Molecular dynamics of ionic transport and electrokinetic effects in realistic silica channels

CD Lorenz and PS Crozier and JA Anderson and A Travesset, JOURNAL OF PHYSICAL CHEMISTRY C, 112, 10222-10232 (2008).

DOI: 10.1021/jp711510k

Silica is one of the most widely used inorganic materials in experiments and applications involving aqueous solutions of biomolecules, nanoparticles, etc. In this paper, we construct a detailed atomistic model of a silica interface that captures the essential experimentally known properties of a silica interface. We then perform all-atom molecular dynamics simulations of a silica nanochannel subjected to either an external pressure or an electric field and provide an atomistic description of ionic transport and both electro-osmotic flow and strean-tin- currents for a solution of monovalent (0.4 M NaCl) as well as divalent (0.2 and 1.0 M CaCl (2)) salts. Our results allow a detailed investigation of zeta-potentials, Stern layer conductance, charge inversion, ionic mobilities, as well as continuum theories and Onsager relations. We con clude with a discussion on the implications of our results for silica nanopore experiments and micro- and nanofluidic devices.

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