Agriculture Reference
In-Depth Information
SOM Model
with Concurrent Irreversible Reaction
Olivier Soil
100
80
C
o
= 100 mg/L
60
80
40
30
20
40
10
20
0
10
0 0
100
150
200
250300
350400
450500
Time, Hours
SOM Model
with Consecutive Irreversible Reaction
Olivier Soil
100
C
o
= 100 mg/L
80
60
8
0
40
20
40
20
0
0 0
100
150
200
250300
350400
450500
Time, Hours
FIGURE 6.20
Experimental results of As(V) concentration in soil solution for Olivier soil versus time for all
values of
C
o
. Dashed curves were obtained using the second-order model with concurrent (top
figure) and consecutive (bottom figure) irreversible reactions.
arsenic adsorption behavior observed on several soil minerals (Fuller et al.,
1993; Raven, Jain, and Loeppert, 1998; Arai and Sparks, 2002) as well as whole
soils (Elkhatib, Bennett, and Wright, 1984; Carbonell-Barrachina et al., 1996)
over different time scales (minutes to months).
A comparison of the multireaction (MRM) and second-order (SOM) mod-
els for their capability to predict arsenic concentration with time is given in
Figure 6.22. Selim and Zhang (2007) found that several model versions fit
the data equally well, but the sorption kinetics prediction capability varied
among the soils investigated. MRM was superior to SOM and the use of irre-
versible reactions for the model formulations was essential. They also found
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