results is pointed out. A new development, based upon a cell model concept, is proposed. This new approach is valid for Newtonian fluids and disordered systems, which imposes the condition of low shear rate, corresponding to the low Newtonian plateau in general flow curves of colloidal suspensions. The theory is valid for moderately concentrated suspensions and thin double layers. The numerical results are analyzed, resulting in a dependence of the electroviscous effect with the particle concentration. A maximum of the electroviscous coefficient with the ζ-potential for every particle concentration and electrokinetic radius is found, although the very high ζ value where the maximum appears makes it inaccessible for experimental tests. The theoretical predictions are compared with a few experimental results. A better agreement in the region of validity of the theory is found.

Ultrasonic wave propagation in concentrated slurries – The modelling problem

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Salt concentration and particle density dependence of electrophoretic mobilities of spherical colloids in aqueous suspension

“…[7][8][9][10][11][12][13]28,29]. Here we use a version allowing for arbitrary zeta potential and κa and thus double-layer overlap, but not including a dynamic Stern layer allowing for specific adsorption/desorption processes nor for conductance behind the hydrodynamic slip plane.…”

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“…The polarisation, in turn, causes a flux of ions and solvent that opposes and decelerates the relative motion. This kind of deceleration affects particle sedimentation (von Smoluchowski 1903;Ohshima et al 1984;Keh and Ding 2000); capillary flow (Bull 1932, Levine et al 1975, the hydrodynamic drag on single particles (Booth 1954) or the viscosity of a suspension (Booth 1950;Ruiz-Reina et al 2003). Note that the primary electroviscous effect is related to individual particles and surfaces; any double layer interaction is excluded.…”