Electroosmosis zeta potential

Electroosmotic flow is also dependent on the zeta potential at the immobilized surface and the strength of the electric field. For electroosmosis, the flow rate generated is... 

What is electroosmosis How is it used to measure the zeta potential ... 

Zeta potential was the first, experimentally available value characterizing edl. The potential of the solid particles in the electrolyte solutions may be determined on the basis of one of the four following phenomena microelectrophoresis, streaming potential, sedimentation potential and electroosmosis. The most popular of them and the best described theoretically and methodically is the electrophoresis. Other papers, concerning the electrophoretic mobility, stationary level determination and the theory of the charged particles transportation in the electric field are still published. 

The purpose of this study was to explore the interaction between slurry particles and wafer surfaces by the measurements of their zeta potentials. The zeta potentials of slurry particles such as fumed and colloidal silica, alumina, ceria and MnOj and substrates such as silicon, TEGS, W, and A1 have been measured by electrophoretic and electroosmosis method to evaluate the electrical properties of surfaces, respectively. The zeta potential of oxide and metal surfaces showed similar values to those of particles as a function of pH. The interaction energy between alumina and silica particles and TEOS, W and A1 substrate were calculated based on DLVO theory. No deposition of silica particles on TEOS and the heavy deposition of alumina particles on metal substrates were observed in the particle deposition test. Experimental results were well agreed with the theoretical calculation. 

B. Potocek, B. Gas, E. Kenndler, and M. Stedry, Electroosmosis in capillary zone electrophoresis with non-uni-form zeta potential, 7. Chromatogr. A 709 51 (1995). 

Depending on the sign of the zeta potential, EOF can be towards either the anode or cathode, and the apparent mobility of an analyte is the sum of its electrophoretic mobility and EOF. Electroosmotic forces act near the capillary wall, which results in a flat flow profile that is less dispersive than the parabolic flow profile associated with pressure-driven flows. EOF can be beneficial since it can enable the analysis of both anions and cations in a single run. Electroosmosis has been investigated extensively as a means for producing fluid flow for various processes in microfluidic devices [227-232]. 

The heavy metals are removed predominantly by the electromigration process, while the organic contaminants are removed by electroosmosis. The presence of heavy metals causes the zeta potential of the soil to be less negative and even result in a positive value, affecting the electro-osmotic flow and sorption of the contaminants. 

In electrokinetic processes, there are two major transport mechanisms electromigration and electro-osmosis. Generally, in an electrical field, electromigration causes cationic metals such as cadmium, zinc, lead, nickel, and copper to move from the anode toward the cathode in electro-osmosis, the direction of movement of the pore water is toward the cathode when the zeta potential of the soil surface is negative. This can result in an enhanced removal of metals because the direction of transport of the ions in both mechanisms is the same. However, the direction of electromigration for anionic pollutants is toward the anode and that for electroosmosis is from anode to cathode, as stated previously. The opposite direction of movement means that the removal rate of anionic pollutants could be reduced. 

When a DC potential is applied to a medium containing water and ions, such as soil, acid is generated at the anode and base at the cathode due to the electrolysis of water. The highly acidic environment near the anode could be detrimental to the electroosmosis process if the zeta potential in the soil falls too low or reverses. Two clever approaches are utilized in the Lasagna process to both minimize the acid effect on soil and keep the anode pH between 5 and 7. First, steel plates are used as the anode material to promote iron oxidation as the main anodic reaction instead of water oxidation, which forms acid (H+). Second, the basic pore water accumulated at the cathode (pH > 12) is recycled by gravity back to the anode as makeup water, which is required for continuing the operation of electroosmosis and at the... 

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