Dielectric Phenomena and Double Layer in Disperse Systems and Polyelectrolytes

Dukhin, S. S.; Shilov, V. N.; Bikerman, J. J.

doi:10.1149/1.2402374

Cited by 375 publications

(514 citation statements)

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“…On the contrary, well-defined mobility maxima as a function of zeta potential are described in suspensions in electrolyte solutions for larger κa values, the "concentration polarization effect", associated with concentration gradients of neutral electrolyte, being responsible for the existence of such maxima. 49,50 In salt-free suspensions, we have only counterions, and therefore, no neutral electrolyte concentration gradients can be established. Hence, no new contributions to the induced dipole moment or additional diffusive ionic fluxes as a consequence of such neutral concentration gradients can affect the salt-free electrophoretic mobility.…”

Section: Resultsmentioning

confidence: 99%

Cell Model of the Direct Current Electrokinetics in Salt-Free Concentrated Suspensions: The Role of Boundary Conditions

2006

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In this paper, a general electrokinetic theory for concentrated suspensions in salt-free media is derived. Our model predicts the electrical conductivity and the electrophoretic mobility of spherical particles in salt-free suspensions for arbitrary conditions regarding particle charge, volume fraction, counterion properties, and overlapping of double layers of adjacent particles. For brevity, hydrolysis effects and parasitic effects from dissolved carbon dioxide, which are present to some extent in more "realistic" salt-free suspensions, will not be addressed in this paper. These issues will be analyzed in a forthcoming extension. However, previous models are revised, and different sets of boundary conditions, frequently found in the literature, are extensively analyzed. Our results confirm the so-called counterion condensation effect and clearly display its influence on electrokinetic properties such as electrical conductivity and electrophoretic mobility for different theoretical conditions. We show that the electrophoretic mobility increases as particle charge increases for a given particle volume fraction until the charge region where counterion condensation takes place is attained, for the abovementioned sets of boundary conditions. However, it decreases as particle volume fraction increases for a given particle charge. Instead, the electrical conductivity always increases with either particle charge for fixed particle volume fraction or volume fraction for fixed particle charge, whatever the set of boundary conditions previously referred. In addition, the influence of the electric permittivity of the particles on their electrokinetic properties in salt-free media is examined for those frames of boundary conditions.

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Section: Resultsmentioning

confidence: 99%

Cell Model of the Direct Current Electrokinetics in Salt-Free Concentrated Suspensions: The Role of Boundary Conditions

2006

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“…For many years, most theories dealing with different electrokinetic phenomena have considered the case of dilute colloidal 1 To whom correspondence should be addressed.…”

Section: Introductionmentioning

confidence: 99%

“…suspensions (1)(2)(3)(4)(5)(6)(7)(8)(9)(10)(11)(12)(13)(14)(15). However, in a great number of practical situations, suspensions are usually more concentrated than those typically considered as dilute, so some theoretical approaches to the issue of concentrated suspensions, including electrophoresis (16), sedimentation (17,18), electrical conductivity (19), and electroacoustic phenomena (20)(21)(22), to mention just a few, have been published in the past few decades.…”

Section: Introductionmentioning

confidence: 99%

Electrokinetics of Concentrated Suspensions of Spherical Colloidal Particles with Surface Conductance, Arbitrary Zeta Potential, and Double-Layer Thickness in Static Electric Fields

Carrique¹,

Arroyo

Delgado

2002

Journal of Colloid and Interface Science

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“…(S1. 23,24) are expressions of the continuity of the electric potential and normal component of the displacement vector, ε rp being the relative permittivity of the particle. Eq.…”

Section: Supplementary Informationmentioning

confidence: 99%

“…There exist classical or standard models that predict that response. To begin with, these models [24][25][26][27][28][29][30][31][32][33][34][35] do not take into account the realistic chemistry of the aqueous solutions or the role of the (added) counterions released by the particles. For dilute suspensions and common electrolyte concentrations in solution, the latter two aspects have been historically underestimated or simply neglected, because of their admitted minor role in comparison with that of the salt.…”

Section: Introductionmentioning

confidence: 99%

General electrokinetic model for concentrated suspensions in aqueous electrolyte solutions: Electrophoretic mobility and electrical conductivity in static electric fields

Carrique

Roa

Arroyo

et al. 2015

Journal of Colloid and Interface Science

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In recent years different electrokinetic cell models for concentrated colloidal suspensions in aqueous electrolyte solutions have been developed. They share some of its premises with the standard electrokinetic model for dilute colloidal suspensions, in particular, neglecting both the specific role of the so-called added counterions (i.e., those released by the particles to the solution as they get charged), and the realistic chemistry of the aqueous solution on such electrokinetic phenomena as electrophoresis and electrical conductivity.These assumptions, while having been accepted for dilute conditions (volume fractions of solids well below 1 %, say), are now questioned when dealing with concentrated suspensions.In this work, we present a general electrokinetic cell model for such kind of systems, including the mentioned effects, and we also carry out a comparative study with the standard treatment (the standard solution only contains the ions that one purposely adds, without ionic contributions from particle charging or water chemistry). We also consider an intermediate model that neglects the realistic aqueous chemistry of the solution but accounts for the correct contribution of the added counterions. The results show the limits of applicability of the classical assumptions and allow one to better understand the relative role of the added counterions and ions stemming from the electrolyte in a realistic aqueous solution, on electrokinetic properties. For example, at low salt concentrations the realistic effects of the aqueous solution are the dominant ones, while as salt concentration is increased, it is this that progressively takes the control of the electrokinetic response for low to moderate volume fractions. As expected, if the solids concentration is high enough the added counterions will play the dominant role (more important the higher the particle surface charge), no matter the salt concentration if it is not too high. We hope this work can help in setting up the real limits of applicability of the standard cell model for concentrated suspensions by a quantitative 4 analysis of the different effects that have been classically disregarded, showing that in many cases they can be determinant to get rigorous predictions.

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Dielectric Phenomena and Double Layer in Disperse Systems and Polyelectrolytes

Abstract: not Available.

Cited by 375 publications

References 0 publications

Cell Model of the Direct Current Electrokinetics in Salt-Free Concentrated Suspensions: The Role of Boundary Conditions

Cell Model of the Direct Current Electrokinetics in Salt-Free Concentrated Suspensions: The Role of Boundary Conditions

Electrokinetics of Concentrated Suspensions of Spherical Colloidal Particles with Surface Conductance, Arbitrary Zeta Potential, and Double-Layer Thickness in Static Electric Fields

General electrokinetic model for concentrated suspensions in aqueous electrolyte solutions: Electrophoretic mobility and electrical conductivity in static electric fields

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