Physicochemical phenomena of electro-kinetic extraction of inorganic contaminants from kaolinite

Abstract

Experiments investigating the use of electro-kinetics for removal of inorganic chemicals from kaolinite clay were performed. Kaolinite was homogeneously saturated with a NaCl solution and consolidated to the desired void ratio. Fluid reservoir chambers, a power supply and data acquisition instrument were connected to the consolidated sample. A voltage difference was applied to electrodes at each end of the sample to induce electro-osmotic fluid flow and ionic migration of NaCl. After electro-kinetic treatment the sample was disconnected from the reservoirs, power supply and data acquisition system, then sectioned to allow water content, sodium and chloride concentration, and pH analyses of each section. The data obtained was reduced and prepared in graph form for analysis of results. Energy for electrolysis, total energy expended, and removal efficiency were calculated and graphed for selected experiments. It was concluded that the voltage gradient became non-linear during experimentation, contaminant distribution was dependent on initial concentration, and zones of altered pH and ion removal did correspond in some experiments. Also, the removal efficiency decreased with time during experimentation and increased with intial contaminant concentration. Comparisons to a predictive model suggested that ionic mobility and dissusivity values varied between experiments and the model.