Reduction of Contaminants in Soil and Water By Direct Electric Current - Electrokinetics for Petroleum and Environmental Engineers - page 62

25

0.5

Voltage
Current

20

0.4

0.3 15

0.2 10

0.1 5

0 0

0 24 48

Time, hrs

72 96

Figure 2.18 Voltage and current evolution in the potlining sludge sample during EK
treatment under constant 15V of potential (Pamukcu and Pervizpour, 1998a)

10

CN at Anode
Flat at Anode
CN at Cathode
Fl at Cathode

8

6

4

2

0

0 4 8 2 6 0 144 168 192

Time, hrs

Figure 2.19 Cumulative mass of CN- and Fl-removed from sample into the electrode
chambers during EK treatment of sludge (Pamukcu and Pervizpour, 1998a)

E. Hexavalent Chromium, Cr(IV) Extraction:
An example of the influence of diffuse double layer reac-
tions can be observed with hexavalent chromium, in Cr(VI)
treatment using electrokinetics. The Cr(VI), which is often
found in anionic species of Cr 2 O 4 - , is readily mobile in soil
pore fluid but may not be readily extracted under an elec-
trical gradient. Figure 2.20 shows typical results of electro-
kinetic extraction of Cr(VI) from a sample of hexavalent
chromium contaminated site in Eastern Pennsylvania
(Pamukcu and Wittle, 1999 - EPA SITE Demonstration