Streaming Current of Polystyrene Porous Plugs: Solvent Composition Effect

trical double layer can be obtained from studies on electrokiThe main purpose of this work is to research the solvent componetic phenomena. sition effect on the streaming current of porous plug formed by Data on colloidal systems and phenomena in mixed media monodisperse polystyrene microspheres. Polystyrene was selected are scarce (2–4), and this holds particularly for electrokias the disperse material because monodisperse, spherical polystynetic data (5, 6) . The objective of this work is to study the rene latexes have proved to be useful model systems, whose surface effect of solvent composition (aqueous alcohol solutions) charge density can be conveniently controlled. A polystyrene latex on the streaming current of ionic porous plugs formed by was prepared by emulsifier-free emulsion polymerization, having negatively charged polystyrene beads. There is a growing a particle size of 1.2 mm and a surface charge density of 034.0 { interest in the effect caused by some organic solvents on 1.0 mC/m. Binary mixtures of ethanol– and 1-propanol–water were used to understand the effect of the liquid phase composition certain separation processes. The addition of organic solon the streaming current of polystyrene porous plugs. For the vents to the electrolyte solution often extends the application ethanol– and 1-propanol–water mixtures the streaming current range of electromigration methods. In capillary zone electrodepends nonlinearly on the molar alcohol fraction. This nonlinear phoresis (CZE), an increase in resolution is often achieved dependence can be explained by the variation of the viscosity and by lowering the electroosmotic flow using aqueous–organic dielectric permittivity of the liquid with solvent composition. The buffer electrolytes. In micellar electrokinetic capillary chroz -potential plays also an important role in the explanation of the matography (MECC), the resolution of the analytes can be above dependence, especially with binary mixtures low in alcohol enhanced when the selectivity is changed by adding organic where a minimum in the z -potential appears. The electrokinetic solvents (7) . Besides, in contrast to aqueous dispersions, the results obtained in this work suggest that the basically hydrophobic surface charge of solid–liquid interfaces in mixed solvents is polystyrene surface is modified by the presence of hydrophilic sites. more sensitive to the nature and the concentration of the Adsorption of alcohol molecules on the charged hydrophilic sites leads to desorption of counterions from the inner part of the electrisupporting electrolyte. This is related to the activities of the cal double layer. q 1998 Academic Press ions in such solvents (8) .