COLL 452 |
| Jeffrey A. Fagan, Paul J. Sides, and Dennis C. Prieve. Department of Chemical Engineering, Carnegie Mellon University, Pittsburgh, PA 15213 |
| In an effort to understand the mechanism of 2-D aggregation of colloidal particles previously observed on a/c electrodes, we have used Total Internal Reflection Microscopy (TIRM) to investigate the response of a single 6 mm polystyrene latex particle very near the horizontal electrode. TIRM can detect changes in elevation of the particle as small as 1 nm. The average height displays a minimum in its frequency and amplitude dependences in KOH but increases monotonically in NaHCO3. Since the electrophoretic properties of the particle are about the same in the two electrolytes, a force not related to the zeta potential of the particle is suggested. We believe this force arises from the action of components of the electric field that are tangent to the electrode acting on a boundary-layer of charge created near the electrode surface by passing current through the solution. The direction of this electrical body force depends on the difference of the transference numbers of the ions carrying charge which has opposite signs in KOH and NaHCO3. |
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ACS Award in Colloid and Surface Chemistry Symposium Honoring Clay Radke
Division of Colloid and Surface Chemistry |