Issue 17, 2012

Ion exclusion and electrokinetic effects resulting from electro-osmotic flow of salt solutions in charged silica nanopores

Abstract

Silica nanopores are the focus of significant scientific interest due to their potential in a wide variety of applications including desalination membranes. In this paper, the results of extensive all-atom molecular dynamics simulations of the electro-osmotic flow of 0.5 M monovalent (NaCl) and divalent (CaCl2) ionic solutions through cylindrical charged silica nanopores are presented. The silica nanopores are produced such that they capture the experimentally observed interfacial properties. The results provide an atomistic description of the ion transport through pores of diameters of 1.5 nm, 2.0 nm, 2.5 nm and 3.0 nm. In doing so, the effect of pore size on ion pairing, ion hydration, and water orientation for each ionic solution was investigated. Also, the transport of the ions through the nanopores is studied, and it is found that in the monovalent solutions the Cl ions are excluded from the nanopores of all sizes. Whereas in the divalent solutions, there is no such preferential exclusion of either ion. This is due to the fact that the interfacial charge is fully compensated for by the Ca2+ ions while it is not the case for the Na+ ions.

Graphical abstract: Ion exclusion and electrokinetic effects resulting from electro-osmotic flow of salt solutions in charged silica nanopores

Supplementary files

Article information

Article type
Paper
Submitted
03 Jan 2012
Accepted
28 Feb 2012
First published
28 Feb 2012

Phys. Chem. Chem. Phys., 2012,14, 5935-5944

Ion exclusion and electrokinetic effects resulting from electro-osmotic flow of salt solutions in charged silica nanopores

N. R. Haria and C. D. Lorenz, Phys. Chem. Chem. Phys., 2012, 14, 5935 DOI: 10.1039/C2CP00013J

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