Electrophoresis of a charge‐regulated toroid normal to a large disk

Hsu, Jyh‐Ping; Kuo, Chung‐Wen; Ku, Ming-Hong

doi:10.1002/elps.200700186

Cited by 11 publications

(5 citation statements)

References 39 publications

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“…To simulate this, we assume that the particle surface contains both acidic functional groups, Q A H, and basic functional groups, Q B . The dissociation/association reactions of these functional groups can be expressed by 32 If we let K A and K B be the equilibrium constant of the dissociation/association reactions of Q A H and Q B , respectively, then Here, subscript s denotes surface properties, and…”

Section: Theorymentioning

confidence: 99%

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Diffusiophoresis of a Charge-Regulated Spherical Particle Normal to Two Parallel Disks

et al. 2010

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The diffusiophoresis of a charge-regulated spherical particle normal to two parallel disks as a response to an applied uniform electrolyte concentration gradient is modeled theoretically. The fixed charge on the particle surface comes from the dissociation/association reactions of the functional groups, yielding a charge-regulated surface, which simulates biological cells. Numerical simulations are conducted to examine the behavior of a particle under various conditions: the parameters considered in the simulation include the thickness of the double layer, the charged conditions on the particle surface, the relative size of the particle, and the particle-disk distance. Because the diffusiophoretic mobility of a particle can be dominated by chemiphoresis, electrophoresis, or osmotic flow, the diffusiophoretic behavior of the particle is complicated. For instance, the diffusiophoretic mobility may have two local maximums and a local minimum as the thickness of the double layer varies. This behavior is of practical significance if diffusiophoresis is adopted as a separation operation or as a tool to characterize the surface properties of a particle.

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Section: Theorymentioning

confidence: 99%

Section: Theorymentioning

confidence: 99%

Diffusiophoresis of a Charge-Regulated Spherical Particle Normal to Two Parallel Disks

et al. 2010

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“…The assumptions of constant surface charge density and constant surface potential were served as two limiting cases for the combined electrostatic and hydrodynamic interaction effects on the charge-regulated surfaces. Under essentially the same assumptions, Hsu and his co-workers − further extended this approach to study several different kinds of boundary effects in electrophoresis. Keh and his co-workers − conducted a series of research in the field of electrophoresis and diffusiophoresis, focusing on the limiting cases of low surface potential or charge density.…”

Section: Introductionmentioning

confidence: 99%

Diffusiophoresis of Concentrated Suspensions of Spherical Particles with Charge-regulated Surface: Polarization Effect with Nonlinear Poisson−Boltzmann Equation

2009

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Diffusiophoresis in concentrated suspensions of spherical colloids with charge-regulated surface is investigated theoretically. The charge-regulated surface considered here is the generalization of conventional constant surface potential and constant surface charge density situations. Kuwabara's unit cell model is adopted to describe the system and a pseudospectral method based on Chebyshev polynomial is employed to solve the governing general electrokinetic equations. Excellent agreements with experimental data available in literature were obtained for the limiting case of constant surface potential and very dilute suspension. It is found, among other things, that in general the larger the number of dissociated functional groups on particle surface is, the higher the particle surface potential, hence the larger the magnitude of the particle mobility. The electric potential on particle surface depends on both the concentration of dissociated hydrogen ions and the concentration of electrolyte in the solution. The electric potential on particle surface turns out to be the dominant factor in the determination of the eventual particle diffusiophoretic mobility. Local maximum of diffusiophoretic mobility as a function of double layer thickness is observed. Its reason and influence is discussed. Corresponding behavior for the constant potential situation, however, may yield a monotonously increasing profile.

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“…Various investigations on the charge-regulated surface have been reported, both in the fields of electrostatics and electrokinetics. − Among them, Carnie and Chan − conducted a series of theoretical investigations about electrostatic interactions between two spherical particles. They observed that the electrostatic interaction or interaction free energy predicted by the charge-regulation model is always intermediate between that predicted by the constant-charged model and the constant-potential model.…”

Section: Introductionmentioning

confidence: 99%

“…The assumptions of constant surface charge density and constant surface potential were served as two limiting cases for the combined electrostatic and hydrodynamic interaction effects on the charge-regulated surfaces. Under essentially the same assumptions, Hsu and his co-workers − further extended this approach to study several different kinds of boundary effects in electrophoresis. It should be noted that there is a fundamental difference between a solid boundary and a free surface such as the air–water interface.…”

Section: Introductionmentioning

confidence: 99%

Electrophoresis of a Charge-Regulated Sphere Normal to an Air–Water Interface

2011

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The electrophoresis of a charge-regulated sphere normal to an air-water interface is investigated theoretically. The charge-regulated surface considered here is the generalization of conventional constant surface potential and constant surface charge density situations and models excellently well biocolloids or particles coated with a thin film of polyelectrolytes. The thickness of the double layer surrounding the particle can be arbitrary. A pseudospectral method based on Chebyshev polynomials is employed to solve the governing electrokinetic equations. We found, among other things, that the electric potential on the particle surface is the most dominant factor in the determination of the eventual particle electrophoretic mobility. The larger the number of dissociated functional groups on the particle surface (N(s)), the higher the absolute surface potential of the particle and hence the larger the magnitude of the mobility. Moreover, the electric potential on the particle surface depends on both the concentration of dissociated hydrogen ions, [H(+)](0), and the concentration of electrolytes, κa, in the solution. If [H(+)](0) and/or κa are small, the bulk condition is advantageous to the dissociation reaction, yielding a higher surface density (higher surface potential) and hence a higher mobility. The air-water interface retards the particle motion in general, especially when the double layer is thick enough to touch the interface. Up to around 60%, reduction of the mobility is observed for some situation. The boundary effect disappears as the double layer gets very thin. This is mainly due to the buildup of the electric potential at the interface right in front of the particle, which in turn generates a repulsive electrostatic force. Comparison with a solid planar wall is carried out to highlight the fundamental nature of the air-water interface, such as the unique phenomenon of the electric potential buildup mentioned above.

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Electrophoresis of a charge‐regulated toroid normal to a large disk

Cited by 11 publications

References 39 publications

Diffusiophoresis of a Charge-Regulated Spherical Particle Normal to Two Parallel Disks

Diffusiophoresis of a Charge-Regulated Spherical Particle Normal to Two Parallel Disks

Diffusiophoresis of Concentrated Suspensions of Spherical Particles with Charge-regulated Surface: Polarization Effect with Nonlinear Poisson−Boltzmann Equation

Electrophoresis of a Charge-Regulated Sphere Normal to an Air–Water Interface

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