| Full text | |
| Author(s): |
Total Authors: 2
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| Affiliation: | [1] Sao Paulo State Univ UNESP, Inst Biosci Human & Exact Sci, Dept Phys, BR-15054000 Sao Jose Do Rio Preto - Brazil
[2] North Dakota State Univ, Dept Phys, Fargo, ND 58108 - USA
Total Affiliations: 2
|
| Document type: | Journal article |
| Source: | MEMBRANES; v. 11, n. 2 FEB 2021. |
| Web of Science Citations: | 0 |
| Abstract | |
Poisson-Boltzmann theory provides an established framework to calculate properties and free energies of an electric double layer, especially for simple geometries and interfaces that carry continuous charge densities. At sufficiently small length scales, however, the discreteness of the surface charges cannot be neglected. We consider a planar dielectric interface that separates a salt-containing aqueous phase from a medium of low dielectric constant and carries discrete surface charges of fixed density. Within the linear Debye-Huckel limit of Poisson-Boltzmann theory, we calculate the surface potential inside a Wigner-Seitz cell that is produced by all surface charges outside the cell using a Fourier-Bessel series and a Hankel transformation. From the surface potential, we obtain the Debye-Huckel free energy of the electric double layer, which we compare with the corresponding expression in the continuum limit. Differences arise for sufficiently small charge densities, where we show that the dominating interaction is dipolar, arising from the dipoles formed by the surface charges and associated counterions. This interaction propagates through the medium of a low dielectric constant and alters the continuum power of two dependence of the free energy on the surface charge density to a power of 2.5 law. (AU) | |
| FAPESP's process: | 17/21772-2 - Extensions of the Poisson-Boltzmann Theory to the study of the differential capacitance of an electrical double layer |
| Grantee: | Guilherme Volpe Bossa |
| Support Opportunities: | Scholarships in Brazil - Post-Doctoral |