The effects of ion size on double layer properties: Theory and Monte Carlo simulations
| Autor: | W.R. Fawcett |
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| Rok vydání: | 2006 |
| Předmět: | |
| DOI: | 10.1016/s1573-4285(06)80049-9 |
| Popis: | This chapter discusses the theory and Monte Carlo (MC) simulations of the effects of ion size on double layer properties. The classical picture of the double layer includes an inner layer immediately at the geometrical interface followed by a diffuse layer, in which the electrical field because of the charged interface gradually decreases because of the effects of thermal motion on the counter ions attracted to the interface. The inner layer that is also called the “Helmholtz layer” is populated only by solvent molecules in the simplest situations. The diffuse layer is the region of the double layer in which the concentration of ions is different from that in the bulk of the solution. The distribution of ions is determined both by the field because of the charge at the interface and by the effects of thermal motion. The chapter discusses the MC method developed for the diffuse layer and the results presented for simple 1: 1 and 2: 1 electrolytes in which all ions have the same size (restricted model). The hypernetted chain approximation (HNCA) equations are presented for a 1:1, 2: 1 and 1:2 electrolytes. A simple analytical solution of the HNCA for 1:1 electrolytes described by Henderson and Blum is described and analyzed in the chapter. It is explained that such an approach can lead to a quantitative expression for the diffuse layer potential drop that reproduces the MC data. MC data for a 1:1 electrolyte in which the ions have different sizes are presented. This study is specifically used to compare the diffuse layer in NaCl and CsCl solutions. |
| Databáze: | OpenAIRE |
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