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Published May 9, 2014 | Version v1
Journal article Open

Kinetic and mechanism investigation on the photochemical degradation of atrazine with activated H2O2, S2O28- and HSO5-

Authors/Creators

  • 1. Radiation Chemistry Laboratory, National Centre of Excellence in Physical Chemistry, University of Peshawar, Peshawar 25120, Pakistan, and Environmental Engineering and Science Program, University of Cincinnati, 705 Engineering Research Center, Cincinnati, OH 45221-0012, United States
  • 2. Environmental Engineering and Science Program, University of Cincinnati, 705 Engineering Research Center, Cincinnati, OH 45221-0012, United States
  • 3. Radiation Chemistry Laboratory, National Centre of Excellence in Physical Chemistry, University of Peshawar, Peshawar 25120, Pakistan
  • 4. Nireas-International Water Research Centre, University of Cyprus, P.O. Box 20537, Nicosia 1678, Cyprus
  • 5. Environmental Engineering and Science Program, University of Cincinnati, 705 Engineering Research Center, Cincinnati, OH 45221-0012, United States, and Nireas-International Water Research Centre, University of Cyprus, P.O. Box 20537, Nicosia 1678, Cyprus

Description

Degradation of atrazine was investigated under UV-254 nm irradiation, alone or in combination with peroxides, i.e., hydrogen peroxide, persulfate (PS) or peroxymonosulfate (PMS). UV/PS was found to be the most efficient process in this study, which was probably due to its higher radical quantum yield under UV irradiation, considering atrazine’s comparable second order rate constant of 2.59 x 109 M-1 s-1 and 2.25 x 109 M-1 s-1 with sulfate radical and hydroxyl radical, respectively. The pH values showed no significant effect on direct photolysis of atrazine, with observed UV fluence based pseudo-first-order rate constant (kobs) of 7.59 x 10-4, 7.73 x 10-4 and 6.72 x 10-4 cm2 mJ-1 at pH 3.0, 5.7 and 11.0, respectively. Performance of UV/H2O2 and UV/PMS were more independent of initial pH values while that of UV/PS appeared to be more efficient at neutral pH condition. UV/PS was observed as a less energy consumption process. Eight new degradation by-products were identified in this study, namely, 2-chloro-4-acetamido-6-(2-hydroxy-isopropylamino)-s-triazine (CDHT), 2-hydroxy-4-(2-hydroxy-ethyl- amino)-6-isopropylamino-s-triazine (ONIT), 2-chloro-4-vinylamino-6-isopropylamino-s-triazine (CVIT), 2-hydroxy-4-vinylamino-6-(2-hydroxy-isopropylamino)-s-triazine (OVHT), 2-hydroxy-4-acetamido-6- isopropenylamino-s-triazine (ODPT), 2-hydroxy-4-(2-hydroxy-ethylamino)-6-vinylamino-s-triazine (ONVT), 2-hydroxy-4-(2-hydroxy-ethylamino)-6-methylamino-s-triazine (ONMT) and 2-chloro-4-vinyla mino-6-amino-s-triazine (CVAT). Potential degradation pathways were further proposed.

Notes

Higher Education Commission (HEC), Islamabad, Pakistan is highly acknowledged for providing financial support for this project through an International Research Support Initiative Program (IRSIP). D.D. Dionysiou, X. He, E. Hapeshi and D. Fatta-Kassinos are grateful to the Cyprus Research Promotion Foundation, as part of the work was funded by the Cyprus Research Promotion Foundation through Desmi 2009-2010 which is co-funded by the Republic of Cyprus and the European Regional Development Fund of the EU under contract number NEA IPODOMI/STRATH/0308/09.

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