MOVING BOUNDARY ELECTROPHORESIS OF CONCENTRATED SUSPENSIONS AND ELECTROOSMOSIS IN POROUS-MEDIA

This is a report of studies designed to validate the unit-cell theory (or swarm theory) of electroosmosis and electrophoresis proposed by Kozak and Davis. That analysis is compared with a numerical analysis of electroosmosis performed by O'Brien and with electrokinetic data of Van der Put and Bijsterbosch. ςpotentials extracted from electroosmosis data by using swarm theory show a greater dependence on the electrical double-layer thickness than does the numerical analysis, but for moderately thick and for thin electrical double layers both analyses roughly agree with microelectrophoretic data of Van der Put and Bijsterbosch. In addition, a composite theory of moving boundary electrophoresis was formulated and used to interpret new data for concentrated suspensions of colloidal particles. The composite theory consists of the previously developed unit-cell theory incorporated into the moving boundary electrophoresis analysis of Marmur.4 Theory and experiment show that the electrophoretic mobility is not a strong function of particle concentration, but the composite analysis fails to predict the characteristics of the leading and following boundaries. © 1990, American Chemical Society. All rights reserved.