Reduction of Contaminants in Soil and Water By Direct Electric Current - Electrokinetics for Petroleum and Environmental Engineers - page 46

1.2

1

Day 5

10

0.8

15

20

0.6

Day 25

0.4

σ 0 = 0.28 S/m
L = 20 cm

0.2

0 0.2 0.4

Distance from anode, x/L

0.6 0.8 1

Figure 2.4 Model predicted spatial and temporal variation of conductivity during EK
transport of Pb in kaolinite clay (Cao, 1997; Pamukcu, 2009)

1

Φ 0 = 2 Volts
L = 20 cm

0.8

0.6

Day 25

0.4

Day 10

0.2

Day 0

0

0 0.2 0.4

Distance from anode, x/L

0.6 0.8 1

Figure 2.5 Model predicted spatial and temporal variation of electric potential during EK
transport of Pb in clay (Cao, 1997; Pamukcu, 2009)

concentrations of the species, (ii) the spatial and temporal distribution of
ionic mobility of each species and (iii) the production rate of H+ at anode.
As the conductivity varies, the lower conductive area requires higher
potential over it to keep a consistent current with the other parts of the soil
column, resulting in a nonlinear electric potential profile across the cell.
This tendency is observed in Figure 2.5 where the time evolution of the
electric potential distribution is presented. As the electrochemical trans-
port continues, the potential curve becomes less steep over the entire cell
except in a narrow region adjacent to the cathode, where the electrical
potential is likely to have the largest gradient. This tendency agrees well