Electroviscous effect of concentrated suspensions in salt-free media: Water dissociation and CO2 influence

Ruiz-Reina, Emilio; Carrique, F.

doi:10.1016/j.jcis.2010.02.014

Cited by 9 publications

(10 citation statements)

References 56 publications

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“…If the suspension is concentrated [5], the particle-particle electrohydrodynamic interactions introduce severe limitations when dealing with the response to external fields, not only for the mathematical difficulties of dealing with many-body interactions, but also for the additional numerical problems raised when it comes to solve the equations, no matter the approximation chosen. The authors have addressed this problem by using a cell model approach to deal with electrokinetic and rheological properties in concentrated suspensions [10][11][12][13][14][15][16][17][18].…”

Section: Introductionmentioning

confidence: 99%

Electric double layer for spherical particles in salt-free concentrated suspensions including ion size effects

Roa

Carrique

2011

Phys. Chem. Chem. Phys.

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The equilibrium electric double layer (EDL) that surrounds the colloidal particles is determinant for the response of a suspension under a variety of static or alternating external fields. An ideal salt-free suspension is composed by the charged colloidal particles and the ionic countercharge released by the charging mechanism. The existing macroscopic theoretical models can be improved by incorporating different ionic effects usually neglected in previous mean-field approaches, which are based on the Poisson-Boltzmann equation (PB). The influence of the finite size of the ions seems to be quite promising because it has been shown to predict phenomena like charge reversal, which has been out of the scope of classical PB approximations. In this work we numerically obtain the surface electric potential and the counterions concentration profiles around a charged particle in a concentrated salt-free suspension corrected by the finite size of the counterions. The results show the large importance of such corrections for moderate to high particle charges at every particle volume fraction, specially, when a region of closest approach of the counterions to the particle surface is considered. We conclude that finite ion size considerations are obeyed for the development of new theoretical models to study nonequilibrium properties in concentrated colloidal suspensions, particularly the salt-free ones with small and highly charged particles.

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Section: Introductionmentioning

confidence: 99%

Electric double layer for spherical particles in salt-free concentrated suspensions including ion size effects

Roa

Carrique

2011

Phys. Chem. Chem. Phys.

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“…Thus, static and dynamic electrophoresis and complex conductivity and dielectric response models were developed by the authors according to such EDL representation. [18][19][20][21] The first conclusion that can be drawn from these studies is the large magnitude of the realistic corrections for any of the latter properties. As a consequence, the neglecting of such corrections could lead to poor comparisons with experimental results.…”

Section: Introductionmentioning

confidence: 94%

“…For details about the cell model approach see the excellent review of Zholkovskij et al [42]. This approach has been successfully used by the authors in the study of DC and AC electrokinetics and rheological properties of pure [14][15][16][17] and realistic [13,[18][19][20][21] salt-free suspensions with point-like ions. We have learned from those works how important the description of the EDL is for the nonequilibrium theoretical responses.…”

Section: A the Cell Modelmentioning

confidence: 99%

“…The aim was to improve the EDL model that could be used to develop nonequilibrium models in concentrated systems, starting from the salt-free ones because of their special theoretical interest. Thus, static and dynamic electrophoresis and complex conductivity and dielectric response models were developed by the au-thors according to such EDL representation [18][19][20][21]. The first conclusion that can be drawn from these studies is the large magnitude of the realistic corrections for any of the latter properties.…”

Section: Introductionmentioning

confidence: 99%

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Ion size effects on the electric double layer of a spherical particle in a realistic salt-free concentrated suspension

Roa

Carrique

2011

Phys. Chem. Chem. Phys.

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A new modified Poisson-Boltzmann equation accounting for the finite size of the ions valid for realistic salt-free concentrated suspensions has been derived, extending the formalism developed for pure salt-free suspensions [Roa et al., Phys. Chem. Chem. Phys., 2011, 13, 3960-3968] to real experimental conditions. These realistic suspensions include water dissociation ions and those generated by atmospheric carbon dioxide contamination, in addition to the added counterions released by the particles to the solution. The electric potential at the particle surface will be calculated for different ion sizes and compared with classical Poisson-Boltzmann predictions for point-like ions, as a function of particle charge and volume fraction. The realistic predictions turn out to be essential to achieve a closer picture of real salt-free suspensions, and even more important when ionic size effects are incorporated to the electric double layer description. We think that both corrections have to be taken into account when developing new realistic electrokinetic models, and surely will help in the comparison with experiments for low-salt or realistic salt-free systems.

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“…To overcome this problem, the authors of [13][14][15][16] introduced a cell model approach, and the approach successfully was applied to dealing with electrokinetic and rheological properties in concentrated suspension. It was confirmed in [17] that up to moderately strong electrostatic couplings, the cell model accurately predicts osmotic pressures of deionised suspensions in agreement with Monte Carlo simulations and renormalized-effective interaction approaches.…”

Section: Introductionmentioning

confidence: 99%

Electric double layer of colloidal particles in salt-free concentrated suspensions including non-uniform size effects and orientational ordering of water dipoles

Sin,

Kim,

et al. 2022

Preprint

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The response of a suspension under a variety of static or alternating external fields strongly depends on the equilibrium electric double layer that surrounds the colloidal particles in the suspension. The theoretical models for salt-free suspensions can be improved by incorporating non-uniform size effects and orientational ordering of water dipoles neglected in previous mean-field approaches, which are based on the Poisson-Boltzmann approach. Our model including non-uniform size effects and orientational ordering of water dipoles seems to have quite a promising effect because the model can predict the phenomena like a heavy decrease in relative permittivity of the suspension and counterion stratification near highly charged colloidal particle. In this work we numerically obtain the electric potential, the counterions concentration and the relative permittivity around a charged particle in a concentrated salt-free suspension corrected by non-uniform size effects and orientational ordering of water dipoles. The results show the worth of such corrections for medium to high particle charges at every particle volume fraction. We conclude that non-uniform size effects and orientational ordering of water dipoles are necessary for the development of new theoretical models to study non-equilibrium properties in concentrated colloidal suspensions.

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Electroviscous effect of concentrated suspensions in salt-free media: Water dissociation and CO2 influence

Cited by 9 publications

References 56 publications

Electric double layer for spherical particles in salt-free concentrated suspensions including ion size effects

Electric double layer for spherical particles in salt-free concentrated suspensions including ion size effects

Ion size effects on the electric double layer of a spherical particle in a realistic salt-free concentrated suspension

Electric double layer of colloidal particles in salt-free concentrated suspensions including non-uniform size effects and orientational ordering of water dipoles

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