title: Degradation of pharmaceutical beta-blockers by electrochemical advanced oxidation processes using a flow plant with a solar compound parabolic collector.
abstract: The degradation of the beta-blockers atenolol, metoprolol tartrate and propranolol hydrochloride was studied by electro-Fenton (EF) and solar photoelectro-Fenton (SPEF). Solutions of 10 L of 100 mg L⁻¹ of total organic carbon of each drug in 0.1 M Na₂SO₄ with 0.5 mM Fe²⁺ of pH 3.0 were treated in a recirculation flow plant with an electrochemical reactor coupled with a solar compound parabolic collector. Single Pt/carbon felt (CF) and boron-doped diamond (BDD)/air-diffusion electrode (ADE) cells and combined Pt/ADE-Pt/CF and BDD/ADE-Pt/CF cells were used. SPEF treatments were more potent with the latter cell, yielding 95-97% mineralization with 100% of maximum current efficiency and energy consumptions of about 0.250 kWh g TOC⁻¹. However, the Pt/ADE-Pt/CF cell gave much lower energy consumptions of about 0.080 kWh g TOC⁻¹ with slightly lower mineralization of 88-93%, then being more useful for its possible application at industrial level. The EF method led to a poorer mineralization and was more potent using the combined cells by the additional production of hydroxyl radicals (•OH) from Fenton's reaction from the fast Fe²⁺ regeneration at the CF cathode. Organics were also more rapidly destroyed at BDD than at Pt anode. The decay kinetics of beta-blockers always followed a pseudo first-order reaction, although in SPEF, it was accelerated by the additional production of •OH from the action of UV light of solar irradiation. Aromatic intermediates were also destroyed by hydroxyl radicals. Ultimate carboxylic acids like oxalic and oxamic remained in the treated solutions by EF, but their Fe(III) complexes were photolyzed by solar irradiation in SPEF, thus explaining its higher oxidation power. NO₃⁻ was the predominant inorganic ion lost in EF, whereas the SPEF process favored the production of NH₄⁺ ion and volatile N-derivatives.
authors.affiliation: Laboratori d'Electroquímica de Materials i del Medi Ambient, Departament de Química Física, Facultat de Química, Universitat de Barcelona, Martí i Franquès 1-11, 08028 Barcelona, Spain.
authors.forename: Eloy
authors.initials: E
authors.lastname: Isarain-Chávez
authors.forename: Rosa María
authors.initials: RM
authors.lastname: Rodríguez
authors.forename: Pere Lluís
authors.initials: PL
authors.lastname: Cabot
authors.forename: Francesc
authors.initials: F
authors.lastname: Centellas
authors.forename: Conchita
authors.initials: C
authors.lastname: Arias
authors.forename: José Antonio
authors.initials: JA
authors.lastname: Garrido
authors.forename: Enric
authors.initials: E
authors.lastname: Brillas
mesh_terms: D000319:Adrenergic beta-Antagonists / Q000737:chemistry*; D001262:Atenolol / Q000737:chemistry; D001895:Boron / Q000737:chemistry; D002244:Carbon / Q000737:chemistry; D018130:Diamond / Q000737:chemistry; D004563:Electrochemistry / Q000379:methods*; D005290:Ferric Compounds / Q000737:chemistry; D006861:Hydrogen Peroxide / Q000737:chemistry*; D007501:Iron / Q000737:chemistry*; D007700:Kinetics; D008790:Metoprolol / Q000737:chemistry; D009566:Nitrates / Q000737:chemistry; D017672:Nitrogen Compounds; D010084:Oxidation-Reduction; D010777:Photochemistry / Q000379:methods*; D010984:Platinum / Q000737:chemistry; D011433:Propranolol / Q000737:chemistry; D000644:Quaternary Ammonium Compounds / Q000737:chemistry; D013472:Sunlight; D014874:Water Pollutants, Chemical / Q000737:chemistry*; D018508:Water Purification / Q000379:methods*
chemical_list: D000319:Adrenergic beta-Antagonists; C045076:Fenton's reagent; D005290:Ferric Compounds; D009566:Nitrates; D017672:Nitrogen Compounds; D000644:Quaternary Ammonium Compounds; D014874:Water Pollutants, Chemical; D010984:Platinum; D001262:Atenolol; D002244:Carbon; D018130:Diamond; D011433:Propranolol; D006861:Hydrogen Peroxide; D007501:Iron; D008790:Metoprolol; D001895:Boron