Soil chemistry effects and flow prediction in electroremediation of soil

This work addresses processes occurring during the removal of contaminants from soils using electric fields. Laboratory experiments and mathematical modeling are used to study the changes in the flows of ions and pore liquid during the process; these flows are directly related to the removal of charged and uncharged contaminants by electromigration and electroosmosis, respectively. Soil properties are explored by electrophoresis measurements, acid! base titrations, and elemental analyses of pore solutions, then incorporated into an electrochemical transport model, and compared to electroremediation experiments. It is found that a soil chemistry model involving cation exchange and aluminum chemistry must be included to describe the process accurately. Varying electroosmotic flow is successfully predicted, but only until the development of a low ionic strength region in the medium. The insight gained allows the mechanisms of electroosmotic flow reversal and cessation to be identified. As importantly, this investigation finds the low ionic strength region to be an undesirable but likely occurrence with or without significant effects from soil chemistry and shows how controlling the system chemistry makes the electroremediation technique more robust in practice.