Particles In Electrolyte Solution Research Articles

Calculation of the Static Permittivity of Suspensions from the Stored Energy

It is shown that the static permittivity of suspensions of charged particles in electrolyte solution can be deduced from the field-induced change of the Gibbs free energy stored outside the double layer. This energy is related to the changes of the electrolyte concentration around the particle and is obtained solving a purely static problem. The method is first verified deducing well-known results corresponding to suspensions of spherical particles. It is then used to calculate the static permittivity of suspensions of spheroidal particles, leading to a new result that cannot be analytically obtained using the classical approach.

On the Possibility of Inductive Properties in Suspensions of Ion Exchange Resin Particles

A theory of the low-frequency relaxation of suspensions of ion exchange resin (IER) particles in electrolyte solution is presented. It is a revision of a previous work on this system (Simonov I. N., and Shilov V. N.,Colloids J.39,891, 1977) and uses a model similar to the one originally developed for suspensions of charged insulating particles (Shilov V. N., and Dukhin S. S.,Colloids J.32,293, 1970). The problem is analytically solved for two extreme cases: a perfectly rigid IER and a weakly bound IER which swells depending on the electrolyte concentration. The results obtained in both cases show a low-frequency high-amplitude relaxation analogous to the one observed in suspensions of polystyrene particles. Furthermore, for weakly bound IER suspensions, some calculated spectra show a frequency range in which the permittivity increases with frequency. The origin of this inductive behavior is not due to inertial effects but rather to differences in the diffusion coefficients of the two types of ions in each medium, and between media.

Theory of the Low-Frequency Electrorotation of Polystyrene Particles in Electrolyte Solution

An interpretation is given for the cofield rotation observed in low-frequency electrorotation experiments using polystyrene particles in electrolyte solution. It is shown that the main cause of the particle rotation is the electroosmotic velocity of the electrolyte inside the thin double layer, rather than the torque exerted by the rotating electric field on the out of phase part of the induced dipole moment.

Role of electrostatic interactions in particle adsorption

The role of the electrostatic double-layer interactions in adsorption of colloid particles at solid/liquid interface was reviewed. The phenomenological formulation of the governing PB equation was presented with the expressions for the pressure tensor enabling one to calculate forces, torques and interaction energies between particles in electrolyte solutions. Then, the limiting analytical results for an isolated double-layer (both spherical and planar) were discussed in relation to the effective surface potential concept. The range of validity of the approximate expression connecting the surface potential and the effective surface potential with surface charge for various electrolytes was estimated. The results for double-layer systems were next presented including the case of two planar double-layers and two dissimilar spherical particles. Limiting solutions for short and long distances as well as for low potentials (linear HHF model) were discussed. The approximate models for calculating interactions of spheres, i.e., the extended Derjaguin summation method and the linear superposition approach (LSA) were also introduced. The results stemming from these models were compared with the exact numerical solution obtained in bispherical coordinate system. Possibilities of describing interactions of nonspherical particles (e.g., spheroids) in terms of the Derjaguin and the equivalent sphere methods were pointed out. In further part of the review the role of these electrostatic interactions in adsorption of colloid particles was discussed. Theoretical predictions were presented enabling a quantitative determination of both the initial adsorption flux for low surface coverages and the surface blocking effects for larger surface coverages. Possibility of bilayer adsorption for dilute electrolytes was mentioned. The theoretical results concerning both the adsorption kinetics and structure formation were then confronted with experimental evidences obtained in the well-defined systems, e.g., the impinging-jet cells and the packed-bed columns of monodisperse spherical particles. The experiments proved that the initial adsorption flux was considerably increased in dilute electrolytes whereas the monolayer coverages were considerably decreased due to lateral interactions among particles. It was then concluded that the good agreement between experimental and theoretical data confirmed the thesis of an essential role of the electrostatic interactions in adsorption phenomena of colloid particles.

Effective ac Conductivity of a Suspension of Charged Particles in Electrolyte Solution by Collocation Method

A collocation method is employed to study the effective ac conductivity of a suspension of charged particles in electrolyte solution. The method is very effective over a wide range of particle concentration and no longer restricted to the assumption made by the Rayleigh method that the two phases of a suspension have the same dielectric constants.

Magnetic Effects on Zeta Potential and Diffusivity of Nonmagnetic Colloidal Particles

Nonmagnetic colloids, polystyrene latex particles in electrolyte solutions, are exposed to a magnetic field of low flux density, and effects of the magnetic exposure on their zeta potential and diffusivity are investigated, measuring the mobility by microelectrophoresis and the diffusivity by photon correlation spectroscopy. The results are compared with the magnetic effects on the coagulation rate reported previously. It is found that (1) the magnetic exposure reduces the zeta potential and diffusivity of colloids, (2) the magnetic effect remains for at least 6 days, (3) the magnetic effect is attributable mainly to the particles rather than the bulk solution, and (4) the magnetic effects on the zeta potential are very similar to those on the coagulation rate. A possible mechanism to explain these results is proposed.

Effects of magnetic fields on stability of nonmagnetic ultrafine colloidal particles

Effects of exposure to a magnetic field on the stability of nonmagnetic colloidal particles, such as ultrafine polystyrene latex and SiO 2 particles in electrolyte solutions, were examined by measuring the rapid coagulation rate constant on a low-angle light-scattering apparatus. It was found that the rapid coagulation rate does depend on the magnetic flux density and the duration of magnetic exposure, even though the magnetic flux density is not high, and that the degree of the magnetic effect depends on the particle size and ions in the medium. It is especially interesting to find that the magnetic effect remains for at least 143 h after the magnetic exposure is completed. It is postulated that these effects are mainly attributable to some alteration of the structure of water molecules and ions adsorbed on the particle surface with the magnetic exposure.

Symmetrized Poisson-Boltzmann equation for mixtures containing colloidal particles and an electrolyte

The collective interactions among colloidal particles in electrolyte solutions are examined employing a symmetrized Poisson-Boltzmann equation for a mixture consisting of charged colloidal particles and a binary electrolyte solution. This equation is derived by using a virial expansion of the Ornstein-Zernike equation and takes into account the interactions among all the charged species of the system. The particle energy thus obtained is compared with that provided by the Poisson-Boltzmann equation. The pair correlation function of the particles indicates that there are conditions under which the electrostatic interactions among the particles generate an effective attraction.

Electrophoretic mobility of colloidal alkane particles in electrolyte solutions

The electrophoretic mobility of intrinsically uncharged docosane particles has been measured in aqueous HCl, KCl, CaCl2 and AlCl3 electrolyte solutions over the concentration range 10–5–0.1 mol dm–3. The measured mobilities are large and vary with both electrolyte type and concentration. Interpretation of the mobilities using the standard electrokinetic theory of O'Brien and White (J. Chem. Soc., Faraday Trans. 2, 1978, 74, 1607) indicates that the magnitude of the effective electrokinetic surface charge, σ, increases with electrolyte concentration for the KCl, CaCl2 and AlCl3 electrolytes. The effective electrokinetic surface charge is negative in HCl, KCl and CaCl2 solutions while in AlCl3, σ turns from negative to positive. The ζ potential shows a maximum absolute value in both KCl (negative) and AlCl3 solutions (positive).

Electrical conductivity of a suspension of charged spherical particles in electrolyte solution

We investigate the influence of interaction between dispersed particles to ac conductivity of suspension of charged particles immersed in electrolyte solution. Using the Rayleigh technique, we establish an identity for charged suspensions, and derive a formula for effective complex conductivity of the systems. A useful scheme for computation of effective constants of composite media is proposed.

Permittivity of a suspension of charged cylindrical particles in electrolyte solution

Un simple modele recemment developpe pour la permittivite basse frequence des suspensions de particules spheriques et chargees dans des solutions d'electrolytes est etendu au cas des particules cylindriques orientees perpendiculairement par rapport au champ applique

Effective interaction of charged particles in electrolyte solutions. III. Influence of the ionic subsystem of the electrolyte on potential of the mean force of interaction

Effective interaction of charged particles in electrolyte solutions. III. Influence of the ionic subsystem of the electrolyte on potential of the mean force of interaction

Permittivity of suspensions of metal particles in electrolyte solution

The dielectric properties were measured from 10 Hz-10 MHz for 5% suspensions of aluminum particles in aqueous KCl solutions and water-dioxane mixtures containing KCl. The suspensions showed a pronounced dielectric relaxation, whose amplitude is independent of the dielectric properties of the suspending medium and whose center frequency is proportional to the conductivity. The data could be fitted using a simple model in which the impedance of the metal-electrolyte interface is represented by a capacitance. The dispersion could originate from two effects that cannot be completely separated in the present data: charging of a layer of oxide surrounding the particle, and charging of the double layer in the surrounding electrolyte.

Permittivity of a suspension of charged spherical particles in electrolyte solution. 2. Influence of the surface conductivity and asymmetry of the electrolyte on the low- and high-frequency relaxations

ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTPermittivity of a suspension of charged spherical particles in electrolyte solution. 2. Influence of the surface conductivity and asymmetry of the electrolyte on the low- and high-frequency relaxationsConstantino GrosseCite this: J. Phys. Chem. 1988, 92, 13, 3905–3910Publication Date (Print):June 1, 1988Publication History Published online1 May 2002Published inissue 1 June 1988https://doi.org/10.1021/j100324a044RIGHTS & PERMISSIONSArticle Views423Altmetric-Citations83LEARN ABOUT THESE METRICSArticle Views are the COUNTER-compliant sum of full text article downloads since November 2008 (both PDF and HTML) across all institutions and individuals. These metrics are regularly updated to reflect usage leading up to the last few days.Citations are the number of other articles citing this article, calculated by Crossref and updated daily. Find more information about Crossref citation counts.The Altmetric Attention Score is a quantitative measure of the attention that a research article has received online. Clicking on the donut icon will load a page at altmetric.com with additional details about the score and the social media presence for the given article. Find more information on the Altmetric Attention Score and how the score is calculated. Share Add toView InAdd Full Text with ReferenceAdd Description ExportRISCitationCitation and abstractCitation and referencesMore Options Share onFacebookTwitterWechatLinked InReddit PDF (650 KB) Get e-Alerts

Osmotic pressure for concentrated suspensions of polydisperse particles with thick double layers

A spherical cell model is used to describe the electrical double layer interaction in concentrated suspensions. The model is used to calculate the osmotic pressure of a system of colloidal particles in electrolyte solution. The model uses the full nonlinear Poisson—Boltzmann equation with constant-potential boundary conditions in spherical coordinates and is therefore not limited to small electrical double layers and small surface potentials. The model, which is applicable to both monodisperse and polydisperse particles, is compared to the pair-potential model of monodisperse systems.

Permittivity of a suspension of charged spherical particles in electrolyte solution

Permittivity of a suspension of charged spherical particles in electrolyte solution

On the zeta potential and surface charge density of montmorillonite in aqueous electrolyte solutions

Experimental data on the electrophoretic mobility of montmorillonite clay particles in electrolyte solutions are employed for the estimation of the zeta potential of the particles in these media. The results obtained through the use of the well-known Smoluchowski formula are compared with those deduced from a more elaborated treatment (R. W. O'Brien and L. R. White, J. Chem. Soc. Faraday Trans. 2 74, 1607, 1978) of electrophoresis. The trends shown by the zeta potential are very similar in both cases for all the suspensions studied, although the numerical calculations give potentials higher in absolute value than the analytical formula, the differences being more important the lower the ionic strength of the solution. This was to be expected given that the numerical results take into account the presence of surface conductance and double layer polarization. The general behavior of the zeta potential is qualitatively analyzed by considering the structural characteristics of the clay particles and their double layers. A similar analysis is carded out on the variations of the electrokinetic charge densities deduced from zeta potentials by making use of the classical theories of the electric double layer.

The interaction of two spherical colloidal particles in electrolyte solution. An application of the hypernetted-chain approximation

The hypernetted-chain approximation is solved numerically for a pair of identical spherical colloidal particles immersed in an electrolyte solution. We consider a simple model system where the ions are hard spheres with embedded point charges and the colloidal particles are much larger hard spheres bearing a uniform surface charge distribution. The surface charge density is considered to be constant independent of the particle separation. We obtain the potential of mean force acting between the colloid particles and the structure of the double layer about a single particle. It is found that under some conditions the colloid-colloid interaction is attractive at small separations even in the absence of van der Waals forces. This result should be of interest in the theory of colloidal stability.

Interactions between particles of arbitrary shape I. Uncharged particles

A method of solution of the Helmholtz equation is developed, for situations in which the boundary can be of an arbitrary shape. The method is applied to calculate dispersion forces between smooth particles in electrolyte solution, with specific expression given for simple geometries, such as spheres, cylinders and elliptical paraboloids.

Repulsive interface forces in overlapping electric double layers in electrolyte solutions

The historical development of the problem of the electric interaction of particles in electrolyte solutions is comprehensively discussed. The existing approaches are divided into force-based methods, where the mechanical (ponderomotive) forces of the electric field are directly calculated, and energy-based methods calculating the free energy of the colloid system (at least the part of the free energy which is determined by the repulsive forces of electrical nature). The fundamental works of Langmuir, Derjaguin, Levine, Verwey and Overbeek are discussed in detail. At the same time, new original methods are proposed: the method of effective displacements; the formula of free energy of overlapping double layers. Special attention is paid to the analysis of electrostriction forces in liquids, particularly in electric double layers. The non-contradictory application of the concepts of classic macroelectrostatics is shown to result in the need to take into account electrostriction forces in overlapping double layers. The main formulas are given for force and energy of repulsion in flat surfaces with a constant density of the electric charge on them. These formulas are derived with electrostriction forces taken into account. A number of the theoretical results are new. Some experiments are discussed in measuring repulsive forces in colloid systems. A qualitative agreement is established between the experimental results of Ottewill et al. and the theory of electrostriction forces in double layers.