Environmental Engineering Reference
In-Depth Information
dichlorvos was higher compared with lindane and methyl parathion. No intermediate was
found during the degradation of dichlorvos.
The GC-MS chromatogram of commercial-grade methyl parathion at the beginning and
end of degradation is given in Figure 25.9. Similarly, GC-MS chromatograms of commercial-
grade dichlorvos at the beginning and end of photocatalytic degradation are given in Figure
25.10. The intermediates formed during the degradation of methyl parathion and lindane using
Degussa P-25 and N-doped TiO
2
under UV, visible, and solar radiation is given in Table 25.2.
9.13
3.08
Final chromatogram
0th chromatogram
(c)
3.30
4.46
3.76
500
1000
1500
2
4
6
8
(a)
3.94
20th min chromatogram
4.04
(b)
2.48
4.83
4.22
6.64
3.28
4.21
6.69
2.47
3.09
500
1000
1500
500
1000
1500
2000
2
4
6
8
10
10
5
Time (min)
Time (min)
FIGURE 25.10
GC-MS analysis of commercial-grade dichlorvos under solar radiation (sample was collected at (a) initial,
(b) middle (20th min), and (c) end of the reaction for 250 μg/L of dichlorvos).
TABLE 25.2
Intermediates Identiied during the Degradation of Methyl Parathion, Dichlorvos, and Lindane
Using UV, Visible, and Solar Radiation
Methyl Parathion
Dichlorvos
Lindane
Methyl paraxon (206)
O
,
O
,
O
-trimethyl
phosphoricthiourate (156)
p-Nitrophenol (140)
2,2-Dichlorovinyl-
O
-methyl
phosphate (206)
O
,
O
,
O
-Trimethyl phosphonic
ester (140)
Hexachlorocyclohexane (289)
Pentachlorocyclohexane (256)
Hexachlorobenzene (284)
1-Hydroxy-2,3,4,5,6-chlorocyclohexane (272)
1-Hydroxy 2,3,4,5,6-chlorobenzene (265)
Pentachlorocyclopentene (239)
1,2,3,4,5-Hydroxy cyclopentene (149)
1,2,3-Hydroxy cyclobutane (99)
