Compensating for electrode polarization in dielectric spectroscopy studies of colloidal suspensions: theoretical assessment of existing methods

Frontiers in Chemistry

Jan van Turnhout¹  Emmanuelle DUBOIS²  Claire Chassagne³  María Luisa Jiménez⁴  Jacques van der Ploeg⁵ 

[1] Delft University of Technology;Sorbonne Universités;Technical University of Delft;Universidad de Granada;none;

关键词: Zeta Potential;    Colloidal suspension;    Complex conductivity;    Electric permittivity;    Logarithmic derivative;    Variable spacing;   

DOI  :  10.3389/fchem.2016.00030

来源: DOAJ

【 摘 要 】

Dielectric spectroscopy can be used to determine the dipole moment of colloidal particles from which important interfacial electrokinetic properties, for instance their zeta potential, can be deduced. Unfortunately, dielectric spectroscopy measurements are hampered by electrode polarization (EP). In this article, we review several procedures to compensate for this effect. First EP in electrolyte solutions is described: the complex conductivity is derived as function of frequency, for two cell geometries (planar and cylindrical) with blocking electrodes. The corresponding equivalent circuit for the electrolyte solution is given for each geometry. This equivalent circuit model is extended to suspensions. The complex conductivity of a suspension, in the presence of EP, is then calculated from the impedance measured. Different methods for compensating for EP are critically assessed, with the help of the theoretical findings. Their limit of validity is given in terms of characteristic frequencies. We can identify with one of these frequencies the frequency range within which data uncorrected for EP may be used to assess the dipole moment of colloidal particles. In order to extract this dipole moment from the measured data, two methods are reviewed: one is based on the use of existing models for the complex conductivity of suspensions, the other is the logarithmic derivative method. An extension to multiple relaxations of the logarithmic derivative method is proposed.

【 授权许可】

Unknown