Karlsruhe Institute of Technology, IKET-Chemical Process Technology, P.O. Box 3640, D-76021 Karlsruhe, Germany.
Langmuir. 2010 Mar 2;26(5):3126-33. doi: 10.1021/la903075w.
Here we study the nature and extent of free electrical charges in nonpolar liquids, using a recently introduced technique of observing droplet deflection generated by electrokinetic flow in a porous substrate. In the presence of dispersed water, surfactant molecules agglomerate and inverted micelles are generated which may act as charge carriers. In the present work, the conductivities of solutions of a nonpolar liquid with several concentrations of a dissolved surfactant are measured by electrical transients. The induced current densities are proportional to the applied voltage, indicating that the solutions represent an ohmic system. The conductivity does not scale simply with the surfactant concentration, though. It is inferred that different micellization mechanisms exist depending on the surfactant concentration, and a model is sketched. Further experiments reveal that flows of such solutions can be generated within saturated porous substrates when they are subjected to moderate electric fields. An investigation of the phenomena leads to the conclusion that these flows exist due to the presence of an electrical double layer; that is, they are of electrokinetic (electroosmotic) origin. Hence, the measured electrokinetic flow rates can be related to the zeta potential of the porous substrate saturated with the solution. Plotting the zeta potential against the logarithm of the ionic strength reveals a linear relationship.
在这里，我们使用一种新引入的技术，通过观察多孔基质中电动力学流动产生的液滴偏转而研究非极性液体中自由电荷的性质和数量。在存在分散水的情况下，表面活性剂分子聚集，形成反胶束，它们可能充当电荷载体。在本工作中，通过电瞬变测量了含有溶解表面活性剂的几种浓度的非极性液体溶液的电导率。感应电流密度与施加的电压成正比，表明溶液代表欧姆系统。但是，电导率并不简单地随表面活性剂浓度而变化。推断出不同的胶束化机制取决于表面活性剂浓度，并提出了一个模型。进一步的实验表明，当这些溶液在适度的电场下被施加于饱和多孔基质中时，可以产生这样的溶液流动。对这些现象的研究得出的结论是，由于存在双电层，这些流动存在；也就是说，它们是电动（电动渗透）起源的。因此，测量的电动流速可以与用溶液饱和的多孔基质的 ζ 电势相关联。将 ζ 电势对离子强度的对数作图揭示了线性关系。
