Environmental Engineering Reference
In-Depth Information
1.0
0.8
0.6
0.4
0.2
0.0
0
40
80
120
160
200
240
B1
B2
B3
B4
75
60
45
30
15
0
0
50
100
150
200
250
300
Time (min)
Fig. 2
Effects of adsorption time on fluoride (
top
) and arsenite (
bottom
) uptake
Different models were used to test the kinetics of adsorbent-adsorbate interactions.
The Lagergren plots of log (
q
e
−
q
t
) vs. time are based on the pseudo first order kinetics
(Lagergren
1898
; Ho
2004
) given by
ln
qq qkt
e
−= −
ln
(3)
1
t
e
where
q
e
and
q
t
are the amounts adsorbed per unit mass at equilibrium and at any
time
t
, and
k
1
is the first order adsorption rate coefficient. The plots are linear (
r
lies
between0.98and1.00forluorideand0.95and0.99forarsenite)andtheirst-order
rate coefficient (
k
1
) is 1.63 × 10
−2
min
−1
(B1), 2.09 × 10
−2
min
−1
(B2), 2.17 × 10
−2
min
−1
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