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

Abstract

Electrokinetic is the effective method for the extraction of contamination from low permeable soil. This work examines the influence of calcium ions on the electroosmosis, and the effects of electric potential, current, and pH variation on the removal of Pb 2+ , Na + , and Clˉ ions from artificially contaminated soil during vertical electrokinetic experiments. The DC electric field of 1V/cm was applied across the soil specimen via steel mesh electrodes for 24, 48 and 72 hours of experiment. The outcomes show that the formation of acidic and alkaline environments in soil specimens affects the transport of ionic charge species by reducing the effect of electroosmosis.To enhance the electroosmotic flow, the anode reservoir filled with and without calcium chloride solution was examined. The enhancement of electroosmosis using calcium ions as an electrolyte increased the extraction efficiency of Pb 2+ and Na + ions instead of the Clˉ ions due to the high electroosmotic flow from anode to cathode. For relatively low electroosmotic flow, the removal rate of Clˉ ions was higher than the Pb 2+ and Na + ions. The results demonstrated that the extraction efficiency was increased with an increase in the treatment time. To avoid the dryness of the soil surface, wet sponges were inserted at the anode side, which connected with the electrolyte.

Effect of voltage gradient on energy consumption and chromium ions removal from salt-affected clayey soils

“…The permeability coefficient of soil was determined by the Darcy law using the constant head method, while the hydraulic flux of soil was determined by the following Eq. [𝑉 = 𝐾𝑖] [23], where "V" is the hydraulic flux (cms -1 ), "K" is the permeability coefficient (cms -1 ) and "i" is the hydraulic gradient (-).…”

“…Vcm -1 were applied across the soil samples, respectively), the potential profile (i.e., Fig. 2(b, c)) colliding with each other [23]. However, the 10 hours delay in the development of a sharp potential drop in soil during E-2 (i.e., applied 1 Vcm -1 ) compared to E-3 (i.e., applied 2 Vcm -1 ) attributed to the higher electric field intensity.…”

“…The electrical conductivity (EC) of soil depends on the total concentration of ionic species in the soil [23]. The EC of soil after the electrokinetic experiment is shown in Fig.…”

Electroosmotic strengthening of soft clay under different electrification modes

“…The electroosmosis method has been attempted on different types of civil engineering processes, such as soil improvement, 1,2 foundation pit dewatering, 3 slope stability, 4 and contaminated soil remediation, 5 and so forth. However, the high energy consumption and the unsatisfactory drainage effect have made it difficult to promote the practical engineering applications of the electroosmosis method.…”