Effects of Interparticle Attractions on Colloidal Sedimentation

Moncho-Jordá, A.; Louis, Ard A.; Padding, JT Johan

doi:10.1103/physrevlett.104.068301

Cited by 41 publications

(49 citation statements)

References 29 publications

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“…[9] (stars with lines, denoted LBP2016 in the legend) and computed in the present work (filled circles) and the SRD simulations of Ref. [22] as interpolated in Ref. [9] (open squares, denoted MLP2010 in the legend).…”

Section: A Comparison Of Simulations and Experimentsmentioning

confidence: 99%

From hindered to promoted settling in dispersions of attractive colloids: Simulation, modeling, and application to macromolecular characterization

2018

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The settling of colloidal particles with short-ranged attractions is investigated via highly resolved immersed boundary simulations. At modest volume fractions, we show that intercolloid attractions lead to clustering that reduces the hinderance to settling imposed by fluid back flow. For sufficient attraction strength, increasing the particle concentration grows the particle clusters, which further increases the mean settling rate in a physical mode termed promoted settling. The immersed boundary simulations are compared to recent experimental measurements of the settling rate in nanoparticle dispersions for which particles are driven to aggregate by short-ranged depletion attractions. The simulations are able to quantitatively reproduce the experimental results. We show that a simple, empirical model for the settling rate of adhesive hard-sphere dispersions can be derived from a combination of the experimental and computational data as well as analytical results valid in certain asymptotic limits of the concentration and attraction strength. This model naturally extends the Richardson-Zaki formalism used to describe hindered settling of hard, repulsive spheres. Experimental measurements of the collective diffusion coefficient in concentrated solutions of globular proteins are used to illustrate inference of effective interaction parameters for sticky, globular macromolecules using this empirical model. Finally, application of the simulation methods and empirical model to other colloidal systems are discussed.

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Section: A Comparison Of Simulations and Experimentsmentioning

confidence: 99%

From hindered to promoted settling in dispersions of attractive colloids: Simulation, modeling, and application to macromolecular characterization

2018

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“…Practically encountered aggregates cover a wide range of structures, comprising slightly distorted regularshaped aggregates such as spheres, ellipsoids, cylinders and discs, to very irregular-shaped aggregates like random coils, wormlike coils, and most generally fractal aggregates. The hydrodynamic properties of all these kinds of aggregates are a pre-requisite in knowing their motion under the influence of different flow fields and forces, and in understanding the physical properties exhibited therewith [1][2][3][4][5]. The properties of aggregates and their dispersions are related to the drag force that they experience in the fluid, which in turn depends on their structure and size [1,6].…”

Section: Introductionmentioning

confidence: 99%

Hydrodynamic properties of rigid fractal aggregates of arbitrary morphology

Harshe

Ehrl

Lattuada

2010

Journal of Colloid and Interface Science

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“…particle resolved) processes of mixing and demixing under settling are still debated 3,4 . It is known for long time that shaken or vibrated granular mixtures can exhibit the "brazil-nut effect", namely that the heavier particles are on top of the lighter ones 5,6 .…”

Section: Introductionmentioning

confidence: 99%

Soft repulsive mixtures under gravity: Brazil-nut effect, depletion bubbles, boundary layering, nonequilibrium shaking

Kruppa

Neuhaus

Messina

et al. 2012

The Journal of Chemical Physics

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A binary mixture of particles interacting via long-ranged repulsive forces is studied in gravity by computer simulation and theory. The more repulsive A-particles create a depletion zone of less repulsive B-particles around them reminiscent to a bubble. Applying Archimedes' principle effectively to this bubble, an A-particle can be lifted in a fluid background of Bparticles. This "depletion bubble" mechanism explains and predicts a brazil nut effect where the heavier A-particles float on top of the lighter B-particles. It also implies an effective attraction of an A-particle towards a hard container bottom wall which leads to boundary layering of A-particles. Additionally, we have studied a periodic inversion of gravity causing perpetuous mutual penetration of the mixture in a slit geometry. In this nonequilibrium case of time-dependent gravity, the boundary layering persists. Our results are based on computer simulations and density functional theory of a two-dimensional binary mixture of colloidal repulsive dipoles. The predicted effects also occur for other long-ranged repulsive interactions and in three spatial dimensions. They are therefore verifiable in settling experiments on dipolar or charged colloidal mixtures as well as in charged granulates and dusty plasmas.

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Effects of Interparticle Attractions on Colloidal Sedimentation

Cited by 41 publications

References 29 publications

From hindered to promoted settling in dispersions of attractive colloids: Simulation, modeling, and application to macromolecular characterization

From hindered to promoted settling in dispersions of attractive colloids: Simulation, modeling, and application to macromolecular characterization

Hydrodynamic properties of rigid fractal aggregates of arbitrary morphology

Soft repulsive mixtures under gravity: Brazil-nut effect, depletion bubbles, boundary layering, nonequilibrium shaking

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