title: Mineralization of metoprolol by electro-Fenton and photoelectro-Fenton processes.
abstract: Solutions of about 0.25 mM of the β-blocker metoprolol tartrate (100 mg L(-1) total organic carbon) with 0.5 mM Fe(2+) in the presence and absence of 0.1 mM Cu(2+) of pH 3.0 have been comparatively degraded under electro-Fenton (EF) and photoelectro-Fenton (PEF) conditions. The electrolyses were carried out with two systems: (i) a single cell with a boron-doped diamond (BDD) anode and an air-diffusion cathode (ADE) for H(2)O(2) electrogeneration and (ii) a combined cell with a BDD/ADE pair coupled with a Pt/carbon felt (CF) cell. Overall mineralization was reached in all PEF treatments using both systems due to the efficient production of hydroxyl radical ((•)OH) from Fenton's reaction induced by UVA light and the quick photolysis of Fe(III) carboxylate complexes formed. In EF, the combined cell was much more potent than the single one by the larger (•)OH generation from the continuous Fe(2+) regeneration at the CF cathode, accelerating the oxidation of organics. However, almost total mineralization in EF was feasible using the combined cell in the presence of 0.1 mM Cu(2+), because of the parallel quick oxidation of Cu(II) carboxylate complexes by (•)OH. Metoprolol decay always followed a pseudo-first-order reaction. Aromatic products related to consecutive hydroxylation/oxidation reactions of metoprolol were detected by gas chromatography-mass spectrometry. The evolution of the aromatic 4-(2-methoxyethyl)phenol and generated carboxylic acids was followed by HPLC. The degradation rate and mineralization degree of metoprolol tartrate were limited by the removal of Fe(III) and Cu(II) complexes of ultimate carboxylic acids such as formic, oxalic, and oxamic. NH(4)(+) ion and to a lesser extent NO(3)(-) ion were released in all treatments, being quantified by ionic chromatography.
authors.affiliation: Laboratori d'Electroquímica dels Materials i del Medi Ambient, Departament de Química Física, Universitat de Barcelona, Martí i Franquès 1-11, 08028 Barcelona, Spain.
authors.forename: Eloy
authors.initials: E
authors.lastname: Isarain-Chávez
authors.forename: José Antonio
authors.initials: JA
authors.lastname: Garrido
authors.forename: Rosa María
authors.initials: RM
authors.lastname: Rodríguez
authors.forename: Francesc
authors.initials: F
authors.lastname: Centellas
authors.forename: Conchita
authors.initials: C
authors.lastname: Arias
authors.forename: Pere Lluís
authors.initials: PL
authors.lastname: Cabot
authors.forename: Enric
authors.initials: E
authors.lastname: Brillas
mesh_terms: D001895:Boron / Q000737:chemistry; D018130:Diamond / Q000737:chemistry; D004563:Electrochemistry / Q000379:methods; D004566:Electrodes; D004572:Electrolysis / Q000379:methods; D005290:Ferric Compounds / Q000737:chemistry; D008401:Gas Chromatography-Mass Spectrometry / Q000379:methods; D006861:Hydrogen Peroxide / Q000737:chemistry*; D017665:Hydroxyl Radical / Q000737:chemistry*; D007501:Iron / Q000737:chemistry*; D008790:Metoprolol / Q000031:analogs & derivatives* / Q000737:chemistry*; D010084:Oxidation-Reduction; D010777:Photochemistry / Q000379:methods; D010984:Platinum / Q000737:chemistry; D014865:Waste Disposal, Fluid / Q000379:methods; D014874:Water Pollutants, Chemical / Q000737:chemistry*
chemical_list: C045076:Fenton's reagent; D005290:Ferric Compounds; D014874:Water Pollutants, Chemical; C054515:3-(4-(1-hydroxy-2-methoxyethyl)phenoxy)-1-(isopropylamino)-2-propanol; D017665:Hydroxyl Radical; D010984:Platinum; D018130:Diamond; D006861:Hydrogen Peroxide; D007501:Iron; D008790:Metoprolol; D001895:Boron