Environmental Engineering Reference
In-Depth Information
(a)
(b)
0.25
0.25
0 min
5 min
10 min
15 min
20 min
30 min
40 min
0 min
5 min
10 min
15 min
20 min
30 min
40 min
0.20
0.20
0.15
0.15
0.10
0.10
0.05
0.05
0.00
400
0.0
400
450
500 550
Wavelength (nm)
600
650
450
500 550
Wavelength (nm)
600
650
(c)
(d)
0min
5min
10min 15min
20min 30min 40min
0min
5min
10min 15min
20min 30min 40min
figure 6.7
UV-vis spectra of a solution of acid fuchsin (AF) (60 ml/l, 30 ml) in the presence of ZVI NP-immobilized hybrid nanofibrous
mats synthesized with two (a) and six (b) cycles of binding/reduction at a time interval of 0, 5, 10, 15, 20, 30, and 40 min, respectively, and
photos of the AF solution treated with ZVI NP-immobilized hybrid nanofibrous mats synthesized with two (c) and six (d) cycles of binding/
reduction at different time intervals. reprinted with permission from ref. [20]. © 2009, American Chemical Society.
table 6.1 decoloration efficiencies of dyes treated with MWcNt-incorporated nanofibrous mats containing Zvi Nps
at 5 and 40 min
Initial concentration
(mg/l)
pH value of
dye solution
Maximum absorption
wavelength (nm)
reaction time
(min)
remaining
percentage (%)
Sample
Methyl blue
60
5.68
600
5
8.91
40
3.84
Acridine orange
60
5.6
493
5
6.93
40
0.626
Acid fuchsin
60
6.8
544
5
37.4
40
9.75
reproduced with permission from ref. [13]. © royal Society of Chemistry.
different from physical absorption of dyes using nonmetal incorporated nanofibers [71], the decoloration using ZVI
NP-immobilized polymer nanofibers is predominantly based on the chemical reactivity of the immobilized ZVI NPs.
Although complete details of the mechanism are still unclear, it is believed that the chromophore of the selected dyes can
be destroyed after the iron reduction process. The reaction between Fe
0
and H
2
o or H
+
can generate atomic H, destroying
the chromophore group of the dyes [74]. Moreover, the intermediate products of Fe
0
such as Fe
2+
, Fe
3+
, Fe(oH)
y
2−
y
, and
Fe(oH)
x
3−
x
were thermodynamically unstable and active [75].
