Reaction behaviors of decomposition of monocrotophos in aqueous solution by UV and UV/O processes.
The decomposition of monocrotophos (cis-3-dimethoxyphosphinyloxy-N-methyl-crotonamide) in aqueous solution by UV and UV/O(3) processes was studied. The experiments were carried out under various solution pH values to investigate the decomposition efficiencies of the reactant and organic intermediates in order to determine the completeness of decomposition. The photolytic decomposition rate of monocrotophos was increased with increasing solution pH because the solution pH affects the distribution and light absorbance of monocrotophos species. The combination of O(3) with UV light apparently promoted the decomposition and mineralization of monocrotophos in aqueous solution. For the UV/O(3) process, the breakage of the >C=C< bond of monocrotophos by ozone molecules was found to occur first, followed by mineralization by hydroxyl radicals to generate CO(3)(2-), PO4(3-), and NO(3)(-) anions in sequence. The quasi-global kinetics based on a simplified consecutive-parallel reaction scheme was developed to describe the temporal behavior of monocrotophos decomposition in aqueous solution by the UV/O(3) process.
Ku
Y
Y
Department of Chemical Engineering, National Taiwan University of Science and Technology, Taipei, Taiwan. ku@mail.ntust.edu.tw
Wang
W
W
Shen
Y S
YS
D000042:Absorption; D002244:Carbon / Q000737:chemistry; D002255:Carbonic Acid / Q000737:chemistry; D015386:Hazardous Substances / Q000032:analysis / Q000528:radiation effects; D006801:Humans; D006863:Hydrogen-Ion Concentration; D017665:Hydroxyl Radical / Q000737:chemistry; D007306:Insecticides / Q000737:chemistry* / Q000528:radiation effects; D007700:Kinetics; D008027:Light; D008999:Monocrotophos / Q000737:chemistry* / Q000528:radiation effects; D017942:Nitric Acid / Q000737:chemistry; D010126:Ozone / Q000737:chemistry*; D010756:Phosphoric Acids / Q000737:chemistry; D010782:Photolysis; D014466:Ultraviolet Rays
D015386:Hazardous Substances; D007306:Insecticides; D010756:Phosphoric Acids; D017665:Hydroxyl Radical; D017942:Nitric Acid; D002255:Carbonic Acid; D010126:Ozone; D008999:Monocrotophos; D002244:Carbon