Environmental Engineering Reference
In-Depth Information
12
C 0(model) =0.05M; L=20 cm
C 0(test) =0.15M; L=10 cm
Model C/C0
Test C/C0 35 days
Model pH
Test pH 35 days
1.6
10
1.2
8
6
0.8
15d C/C 0
4
0.4
35d pH
2
35d C/C 0
0
0
0
0.2
0.4
Distance from anode, x/L
0.6
0.8
1
Figure 2.7 Model predicted and measured distribution of pH and total Pb concentration
at 35-day EK transport (Pamukcu, 2009)
ions to the narrow high pH zone to be accumulated by precipitation, hence
evacuating the region immediately behind it. The progression of this effect
is clearly seen by the evolution of lead distribution from 15 to 35 days,
as the distribution towards the cathode regions continues to dip behind
the high pH zone. The distribution of lead near the anode does not dip
at the same rate because the conductivity remains high and the electric
potential distribution tends to flatten there. Consequently the ions slow
down responding to a lower electric field. Factors such as sorption, retar-
dation and precipitation influence the model predictions, but their relative
contributions may be small other than the narrow high pH zone near the
cathode.
2.2.4 Theoretical Considerations: Electrochemical
Transformations
Transport and extraction of both the inorganic and organic substances from
clay pores frequently involve the addition of one or more chemical reagents
to the system (Liu and Wang, 2013, Chen et al., 2011, Ryu et al., 2011,
Chang et al., 2010, Pazos et al., 2008 and Hansen et al., 2005), introduc-
ing with it the possibility of secondary pollution. Recently, “green technol-
ogy” has been explored for in-situ destruction of contaminants enhancing
beneficial electrochemical reactions by electrokinetics. Optimization
parameters include changing electric field direction and intensity (Peng
et al., 2013), applying a sinusoidal electric field with pulses and a polarity
 
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