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Published on: July 17, 2020
Phenol transformation photosensitised by quinoid compounds
Valter Maurino1, Andrea Bedini, Daniele Borghesi
1Dipartimento di Chimica Analitica, Università di Torino, Torino, Italy.
Physical Chemistry Chemical Physics : PCCP
|May 17, 2011
Summary
Quinoid compounds like 2-ethylanthraquinone (EtAQ) accelerate phenol photodegradation in water. These compounds also oxidize nitrite, potentially forming nitrogen dioxide and nitrophenols in atmospheric aerosols.
Area of Science:
- Environmental Chemistry
- Photochemistry
- Atmospheric Science
Background:
- Phenol is a common pollutant in aqueous environments.
- Quinoid compounds are frequently found on atmospheric particulate matter.
- Understanding phenol's environmental fate is crucial for assessing pollution impacts.
Purpose of the Study:
- To investigate the photosensitized transformation of phenol by various quinoid compounds.
- To elucidate the role of quinones in phenol degradation under different light conditions.
- To explore the potential for quinones to generate nitrogen dioxide and nitrophenols.
Main Methods:
- Phototransformation experiments of phenol in aqueous solutions.
- Irradiation using blue light and simulated sunlight.
- Quantum mechanical calculations of quinone triplet states.
- Kinetic modeling to identify reactive species.
Main Results:
- All tested quinones (AQ, BAD, EtAQ, NQ, DAQ) sensitized phenol phototransformation.
- Photodegradation efficiency under blue light followed the order: AQ > BAD > EtAQ > NQ > DAQ.
- 2-ethylanthraquinone (EtAQ) showed the highest phenol degradation rate under simulated sunlight.
- Quinones oxidized nitrite to nitrogen dioxide, leading to phenol nitration.
Conclusions:
- Quinoid compounds significantly influence phenol's photochemical fate in aqueous systems.
- The spin distribution in quinone triplet states affects their reactivity.
- The oxidation of nitrite by quinones is a potential atmospheric source of nitrogen dioxide and nitrophenols.
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