Influence of the finite ion size on the predictions of the standard electrokinetic model: Frequency response

Abstract

An extension into the frequency domain of our previous static and stationary works that modify the standard electrokinetic model taking into account the finite size of ions in the electrolyte solution [J.J. López-García, M.J. Aranda-Rascón, J. Horno, J. Colloid Interface Sci. 316 (2007) 196; J.J. López-García, M.J. Aranda-Rascón, J. Horno, J. Colloid Interface Sci. 323 (2008) 146; M.J. Aranda-Rascón, C. Grosse, J.J. López-García, J. Horno, J. Colloid Interface Sci., in press] is presented. It is shown that the excluded volume effect can be quite substantial in some cases and is not negligible even for weakly charged particles. Furthermore, it generally improves on the predictions of the standard electrokinetic model since the low-frequency dielectric and conductivity increments as well as the electrophoretic mobility increase with the ion size.