Field-induced dipolar attraction between like-charged colloids

The field induced anisotropic interactions between like-charged colloidal particles is studied using direct numerical simulations, where the polarization of the electric double layer is explicitly computed under external AC electric fields.

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Electric double layer and electrokinetic potential of pectic macromolecules in sugar beet

Acta periodica technologica ◽

10.2298/apt0839021k ◽

2008 ◽

pp. 21-28

Author(s):

Tatjana Kuljanin ◽

Ljubinko Levic ◽

Nevena Misljenovic ◽

Gordana Koprivica

Keyword(s):

Sugar Beet ◽

Double Layer ◽

Electric Double Layer ◽

Colloidal Particles ◽

Colloidal Particle ◽

Electrokinetic Potential ◽

Shear Plane ◽

Colloidal System ◽

Cu Ions ◽

Measurable Property

Electrokinetic potential is an important property of colloidal particles and, regarding the fact that it is a well defined and easily measurable property, it is considered to be a permanent characteristic of a particular colloidal system. In fact, it is a measure of electrokinetic charge that surrounds the colloidal particle in a solution and is in direct proportion with the mobility of particles in an electric field. Gouy-Chapman-Stern-Graham's model of electric double layer was adopted and it was proven experimentally that the addition of Cu++ ions to sugar beet pectin caused a reduction in the negative electrokinetic potential proportional to the increase of Cu++ concentration. Higher Cu++ concentrations increased the proportion of cation specific adsorption (Cu++ and H+) with regard to electrostatic Coulombic forces. Consequently, there is a shift in the shear plane between the fixed and diffuse layers directed towards the diffuse layer, i.e. towards its compression and decrease in the electrokinetic potential or even charge inversion of pectin macromolecules.

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Polarization and interactions of colloidal particles in ac electric fields

The Journal of Chemical Physics ◽

10.1063/1.2969103 ◽

2008 ◽

Vol 129 (6) ◽

pp. 064513 ◽

Cited By ~ 69

Author(s):

Manish Mittal ◽

Pushkar P. Lele ◽

Eric W. Kaler ◽

Eric M. Furst

Keyword(s):

Electric Fields ◽

Colloidal Particles ◽

Ac Electric Fields

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Manipulation of Organic and Inorganic Colloidal Particles by Dielectrophoretic Forces

Volume 11: Micro and Nano Systems, Parts A and B ◽

10.1115/imece2007-44093 ◽

2007 ◽

Author(s):

Ramazan Asmatulu ◽

Dennis Siginer

Keyword(s):

Liquid Medium ◽

Electric Fields ◽

Colloidal Particles ◽

Dielectrophoretic Force ◽

Inorganic Particles ◽

Ac Electric Fields ◽

The Creation ◽

Manipulation Process

Recently, manipulation of the micro and nanoscale objects has been of great interest in verity of engineering and scientific areas. Dielectrophoretic force (DEP) induced technique is predominantly used in the manipulation process in a liquid medium. The phenomenon behind DEP involves the creation of electric forces on particles to generate momentum in nonuniform electric fields, usually coming from AC electric fields. In the present study, we will discuss about the effects of DEP for the manipulation of organic and inorganic particles at micro and nanoscale in detail.

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Fluid flow induced by nonuniform ac electric fields in electrolytes on microelectrodes. II. A linear double-layer analysis

Physical Review E ◽

10.1103/physreve.61.4019 ◽

2000 ◽

Vol 61 (4) ◽

pp. 4019-4028 ◽

Cited By ~ 279

Author(s):

A. González ◽

A. Ramos ◽

N. G. Green ◽

A. Castellanos ◽

H. Morgan

Keyword(s):

Fluid Flow ◽

Electric Fields ◽

Double Layer ◽

Ac Electric Fields ◽

Layer Analysis

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Direct Numerical Simulations of Electrophoresis of Charged Colloids

Physical Review Letters ◽

10.1103/physrevlett.96.208302 ◽

2006 ◽

Vol 96 (20) ◽

Cited By ~ 77

Author(s):

Kang Kim ◽

Yasuya Nakayama ◽

Ryoichi Yamamoto

Keyword(s):

Numerical Simulations ◽

Direct Numerical Simulations ◽

Charged Colloids

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Electric Conductance

Chemistry of Variable Charge Soils ◽

10.1093/oso/9780195097450.003.0011 ◽

1997 ◽

Author(s):

C. B. Li

Keyword(s):

Electric Field ◽

Electric Fields ◽

Colloidal Particles ◽

Free Solution ◽

Soil Particles ◽

Electric Conductance ◽

Variable Charge ◽

Ac Electric Fields ◽

The Difference ◽

Variable Charge Soils

The migration of colloidal soil particles in an applied electric field has been discussed in Chapter 7. Soil particles carrying electric charges invariably adsorb equivalent amounts of ions of the opposite charge. Generally there is a certain amount of free ions present in soil solution. When an electric field is applied to a soil system, a phenomenon known as electric conductance occurs. As in the case for electrolyte solutions, soil particles and various ions interact with one another during their migration, and these interactions can affect the electric conductance of the system. Variable charge soils carry both positive and negative surface charges, and it can be expected that their interactions with various ions would be rather complicated during conductance. On the other hand, this makes the measurement of electric conductance an effective means in elucidating the mechanisms of interactions between variable charge soils and ions. Both direct-current (DC) electric fields and alternating-current (AC) electric fields can induce the migration of charged particles. In the latter case, the migration of these particles should be related to the frequency of the applied AC electric field. Therefore, in this chapter, after describing the principles of electric conductance of ions and colloids and the factors that affect the conductance of a soil, emphasis shall be placed on the interaction between variable charge soils and various ions as reflected by the frequency effect in electric conductance. For a colloidal suspension, the electric conductance may be regarded as the contribution of conductances of both charged colloidal particles and ions. These two parts may be called the electric conductance of colloidal panicles and the electric conductance of ions, respectively. However, in actual cases it is difficult to distinguish between these two parts. Therefore, it is a general practice to distinguish the electric conductance as that caused by colloidal particles plus their counterions from that caused by ions of the free solution. These may be called electric conductance of the colloid and electric conductance of the free solution. The former conductance is the difference between the electric conductance of the suspension and that of the free solution.

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