Environmental Engineering Reference
In-Depth Information
The elution rate of zinc ions (d
Q
/d
t
) is shown in Table 30.4. As expected, the release of zinc
increased with the low of water.
An experiment was conducted using a pitcher with a column of 8.5-cm length and
4.0-cm diameter containing 140 g of ZZ, and a low of drinking water of 0.2 L/min, for
45 days, with daily monitoring of the volume of drinking water treated to analyze the
performance of the ZZ system. Figure 30.7 describes the kinetic curves of Zn elution from
ZZ for different days, showing almost identical behavior and quantity of zinc released to
drinking water that remained below 2 mg/L.
The kinetic exchange parameters—elution rate (d
Q
/d
t
), internal effective diffusion (
D
),
and internal diffusion rate constant (
B
)—determined during the study (Table 30.5) con-
irmed that their values increased indicating a better performance of ZZ. See that the three
parameters improved after 8 days of continuous process of drinking water treatment.
TABLE 30.4
Elution Rate of Zn
2+
Ions as a Function of the Flow of Drinking Water
Flow of Drinking Water
d
Q
/d
t
× 10
−3
(meq g
−1
seg
−1
)
15 mL/min (1)
5.26
25 mL/min
11.34
100 mL/min
28.40
2
1
Eighth test
0
0
5
10
15
20
25
4
2
ird test
0
0
5
10
15
20
25
3
2
1
Second test
0
0
5
10
15
20
25
3
2
1
First test
0
0
10
20
30
40
50
Time (h)
FIGURE 30.7
Kinetic curves of Zn
2+
ions in drinking water for different days.
TABLE 30.5
Kinetic Exchange Parameters of Zn Released from ZZ
Day d
Q
/d
t
(10
−5
meq s
−1
)
D
(10
−11
m
2
s
−1
)
B
(10
−4
s
−1
)
1 0.68 ± 0.03 1.42 ± 0.07 0.83 ± 0.04
2 1.79 ± 0.08 2.85 ± 0.14 1.66 ± 0.08
3 3.94 ± 0.19 3.33 ± 0.16 1.94 ± 0.09
8 6.78 ± 0.33 16.33 ± 0.81 9.53 ± 0.47
Note:
d
Q
/d
t
is the elution rate of Zn
2+
,
D
is the internal effective diffusion coeficient,
and
B
is the internal diffusion rate constant.
