title: Electro-fenton and photoelectro-fenton degradation of sulfanilic acid using a boron-doped diamond anode and an air diffusion cathode.
abstract: The mineralization of sulfanilic acid has been studied by electro-Fenton (EF) and photoelectro-Fenton (PEF) reaction with UVA light using an undivided electrochemical cell with a boron-doped diamond (BDD) anode and an air diffusion cathode able to generate H(2)O(2). Organics were then oxidized by hydroxyl radicals formed at the anode surface from water oxidation and in the bulk from Fenton's reaction between generated H(2)O(2) and added Fe(2+). The UVA irradiation in PEF enhanced the production of hydroxyl radicals in the bulk, accelerating the removal of organics and photodecomposed intermediates like Fe(III)-carboxylate complexes. Partial decontamination of 1.39 mM sulfanilic acid solutions was achieved by EF until 100 mA cm(-2) at optimum conditions of 0.4 mM Fe(2+) and pH 3.0. The increase in current density and substrate content led to an almost total mineralization. In contrast, the PEF process was more powerful, yielding almost complete mineralization in less electrolysis time under comparable conditions. The kinetics for sulfanilic acid decay always followed a pseudo-first-order reaction. Hydroquinone and p-benzoquinone were detected as aromatic intermediates, whereas acetic, maleic, formic, oxalic, and oxamic acids were identified as generated carboxylic acids. NH(4)(+) ion was preferentially released in both treatments, along with NO(3)(-) ion in smaller proportion.
authors.affiliation: Laboratori d'Electroquímica dels Materials i del Medi Ambient, Departament de Química Física, Universitat de Barcelona, Spain.
authors.forename: Abdellatif
authors.initials: A
authors.lastname: El-Ghenymy
authors.forename: José Antonio
authors.initials: JA
authors.lastname: Garrido
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: Rosa María
authors.initials: RM
authors.lastname: Rodríguez
authors.forename: Enric
authors.initials: E
authors.lastname: Brillas
mesh_terms: D000388:Air; D001895:Boron / Q000737:chemistry*; D004058:Diffusion; D004566:Electrodes; D004583:Electrons; D006861:Hydrogen Peroxide / Q000737:chemistry*; D007477:Ions / Q000737:chemistry; D007501:Iron / Q000737:chemistry*; D007700:Kinetics; D009584:Nitrogen / Q000737:chemistry; D055668:Photochemical Processes; D013425:Sulfanilic Acids / Q000737:chemistry*; D013997:Time Factors
chemical_list: C045076:Fenton's reagent; D007477:Ions; D013425:Sulfanilic Acids; D006861:Hydrogen Peroxide; D007501:Iron; D009584:Nitrogen; D001895:Boron