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Removal of mixed pesticides from drinking water system by photodegradation using suspended and immobilized TiO2
Jaganathan Senthilnathan,
Published in
2009
PMID: 19280479
Volume: 44
   
Issue: 3
Pages: 262 - 270
Abstract
Lindane (1α, 2α, 3β, 4α, 5α, 6β-hexachloro cyclohexane), methyl parathion (O,O-dimethyl-O-4-nitrophenyl phosphorothioate) and dichlorvos (2,2-dichlorovinyl-O-O-dimethyl phosphate) are removed from water individually and as a mixture by photo degradation using suspended and immobilized forms of TiO2 (Degussa P-25). Studies were conducted to optimize the coating thickness of immobilized photo catalyst. The rate of degradation of pesticides was compared in both suspended and immobilized TiO2 systems. Degradation studies of mixed pesticides were carried out with low concentrations (1.0 and 2.5 mg/L) of pesticides. Only three intermediate byproducts such as methyl paraoxon, O,O,O-trimethyl phosphonic thionate and p-nitrophenol were observed during the methyl parathion degradation in suspended, immobilized TiO2 systems and mixed pesticides degradation studies. At the end of the reaction methyl parathion and its by-products were completely degraded. During lindane degradation hexachloro cyclohexane, pentachloro cyclohexane, hexachloro benzene, 1-hydroxy 2,3,4,5,6-chlorocyclohexane, 1-hydroxy 2,3,4,5,6-chlorobenzene, pentachloro cyclopentadiene, 1,2,3,4,5-hydroxy cyclopentene and 1,2,3-hydroxy cyclobutane were identified in suspended and immobilized TiO2 systems, whereas only hexachloro cyclohexane, pentachloro cyclohexane, hexachloro benzene and pentachloro cyclopentadiene were observed during mixed pesticides degradation. No intermediate by-product was observed during the photo degradation of dichlorvos. Langmuir-Hinshelwood pseudo first order kinetic equation showed that there was not much change in the rates of degradation in both suspended and immobilized TiO2 systems irrespective of the pesticide. During mixed pesticides degradation, the degradation pattern was not similar to that of single pesticide. © Taylor & Francis Group, LLC.
About the journal
JournalJournal of Environmental Science and Health - Part B Pesticides, Food Contaminants, and Agricultural Wastes
ISSN03601234
Open AccessNo
Concepts (43)
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    DICHLORVOS
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    IMMOBILIZED TIO<SUB>2</SUB>
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    Lindane
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    METHYL PARATHION
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    MIXED PESTICIDES
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    AGRICULTURAL CHEMICALS
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    Benzene
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    Butane
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    Byproducts
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    Coatings
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    Cyclohexane
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    Insecticides
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    Integral equations
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    Olefins
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    Photodegradation
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    Potable water
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    Thickness measurement
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    Water pollution control
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    Catalyst
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    Drinking water
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    PESTICIDE RESIDUE
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    Pollutant removal
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    Reaction kinetics
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    Titanium
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    DICHLORVOS
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    PARATHION METHYL
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    Pesticide
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    Titanium dioxide
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    Water
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    Article
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    Chemical structure
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    Chemistry
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    Instrumentation
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    Methodology
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    Photochemistry
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    Water management
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    Water pollutant
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    DICHLORVOS
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    METHYL PARATHION
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    Molecular structure
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    Pesticides
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    Water pollutants, chemical
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    Water purification