Agriculture Reference
In-Depth Information
solution. The greater value of
K
d
indicated the greater adsorption capacity of
soil to pollutant. Compared the values of
K
d
in Table 3, it can be found that the
adsorption capacity of the soil to Cr(VI) was much greater than that of
organchlorine pesticides. The values
of
Γ
max
in Table 3 indicated that the
adsorption capacity of soil to Pb / Cd was much greater than that of As (V). As
shown in Figure 2, Cr (VI) and As (V) adsorption capacity were almost equal.
Therefore, it could be concluded that the adsorption capacity of soil to the four
heavy metals were much greater than that of organochlorine pesticides. For
each pollutant, adsorption capacity of the two soils had little difference, which
was relevant to the similar physical and chemical properties of the two soils.
5000
Cd
10000
Pb
4000
Soil A
Soil B
Langmuir isotherm
8000
Soil A
Soil B
Langmuir isotherm
3000
6000
2000
4000
1000
2000
0
0
0
2
4
6
8
0.0
0.2
0.4
0.6
0.8
1.0
Equilibrium concentration(mg·L
-1
)
Equilibrium concentration(mg·L
-1
)
40
As(V)
80
C
r(
VI
)
Soil A
Soil B
Langmuir isotherm
30
60
Soil A
Soil B
Linear isotherm
20
40
10
20
0
0
0
1
2
3
4
5
6
0
1
2
3
4
5
Equilibrium concentration(mg·L
-1
)
Equilibrium concentration
(
mg
·
L
-1
)
1.0
1.5
a
-BHC
Soil A
Soil B
Linear isotherm
β
-BHC
Soil A
Soil B
Linear isotherm
0.8
1.2
0.6
0.9
0.4
0.6
0.2
0.3
0.0
0.0
0
5
10
15
20
25
0
10
20
30
Equilibrium concentration
(
µ
g·
L
-1
)
Equilibrium concentration
(
µ
g·
L
-1
)
1.0
1.5
γ
-BHC
Soil A
Soil B
Linear isotherm
δ
-BHC
Soil A
Soil B
Linear isotherm
0.8
1.2
0.6
0.9
0.4
0.6
0.2
0.3
0.0
0.0
0
5
10
15
20
25
30
35
40
0
5
10
15
20
25
Equilibrium concentration
(
µ
g·
L
-1
)
Equilibrium concentration
(
µ
g·
L
-1
)
1.5
1.5
o,p'-DDT
Soil A
Soil B
Linear isotherm
p,p'-DDT
Soil A
Soil B
Linear isotherm
1.2
1.2
0.9
0.9
0.6
0.6
0.3
0.3
0.0
0.0
0
5
10
15
20
25
0
5
10
15
20
25
Equilibrium concentration
(
µ
g·
L
-1
)
Equilibrium concentration
(
µ
g·
L
-1
)
Figure 2. Thermodynamics isotherms of heavy metals and organochlorine pesticides
adsorption by Soil A and Soil B.
