Environmental Engineering Reference
In-Depth Information
PHREEQC (Parkhurst
1995
). Another extension uses a different formulation
of the last term:
A z
i
2
m
p
p
þB
0
m
log
g
i
¼
þBa
i
1
This is implemented in the CHESS code (van der Lee
1998
). The temper-
ature-dependency of the parameters is shown in Table
8.1
. If activities are
considered, the derivation above leads to equation
u
¼
U
c
S
½
log
ðgÞþ
log
ð
c
Þ
¼
log
ð
K
Þ
instead of (
8.22
), where
g
denotes the vector of activity coefficients.
Table 8.1 Coefficients
in extended equations
for
activity equations
(Berner
1971
;
van der Lee
1998
)
Temperature [
C]
A
B
B'
0
0.4883
0.3253
0.0374
5
0.4921
10
0.4960
15
0.5000
20
0.5042
25
0.5085
0.3288
0.0410
30
0.5130
35
0.5175
40
0.5221
50
0.5319
60
0.5425
0.3346
0.0440
100
0.9595
0.3421
0.0460
c
s
c
¼ K c
s;
max
c
s
(8.29)
or, resolved for
c
s
:
Kc
s;
max
c
1
c
s
¼
(8.30)
þK c
a
L
2
¼ K
1
this is the already mentioned
Langmuir isotherm (6.7). A generalization of this formula results for species
which participate with more than one unit on the reaction, as for example gaseous
O
2
. Starting from the reaction terms:
With parameters
a
L
1
¼ c
s;
max
and
