Looking deeper into the structure of mixed electric double layers near the point of zero charge

Wang, Zhi-Yong; Xie, Yangmin; Liang, Qing; Ma, Zengwei; Wei, Jianwei

doi:10.1063/1.4765101

Cited by 7 publications

(2 citation statements)

References 51 publications

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“…The solution set of equations given by (17) can be given as where I 0 , I 1 and K 0 , K 1 are the first and second kind modified Bessel function of order 0 and 1. The integral constants c 1 and c 2 are given by…”

Section: A Formulation Without Considerations Of Charge-induced Thicmentioning

confidence: 99%

“…2,3 The central idea behind electrokinetics revolves around the formation of electrical double layer (EDL), which is described, in the simplest form, by the Poisson-Boltzmann equation, 1-3 the modified Poisson-Boltzmann equation [5][6][7][8][9][10][11][12] and its other suitable variants. [13][14][15][16][17][18][19][20][21] Although the PoissonBoltzmann model is able to capture the essential underlying physics (at least over microscopic scales and for dilute solutions) in many scenarios, it suffers from several drawbacks. Numerous models have been recently reported in the literature in an effort to resolve these drawbacks.…”

Section: Introductionmentioning

confidence: 99%

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Regimes of streaming potential in cylindrical nano-pores in presence of finite sized ions and charge induced thickening: An analytical approach

Bandopadhyay

Goswami

Chakraborty

2013

The Journal of Chemical Physics

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We obtain approximate analytical expressions for the streaming potential and the effective viscosity in a pure pressure-driven flow through a cylindrical pore with electrokinetic interactions, duly accounting for the finite size effects of the ionic species (steric effects) and charge-induced thickening. Our analytical results show a remarkable agreement with the numerical solution even for high surface potentials and small channel radii. We demonstrate a consistent increment in the predicted value of the streaming potential and effective viscosity when finite size effects of the ionic species are accounted for. In addition to this, we account for the radial variation of in the viscosity of the fluid due to charge-induced thickening. We show that this so-called viscoelectric effect leads to a decrease in the induced streaming potential especially at high steric factors and high surface potentials. However, the viscoelectric effect, which is prominent at high zeta potential and narrow channels, does not cause significant changes in the electrokinetic conversion efficiency. These results shed light on the interesting confluence of the steric factor, the channel radius, the electrical double layer screening length, and the surface charge density in conjunction with the charge induced thickening, and thus provide ion-size dependent analytical framework for accurate system design and better interpretation of electrokinetic data.

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Section: A Formulation Without Considerations Of Charge-induced Thicmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Regimes of streaming potential in cylindrical nano-pores in presence of finite sized ions and charge induced thickening: An analytical approach

Bandopadhyay

Goswami

Chakraborty

2013

The Journal of Chemical Physics

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Consistent prediction of streaming potential in non-Newtonian fluids: the effect of solvent rheology and confinement on ionic conductivity

Bandopadhyay

Chakraborty

2015

Phys. Chem. Chem. Phys.

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By considering an ion moving inside an imaginary sphere filled with a power-law fluid, we bring out the implications of the fluid rheology and the influence of the proximity of the other ions towards evaluating the conduction current in an ionic solution. We show that the variation of the conductivity as a function of the ionic concentration is both qualitatively and quantitatively similar to that predicted by the Kohlrausch law. We then utilize this consideration for estimating streaming potentials developed across narrow fluidic confinements as a consequence of the transport of ions in a convective medium constituting a power-law fluid. These estimates turn out to be in sharp contrast to the classical estimates of streaming potential for non-Newtonian fluids, in which the effect of rheology of the solvent is merely considered to affect the advection current, disregarding its contributions to the conduction current. Our results have potential implications of devising a new paradigm of consistent estimation of streaming potentials for non-Newtonian fluids, with combined considerations of the confinement effect and fluid rheology in the theoretical calculations.

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On the physics of both surface overcharging and charge reversal at heterophase interfaces

Wang

Zhang

2018

Phys. Chem. Chem. Phys.

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The conventional paradigm for characterizing surface overcharging and charge reversal is based on the so-called Stern layer, in which surface dissociation reaction and specific chemical adsorption are assumed to take place. In this article, a series of Monte Carlo simulations have been applied to obtain useful insights into the underlying physics responsible for these two kinds of anomalous phenomena at the interface of two dielectrics, with special emphasis on the case of divalent counterions that are more relevant in natural and biological environments. At a weakly charged surface, it is found that independent of the type of surface charge distribution and the dielectric response of the solution, the overcharging event is universally driven by the ion size-asymmetric effect. Exceptionally, the overcharging still persists when the surface is highly charged but is only restricted to the case of discrete surface charge in a relatively low dielectric medium. As compared to the adsorption onto the homogeneously smeared charge surface that has the same average affinity for counterions, on the other hand, charge reversal under the action of a dielectric response can be substantially enhanced in the discrete surface charge representation due to strong association of counterions with interfacial groups, and the degree of enhancement depends in a nontrivial way on the reduction of the medium dielectric constant and the steric effects of finite ion size. Rather interestingly, the charge reversal is of high relevance to the overcharging of interfaces because the overwhelming interfacial association forces the coions closer to the surface due to their smaller size than the counterions. Upon the addition of a monovalent salt to the solution, the interfacial association with divalent counterions makes surface overcharging and charge reversal widely unaffected, in contrast to the prevailing notion that screening of surface charge of a homogeneous nature is determined by the competitive effects between size-exclusion effects and energetic contributions. Overall, the present work highlights that the complex interplay between the electrostatic and steric interactions should be coupled to the realistic character of surface charge to establish a faithful description of the overcharging and charge reversal at heterophase interfaces.

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Looking deeper into the structure of mixed electric double layers near the point of zero charge

Cited by 7 publications

References 51 publications

Regimes of streaming potential in cylindrical nano-pores in presence of finite sized ions and charge induced thickening: An analytical approach

Regimes of streaming potential in cylindrical nano-pores in presence of finite sized ions and charge induced thickening: An analytical approach

Consistent prediction of streaming potential in non-Newtonian fluids: the effect of solvent rheology and confinement on ionic conductivity

On the physics of both surface overcharging and charge reversal at heterophase interfaces

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