Effective charge saturation in colloidal suspensions

Bocquet, Lydéric; Trizac, Emmanuel; Aubouy, Miguel

doi:10.1063/1.1511507

Cited by 141 publications

(201 citation statements)

References 65 publications

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“…This expression -valid up to corrections of order (κa) −1 , which turn out to be quite small as soon as κa > 1, is very close to the approximation (4), derived from the matching procedure detailed in [20,22]. The effective charge depends strongly on the electrolyte concentration inside the suspension.…”

Section: Role Of Volume Termssupporting

confidence: 78%

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On the fluid–fluid phase separation in charged-stabilized colloidal suspensions

Levin¹,

Trizac²,

Bocquet³

2003

J. Phys.: Condens. Matter

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We develop a thermodynamic description of particles held at a fixed surface potential. This system is of particular interest in view of the continuing controversy over the possibility of a fluidfluid phase separation in aqueous colloidal suspensions with monovalent counterions. The condition of fixed surface potential allows in a natural way to account for the colloidal charge renormalization. In a first approach, we assess the importance of the so called "volume terms", and find that in the absence of salt, charge renormalization is sufficient to stabilize suspension against a fluid-fluid phase separation. Presence of salt, on the other hand, is found to lead to an instability. A very strong dependence on the approximations used, however, puts the reality of this phase transition in a serious doubt. To further understand the nature of the instability we next study a Jelliumlike approximation, which does not lead to a phase separation and produces a relatively accurate analytical equation of state for a deionized suspensions of highly charged colloidal spheres. A critical analysis of various theories of strongly asymmetric electrolytes is presented to asses their reliability as compared to the Monte Carlo simulations.

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Section: Role Of Volume Termssupporting

confidence: 78%

“…Evaluating the partial derivative in Eq. (20), the osmotic pressure inside the suspension takes a particularly simple form…”

Section: The Equation Of Statementioning

confidence: 99%

On the fluid–fluid phase separation in charged-stabilized colloidal suspensions

Levin¹,

Trizac²,

Bocquet³

2003

J. Phys.: Condens. Matter

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“…Within the linearized PB theory it is a common practice to use renormalized instead of bare surface charge densities in order to capture the correct asymptotic behavior of the electrostatic potential at large distances [32]. However, in the present study we are interested in the opposite limit of short distances.…”

Section: A L-dependent Interactionsmentioning

confidence: 99%

“…This implies a replacement of the bare surface charge density (σ i ) with an effective charge density (±σ (i) eff ) if σ (i) eff < |σ i |. The analytic expression for the effective surface charge density is known for a single charged wall in contact with a semi-infinite electrolyte solution and is given by σ (i) eff = eκ i ε r,i /(πℓ B ), i ∈ {1, 2}, with κ(x > 0) = κ 1 and κ(x < 0) = κ 2 [32]. For the above mentioned standard set of parameters, we have calculated separately σ (i) eff for a single wall in contact with medium i ∈ {1, 2}; it turns out that σ (1) eff < σ 1 whereas σ (2) eff > σ 2 .…”

Section: A L-dependent Interactionsmentioning

confidence: 99%

Poisson-Boltzmann study of the effective electrostatic interaction between colloids at an electrolyte interface

Majee¹,

Bier²,

Dietrich

2016

The Journal of Chemical Physics

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The effective electrostatic interaction between a pair of colloids, both of them located close to each other at an electrolyte interface, is studied by employing the full, nonlinear Poisson-Boltzmann (PB) theory within classical density functional theory. Using a simplified yet appropriate model, all contributions to the effective interaction are obtained exactly, albeit numerically. The comparison between our results and those obtained within linearized PB theory reveals that the latter overestimates these contributions significantly at short inter-particle separations. Whereas the surface contributions to the linear and the nonlinear PB results differ only quantitatively, the line contributions show qualitative differences at short separations. Moreover, a dependence of the line contribution on the solvation properties of the two adjacent fluids is found, which is absent within the linear theory. Our results are expected to enrich the understanding of effective interfacial interactions between colloids.

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“…Given proper boundary conditions, the WS cell reduces the initial many-particle system to the much simpler problem of a single macroparticle [49][50][51][52][53][54][55]. It is most noticeable that all the theories mentioned above assumed that the WS cells with spherical macroparticle are isotropic, i.e., the potential distribution is symmetrical ball.…”

Section: Introductionmentioning

confidence: 99%

The Anisotropic Cell Model in the Colloidal Plasmas

Ye¹,

Lu²

2010

PIER

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Abstract-The anisotropic spherical Wigner-Seitz (WS) cell model -introduced to describe colloidal plasmas -is investigated using the linearized Poisson-Boltzmann (PB) equation. As an approximation, the surface potential of the spherical macroparicle expanded in terms of the monopole (q) and the dipole (p) is considered as an anisotropic boundary condition of the linear PB equation. Here, the "apparent" moments q and p are the moments 'seen' in the microion cloud, respectively. Based on a new physical concept, the momentneutrality, the potential around the macroparticle can be solvable analytically if the relationship between the actual moment and the "apparent" moment can be obtained according to the momentneutrality condition in addition to the usual electroneutrality. The calculated results of the potential show that there is an attractive region in the vicinity of macroparticle when the corresponding dipole part of the potential dominates over the monopole part, and there is an attractive region and a repulsive region at the same time, i.e., a potential well, when the corresponding dipole part of the potential just comes into play. It provides the possibility and the conditions of the appearance of periodic structure of the colloidal plasmas, although it is a result of a simple theoretical model.

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Effective charge saturation in colloidal suspensions

Cited by 141 publications

References 65 publications

On the fluid–fluid phase separation in charged-stabilized colloidal suspensions

On the fluid–fluid phase separation in charged-stabilized colloidal suspensions

Poisson-Boltzmann study of the effective electrostatic interaction between colloids at an electrolyte interface

The Anisotropic Cell Model in the Colloidal Plasmas

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