Use of trajectory analysis to study stability of colloidal dispersions in flow fields
TL;DR: In this paper, trajectories have been computed for two equal sized spherical particles in simple laminar shearing and in uniaxial extensional flows, and effects of interparticle attraction, electrostatic repulsion, and hydrodynamics were included.
Abstract: Trajectories have been computed for two equal sized spherical particles in simple laminar shearing and in uniaxial extensional flows. Effects of interparticle attraction, electrostatic repulsion, and hydrodynamics were included.
The results are pertinent to questions of colloidal stability under various conditions of flow. Particulate dispersions can react in several different ways as the intensity of shearing is increased from zero: the dispersion can remain stable; it can be redispersed, if it had been initially flocculated into a weak secondary minimum in the interparticle potential curve; it can be flocculated into a strong primary minimum in the potential curve; or, in extreme cases, it can be redispersed from the primary minimum. Results are presented which illustrate criteria for flocculation or stability to both laminar shearing and extensional flow. It is shown that hydrodynamic effects can significantly alter the criteria developed for stability of dispersions to Brownian coagulation.
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TL;DR: The flow decline is studied in typical experiments with dead-end microfiltration of BSA solutions through Cyclopore® track-etched polycarbonate membranes, with an increase in shear stress results in a decrease in deposition, probably due to a reduction in protein-surface interaction times.
442 citations
TL;DR: In this article, a three-dimensional modified discrete element method (mDEM) is proposed to simulate the deformation and breakup process of large aggregates in flows, where the effective particle surface for the hydrodynamic drag force and the disturbance of neighboring particles on the flow field are taken into account.
181 citations
Journal Article•
TL;DR: In this article, the authors describe the kinetics of flocculation of heterodisperse suspensions like those in water treatment plants using the Smoluchowski equation, which incorporates collision frequency functions for particle collisions by Brownian motion, fluid shear, and differential sedimentation.
Abstract: The kinetics of flocculation of heterodisperse suspensions like those in water treatment plants are usually described by the Smoluchowski equation, which incorporates collision frequency functions for particle collisions by Brownian motion, fluid shear, and differential sedimentation. These collision-frequency functions are based on a rectilinear view of collisions, i.e., one that ignores short-range forces and changes in fluid motion as particles approach one another.
166 citations
TL;DR: An experimental study of permeation of dilute BSA solutions (filtration) at microfiltration membranes has been carried out, finding this phenomenon is quite different to adsorption of protein at such surfaces, this latter giving only sub‐monolayer or monolayer protein coverage under the conditions studied.
Abstract: An experimental study of permeation of dilute BSA solutions (filtration) at microfiltration membranes has been carried out. Most measurements were made with capillary pore aluminum oxide membranes, with some comparative measurements with tortuous and capillary pore polymeric membranes. In all cases, a continuous and substantial decrease in the rate of permeation with time was observed. This decrease in permeation with time was observed. This decrease in permeation rate was due neither to concentration polarization nor to protein adsorption alone. However, it could be quantified using the standard blocking filtration law, which describes a decrease in pore volume due to deposition of protein on the walls of the pore. The maximum calculated thickness of the deposited layers was 55 nm on the walls of 200-nm diameter pores. This phenomenon is quite different to adsorption of protein at such surfaces, this latter giving only sub-monolayer or monolayer protein coverage under the conditions studied.
165 citations
TL;DR: In this article, the authors describe the kinetics of flocculation of heterodisperse suspensions like those in water treatment plants using the Smoluchowski equation, which incorporates collision frequency functions for particle collisions by Brownian motion, fluid shear, and differential sedimentation.
Abstract: The kinetics of flocculation of heterodisperse suspensions like those in water treatment plants are usually described by the Smoluchowski equation, which incorporates collision frequency functions for particle collisions by Brownian motion, fluid shear, and differential sedimentation. These collision-frequency functions are based on a rectilinear view of collisions, i.e., one that ignores short-range forces and changes in fluid motion as particles approach one another.
159 citations