Agriculture Reference
In-Depth Information
SOM Model
with Concurrent Irreversible Reaction
Windsor Soil
100
80
60
C
o
= 100 mg/L
40
80
20
40
20
0
10
0 0
100
150
200
250 00
350 00
450 00
Time, Hours
SOM Model
with Consecutive Irreversible Reaction
Windsor Soil
100
80
C
o
= 100 mg/L
60
8
0
40
20
40
0
20
0 0
100
150
200
250 00
350 00
450 00
Time, Hours
FIGURE 6.19
Experimental results of As(V) concentration in soil solution for Windsor 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.
SOM provided good overall predictions of the kinetic adsorption data for
arsenic.
The question arises whether SOM model improvements can be realized
when one relaxes the assumption of the use of Langmuir
S
max
and utilizes
parameter optimization to arrive at a best estimate of the rate coefficients (e.g.,
k
1
,
k
2
, and
k
irr
or
k
3
,
k
4
, and
k
5
) as well as
S
max
. Based on these results, Selim and
Zhang (2007) concluded that the use of Langmuir
S
max
as an input param-
eter provided good predictions of the adsorption results. Moreover, reten-
tion kinetics predictions of As(V) shown are in agreement with the biphasic
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