title: Influence of steric interactions on the dielectric and electrokinetic properties in colloidal suspensions.
abstract: One of the main assumptions of the standard electrokinetic model is that ions behave as point like entities. In this work we remove this assumption and analyze the main consequences of finite ionic size on the dielectric and electrokinetic properties of colloidal suspensions. We represent the steric interactions by means of the Bikerman and the Carnahan-Starling equations and solve numerically the standard linearized electrokinetic equations in the stationary and the frequency domains, for surface charge density and electrolyte solution concentration values typically encountered in colloidal suspensions. In all cases the steric interactions improve upon the predictions of the standard model since the surface potential, the electrophoretic mobility, and the conductivity and permittivity increments increase. However, the corrections introduced by the Bikerman equation are generally small: less than 10% as compared to the standard model. On the contrary, the Carnahan-Starling equation leads to corrections to the surface potential versus surface charge and the electrophoretic mobility values that easily surpass 10% and can attain values as high as 50%. Corrections to the conductivity and permittivity increments are smaller but still non negligible.
authors.affiliation: Departamento de Física, Universidad de Jaén, Campus Las Lagunillas, Ed. A-3, 23071 Jaén, Spain.
authors.forename: José Juan
authors.initials: JJ
authors.lastname: López-García
authors.affiliation: Departamento de Física, Universidad de Jaén, Campus Las Lagunillas, Ed. A-3, 23071 Jaén, Spain. Electronic address: jhorno@ujaen.es.
authors.forename: José
authors.initials: J
authors.lastname: Horno
authors.affiliation: Departamento de Física, Universidad Nacional de Tucumán, Av. Independencia 1800, 4000 San Miguel de Tucumán, Argentina; Consejo Nacional de Investigaciones Científicas y Técnicas, Av. Rivadavia 1917, 1033 Buenos Aires, Argentina.
authors.forename: Constantino
authors.initials: C
authors.lastname: Grosse
mesh_terms: D003102:Colloids / Q000737:chemistry*; D004586:Electrophoresis; D007477:Ions; D007700:Kinetics; D008962:Models, Theoretical; D013535:Suspensions / Q000737:chemistry*
chemical_list: D003102:Colloids; D007477:Ions; D013535:Suspensions
keywords: Conductivity increment; Dielectric increment; Electrophoretic mobility; Ion size effect; Standard electrokinetic model