Average electrophoretic mobility

Determination of the effective transport coefficients, i.e., dispersion coefficient and electrophoretic mobility, as functions of the geometry of the unit cell requires an analogous averaging of the species continuity equation. Locke [215] showed that for this case the closure problem is given by the following local problems ... 

The velocity of particle migration, v, across the field is a function of the surface charge or zeta potential and is observed visually by means of an ultramicroscope equipped with a calibrated eyepiece and a scale. The movement is measured by timing the individual particles over a certain distance, and the results of approximately 10-15 timing measurements are then averaged. From the measured particle velocity, the electrophoretic mobility (defined as v/E, where E is the potential gradient) can be calculated. 

Electrokinetic Measurements. Electrophoretic mobilities were measured with a flat-cell apparatus manufactured by Rank Brothers, Cambridge, England. In addition, several mobility values were checked for accuracy with a Zeta Meter, New York. Mobilities were determined with a small volume of the suspension (approximately 25 cc) that had been prepared for the adsorption experiments. The pH of the solution was measured prior to determining the electrophoretic mobilities, which involved measuring the velocities of five to ten particles in each direction. An average value of the mobilities was recorded. Samples containing the flocculated particles were dipped into an ultrasonic bath for approximately one second prior to making the pH and mobility measurements. 

In the study of Neirynck et al. (2007), the electrophoretic mobility data indicated that whey protein-stabilized emulsion droplets became gradually more negatively charged with pectin addition at pH = 5.5. This change was not only reflected in a smaller average droplet size, but also in a significant improvement in the creaming stability of the emulsions. 

Particles of Fe203 with an average diameter of 1 /un were dispersed in xylene containing 5 x 10 3 mole liter 1 of copper(I) oleate. These showed an electrophoretic mobility of 0.110 fim s V-1 cm. The conductivity of the solution was 4.7 x 10 10 ohm cm-1, indicating an ion... 

The fragments were aligned using genetic markers, and their lengths were estimated by their electrophoretic mobilities.77 The time-of-entry map has been added on a distorted scale in Fig. 26-4B. There are, on the average, 46.4 kb of DNA per minute, but this amount varies around the chromosome between 38 and 61 kb / min. 

In practical applications of electrophoresis, collections of colloidal particles in bounded systems are usually encountered and the experimentally measured electrophoretic mobility is actually the average value for the entire suspension. It is therefore necessary to determine the average electrophoretic velocity for a suspension of colloidal particles. For dilute dispersions, the first order correction to the mobility of an isolated particle can be determined from the... 

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