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Theoretical treatment and numerical simulation of potential and concentration profiles in extremely thin non-electroneutral membranes used for ion-selective electrodes
- Source :
-
Journal of Electroanalytical Chemistry . Mar2010, Vol. 641 Issue 1/2, p45-56. 12p. - Publication Year :
- 2010
-
Abstract
- Abstract: The applicability of extremely thin non-electroneutral membranes for ion-selective electrodes (ISEs) is investigated. A theoretical treatment of potential and concentration profiles in space-charge membranes of ≪1μm thickness is presented. The theory is based on the Nernst–Planck equation for ion fluxes, which reduces to Boltzmann’s formula at equilibrium, and on the Poisson relationship between space-charge density and electric field gradient. A general solution in integral form is obtained for the potential function and the corresponding ion profiles at equilibrium. A series of explicit sub-solutions is derived for particular cases. Membrane systems with up to three different ion species are discussed, including trapped ionic sites and co-extracted ions. Solid-contacted thin membranes (without formation of aqueous films at the inner interface) are shown to exhibit a sub-Nernstian response. The theoretical results are confirmed by numerical simulations using a simplified finite-difference procedure based on the Nernst–Planck–Poisson model, which are shown to be in excellent agreement. [Copyright &y& Elsevier]
Details
- Language :
- English
- ISSN :
- 15726657
- Volume :
- 641
- Issue :
- 1/2
- Database :
- Academic Search Index
- Journal :
- Journal of Electroanalytical Chemistry
- Publication Type :
- Academic Journal
- Accession number :
- 48409322
- Full Text :
- https://doi.org/10.1016/j.jelechem.2010.01.001