REMOVAL OF CONTAMINANTS FROM SATURATED CLAY BY ELECTROOSMOSIS

The feasibility of using electroosmosis for purging contaminants from saturated clay is investigated by laboratory experiments and theoretical modeling. The experiments consist of purging a prepared kaolinite sample which is loaded with a known amount of phenol or acetic acid. The process is shown to be very effective at removing these species from the clay, achieving at least 94% removal under certain conditions. The measured energy costs were about $2/ton of effluent removed. The factors which determine the success of the decontamination are the combined effects of electroosmotic convection, ionic migration, chemical equilibria, and electrochemical reactions. These phenomena are analyzed in a model which compares well with experiments; both show the development of sharp fronts, some propagating with the electroosmotic flow and others stationary. at the electrodes. The pH of the purging solution is shown to have significant influence on the electroosmotic velocity and can be selected to optimize the process.