Scaling of selectivity in uniformly charged nanopores through a modified Dukhin number for 1:1 electrolytes

• DOI: 10.48550/arxiv.2012.14265
• Publication Date: 2020-01-01
• Authors: Zsófia Sarkadi; Dávid Fertig; Mónika Valiskó; Dezső Boda
• Keywords: Nanopore; Sigma

We show that a modified version of the Dukhin number is an appropriate scaling parameter for ionic selectivity uniformly charged nanopores. The unambiguous function variables $\sigma$ (surface charge), $R$ (pore radius), and $c$ (salt concentration), defined as $\mathrm{mDu}=|\sigma|/e(R/\lambda)$, where $\lambda$ screening length electrolyte carrying dependence ($\lambda\sim c^{-1/2}$). Scaling means device (selectivity) smooth (in this case) monotonic mDu. original $\mathrm{Du}=|\sigma|/eRc$ ($c^{-1}$ dependence) was introduced to indicate whether surface or volume conduction dominant in pore. satisfies characterizes intermediate regime, both bulk conductions are present pore neither perfectly selective, nor non-selective. Our modeling study using Local Equilibrium Monte Carlo method Poisson-Nernst-Planck theory provides radial flux profiles from which profile can be computed. These region nanopore dominates given combination $\sigma$, $R$, $c$. inflection point curve may used characterize transition between conductions.