Observation of the mobility maximum predicted by the standard electrokinetic model for highly charged amidine latex particles
Observation of the mobility maximum predicted by the standard electrokinetic model for highly charged amidine latex particles
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DOI：
10.1021/la9916373
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发表时间：
2000-05-30
期刊：
影响因子：
3.9
通讯作者：
Semmler, M
中科院分区：
文献类型：
--
作者：
Borkovec, M;Behrens, SH;Semmler, M
电动力学方法是评估胶体颗粒和界面带电特性的核心工具。这些信息通常与胶体稳定性、沉积动力学和浮选现象相关。1-3最常用的技术是电泳，借此探测带电胶体粒子在外加电场中的迁移速度。虽然这样的实验相当简单，但它们的解释却不是。这个问题已经由Smoluchowski在世纪之交解决了，4但电解质溶液中球形颗粒的电泳迁移率的精确计算仅在20年前由奥布莱恩和白色提出。[5]这些作者在泊松-玻尔兹曼模型中得到了带电粒子存在时的流场。他们的解决方案现在可以作为商业计算机代码使用。这种所谓的“标准动电模型”评估剪切平面处的动电势，并且忽略由于该平面后面的电导引起的任何贡献。标准动电模型预测在固定筛选长度处作为动电势的函数绘制时电泳迁移率的显著最大值。为了在实验中观察到这一有趣的特征，一些工作人员系统地改变了表面电位。6，7虽然结果与标准电动模型基本一致，但迁移率没有显示任何明显的最大值。然而，更常见的是，表面电位和屏蔽长度同时变化;一个典型的例子是作为电解质函数的迁移率测量
Electrokinetic methods represent a central tool for the assessment of the charging properties of colloidal particles and interfaces. This information can often be correlated with colloid stability, deposition kinetics, and flotation phenomena. 1-3 The most frequently used technique is electrophoresis, whereby the migration velocity of a charged colloidal particle in an applied electrical field is probed. While such experiments are rather straightforward, their interpretation is not. This problem was already tackled by Smoluchowski at the turn of the century, 4 yet the exact calculation of the electrophoretic mobility of a spherical particle in an electrolyte solution was presented only 20 years ago by O’Brien and White. 5 These authors have obtained the flow field in the presence of a charged particle within the Poisson-Boltzmann model. Their solution is now available as a commercial computer code. This so-called “standard electrokinetic model” evaluates the electrokinetic potential at the plane of shear,, and neglects any contributions due to electrical conductance behind this plane.The standard electrokinetic model predicts a pronounced maximum in the electrophoretic mobility when plotted as a function of the electrokinetic potential at fixed screening length. To observe this intriguing feature experimentally, some workers have systematically varied the surface potential. 6, 7 While the results were in general agreement with the standard electrokinetic model, the mobilities did not display any clear maxima. More frequently, however, the surface potential and the screening length are varied simultaneously; a typical example are mobility measurements as a function of electrolyte