2020/12/28 by Zsófia Sarkadi, Dávid Fertig, Sarkadi, Zsófia +5
Chemistry · Engineering · #Chemical Physics (physics.chem-ph) #Electrochemical Analysis and Applications #Electrostatics and Colloid Interactions #FOS: Physical sciences #Mesoscale and Nanoscale Physics (cond-mat.mes-hall) #Nanopore and Nanochannel Transport Studies
paper · pdf · doi:10.48550/arxiv.2012.14265
openalex publication_date 2020/12/28 · openalex created_date 2022/10/01 · openalex updated_date 2026/07/28
We show that a modified version of the Dukhin number is an appropriate\nscaling parameter for the ionic selectivity of uniformly charged nanopores. The\nmodified Dukhin number is an unambiguous function of the variables \σ\n(surface charge), R (pore radius), and c (salt concentration), and defined\nas \mDu=|\σ|/e(R/\λ), where \λ is the screening\nlength of the electrolyte carrying the c dependence (\λ\∼ c-1/2).\nScaling means that the device function (selectivity) is a smooth and (in this\ncase) monotonic function of mDu. The original Dukhin number defined as\n\Du=|\σ|/eRc (c-1 dependence) was introduced to indicate\nwhether the surface or the volume conduction is dominant in the pore. The\nmodified version satisfies scaling and characterizes selectivity in the\nintermediate regime, where both surface and bulk conductions are present and\nthe pore is neither perfectly selective, nor perfectly non-selective. Our\nmodeling study using the Local Equilibrium Monte Carlo method and the\nPoisson-Nernst-Planck theory provides the radial flux profiles from which the\nradial selectivity profile can be computed. These profiles show in which region\nof the nanopore the surface or the volume conduction dominates for a given\ncombination of the variables \σ, R, and c. We show that the\ninflection point of the scaling curve may be used to characterize the\ntransition point between the surface and volume conductions.\n