Radiolytic degradation of 4-nitrophenol in aqueous solutions: Pulse and steady state radiolysis study |
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| Affiliation: | 1. Laboratoire de Matière Condensée et Nanostructures (LMCN), Faculté des Sciences et Techniques Guéliz, Université Cadi Ayyad, BP 549, Marrakech, Morocco;2. CIRIMAT, Université de Toulouse, CNRS-UPS-INP, ENSIACET, 4 allée Emile Monso, BP 44362, 31030Toulouse cedex 4, France;3. Institut de Sciences des Matériaux de Mulhouse (IS2M), LRC 7228—CNRS, 15 rue Jean Starcky, BP 2488, 68057Mulhouse cedex, France;4. Laboratoire de Géosciences et Géoenvironnement, Faculté des Sciences et Techniques Guéliz, Université Cadi Ayyad, BP 549, Marrakech, Morocco;1. Laboratoire de Matière Condensée et Nanostructures (LMCN), Faculté des Sciences et Techniques Guéliz, Université Cadi Ayyad, BP 549 Marrakech, Morocco;2. CIRIMAT, Université de Toulouse, CNRS-UPS-INP, ENSIACET, 4 allée Emile Monso, BP 44362, 31030 Toulouse, cedex 4, France;3. Institut de Sciences des Matériaux de Mulhouse (IS2M), LRC 7228 – CNRS, 15 rue Jean Starcky, BP 2488, 68057 Mulhouse cedex, France;4. Laboratoire Geoscience et Géoenvironnement, Faculté des Sciences et Techniques Guéliz, Université Cadi Ayyad, BP 549, Marrakech, Morocco;1. University of Belgrade, “Vinča” Institute of Nuclear Sciences, 11000 Belgrade, Serbia;2. University of Belgrade, Faculty of Technology and Metallurgy, 11000 Belgrade, Serbia;3. University of Niš, Faculty of Sciences and Mathematics, 18000 Niš, Serbia;4. High Chemical Technological School, 37000 Kruševac, Serbia |
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| Abstract: | The radiation induced degradation of 4-nitrophenol (4-NP) has been studied by gamma irradiation, while the reactivity and spectral features of the short lived transients formed by reaction with primary transient radicals at different pHs has been investigated by pulse radiolysis technique. In steady state radiolysis a dose of 4.4 k Gy is able to degrade 98% of 1×10−4 mol dm−3 4-NP. 4-NP has pKa at 7.1, above which it is present in the anionic form. At pH 5.2, •OH and N3• radicals were found to react with 4-NP with rate constants of 4.1×109 dm3 mol−1 s−1 and 2.8×108 dm3 mol−1 s−1, respectively. Differences in the absorption spectra of species formed in the reactions of 4-NP with •OH and N3• radicals suggested that •OH radicals add to the aromatic ring of 4-NP along with electron transfer reaction, whereas N3• radicals undergo only electron transfer reaction. At pH 9.2, rate constants for the reaction of •OH radicals with 4-NP was found to be higher by a factor of 2 compared to that at pH 5.2. This has been assigned to the deprotonation of 4-NP at pH 9.2. |
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