Primitive Model Electrophoresis

✍ Scribed by Marcelo Lozada-Cassou; Enrique González-Tovar

• Publisher: Elsevier Science
• Year: 2001
• Tongue: English
• Weight: 135 KB
• Volume: 239
• Category: Article
• ISSN: 0021-9797
• DOI: 10.1006/jcis.2001.7680

✦ Synopsis

The electrophoresis of a spherical macroion is calculated with the new primitive model electrophoresis (PME) theory, which incorporates the ionic size. The results are compared with the classical theory of Wiersema, O'Brien, and White. The PME mobility, as a function of the macroion's surface charge (σ ) or zeta potential (ζ ), is found to depend on the ionic valence, radius and concentration, and macroion hydrodynamical radius (A); i.e., it is not universal with κA, as predicted by the classical theory. The mobility is very nonlinear as a function of ζ . This behavior is related to the nonlinear dependence of ζ , as a function of σ , when ionic size is included in the theory. In the classical theory ζ is a monotonic function of σ . Important quantitative and/or qualitative differences between PME and the classical theory are found. However, in the limit of zero ionic diameter, and/or low salt concentration, and low macroion charge, the new theory reduces to the classical theory. The agreement of the PME with experimental data is very good. In particular, the prediction of reversed mobility is corroborated by recent experimental data.