Environmental Fluid Mechanics, Faculty of Civil Engineering and Geosciences, Delft University of Technology Delft, Netherlands.
Laboratoire PHENIX, Centre National de la Recherche Scientifique, Sorbonne Universités, UPMC Université Paris 06 Paris, France.
Front Chem. 2016 Jul 19;4:30. doi: 10.3389/fchem.2016.00030. eCollection 2016.
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. 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.
介电谱可以用于确定胶体粒子的偶极矩，从中可以推导出重要的界面电动性质，例如它们的动电电位。不幸的是，介电谱测量受到电极极化（EP）的限制。在本文中，我们回顾了几种补偿这种效应的方法。首先描述了电解质溶液中的 EP：为具有阻塞电极的两种电池几何形状（平面和圆柱）推导了复电导率作为频率的函数。为每个几何形状给出了电解质溶液的相应等效电路。该等效电路模型扩展到悬浮液中。然后，通过阻抗计算存在 EP 时悬浮液的复电导率。借助理论结果，对补偿 EP 的不同方法进行了严格评估。以特征频率的形式给出了它们的有效性限制。我们可以用其中一个频率来识别未校正 EP 的数据的频率范围，这些数据可用于评估胶体粒子的偶极矩。为了从测量数据中提取这个偶极矩，我们回顾了两种方法：一种是基于悬浮液复电导率的现有模型的使用，另一种是对数导数方法。对数导数方法的扩展到多个弛豫的方法被提出。
