期刊
CHEMOSPHERE
卷 93, 期 9, 页码 1948-1956出版社
PERGAMON-ELSEVIER SCIENCE LTD
DOI: 10.1016/j.chemosphere.2013.06.079
关键词
Ultraviolet photolysis; Pharmaceuticals Quantum yield; Photosensitized reactions; Singlet oxygen; Photopolymerization
资金
- U.S. Environmental Protection Agency (EPA) [FP917136]
- EPA [672931, FP917136] Funding Source: Federal RePORTER
Dimer formation was observed during ultraviolet (UV) photolysis of the anti-inflammatory drug diclofenac, and confirmed with mass spectrometry, NMR and fluorescence analysis. The dimers were combinations of the two parent molecules or of the parent and the product of photolysis, and had visible color. Radical formation during UV exposure and dissolved oxygen photosensitized reactions played a role in dimer formation. Singlet oxygen formed via photosensitization by photolysis products of diclofenac. It reacted with diclofenac to form an epoxide which is an intermediate in some dimer formation pathways. Quantum yield of photolysis for diclofenac was 0.21 +/- 0.02 and 0.19 +/- 0.02 for UV irradiation from medium pressure and low pressure mercury vapor lamps, respectively. Band pass filter experiments revealed that the quantum yield is constant at wavelengths >200 nm. The same dimers formed in laboratory grade water when either of the two UV sources was used. Dimers did not form in wastewater effluent matrix, and diclofenac epoxide molecules may have formed bonds with organic matter rather than each other Implications for the importance of dimer formation in NOM are discussed. (C) 2013 Elsevier Ltd. All rights reserved.
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