title: Photomineralization of aqueous salicylic acids. Photoproducts characterization and formation of light induced secondary OH precursors (LIS-OH).
abstract: The photolysis of aqueous 5-chlorosalicylic acid (ClSA) and dihydroxybenzoic acid (DHBA), its main photoproduct, was studied to determine the extent of degradation caused by simulated solar light. Photoproducts identification was achieved using high resolution LC-MS and GC-MS. About 40 photoproducts from C19to C1were characterized, including a dihydroxycyclopentadienic acid, a ring contraction photoproduct, and numerous carbonyls and carboxylic acid derivatives that were detected thanks to derivatization. UV-visible spectral monitoring of the reactions revealed that ClSA and DHBA underwent photobleaching after developing a temporarily featureless absorbance between 300 and 500 nm. Measurement of OH radicals using terephtalic acid as a probe showed that OH radicals were generated with an average rate of 7 × 10-9M s-1and a total cumulated concentration of 10-3M, corresponding to ∼ 5-fold the initial concentration of DHBA. Furthermore, TOC analysis indicated that significant mineralization (51-90%) occurred. These findings are consistent with the formation of light induced secondary OH (LIS-OH) precursors such as featureless long wavelength absorbing compounds as well as non-absorbing hydroperoxides. The formation of LIS-OH illustrated here may also take place in the aqueous photodegradation of other substituted phenols likely present in dissolved organic matter and humic substructures, it deserves to be studied in more details.
authors: Université Clermont Auvergne, Université Blaise Pascal, Institut de Chimie de Clermont Ferrand, BP 10448, F-63000, Clermont-Ferrand, France; CNRS, UMR 6296, ICCF, F-63178, Aubiere, France; Université des Frères Mentouri, Constantine 1, Laboratoire des Techniques Innovantes de Préservation de l'Environnement, Route de Ain El Bey, Constantine, 25017, Algeria.
authors: R
authors: R
authors: Tafer
authors: Université Clermont Auvergne, Université Blaise Pascal, Institut de Chimie de Clermont Ferrand, BP 10448, F-63000, Clermont-Ferrand, France; Université Clermont Auvergne, SIGMA Clermont, Institut de Chimie de Clermont-Ferrand, BP 10448, F-63000, Clermont-Ferrand, France.
authors: M
authors: M
authors: Sleiman
authors: Université des Frères Mentouri, Constantine 1, Laboratoire des Techniques Innovantes de Préservation de l'Environnement, Route de Ain El Bey, Constantine, 25017, Algeria.
authors: A
authors: A
authors: Boulkamh
authors: Université Clermont Auvergne, Université Blaise Pascal, Institut de Chimie de Clermont Ferrand, BP 10448, F-63000, Clermont-Ferrand, France; CNRS, UMR 6296, ICCF, F-63178, Aubiere, France. Electronic address: claire.richard@univ-bpclermont.fr.
authors: C
authors: C
authors: Richard
mesh_terms: D017665:Hydroxyl Radical / Q000737:chemistry*; D008027:Light; D010782:Photolysis; D012459:Salicylates; D014867:Water / Q000737:chemistry
chemical_list: D012459:Salicylates; D014867:Water; D017665:Hydroxyl Radical
keywords: Derivatization agents T-Box, BSTFA, DNPH; Hydroperoxides; OH radical; Photolysis; Substituted phenols