- Comparative studies of various iron-mediated oxidative systems for the photochemical degradation of endosulfan in aqueous solution
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This study investigated iron-mediated oxidative processes for the photochemical degradation of endosulfan, a chlorinated insecticide and central nervous system disruptor. At UV fluence of 360 mJ/cm2, 52.4% and 32.0% removal of 2.45 μM initial endosulfan was observed by UV/Fe3+ and UV/Fe2+ processes, respectively, at an initial concentration of 17.8 μM iron. The degradation of endosulfan by UV/Fe3+ or UV/Fe2+ was dramatically enhanced by adding peroxide (i.e., H2O2, S2O82- or HSO5-). Among the UV/peroxide/Fe processes, the highest degradation efficiency of 99.0% at UV fluence of 360 mJ/cm2 was observed by UV/HSO5-/Fe2+ with 2.45 μM [endosulfan]0, 17.8 μM [Fe2+]0, and 49.0 μM [HSO5-]0. The observed degradation rate constant of endosulfan was promoted either by increasing [Fe2+]0 and/or [peroxide]0 or by decreasing [endosulfan]0, while the initial degradation rate of endosulfan increased with increasing [Fe2+]0, [peroxide]0, or [endosulfan]0. At UV fluence of 6000 mJ/cm2, 45.0% mineralization as represented by the decrease in total organic carbon content was observed by UV/HSO5-/Fe2+ at 9.80 μM [endosulfan]0, 980 μM [HSO5-]0, and 17.8 μM [Fe2+]0. The major by-product of endosulfan was observed in all cases to be endosulfan ether which was further degraded with an extended reaction time. The results suggest that iron-mediated advanced oxidation processes (AOPs) have a high potential for the removal of endosulfan and its by-product from contaminated water.
- Shah, Noor S.,He, Xuexiang,Khan, Javed Ali,Khan, Hasan M.,Boccelli, Dominic L.,Dionysiou, Dionysios D.
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- Photoinduced Reactions: Part IV - Studies on Photochemical Fate of 6,7,8,9,10,10-Hexachloro-1,5,5a,6,9,9a-hexahydro-6,9-methano-2,4,3-benzodioxathiepin-3-oxide (Endosulphan), an Important Insecticide
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The photolysis of the cyclodiene insecticide endosulphan (6,7,8,9,10,10-hexachloro-1,5,5a,6,9,9a-hexahydro-6,9-methano-2,4,3-benzodioxathiepin-3-oxide) has been examined under different conditions, including environmental.Two new photometabolites, photo-α-endosulphan and photo-β-endosulphan have been isolated from α- and β-isomers of endosulphan respectively and characterised on the basis of their 13C NMR spectra and other data.Irradiation in polar solvents gives metabolites similar to those formed under biotic conditions.When exposed to sunlight on plant leaves, α-endosulphane not only forms the photometabolite but also undergoes isomerisation to β-isomer.On the other hand β-isomer is relatively more stable.This explains the relatively longer persistence of β-endosulphan in the environment and may have some significance on their toxicity.
- Dureja, P.,Mukerjee, S. K.
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p. 411 - 413
(2007/10/02)
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