Date of Award

1994

Document Type

Dissertation

Degree Name

Doctor of Philosophy (PhD)

Department

Chemistry

First Advisor

Robert J. Gale

Abstract

Capillary electroosmosis is an important factor in capillary zone electrophoresis (CZE) and micellar electrokinetic capillary chromatography (MECC). A new application of electrokinetic phenomena in environmental science is electrokinetic soil processing, which is an emerging technique with the capability to decontaminate polluted soils. Chapter 1 discusses the fundamental theory behind electroosmosis, CZE, MECC, and electrokinetic soil processing. In chapter 2, the surface conductances of different concentrations of KCl solutions in 50 and 100 $\mu$m capillaries were measured using an AC method, to attempt to characterize capillary double layers. With increase of KCl concentration, the surface conductance increases. Chapter 3 involves fundamental studies of hydraulic and electroosmotic flows through 50 and 100 $\mu$m capillaries. The results show that hydraulic flow follows the Poiseuille relation. The energy consumptions for these two flows are compared and hydraulic flow is much more energy efficient than electroosmotic flow because of bulk IR losses in the latter. In chapter 4, more detailed studies of capillary electroosmosis indicate that the electroosmotic velocities for KCl, LiCl, and butylpyridinium chloride (BPC) in a 95 $\mu$m capillary are similar, whereas for tetrahexylammonium chloride (THAC) no flow was detected. Due to the electrophoretic effect, the bulk flow of sodium dodecyl sulfate (SDS) solutions with concentrations above its CMC (critical micelle concentration, 8.4 mM) were reversed (cathode toward anode); however, with concentrations of SDS below its CMC, anodic to cathodic electroosmotic flows were observed. Due to the adsorptive effect of cetyltrimethylammonium ion on the capillary surface, reverse electroosmotic flows of cetyltrimethylammonium chloride (CTAC) solutions were observed with its concentration above its CMC (0.03 mM). Finally, Chapter 5 contains the results of electroosmotic flow behavior and electrochemistry (voltage, current, resistance, pH gradients and conductivity variations) for phenol removal from kaolinite clay by electroosmosis. The adsorbed phenol (at concentration of 500 ppm) was removed 85% to 95% by the process and the energy expenditure was 18-39 kWh/m$\sp3$ of soil processed.

Pages

152

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