title: Degradation of 5-FU by means of advanced (photo)oxidation processes: UV/H2O2, UV/Fe2+/H2O2 and UV/TiO2--Comparison of transformation products, ready biodegradability and toxicity.
abstract: The present study investigates the degradation of the antimetabolite 5-fluorouracil (5-FU) by three different advanced photo oxidation processes: UV/H2O2, UV/Fe(2+)/H2O2 and UV/TiO2. Prescreening experiments varying the H2O2 and TiO2 concentrations were performed in order to set the best catalyst concentrations in the UV/H2O2 and UV/TiO2 experiments, whereas the UV/Fe(2+)/H2O2 process was optimized varying the pH, Fe(2+) and H2O2 concentrations by means of the Box-Behnken design (BBD). 5-FU was quickly removed in all the irradiation experiments. The UV/Fe(2+)/H2O2 and UV/TiO2 processes achieved the highest degree of mineralization, whereas the lowest one resulted from the UV/H2O2 treatment. Six transformation products were formed during the advanced (photo)oxidation processes and identified using low and high resolution mass spectrometry. Most of them were formed and further eliminated during the reactions. The parent compound of 5-FU was not biodegraded, whereas the photolytic mixture formed in the UV/H2O2 treatment after 256 min showed a noticeable improvement of the biodegradability in the closed bottle test (CBT) and was nontoxic towards Vibrio fischeri. In silico predictions showed positive alerts for mutagenic and genotoxic effects of 5-FU. In contrast, several of the transformation products (TPs) generated along the processes did not provide indications for mutagenic or genotoxic activity. One exception was TP with m/z 146 with positive alerts in several models of bacterial mutagenicity which could demand further experimental testing. Results demonstrate that advanced treatment can eliminate parent compounds and its toxicity. However, transformation products formed can still be toxic. Therefore toxicity screening after advanced treatment is recommendable.
authors.affiliation: Sustainable Chemistry and Material Resources, Institute of Sustainable and Environmental Chemistry, Faculty of Sustainability, Leuphana University of Lüneburg, Scharnhorststraße 1/C13, DE-21335 Lüneburg, Germany; Graduate Program in Environmental Technology, Universidade de Santa Cruz do Sul - UNISC, Av. Independência, 2293, CEP 96815-900 Santa Cruz do Sul, Rio Grande do Sul, Brazil. Electronic address: lutterbeck@leuphana.de.
authors.forename: Carlos Alexandre
authors.initials: CA
authors.lastname: Lutterbeck
authors.affiliation: Sustainable Chemistry and Material Resources, Institute of Sustainable and Environmental Chemistry, Faculty of Sustainability, Leuphana University of Lüneburg, Scharnhorststraße 1/C13, DE-21335 Lüneburg, Germany. Electronic address: wilde@leuphana.de.
authors.forename: Marcelo Luís
authors.initials: ML
authors.lastname: Wilde
authors.affiliation: Sustainable Chemistry and Material Resources, Institute of Sustainable and Environmental Chemistry, Faculty of Sustainability, Leuphana University of Lüneburg, Scharnhorststraße 1/C13, DE-21335 Lüneburg, Germany. Electronic address: ewelina.baginska@leuphana.de.
authors.forename: Ewelina
authors.initials: E
authors.lastname: Baginska
authors.affiliation: Sustainable Chemistry and Material Resources, Institute of Sustainable and Environmental Chemistry, Faculty of Sustainability, Leuphana University of Lüneburg, Scharnhorststraße 1/C13, DE-21335 Lüneburg, Germany. Electronic address: cleder@leuphana.de.
authors.forename: Christoph
authors.initials: C
authors.lastname: Leder
authors.affiliation: Graduate Program in Environmental Technology, Universidade de Santa Cruz do Sul - UNISC, Av. Independência, 2293, CEP 96815-900 Santa Cruz do Sul, Rio Grande do Sul, Brazil. Electronic address: enio@unisc.br.
authors.forename: Ênio Leandro
authors.initials: ÊL
authors.lastname: Machado
authors.affiliation: Sustainable Chemistry and Material Resources, Institute of Sustainable and Environmental Chemistry, Faculty of Sustainability, Leuphana University of Lüneburg, Scharnhorststraße 1/C13, DE-21335 Lüneburg, Germany. Electronic address: klaus.kuemmerer@uni.leuphana.de.
authors.forename: Klaus
authors.initials: K
authors.lastname: Kümmerer
mesh_terms: D048908:Aliivibrio fischeri; D001673:Biodegradation, Environmental; D005472:Fluorouracil / Q000737:chemistry* / Q000633:toxicity; D006861:Hydrogen Peroxide / Q000737:chemistry; D010084:Oxidation-Reduction; D010782:Photolysis; D014025:Titanium / Q000737:chemistry; D014874:Water Pollutants, Chemical / Q000737:chemistry* / Q000633:toxicity
chemical_list: D014874:Water Pollutants, Chemical; C009495:titanium dioxide; D006861:Hydrogen Peroxide; D014025:Titanium; D005472:Fluorouracil
keywords: 5-Fluorouracil; Advanced oxidation process; Biodegradation; Toxicity; Transformation product