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Photocatalysis of the Organophosphorus Fenamiphos: Insight into the Degradation Mechanism

DOI: 10.1155/2013/319178

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Abstract:

The photocatalytic degradation of the organophosphorus fenamiphos (FN) was studied using titanium dioxide as a photocatalyst and 365?nm as an excitation wavelength. Under our experimental conditions and in aerated solutions, the irradiation in the presence of TiO2 P25 (1.0?g?L?1) permitted the evaluation of the half lifetime to 9.5 minutes. Laser flash photolysis experiments showed the formation of an initial species owing to the attack of the hydroxyl radical on FN. It was identified as the adduct -FN. The second order rate constant for its formation was evaluated to ?moL?1?L?s?1. All the products are formed via the formation of such transient intermediate. They were identified by means of HPLC/MS using electrospray in positive mode ( ). Two main processes are responsible for FN photocatalytic transformation: (i) hydroxylation on the aromatic structure and (ii) the scission of the C–O bond. A mechanistic scheme was proposed for the photocatalytic process of FN using titanium dioxide. An efficient mineralization was observed within 24 hours by using a suntest setup. 1. Introduction Owing to the intensive agriculture within the last three decades, the varieties of employed pesticides have increased considerably. The presence of these chemicals in groundwater, streams, rivers lakes, and waste water effluents may present serious problems to the environment, human health, and the equilibrium of ecosystems. A considerable number of these pesticides in aqueous solutions may absorb in the actinic portion of the solar spectrum leading then to photochemical processes with solar light through direct as well as indirect photoreactions ( ?nm) [1–5]. Within the former process, photochemical reactions such as dissociations, oxidation, and hydrolysis are observed and may lead to the generation of various byproducts that, in some cases, may be more harmful than the parent compound. In natural waters, indirect processes may be also observed via the excitation of substances such as Natural Organic Matters (NOM) [6–8]. The solar light excitation of these substances leads to the formation of several reactive species such as triplet excited states or/and reactive oxygen species (ROS). Among these latter species, singlet oxygen , superoxide anion , and hydroxyl radical represent the main reactive ones [6, 9]. When an efficient remediation of the contaminated environmental compartments is concerned, research activities toward the development of new treatment methods are undertaken. Various methods, the so-called advanced oxidation processes (AOPs), have been the subject of

References

[1]  M. L. Canle, J. A. Santaballa, and E. Vulliet, “On the mechanism of TiO2-photocatalyzed degradation of aniline derivatives,” Journal of Photochemistry and Photobiology A, vol. 175, no. 2-3, pp. 192–200, 2005.
[2]  O. Hutzinger, Environmental Photochemistry, The Hanbook of Environmental Chemistry, vol. 2, part l, Springer, 1999.
[3]  O. Legrini, E. Oliveros, and A. M. Braun, “Photochemical processes for water treatment,” Chemical Reviews, vol. 93, no. 2, pp. 671–698, 1993.
[4]  H. D. Burrows, L. M. Canle, J. A. Santabella, and S. Steenken, “Reaction pathways and mechanisms of photodegradation of pesticides,” Journal of Photochemistry and Photobiology B, vol. 67, pp. 71–108, 2002.
[5]  P. Wong-Wah-Chung, S. Rafqah, G. Voyard, and M. Sarakha, “Photochemical behaviour of triclosan in aqueous solutions: kinetic and analytical studies,” Journal of Photochemistry and Photobiology A, vol. 191, no. 2-3, pp. 201–208, 2007.
[6]  S. Kouras-Hadef, A. Amine-Khodja, S. Halladja, and C. Richard, “Influence of humic substances on the riboflavin photosensitized transformation of 2,4,6-trimethylphenol,” Journal of Photochemistry and Photobiology A, vol. 229, pp. 33–38, 2012.
[7]  R. G. Zepp, G. L. Baughman, and P. F. Schlotzhauer, “Comparison of photochemical behavior of various humic substances in water: I. Sunlight induced reactions of aquatic pollutants photosensitized by humic substances,” Chemosphere, vol. 10, pp. 109–117, 1981.
[8]  R. G. Zepp, G. L. Baughman, and P. F. Schlotzhauer, “Comparison of photochemical behavior of various humic substances in water: II. Photosensitized oxygenations,” Chemosphere, vol. 10, no. 1, pp. 119–126, 1981.
[9]  J. P. Aguer and C. Richard, “Reactive species produced on irradiation at 365 nm of aqueous solutions of humic acids,” Journal of Photochemistry and Photobiology A, vol. 93, pp. 193–198, 1996.
[10]  R. Andreozzi, V. Caprio, A. Insola, and R. Marotta, “Advanced oxidation processes (AOP) for water purification and recovery,” Catalysis Today, vol. 53, no. 1, pp. 51–59, 1999.
[11]  M. Qamar, M. Muneer, and D. Bahnemann, “Heterogeneous photocatalysed degradation of two selected pesticide derivatives, triclopyr and daminozid in aqueous suspensions of titanium dioxide,” Journal of Environmental Management, vol. 80, no. 2, pp. 99–106, 2006.
[12]  P. Calza, C. Massolino, and E. Pelizzetti, “Light induced transformations of selected organophosphorus pesticides on titanium dioxide: Pathways and by-products evaluation using LC-MS technique,” Journal of Photochemistry and Photobiology A, vol. 199, no. 1, pp. 42–49, 2008.
[13]  M. Abu Tariq, M. Faisal, M. Muneer, and D. Bahnemann, “Photochemical reactions of a few selected pesticide derivatives and other priority organic pollutants in aqueous suspensions of titanium dioxide,” Journal of Molecular Catalysis A, vol. 265, no. 1-2, pp. 231–236, 2007.
[14]  C. Minero and D. Vione, “A quantitative evalution of the photocatalytic performance of TiO2 slurries,” Applied Catalysis B, vol. 67, pp. 257–269, 2006.
[15]  N. Serpone and A. Salinaro, “Terminology, relative photonic efficiencies and quantum yields in heterogeneous photocatalysis. Part I: suggested protocol,” Pure and Applied Chemistry, vol. 71, pp. 303–320, 1999.
[16]  A. Salinaro, A. V. Emeline, J. Zhao, H. Hidaka, V. K. Ryabchuk, and N. Serpone, “Terminology, relative photonic efficiencies and quantum yields in heterogeneous photocatalysis. Part II: experimental determination of quantum yields,” Pure and Applied Chemistry, vol. 71, pp. 321–335, 1999.
[17]  J. W. Trucker and C. Q. Thompson, “Dangers of using organophosphotus pesticides and diesel oil in fish ponds,” Aquaculture Magazine, vol. 13, pp. 62–63, 1987.
[18]  H. Floesser-Mueller and W. Schwack, “Photochemistry of organophosphorus insecticides,” Reviews of Environmental Contamination and Toxicology, vol. 172, pp. 129–228, 2001.
[19]  G. Patrick, A. Chiri, D. Randall, L. Libelo, and J. Jones, “Fenamiphos environmental risk assessment,” US Environmental Protection Agency. Provided for SRRD by EFED’s Fenamiphos RED Team, http://www.epa.gov/oppsrrd1/op/fenamiphos/env_risk.pdf, 2001.
[20]  L. Lhomme, S. Brosillon, D. Wolbert, and J. Dussaud, “Photocatalytic degradation of a phenylurea, chlortoluron, in water using an industrial titanium dioxide coated media,” Applied Catalysis B, vol. 61, no. 3-4, pp. 227–235, 2005.
[21]  C. Catastini, M. Sarakha, G. Mailhot, and M. Bolte, “Iron (III) aquacomplexes as effective photocatalysts for the degradation of pesticides in homogeneous aqueous solutions,” Science of the Total Environment, vol. 298, no. 1–3, pp. 219–228, 2002.
[22]  N. Brand, G. Mailhot, and M. Bolte, “Degradation photoinduced by Fe(III): method of alkylphenol ethoxylates removal in water,” Environmental Science and Technology, vol. 32, no. 18, pp. 2715–2720, 1998.
[23]  H. Park and W. Choi, “Visible light and Fe(III)-mediated degradation of Acid Orange 7 in the absence of H2O2,” Journal of Photochemistry and Photobiology A, vol. 159, pp. 241–2247, 2003.
[24]  W. Feng and D. Nansheng, “Photochemistry of hydrolytic iron (III) species and photoinduced degradation of organic compounds. A minireview,” Chemosphere, vol. 41, no. 8, pp. 1137–1147, 2000.
[25]  H. J. Benkelberg and P. Warneck, “Photodecomposition of iron(III) hydroxo and sulfato complexes in aqueous solution: wavelength dependence of OH and SO4- quantum yields,” The Journal of Physical Chemistry, vol. 99, pp. 5214–5221, 1995.
[26]  S. P. Ramnani, S. Dhanya, and P. K. Bhattacharyya, “Pulse radiolytic studies on the reactions of some oxidizing and reducing radicals with sulfanilamide in aqueous medium,” Radiation Physics and Chemistry, vol. 50, no. 3, pp. 277–282, 1997.
[27]  D. Behar and B. Behar, “Pulse radiolysis studies of aminobenzenesulfonates: formation of cation radicals,” Journal of Physical Chemistry, vol. 95, no. 19, pp. 7552–7556, 1991.
[28]  U. Stafford, K. A. Gray, and P. V. Kamat, “Radiolytic and TiO2-assisted photocatalytic degradation of 4-chlorophenol. A comparative study,” Journal of Physical Chemistry, vol. 98, no. 25, pp. 6343–6351, 1994.

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