The interpretation of dielectric response measurements on colloidal dispersions using the dynamic Stern layer model

Abstract

Articles you may be interested inDynamic and dielectric response of charged colloids in electrolyte solutions to external electric fields Sound speed dispersion measurements and their interpretation in the presence of a shallow buried layer.The standard description of electrokinetic phenomena deals with a particle whose charge is uniformly smeared over its surface and considers ion transport only within a Gouy-Chapman diffuse layer. Experimental studies with colloidal dispersions have shown that this model is not applicable to many systems. To encompass a wider class of behavior, the standard model was extended to include ion migration within the Stern layer, the region between the shear envelope and the rigid particle. Computations show that Stern layer transport increases the conductivity and dielectric response of suspensions as well as the magnitude of the {; potential inferred from mobility measurements. Model predictions are compared with experimental measurements on two well-defined systemscolloidal silica and a polymer latex. The inclusion of surface transport processes markedly improves agreement between theory and the experimental data. For example, in situations where the standard theory underpredicts the measured dielectric increments by factors of 2 or 3, the dynamic Stern layer model yields results within 5% to 20% of the experimental data at frequencies in the kHz range.cess,

Electrokinetics of Concentrated Suspensions of Spherical Colloidal Particles with Surface Conductance, Arbitrary Zeta Potential, and Double-Layer Thickness in Static Electric Fields

“…More recently, Kijlstra et al (12) applied the theory of Stern layer transport to the study of the low-frequency dielectric response of colloidal suspensions, extending the thin double-layer theory of Fixman (3, 7). Likewise, Rosen et al (13) generalized the standard theory of the conductivity and dielectric response of a colloidal suspension in AC fields of DeLacey and White (5), assuming the model of Stern layer developed by Zukoski and Saville. Mangelsdorf and White (14, 15) also developed a general dynamic Stern layer model to be applied to electrophoresis and dielectric response in oscillating electric fields.…”

“…suspensions (1)(2)(3)(4)(5)(6)(7)(8)(9)(10)(11)(12)(13)(14)(15). However, in a great number of practical situations, suspensions are usually more concentrated than those typically considered as dilute, so some theoretical approaches to the issue of concentrated suspensions, including electrophoresis (16), sedimentation (17,18), electrical conductivity (19), and electroacoustic phenomena (20)(21)(22), to mention just a few, have been published in the past few decades.…”

Induced polarization signatures of cations exhibiting differential sorption behaviors in saturated sands

“…Rosen et al [1993] considered in their model the possible exchange of counterions between the Stern layer and the diffuse layer, while Schwarz [1962] considered that the counterions of the entire electrical double layer can only move tangentially along the mineral surface. However, the kinetics of the sorption/desorption of the counterions is a slow process, and we believe that this effect can be neglected at the frequencies typically considered for induced polarization (generally above 1 mHz).…”

“…[62] For such a lognormal distribution of polarization length scales, the related distribution of the relaxation times is given by [Revil and Florsch, 2010] Schwarz, 1962;Schurr, 1964] or numerically [Rosen et al, 1993]. Rosen et al [1993] considered in their model the possible exchange of counterions between the Stern layer and the diffuse layer, while Schwarz [1962] considered that the counterions of the entire electrical double layer can only move tangentially along the mineral surface.…”

“…Appendix B: Microscopic Description of the Stern Layer Polarization [63] In order to get a better insight as to what the Stern layer polarization is, we introduce here the microscopic equations describing the physics of the transport of the counterions located in the Stern layer (see Schwarz [1962], Schurr [1964], and Rosen et al, [1993] for additional details). The existence of the Stern layer of weakly sorbed counterions is demonstrated, for example, by molecular dynamic simulations [Tournassat et al, 2009].…”