Photochemistry and environment Part XIV. Phototransformation of nitrophenols induced by excitation of nitrite and nitrate ions

Alif, Admin; Boule, Pierre

doi:10.1016/1010-6030(91)87087-c

Cited by 90 publications

(61 citation statements)

References 24 publications

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“…The ability of nitrite to substantially absorb sunlight, and its elevated photolysis quantum yield, can cause signifi cant contribution to • OH photogeneration despite usually low concentrations (Mopper and Zhou, 1990;Alif and Boule, 1991;Takeda et al, 2004;Vione et al, 2005a).…”

Section: Resultsmentioning

confidence: 99%

Photochemincal processes involving nitrite in surface water samples

Chirón²,

et al. 2007

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A study into nitrite photochemistry was carried out on surface (both lake and river) water samples. In the tested samples, nitrite photolysis accounted for 0-60 % of • OH photoproduction, nitrate for 0-40 %, and dissolved organic matter (DOM) photochemistry played on average the main role. In real surface waters, an effect of radiation extinction by the water column would also be observed, and is expected to inhibit nitrate photochemistry at a higher extent compared to nitrite or DOM. Nitrite showed a defi nite time evolution with irradiation. Photodegradation prevailed in samples with the highest initial concentrations, while photogeneration with DOM transformation was evident in the presence of undetectable initial nitrite levels. Nitrite also accounted for up to 9 % of • OH scavenging, which would produce up to 66 % of photoformed nitrogen dioxide. The remaining percentage of nitrogen dioxide generation is accounted for by nitrate photolysis. Photogenerated nitrogen dioxide could then be involved in signifi cant processes of aromatic nitration, in particular in the transformation of phenol into nitrophenols.

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Section: Resultsmentioning

confidence: 99%

Photochemincal processes involving nitrite in surface water samples

Chirón²,

et al. 2007

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“…The aqueous phase quantum yields are B0.9% for OH (1a) and B0.1% for O( 3 P) (1b) at 305 nm and 298 K. [16][17][18][19][20][21] This photochemistry is believed to be important in the Arctic and Antarctic snowpacks, generating NO x as well as OH and O( 3 P) which can carry out subsequent oxidations. [22][23][24][25] Less is known about the photochemistry of nitrate in complex aerosol mixtures, such as in processed sea salt aerosols.…”

Section: Introductionmentioning

confidence: 99%

Enhanced surface photochemistry in chloride–nitrate ion mixtures

Wingen

Moskun

Johnson

et al. 2008

Phys. Chem. Chem. Phys.

116

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Heterogeneous reactions of sea salt aerosol with various oxides of nitrogen lead to replacement of chloride ion by nitrate ion. Studies of the photochemistry of a model system were carried out using deliquesced mixtures of NaCl and NaNO 3 on a Teflon s substrate. Varying molar ratios of NaCl to NaNO 3 (1 : 9 Cl À : NO 3 À , 1 : 1 Cl À : NO 3 À , 3 : 1 Cl À : NO 3 À , 9 : 1 Cl À : NO 3 À) and NaNO 3 at the same total concentration were irradiated in air at 299 AE 3 K and at a relative humidity of 75 AE 8% using broadband UVB light (270-380 nm). Gaseous NO 2 production was measured as a function of time using a chemiluminescence NO y detector. Surprisingly, an enhanced yield of NO 2 was observed as the chloride to nitrate ratio increased. Molecular dynamics (MD) simulations show that as the Cl À : NO 3 À ratio increases, the nitrate ions are drawn closer to the interface due to the existence of a double layer of interfacial Cl À and subsurface Na + . This leads to a decreased solvent cage effect when the nitrate ion photodissociates to NO 2 +O À , increasing the effective quantum yield and hence the production of gaseous NO 2 . The implications of enhanced NO 2 and likely OH production as sea salt aerosols become processed in the atmosphere are discussed.

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“…NO 3 -was chosen as photosensitizer and source of OH radicals since (i) quantum yield of OH formation (Φ OH ) from NO 3 -photolysis is well known [25,26,29], (ii) NO 3 -is very poor OH scavenger (k < 1.10 5 s -1 ) compared to NO 2 -(k = 1.10 10 s -1 ) in aqueous solutions [25] and (iii) in natural waters NO 3 -is often found in much higher concentrations than NO 2 -. The production of OH from the UV-B photolysis of NO 3 -is described by the equations [30,31]:…”

Section: Introductionmentioning

confidence: 99%

Hydroxyl radical-induced photochemical formation of dicarboxylic acids from unsaturated fatty acid (oleic acid) in aqueous solution

Tedetti

Kawamura

Narukawa

et al. 2007

Journal of Photochemistry and Photobiology A: Chemistry

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In this study, we assess under laboratory controlled conditions the direct and hydroxyl radical ( OH)-induced photochemical production of low molecular weight (LMW) dicarboxylic acids and related compounds (C 2 -C 9 ) (DCAs) from oleic acid (cis-9-octadecenoic, 9C 18 ) in aqueous solution. Nitrate (NO 3 -)-amended and unamended oleate solutions were irradiated under ultraviolet-B radiation (UV-B, 313 nm) for 5 h, with NO 3 -being the source of OH. The OH-induced photochemical production of DCAs (C 2di -C 9di ) (165 ± 32 nM h -1 ) was much higher than that induced by the direct effect of UV-B (33 ± 31 nM h -1 ), accounting for 85% of the total (direct + OH-induced) photochemical production of DCAs (C 2di -C 9di ) (194 ± 6 nM h -1 ). Azelaic acid (C 9di ) was the dominant photoproduct (comprising 63 and 44% of DCAs in the direct and OH-induced photochemical production, respectively) followed by C 8di , C 7di and C 6di , whereas shorter chain compounds (C 2di -C 5di ) were minor produced species. Using our estimate of OH photoproduction (P-OH in nM h -1 ), the production of C 9di from 50 µM of oleic acid was evaluated to ~ 36 nM (nM OH) -1 . We propose in this work a chemical mechanism for the reaction of OH with oleic acid in aqueous solution from the cleavage of its double bond, and the subsequent formation of DCAs through oxidation and decarboxylation processes.

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Photochemistry and environment Part XIV. Phototransformation of nitrophenols induced by excitation of nitrite and nitrate ions

Cited by 90 publications

References 24 publications

Photochemincal processes involving nitrite in surface water samples

Photochemincal processes involving nitrite in surface water samples

Enhanced surface photochemistry in chloride–nitrate ion mixtures

Hydroxyl radical-induced photochemical formation of dicarboxylic acids from unsaturated fatty acid (oleic acid) in aqueous solution

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