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Electrokinetic flow of aqueous electrolyte in amorphous silica nanotubes

Abstract

We study pressure-driven flow of aqueous NaCl in amorphous silica nanotubes using nonequilibrium molecular dynamics simulations featuring both polarizable and non-polarizable molecular models. Different pressures, electrolyte concentrations and pore sizes are examined. Our results indicate flow that deviates considerably from the predictions of Poiseuille fluid mechanics. Due to preferential adsorption of the different ionic species by surface SiO$^-$ or SiOH groups we find that significant electric current is generated, but with opposite polarities using polarizable vs. fixed charge models for water and ions, emphasizing the need for careful parameterization in such complex systems. We also examine the influence of partial deprotonation of the silica surface, and we find that much more current is generated in a dehydrogenated nanopore, even though overall efficiency remains low. These findings indicate that different methods of nanopore preparation which can produce a range of surface properties should be examined more closely in related experimental methods to generate electrokinetic current.

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Publication details

The article was received on 14 Jun 2018, accepted on 04 Oct 2018 and first published on 12 Oct 2018


Article type: Paper
DOI: 10.1039/C8CP03791D
Citation: Phys. Chem. Chem. Phys., 2018, Accepted Manuscript
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    Electrokinetic flow of aqueous electrolyte in amorphous silica nanotubes

    C. D. Daub, N. Cann, D. Bratko and A. luzar, Phys. Chem. Chem. Phys., 2018, Accepted Manuscript , DOI: 10.1039/C8CP03791D

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