3.3.1 Cations
During the application of EK process, electromigration and
electroosmosis were two main mechanisms (Klouche et al., 2020).
Electromigration results in the migration and movement of ionic
compounds, while the electroosmosis mechanism is drive the flow of water
along with solutes from anode to the cathode. Fahadani et al (2018)
noticed that at low contamination, the dominant phenomenon in migrating
the contaminations is electromigration process, and in case of high
contamination, the electroosmosis process is dominant.
Fig.4 and Fig. S4 shows the concentration distributions of cations
include Na+ (exogenous added ion),
K+, Mg2+ and Ca2+in different soil layers after V-EK treatment. For control column
(applied voltage = 0 V), the Na+ concentration
decreases from the bottom up but accumulates in the surface layer. It is
because the ion exchange reaction that displacement of
Ca2+ and Mg2+ from a soil adsorption
complex by Na+ resulting in the loss of Na (Sun et
al., 2012; Kim et al., 2010), and this can be seen from the increase
tendency of Ca2+ and Mg2+.
Even so, the maximum increasement percentage of Na+,
K+, Ca2+ and Mg2+were 1528%, 318%, 2182% and 2451% respectively compared with the
initial value of soil.