title: Fenton process on single and mixture components of phenothiazine pharmaceuticals: Assessment of intermediaries, fate, and preliminary ecotoxicity.
abstract: Pharmaceuticals do not occur isolated in the environment but in multi-component mixtures and may exhibit antagonist, synergistic or additive behavior. Knowledge on this is still scarce. The situation is even more complicated if effluents or potable water is treated by oxidative processes or such transformations occur in the environment. Thus, determining the fate and effects of parent compounds, metabolites and transformation products (TPs) formed by transformation and degradation processes in the environment is needed. This study investigated the fate and preliminary ecotoxicity of the phenothiazine pharmaceuticals, Promazine (PRO), Promethazine (PRM), Chlorpromazine (CPR), and Thioridazine (THI) as single and as components of the resulting mixtures obtained from their treatment by Fenton process. The Fenton process was carried out at pH7 and by using 0.5-2mgL-1of [Fe2+]0and 1-12.5mgL-1of [H2O2]0at the fixed ratio [Fe2+]0:[H2O2]0of 1:10 (w:w). No complete mineralization was achieved. Constitutional isomers and some metabolite-like TPs formed were suggested based on their UHPLC-HRMSndata. A degradation pathway was proposed considering interconnected mechanisms such as sulfoxidation, hydroxylation, N-dealkylation, and dechlorination steps. Aerobic biodegradation tests (OECD 301 D and OECD 301 F) were applied to the parent compounds separately, to the mixture of parent compounds, and for the cocktail of TPs present after the treatment by Fenton process. The samples were not readily biodegradable. However, LC-MS analysis revealed that abiotic transformations, such hydrolysis, and autocatalytic transformations occurred. The initial ecotoxicity tested towards Vibrio fischeri as individual compounds featured a reduction in toxicity of PRM and CPR by the treatment process, whereas PRO showed an increase in acute luminescence inhibition and THI a stable luminescence inhibition. Concerning effects of the mixture components, reduction in toxicity by the Fenton process was predicted by concentration addition and independent action models.
authors.affiliation: Formerly: Sustainable Chemistry and Material Resources, Institute of Sustainable Environmental Chemistry, Leuphana University Lüneburg, C13, DE-21335 Lüneburg, Germany. Electronic address: marcelolw@gmail.com.
authors.forename: Marcelo L
authors.initials: ML
authors.lastname: Wilde
authors.affiliation: Sustainable Chemistry and Material Resources, Institute of Sustainable Environmental Chemistry, Leuphana University Lüneburg, C13, DE-21335 Lüneburg, Germany. Electronic address: mandy.schneider@leuphana.de.
authors.forename: Mandy
authors.initials: M
authors.lastname: Schneider
authors.affiliation: Sustainable Chemistry and Material Resources, Institute of Sustainable Environmental Chemistry, Leuphana University Lüneburg, C13, DE-21335 Lüneburg, Germany. Electronic address: klaus.kuemmerer@uni.leuphana.de.
authors.forename: Klaus
authors.initials: K
authors.lastname: Kümmerer
mesh_terms: D006861:Hydrogen Peroxide; D007501:Iron; D010640:Phenothiazines / Q000032:analysis* / Q000378:metabolism / Q000633:toxicity; D014865:Waste Disposal, Fluid; D014874:Water Pollutants, Chemical / Q000032:analysis* / Q000378:metabolism / Q000633:toxicity
chemical_list: C045076:Fenton's reagent; D010640:Phenothiazines; D014874:Water Pollutants, Chemical; D006861:Hydrogen Peroxide; D007501:Iron
keywords: Fenton process; Pharmaceutical mixtures; Phenothiazine-derived pharmaceuticals; Preliminary ecotoxicity; Ready biodegradability; Transformation products