Optimization of electroosmotic flow to enhance the removal of contaminants from low‑permeable soils

Abstract

Electrokinetic is an effective method for the extraction of contaminants from low-permeable soils. This work examines the influence of Ca+2 ions on the electroosmotic flow and the effect of electric potential, current, and pH variations on the removal of Pb2+, Na+, and Clˉ ions from artificially contaminated soil during vertical electrokinetic experiments. The DC electric field of 1 Vcm−1 was applied across the soil specimen via steel mesh electrodes for 24, 48, and 72 h of the experiment. In this work, the vertical electrokinetic cell was used to avoid the deposition of Na+ and Pb +2 ions near the soil surface after the treatment. making it even less permeable. The results show that the formation of acidic and alkaline environments in soil specimens affects the transport of ionic species by reducing the effect of electromigration and electroosmotic water flow. The enhancement of electroosmosis using Ca+2 ions as an electrolyte increased the extraction efficiency of Pb2+ (i.e., 41%) and Na+ (i.e., 82%) ions instead of the Clˉ (i.e., 69%) ions due to the high electroosmotic flow (i.e., 81 mL) from anode to the cathode. For relatively low electroosmotic flow (i.e., 19 mL), the extraction efficiency of Clˉ ions (i.e., 76%) was higher than that of Pb2+ (i.e., 27%) and Na+ (i.e., 44%) ions. The results demonstrated that the extraction efficiency of ions and energy consumption increased with treatment time and were higher during the first 24 h of the experiments.Graphical Abstract