Fotoquímica de contaminantes atmosféricos
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Transcript of Fotoquímica de contaminantes atmosféricos
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I s a t i s M . C i n t r n
L a b . R a f a e l A r c e P h . D
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2
RELEVANCENPAH
Ubiquitous pollutant.Emitted from the incomplete combustion ofcombustible fossil and biomass.
2-NF: secondary pollutant generated fromatmospheric reactions between hydroxylradicals (OH) and fluoranthene.
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FORMATION OF 2-NITROFLUORANTHENE IN THEATMOSPHERE
Add reference of this synthesis
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RELEVANCE
2-nitrofuorantheneMutagenic and carcinogen properties
One of the most prevalent Nitro-PAHin aerosol (Wilson et al., 1995)Occurrence in PM 10-2.5 y PM 2.5
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SIGNIFICANCEPollutant can react via hydrogen abstraction from phenolic compounds fromtriplet excited state.Co-solutes: Phenol and 4-hydroxy-3-methoxybenzoic acid (vanillic acid)
Similar oxidation potential specific effect of structure Objectives
Study the effect of phenolic co-solutes on the rate of photodegradation of 2-NF under anaerobic or aerobic conditions in methanol .Determine whether the presence of co-solutes results in the creation of newphotoproducts.
HypothesisThe photodegradation of 2-NF is accelerated by the presence of co-solutes.
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EXPERIMENTAL PROCEDURE
2-NF 3.0x10 -5 Mphenol co-solute
in methanolPurge Irradiate
UV-visFluorescenceHPLC UV-vis
300-400nm
N2
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Photochemistry of 2-Nitrofluoranthenewith co-solute phenol in methanol
NO 2
+
OH
CH 3 OH
N 2h
Photoproducts
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UV-vis spectra for 2NF solutions in methanol atdifferent irradiation times
Legend(irradiation time)t=0 min
t=30 min
Wavelength (nm)
A b s
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A b s
Wavelength (nm)
UV-vis spectra of 2NF with co-solute phenol solutions inmethanol a different irradiation times
A b s .
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Fluorescence spectra of 2NF with co-solute phenolsolutions in methanol a different irradiation times
Legendt=5min
t=10min
t=30mint=60mint=90min
t=120mint=240min
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Chromatogram of the irradiated solution (30 minutes) of 2-NFwith co-solute phenol in methanol.
2NF
F#1 F#2 F#3
La estructura que tienes dibujada del nitrofluoranteno es el de la posicion 3 y no la 2
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UV-Vis spectra for the photoproduct # 1 of 2NF and phenol co-solute in methanol at 30 minutes of irradiation.
m A u
Wavelength (nm)
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UV-Vis spectra for the photoproduct # 2 of 2NF and phenol co-solute in methanol at 30 minutes of irradiation.
m A u
Wavelength (nm)
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m A u
Wavelength (nm)
UV-Vis spectra for the photoproduct # 3 of 2NF and phenol co-solute in methanol at 90 minutes of irradiation.
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2-Nitrofluoranthene with co-solute 4-hydroxy-3-methoxybenzoic acid (vanillic acid)
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UV-vis spectra of 2NF with co-solute vanillic acid solutions inmethanol at different irradiation times
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Fluorescence spectrum of photodegradation 2-NF andvanillic acid co-dissolved in methanol at differentirradiation times.
Legendt=0min
t=10min
t=20mint=40mint=60min
El mximo en el eje de y debe ser 400
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Chromatogram the irradiated solution of 2-NF withvanillic acid in methanol after 30 minutes
2NF
F#4F#5
La estructura que tienes dibujada del nitrofluoranteno es el de la posicion 3 y no la 2
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Kinetics of photoproducts from 2nf and vanillic acid co-dissolved in methanol at different times of irradiation
0
5000
10000
15000
20000
25000
30000
35000
0 5 10 15 20 25 30
P e a
k A r e a
( A )
Irradiation time (t)
Photoproduct # 4
Photoproduct # 5
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UV-Vis spectra for the photoproduct # 1 of 2-NF and vanillicacid co-solute in methanol at 30 minutes of irradiation.
m A u
Wavelength (nm)
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m A u
Wavelength (nm)
UV-Vis spectra for the photoproduct # 2 of 2NF and vanillicacid co-solute in methanol at 30 minutes of irradiation.
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y = -0.0027x - 0.0142
y = -0.0595x - 0.0037
-2
-1.5
-1
-0.5
0
0.5
0 20 40 60 80 100 120 140 160
l n ( A / A 0 )
Irradiation time (t)
Photodegradation rate of 2-NF with phenols co-solutes inmethanol
Photodegradation in phenol
Photodegradation in vanillic acid
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CONCLUSIONS
The photoreactions of 2-nitrofluoranthene is accelerated with both
co-solutes.
Since 2-NF does not exhibit fluorescence, the increase in thefluorescence band near 500nm suggests a formation ofphotoproducts.
The photoproducts have a larger epsilon than the 2-NF in thevisible region.
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CONCLUSIONS
P h e n o l
The formation of 3 photoproducts was observed with co-solutephenol.
The band around 480nm increase for the first 30 minutes ofreaction demonstrating the formation of photoproducts #1 and
#2.
After 30 minutes of reaction with co-solute phenol, degradation ofthe photoproducts is also observed.
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CONCLUSIONSVani l l i c ac id
The formation of 2-photoproducts was observed with co-solute 4-hydroxy-3-methoxybenzoic acid.
The band around 500nm shows an increase as the photodegradationoccurs.
2-nitrofluoranthene degrades more rapidly with vanillic acid than withphenol.
* Photoproducts are different suggesting reactions from phenolsintermediaries.
* The results are opposed with what we expected steric hindrance does not
influence in the rate of photodegradation.
* 2 OH groups in vanillic acid increase in probability of reaction.
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ACKNOWLEDGEMENTS
Lab IntegrantsDr. Rafael Arce
Salvador Gavald
Luis Piero
Melanie Burgos
Zulma GarcaYisaira Daz
RISE Program NIH Grant: 2 R25 GM061151