What makes a nano-channel? A limiting-current criterion

Yaroshchuk, Andriy

doi:10.1007/s10404-011-0902-6

Cited by 26 publications

(21 citation statements)

References 37 publications

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“…Therefore, the present study could be useful to identify the role of multivalent heavy metal ions on the formation and development of electroconvective instabilities. The principle of electroconvection to transform electrical energy in mechanical energy has also increased the scope of utilization of overlimiting current regimes in the field of micro-and nanofluidics [61,[92][93][94].…”

Section: Fig 475mentioning

confidence: 99%

Determination of transport properties of Ni(II) through a Nafion cation-exchange membrane in chromic acid solutions

Martí-Calatayud

García-Gabaldón

Pérez-Herranz

et al. 2011

Journal of Membrane Science

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Acknowledgements / Agradecimientos / AgraïmentsEn primer lugar quisiera agradecer a Valentín y a Montse por haberme dado la oportunidad de investigar con ellos, por introducirme en un mundo que me ha fascinado, por haberme dirigido, por haberme ayudado en momentos de desasosiego; porque, en definitiva, creo que hemos formado un gran equipo.Quisiera agradecer a la Universitat Politècnica de València la financiación recibida para realizar la tesis. En general, he de agradecer al sistema de educación pública que ha permitido que un hijo de trabajadores como yo haya podido llegar hasta aquí. Además, quiero aprovechar para exigir un sistema de educación público, de calidad, e igualitario, que forme a personas con espíritu crítico y libre; puesto que sólo así se conseguirá que progresemos como sociedad.I would also like to thank to all the people from the group of Chemical Process Engineering of the RWTH Aachen University, especially to Matthias Wessling and Said Abdu, for accepting me in their research group. They have been very kind to me and I have learnt a lot from them and from this fruitful and unforgettable experience in Aachen.También quisiera agradecer a Daniella Buzzi por haberme dejado ser su "chefinho", por tantos momentos buenos y algún que otro momento crítico vividos juntos, porque es bonito saber que tengo una gran amiga al otro lado del charco.Gracias al Grupo IEC, en especial a mis compañeros, con los que he pasado más momentos juntos. Ellos han sido mi familia investigadora. Gracias a Isaac y Carlos, porque han sido para mí un referente, a Jordi y Ramón, porque han estado desde el principio, han sido como mis hermanos, y a Vir y Tepe, ellas han contribuido a que haya un ambiente de trabajo inmejorable! Quiero también dar las gracias al resto de componentes del grupo por su ayuda, en especial a Emma Ortega, a José Luis Guiñón por su ayuda con los equilibrios, y a Anna Igual porque con su energía consigue contagiar su pasión por la investigación.El fruto del trabajo de todos estos años tampoco sería posible sin los momentos vividos junto a mis amigos, el "Kanchy". Ellos son "los de toda la vida", los que siempre han estado, están y estarán ahí. Quisiera hacer mención especial a Lidia por su ayuda con la Tesis, y cómo no, a Sergio, porque juntos hemos arreglado el mundo un millón de veces… ¡para volverlo a destrozar otras tantas! No quiero olvidarme de ninguna de las personas con las que he coincidido y he pasado buenos momentos tanto en Valencia, como en Berlín o en Aachen… Maite, Laura, Guillaume… es imposible nombrarlos a todos… pero quiero agradecer en especial a Tania, porque con ella no existe el tiempo ni la distancia, sé que siempre está ahí a mi lado.Ha arribat el moment d'agrair a les quimixiques els grans moments viscuts. Amb elles hem format una gran família. Em sent molt afortunat d'haver caigut en un grup tan de "puça mare": gràcies a les Silvies, Elena, Gabriel·la, Angeleta, Rosa de Xeraco, Alicia, i en especial a Susana, la meua companya de batalles, i a Ingrid, una gran amiga.Per últim...

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Section: Fig 475mentioning

confidence: 99%

Determination of transport properties of Ni(II) through a Nafion cation-exchange membrane in chromic acid solutions

Martí-Calatayud

García-Gabaldón

Pérez-Herranz

et al. 2011

Journal of Membrane Science

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“…At low currents, the profile is concave down. With increasing current density, the profile moves down until an inflection point concentration is reached (note that this concentration is different from the limiting case of infinitely thick nanoblocks because the limiting relationships of Equations (29) and (31) are not exactly applicable to nanoblocks of finite thickness). After that, the profile takes the S-like shape and the concentration close to the upstream side (including the interface concentration) keeps decreasing locally.…”

Section: Supercritical Concentrationsmentioning

confidence: 98%

“…To find the limiting-current density, we use Equation (15) where we put c i = 0. Since we are considering the limiting case of very thick nanoblocks, we can use the approximate Equations (29) and (31) to express the volume and effective salt fluxes through the current density. After some identical transformations, for the limiting-current density we obtain…”

Section: Limiting Case Of Very Thick Nanoblocksmentioning

confidence: 99%

“…Even at moderate to large (but finite) thicknesses there are particularities in the salt-concentration profiles that influence the rate of volume transfer and of convective salt delivery to the polarized interface through the unstirred layer. More specifically, Equations (29) and (31) are not quite applicable at finite thicknesses (because within noticeable parts of the nanoblock the virtual salt concentration is not equal to the inflection-point value), which brings about some shifts in the inflection-point concentration. This has considerable impact on the CICP.…”

Section: Nanoblocks Of Finite Thicknessmentioning

confidence: 99%

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Current‐Induced Concentration Polarization of Nanoporous Media: Role of Electroosmosis

Yaroshchuk

Bondarenko

2018

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Current-induced concentration polarization of nanoporous media is explored theoretically by using approach of local thermodynamic equilibrium within nanopore cross-sections. The problem is solved in quadratures in terms of irreversible thermodynamics. The phenomenological coefficients are further specified by using capillary space-charge model for straight slit-like and cylindrical capillaries. This analysis reveals several novel features of current-induced concentration polarization related to the (electro)osmotic volume transfer. It confirms the previous finding that volume transfer can suppress the limiting-current phenomena but obtains more accurate criteria for this. In particular, it shows that the critical nanopore size and/or electrolyte concentration depend on the nanoporous-medium relative thickness. Under no-limiting-current conditions, the salt concentration at the interface between nanoporous medium and unstirred layer is a nonmonotone function of current density. This gives rise to unconventional current-voltage characteristics. Moreover, under certain conditions, the analysis predicts the existence of ranges of "prohibited" current densities where the problem does not have 1D stationary solution, which could give rise to a kind of "phase separation" with coexisting zones of different local current densities corresponding to the same voltage. Besides the advanced understanding of current-induced concentration polarization of nanoporous media, this analysis provides guidelines for the optimization of sample preconcentration systems in (bio)chemical microanalysis.

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“…where N is the dimensionless fixed charge density in the membrane (scaled by the product of positive elementary electric charge and the dimensional reservoir concentration), [14],…”

Section: Driving Factors Of Hydrodynamic Instability In Cpmentioning

confidence: 99%

Driving factors of electro-convective instability in concentration polarization

2016

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Ionic current in a binary electrolyte passing through a charge-selective interface (electrode, ion exchange membrane, micro-nano-channel junction) is a basic element of many electrochemical engineering and micro-fluidic processes, such as electrodeposition, electrodialysis and protein preconcentration. Such current passage is diffusion-limited in the sense that it induces a decrease of electrolyte concentration towards the interface (concentration polarization) whose expression is the saturation of current upon increasing voltage at some value -the limiting current. Upon a further increase of voltage, this saturation is followed by a relatively rapid current increase -over-limiting conductance regime. It is commonly accepted that in open systems over-limiting conductance is mediated by a micro-scale vortical flow which spontaneously develops as a result of electro-convective instability of quiescent concentration polarization near the limiting current. Electro-convection is a flow driven by the electric force acting either upon the space charge of the interfacial electric double layer (electro-osmosis) or the residual space charge of the quasi-electroneutral bulk (bulk electroconvection). There are two types of electro-osmosis, the equilibrium and the non-equilibrium one, the former relating to the action of the tangential electric field upon the space charge of the electric double layer, and the latter pertaining to the similar action upon the extended space charge which forms next to the electric double layer near the limiting current. For a perfectly charge-selective interface, concentration polarization under the equilibrium electro-osmotic slip condition is stable, and so it is with respect to bulk electro-convection, as opposed to non-equilibrium electro-osmosis which may cause instability. For this reason until recently, the electro-convective instability in concentration polarization was attributed to this latter mechanism. Lately, it was shown that imperfect charge-selectivity of the interface makes equilibrium instability possible, driven by either equilibrium electro-osmosis or bulk electro-convection, or both. In this paper we identify and analyze the major surface and bulk factors affecting the electro-convective instability. These factors, some known previously under the names of diffusio-osmosis, electro-osmosis or bulk electroconvection, and some newly identified in this paper, are manifestations of the electric force and pressure gradient, balanced by the viscous force acting in various locations in solution. The contribution of these factors to hydrodynamic stability in concentration polarization is analyzed for a varying perm-selectivity of the interface.

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What makes a nano-channel? A limiting-current criterion

Cited by 26 publications

References 37 publications

Determination of transport properties of Ni(II) through a Nafion cation-exchange membrane in chromic acid solutions

Determination of transport properties of Ni(II) through a Nafion cation-exchange membrane in chromic acid solutions

Current‐Induced Concentration Polarization of Nanoporous Media: Role of Electroosmosis

Driving factors of electro-convective instability in concentration polarization

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