Environmental Engineering Reference
In-Depth Information
C
g
C
l
K
H
=
m
=
(21.7)
with:
K
H
=
dimensionless Henry constant (-),
m
distribution coëfficiënt (-),
C
g
=
=
concentration contamination in the gas phase (mol/m
3
).
The dimensionless Henry coefficient can be derived from the ideal gas law as:
H
K
H
=
m
=
(21.8)
R
∗
T
with:
R
=
gas constant (J/mol/K),
T
=
temperature (K).
In nearly all cases, the value of the Henry coefficient is constant, therefore the
Henry coefficient can be calculated from Eq. (
21.8
) as the ratio of the maximal
vapour pressure (
P
s
) and the water solubility (
S
):
P
s
S
H
=
(21.9)
with:
P
s
=
saturated vapour pressure (Pa),
water solubility (mol/m
3
).
S
=
The dimensionless Henry coefficient can also be calculated as:
C
g
S
K
H
=
=
m
(21.10)
with:
C
∗
g
=
maximum concentration in gas phase (mol/m
3
).
Solubility in water and the maximum concentration in the gas phase are
dependent on the temperature.
The equilibrium relation between the amount of adsorbed contaminants and the
contaminants in the gas phaseis comparable to Eq. (
21.2
):
K
d
∗
q
s
=
C
g
(21.11)
with:
K
d
=
soil-gas partitioning coefficient (m
3
/kg dm)
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