Journal
JOURNAL OF HAZARDOUS MATERIALS
Volume 317, Issue -, Pages 36-43Publisher
ELSEVIER SCIENCE BV
DOI: 10.1016/j.jhazmat.2016.05.050
Keywords
AOP; Emerging contaminants; Photo-ozonation; UVA-visible radiation; Water treatment
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Funding
- Spanish MINECO
- European Feder Funds [CTQ2012-35789-C02-01]
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The decomposition of aqueous ozone by UV-vis radiation has been investigated with focus on the impact of ozone photolysis on the degradation of water pollutants during solar ozonation processes. The apparent first-order rate constants of the decomposition of ozone (k(obs)) have been determined at various pHs in the 4-9 range using radiation of different wavelengths in the UV-vis range. It was found that UVA-visible radiation (lambda > 320 nm) highly enhanced ozone decomposition, especially at pH 4, for which kobs was three-folded with respect to the process in the absence of radiation. Hydrogen peroxide was identified as a main intermediate of ozone photo-decomposition at pH 4. Experiments of degradation of oxalic acid by ozone showed that solar irradiation brings about an increase in the hydroxyl radical to ozone exposures ratio (R-ct). Finally, photo-ozonation (lambda > 300 nm) was shown advantageous over single ozonation in the mineralization of a selection of emerging contaminants (metoprolol, ibuprofen, N,N-diethyl-meta-toluamide and clofibric acid) in both ultrapure water and a synthetic secondary effluent. Thus, TOC removal in 2-h treatments increased from 10 to 25% in the absence of radiation to about 50% in the presence of radiation. (C) 2016 Elsevier B.V. All rights reserved.
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