title: Photo-Fenton oxidation of 3-amino-5-methylisoxazole: a by-product from biological breakdown of some pharmaceutical compounds.
abstract: The present study aims to assess the removal of 3-amino-5-methylisoxazole (AMI), a recalcitrant by-product resulting from the biological breakdown of some pharmaceuticals, applying a solar photo-Fenton process assisted by ferrioxalate complexes (SPFF) (Fe3+/H2O2/oxalic acid/UVA-Vis) and classical solar photo-Fenton process (SPF) (Fe2+/H2O2/UVA-Vis). The oxidation ability of SPFF was evaluated at different iron/oxalate molar ratios (1:3, 1:6, and 1:9, with [total iron] = 3.58 × 10-2mM and [oxalic acid] = 1.07 × 10-1, 2.14 × 10-1and 3.22 × 10-1mM, respectively) and pH values (3.5-6.5), using low iron contents (2.0 mg Fe3+L-1). Additionally, the use of other organic ligands such as citrate and ethylenediamine-N,N'-disuccinic acid (EDDS) was tested. The oxidation power of the classical SPF was assessed at different pH values (2.8-4.0) using 2.0 mg Fe2+per liter. Furthermore, the effect of AMI concentration (2-20 mg L-1), presence of inorganic ions (Cl-, SO42-, NO3-, HCO3-, NH4+), and radical scavengers (sodium azide and D-mannitol) on the SPF method at pH 3.5 was also assessed. Experiments were done using a lab-scale photoreactor with a compound parabolic collector (CPC) under simulated solar radiation. A pilot-scale assay was conducted using the best operation conditions. While at near neutral pH, an iron/oxalate molar ratio of 1:9 led to the removal of 72 % of AMI after 90 min of SPFF, at pH 3.5, an iron/oxalate molar ratio of 1:3 was enough to achieve complete AMI degradation (below the detection limit) after 30 min of reaction. The SPF process at pH 3.5 underwent a slower AMI degradation, reaching total AMI degradation after 40 min of reaction. The scale up of SPF process showed a good reproducibility. Oxalic and oxamic acids were identified as the main low-molecular-weight carboxylic acids detected during the pilot-scale SPF reaction. Graphical abstract ᅟ.
authors.affiliation: LSRE-Laboratory of Separation and Reaction Engineering-Associate Laboratory LSRE/LCM, Departamento de Engenharia Química, Faculdade de Engenharia, Universidade do Porto, Rua Dr. Roberto Frias, 4200-465, Porto, Portugal.|Chemical Engineering Program-COPPE, Federal University of Rio de Janeiro, P.O. Box 68502, 21941-972, Rio de Janeiro, RJ, Brazil.
authors.forename: Bianca M
authors.initials: BM
authors.lastname: Souza
authors.affiliation: LSRE-Laboratory of Separation and Reaction Engineering-Associate Laboratory LSRE/LCM, Departamento de Engenharia Química, Faculdade de Engenharia, Universidade do Porto, Rua Dr. Roberto Frias, 4200-465, Porto, Portugal.
authors.forename: Belisa A
authors.initials: BA
authors.lastname: Marinho
authors.affiliation: LSRE-Laboratory of Separation and Reaction Engineering-Associate Laboratory LSRE/LCM, Departamento de Engenharia Química, Faculdade de Engenharia, Universidade do Porto, Rua Dr. Roberto Frias, 4200-465, Porto, Portugal.
authors.forename: Francisca C
authors.initials: FC
authors.lastname: Moreira
authors.affiliation: Chemical Engineering Program-COPPE, Federal University of Rio de Janeiro, P.O. Box 68502, 21941-972, Rio de Janeiro, RJ, Brazil.
authors.forename: Márcia W C
authors.initials: MWC
authors.lastname: Dezotti
authors.affiliation: LSRE-Laboratory of Separation and Reaction Engineering-Associate Laboratory LSRE/LCM, Departamento de Engenharia Química, Faculdade de Engenharia, Universidade do Porto, Rua Dr. Roberto Frias, 4200-465, Porto, Portugal.
authors.forename: Rui A R
authors.initials: RAR
authors.lastname: Boaventura
authors.affiliation: LSRE-Laboratory of Separation and Reaction Engineering-Associate Laboratory LSRE/LCM, Departamento de Engenharia Química, Faculdade de Engenharia, Universidade do Porto, Rua Dr. Roberto Frias, 4200-465, Porto, Portugal. vilar@fe.up.pt.
authors.forename: Vítor J P
authors.initials: VJP
authors.lastname: Vilar
mesh_terms: D004350:Drug Residues / Q000737:chemistry*; D006861:Hydrogen Peroxide / Q000737:chemistry*; D006863:Hydrogen-Ion Concentration; D007501:Iron / Q000737:chemistry*; D007555:Isoxazoles / Q000737:chemistry*; D019815:Oxalic Acid / Q000737:chemistry; D010084:Oxidation-Reduction; D055668:Photochemical Processes
chemical_list: C000611126:3-amino-5-methylisoxazole; C045076:Fenton's reagent; D007555:Isoxazoles; D019815:Oxalic Acid; D006861:Hydrogen Peroxide; D007501:Iron
keywords: 3-amino-5-methylisoxazole; CPCs; Ferrioxalate complexes; Solar photo-Fenton