title: Degradation of the cytostatic 5-Fluorouracil in water by Fenton and photo-assisted oxidation processes.
abstract: Cytostatics are part of the forefront research topics due to their high prescription, high toxicity, and the lack of effective solutions to stop their entrance and spread in the environment. Among them, 5-Fluorouracil (5-Fu) has received particular attention because is one of the most prescribed active substances in chemotherapy worldwide. The degradation of 5-Fu by advanced oxidation processes (AOPs) is a poorly addressed topic, and this work brings valuable inputs concerning this matter. Herein, the efficacy of Fenton's process in the degradation of 5-Fu is explored for the first time; the study of the main variables and its successful application to the treatment of real wastewaters is demonstrated. Moreover, hydrogen peroxide-based and photo-assisted techniques (direct photolysis, photodegradation with H2O2and photo-Fenton) are also investigated for purposes of comparison. Under the best operation conditions obtained (T = 30 °C, [Fe2+]0= 0.5 mM; [H2O2]0= 240 mM and pH = 3 for [5-Fu]0= 0.38 mM), 5-Fu was completely eliminated after 2 h of Fenton's reaction and about 50 % of mineralization was reached after 8 h. The best performance was obtained by the photo-Fenton process, with 5-Fu mineralization level as high as 67 %, using an iron dose within the legal limits required for direct water discharge. Toxicity (towards Vibrio fischeri) of the effluents that resulted from the application of the above-mentioned AOPs was also evaluated; it was found that the degradation products generated from the photo-assisted processes are less toxic than the parent compound, putting into evidence the relevance of such technologies for degradation of cytostatics like 5-Fu.
authors.affiliation: LEPABE-Laboratory for Process Engineering, Environment, Biotechnology and Energy, Faculty of Engineering, University of Porto, R. Dr. Roberto Frias, s/n, 4200-465, Porto, Portugal.
authors.forename: Mariana
authors.initials: M
authors.lastname: Governo
authors.affiliation: LEPABE-Laboratory for Process Engineering, Environment, Biotechnology and Energy, Faculty of Engineering, University of Porto, R. Dr. Roberto Frias, s/n, 4200-465, Porto, Portugal.
authors.forename: Mónica S F
authors.initials: MSF
authors.lastname: Santos
authors.affiliation: LEPABE-Laboratory for Process Engineering, Environment, Biotechnology and Energy, Faculty of Engineering, University of Porto, R. Dr. Roberto Frias, s/n, 4200-465, Porto, Portugal.
authors.forename: Arminda
authors.initials: A
authors.lastname: Alves
authors.affiliation: LEPABE-Laboratory for Process Engineering, Environment, Biotechnology and Energy, Faculty of Engineering, University of Porto, R. Dr. Roberto Frias, s/n, 4200-465, Porto, Portugal. mmadeira@fe.up.pt.
authors.forename: Luís M
authors.initials: LM
authors.lastname: Madeira
mesh_terms: D048908:Aliivibrio fischeri / Q000378:metabolism; D000964:Antimetabolites, Antineoplastic / Q000032:analysis* / Q000528:radiation effects / Q000633:toxicity; D005472:Fluorouracil / Q000032:analysis* / Q000528:radiation effects / Q000633:toxicity; D006861:Hydrogen Peroxide / Q000737:chemistry*; D007501:Iron / Q000737:chemistry*; D008962:Models, Theoretical; D010084:Oxidation-Reduction; D010782:Photolysis; D014466:Ultraviolet Rays; D062065:Wastewater / Q000737:chemistry; D014874:Water Pollutants, Chemical / Q000032:analysis* / Q000528:radiation effects / Q000633:toxicity; D018508:Water Purification / Q000379:methods*
chemical_list: D000964:Antimetabolites, Antineoplastic; D005472:Fluorouracil; D006861:Hydrogen Peroxide; D007501:Iron; D062065:Wastewater; D014874:Water Pollutants, Chemical; C045076:Fenton's reagent
keywords: 5-fluorouracil; Advanced oxidation processes; Cytostatic; Fenton’s reagent; Hydrogen peroxide; Photo-assisted technologies