Reduction of Contaminants in Soil and Water By Direct Electric Current - Electrokinetics for Petroleum and Environmental Engineers - page 52

-700

4.5

Cu] = 650 ppm; Applied potential = 1V

4

3.5

-600

3

2.5

-500

2

0.075 mg/l clay
0.02 mg/l clay
0 mg/l clay

0.05 mg/l clay
0.005 mg/l clay
pH

1.5

-400 1

0 5 10 15 20 25 30

Time (hrs)

Figure 2.9 Temporal variation and shift of E h with direct current in Cu(II)-Fe(II)
mixtures of clay where maximum E h shift up is 0.50V (Brosky and Pamukcu, 2013)

40

0.075 mg/l clay
0.05 mg/l clay
0.002 mg/l clay
0.0005 mg/l clay
Clay w/o Cu-Fe

20

0
-20

-40

-60

-80

-100

PZC~2.4

-120

0 1 2 3

pH

4 5 6 7

Figure 2.10 Zeta Potential with pH in Cu(II)-Fe(II) mixtures of clay (Brosky and
Pamukcu, 2013)

shift from base E h is maximized (~ between 4-6 hours) when the pH of the
system is recorded at around 2.4. This is consistent with the PZC of 2.4
shown in Figure 2.10.
Evidence of DDL-enhanced Cr(VI) reduction to less toxic Cr(III)
by direct current application has been reported previously (Banarjee et
al., 1987; Pamukcu et al., 2004,2008; Alshawabkeh and Sarahney, 2005;
Hannum and Pamukcu, 2007). Electrolytic transformations of selected
CHCs and PAHs have also been demonstrated successfully in water and