Diffusioosmotic flows in slit nanochannels

Qian, Shizhi; Das, Biswajit; Luo, Xiaobing

doi:10.1016/j.jcis.2007.06.075

Cited by 67 publications

(57 citation statements)

References 24 publications

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“…The mathematical model and its implementation with COMSOL have been extensively validated by comparing its results of electroosmotic, electrophoretic, and diffusioosmotic flows with the corresponding approximate analytical solution and experimental results obtained from the literature. [17,[55][56][57][58]61] In this section, we present a few numerical results of the diffusiophoretic motion of a charged elongated cylindrical nanoparticle in a nanopore as functions of the imposed concentration ratio, a, the ratio of the particle size to the EDL thickness, ka p , the dimensionless surface charge density of the particle, " s p , the particle aspect ratio, L p /a p , the ratio of the pore size to the particle's size, a/a p , the dimensionless surface charge density of the nanopore, " s w , and the type of salt. To show the effect of the induced electrophoresis driven by the generated electric field, E diffusivity , arising from the difference in the ionic diffusivities, salts KCl and NaCl at temperature T = 300 K are used.…”

Section: Resultsmentioning

confidence: 99%

Diffusiophoresis of an Elongated Cylindrical Nanoparticle along the Axis of a Nanopore

et al. 2010

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The translation of a charged, elongated cylindrical nanoparticle along the axis of a nanopore driven by an imposed axial salt concentration gradient is investigated using a continuum theory, which consists of the ionic mass conservation equations for the ionic concentrations, the Poisson equation for the electric potential in the solution, and the modified Stokes equations for the hydrodynamic field. The diffusiophoretic motion is driven by the induced electrophoresis and chemiphoresis. The former is driven by the generated overall electric field arising from the difference in the ionic diffusivities and the double layer polarization, while the latter is generated by the induced osmotic pressure gradient around the charged particle. The induced diffusiophoretic motion is investigated as functions of the imposed salt concentration gradient, the ratio of the particle's radius to the double layer thickness, the cylinder's aspect ratio (length/radius), the ratio of the nanopore size to the particle size, the surface charge densities of the nanoparticle and the nanopore, and the type of the salt used. The induced diffusiophoretic motion of a nanorod in an uncharged nanopore is mainly governed by the induced electrophoresis, driven by the induced electric field arising from the double layer polarization. The induced particle motion is driven by the induced electroosmotic flow, if the charges of the nanorod and nanopore wall have the same sign.

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Section: Resultsmentioning

confidence: 99%

Diffusiophoresis of an Elongated Cylindrical Nanoparticle along the Axis of a Nanopore

et al. 2010

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“…The numerical simulation of DNA translocation is implemented by solving the electric field, the ionic [31][32][33]36]; while the fluid flow is governed by the modified Stokes equations as the inertial terms are negligible due to a very small Reynolds number in this study. The governing equations are normalized based on the bulk concentration c 0 as the ionic concentration scale, f 0 5 R U T/F as the potential scale, the particle radius a as the length scale, u 0 ¼ eR…”

Section: Mathematical Modelmentioning

confidence: 99%

“…It has been confirmed that all the results are mesh-independent. The mathematical model and its implementation with COMSOL have been validated by testing many benchmark problems, as discussed in our previous studies [33,36]. We also simulate the electrophoresis of a sphere translocating along the axis of an uncharged dielectric cylindrical nanopore, whose analytical solution is available when the zeta potential of the particle is relatively small and the EDL of the particle is not disturbed by the external electric field, flow field and the solid boundary [44].…”

Section: Code Validationmentioning

confidence: 99%

Electrokinetic particle translocation through a nanopore containing a floating electrode

Zhang

Sharma

et al. 2011

Electrophoresis

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Electrokinetic particle translocation through a nanopore containing a floating electrode is investigated by solving a continuum model, composed of the coupled Poisson-Nernst-Planck (PNP) equations for the ionic mass transport and the modified Stokes equations for the flow field. Two effects due to the presence of the floating electrode, the induced-charge electroosmosis (ICEO) and the particle-floating electrode electrostatic interaction, could significantly affect the electrokinetic mobility of DNA nanoparticles. When the electrical double layers (EDLs) of the DNA nanoparticle and the floating electrode are not overlapped, the particle-floating electrode electrostatic interaction becomes negligible. As a result, the DNA nanoparticle could be trapped near the floating electrode arising from the induced-charge electroosmosis when the applied electric field is relatively high. The presence of the floating electrode attracts more ions inside the nanopore resulting in an increase in the ionic current flowing through the nanopore; however, it has a limited effect on the deviation of the current from its base current when the particle is far from the pore.

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“…Recently, applications of the diffusioosmotic flow of electrolyte solutions in porous media, such as a permeable membrane, in the molecular separation and sorting technologies (Hill 2006), nanofluidic devices for biological and chemical analysis (Qian et al 2007), and polymer electrolyte fuel cells (Keh and Ma 2008) have been reported. When one considers the general diffusioosmosis of an electrolyte solution in a fibrous porous system constructed by an assemblage of parallel cylinders, the imposed electrolyte concentration gradient can be taken as a combination of its transverse and longitudinal components with respect to the orientation of the cylinders.…”

Section: Introductionmentioning

confidence: 99%

Diffusioosmotic flow of electrolyte solutions in fibrous porous media at arbitrary zeta potential and double-layer thickness

Keh

Hsu

2009

Microfluid Nanofluid

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The diffusioosmosis of electrolyte solutions in the fibrous medium constructed by a homogeneous assemblage of parallel, charged, circular cylinders caused by a uniform concentration gradient prescribed in their axial direction is studied theoretically. The electric double layers adjacent to the cylinders may have an arbitrary thickness. A unit cell model is used to account for the interaction effect among the cylinders. The electrostatic potential distribution in the fluid phase is determined with an analytical approximation to the solution of the PoissonBoltzmann equation. By solving the fluid momentum equation with the constraint of no net electric current arising from the co-current diffusion, electric migration, and diffusioosmotic convection of the electrolyte ions, the macroscopic electric field and the fluid velocity in the axial direction induced by the applied electrolyte concentration gradient are obtained semi-analytically as functions of the radial position in a cell in a self-consistent manner. The magnitude and direction of the diffusioosmotic flow relative to the concentration gradient are determined by the combination of the porosity of the array of cylinders, the zeta potential of the cylinders, the properties of the electrolyte solution, and other relevant factors. The fluid velocity generally increases with increasing porosity of the array of cylinders, but there are exceptions. The effects of the radial distribution of the induced electric field and of the ionic convection in the double layers on the diffusioosmotic flow are significant.

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Diffusioosmotic flows in slit nanochannels

Cited by 67 publications

References 24 publications

Diffusiophoresis of an Elongated Cylindrical Nanoparticle along the Axis of a Nanopore

Diffusiophoresis of an Elongated Cylindrical Nanoparticle along the Axis of a Nanopore

Electrokinetic particle translocation through a nanopore containing a floating electrode

Diffusioosmotic flow of electrolyte solutions in fibrous porous media at arbitrary zeta potential and double-layer thickness

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