Monte Carlo simulations of colloidal stability—beyond the Poisson—Boltzmann approximation

✍ Scribed by Torbjörn Åkesson; Bo Jönsson

• Publisher: Elsevier Science
• Year: 1991
• Tongue: English
• Weight: 504 KB
• Volume: 36
• Category: Article
• ISSN: 0013-4686
• DOI: 10.1016/0013-4686(91)85034-5

✦ Synopsis

Monte

Carlo simulations of the interaction between two charged surfaces immersed in an electrolyte solution have been performed in the canonical ensemble. The effect of salt concentration on the osmotic pressure was investigated and the results were compared with predictions from the Poisson-Boltzmann (PB) equation. The PB results are in reasonable agreement with simulations for systems containing monovalent counterions at low salt concentration. In the presence of divalent couuterions and/or high salt concentration the approximate theory fails and there is a qualitative difference between PB and the enact results. In these cases, the net osmotic pressure is negative as a result of different ionic densities, and as a consequence different correlation effects in the bulk and in the double layer. At low salt concentration and not too small separations, these seem to be mainly of electrostatic origin, while at higher salt concentration hard core correlations come into play as well.