Charge inversion of divalent ionic solutions in silica channels

CD Lorenz and A Travesset, PHYSICAL REVIEW E, 75, 061202 (2007).

DOI: 10.1103/PhysRevE.75.061202

Recent experiments F. H. J. van der Heyden , Phys. Rev. Lett. 96, 224502 (2006) of streaming currents in silica nanochannels with divalent ions report charge inversion, i.e., interfacial charges attracting counterions in excess of their own nominal charge, in conflict with existing theoretical and simulation results. We reveal the mechanism of charge inversion by using all-atomic molecular dynamics simulations. Our results show excellent agreement with experiments, both qualitatively and quantitatively. We further discuss the implications of our study for the general problem of ionic correlations in solutions as well as in regards to the properties of silica-water interfaces.

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