Photocatalytic ozonation of monuron - effect of reaction parameters on the hydroxyl radical formation and monuron transformation
The combination of ozonation and heterogeneous photocatalysis (photocatalytic ozonation) can enhance the efficiency of the transformation of target pollutant and sometime results in synergistic effect, which is generally explained by the higher rate of formation of hydroxyl radical due to the presen...
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| Dokumentumtípus: | Könyv része |
| Megjelent: |
2017
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| Sorozat: | Proceedings of the International Symposium on Analytical and Environmental Problems
23 |
| Kulcsszavak: | Analitikai kémia, Szervetlen kémia, Fotokatalízis, Környezetkémia |
| Online Access: | http://acta.bibl.u-szeged.hu/56159 |
| Tartalmi kivonat: | The combination of ozonation and heterogeneous photocatalysis (photocatalytic ozonation) can enhance the efficiency of the transformation of target pollutant and sometime results in synergistic effect, which is generally explained by the higher rate of formation of hydroxyl radical due to the presence of ozone. The transformation of organic pollutants on the surface of the photocatalyst is very complex, mainly in the presence of ozone. In the case of the heterogeneous photocatalysis the efficiency highly depends on the chemical structure of the target pollutant which determines its rate of reaction with molecular ozone and/or hydroxyl radical, and the adsorbed amount of pollutants on the surface of the photocatalyst, which is crucial in the case of the transformation by direct charge transfer. Moreover the properties of the solutions such as pH and ionic straight, affect the way and efficiency of the transformation trough the modification of the surface properties of the photocatalyst (surface charge and potential, adsorption properties). In the presence work, the ozonation, heterogeneous photocatalysis and photocatalytic ozonation of monuron and coumarin were investigated. Monuron, one of the phenyl urea pesticide and suspected endocrine disruptor was used as target substance, while the rate of formation of hydroxylated byproduct of coumarin (umbelliferone) was used to compare the formation rate of hydroxyl radical under various circumstances. Both ozonation and photocatalysis were found to be effective in the transformation of coumarine and monuron. Efficiency was enhanced using photocatalytic ozonation, but synergism was not observed. pH had significant effect neither in the case of monuron nor coumarin. The formation rate of umbelliferone formed from coumarin due to its reaction with hydroxyl radical was much higher during photocatalysis compared to ozonation, verifying the importance of the HO•, which was confirmed by the negative effect of methanol as HO• scavanger. Addition of NaF proved the importance of catalyst surface properties during photocatalytic ozonation. |
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| Terjedelem/Fizikai jellemzők: | 75-79 |
| ISBN: | 978-963-306-563-1 |