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8
Cd-Windsor(C
o
= 10 mg/L)
6
Equilibrium
4
Kinetic:
α = 5
α = 1 d
-1
2
Experimental
0
20
70
120
170
220
V/V
o
FIGURE 7.8
Measured (closed circles) and predicted breakthrough curves in Windsor soil column for three
Cd pulses of
C
o
= 10 mg L
-1
. Curves are predictions using equilibrium and kinetic ion exchange
with different α values. (From H. M. Selim and M. C. Amacher. 1997.
Reactivity and Transport of
Heavy Metals in Soils
. Boca Raton, FL: CRC Press. With permission.)
volumes of each input pulse (Selim et al., 1992). Lower peak concentrations
for 10 mg L
-1
in comparison to 100 mg L
-1
is perhaps related to the equiva-
lent fraction of Cd on exchange surfaces for Windsor soil. In Figure 7.8, the
maximum
C
/
C
o
increased from 0.9 to 1.6 and reached 3.0 for the third Cd
8
Cd-Windsor (C
o
= 100 mg/L)
Experimental
6
Equilibrium
4
Kinetic;
α = 5
α = 1 d
-1
2
0
0
30
60
90
120
150
V/V
o
FIGURE 7.9.
Measured (closed circles) and predicted breakthrough curves in Windsor soil column for
three Cd pulses of
C
o
= 100 mg L
-1
. Curves are predictions using equilibrium and kinetic ion
exchange with different α values. (From H. M. Selim and M. C. Amacher. 1997.
Reactivity and
Transport of Heavy Metals in Soils
. Boca Raton, FL: CRC Press. With permission.)
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