title: Electrochemical incineration of sulfanilic acid at a boron-doped diamond anode.
abstract: The anodic oxidation of sulfanilic acid solutions has been studied in acidic medium using a divided cell with a boron-doped diamond (BDD) anode and a stainless steel cathode. Overall mineralization was achieved under all experimental conditions tested due to the efficient destruction of sulfanilic acid and all its by-products with hydroxyl radicals generated at the BDD anode from water oxidation. The alternative use of an undivided cell with the same electrodes gave rise to the coating of the cathode with polymeric compounds, thus preventing the complete electrochemical incineration of sulfanilic acid. The solutions treated in the anodic compartment of the divided cell were degraded at similar rate under pH regulation within the pH interval 2.0-6.0. The mineralization current efficiency was enhanced when the applied current decreased and the initial substrate concentration increased. The decay of sulfanilic acid was followed by reversed-phase HPLC, showing a pseudo first-order kinetics. Hydroquinone and p-benzoquinone were identified as aromatic intermediates by gas chromatography-mass spectrometry and/or reversed-phase HPLC. Maleic, acetic, formic, oxalic and oxamic acids were detected as generated carboxylic acids by ion-exclusion HPLC. Ionic chromatographic analysis of electrolyzed solutions revealed that the N content of sulfanilic acid was mainly released as NH(4)(+) ion and in much smaller proportion as NO(3)(-) ion.
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: Abdellatif
authors.initials: A
authors.lastname: El-Ghenymy
authors.forename: Conchita
authors.initials: C
authors.lastname: Arias
authors.forename: Pere Lluís
authors.initials: PL
authors.lastname: Cabot
authors.forename: Francesc
authors.initials: F
authors.lastname: Centellas
authors.forename: José Antonio
authors.initials: JA
authors.lastname: Garrido
authors.forename: Rosa María
authors.initials: RM
authors.lastname: Rodríguez
authors.forename: Enric
authors.initials: E
authors.lastname: Brillas
mesh_terms: D001895:Boron / Q000737:chemistry*; D002853:Chromatography, Liquid; D018130:Diamond / Q000737:chemistry*; D055664:Electrochemical Techniques; D004566:Electrodes; D008401:Gas Chromatography-Mass Spectrometry; D006863:Hydrogen-Ion Concentration; D010084:Oxidation-Reduction; D013193:Stainless Steel / Q000737:chemistry; D013425:Sulfanilic Acids / Q000737:chemistry*; D014865:Waste Disposal, Fluid; D014874:Water Pollutants, Chemical / Q000737:chemistry*
chemical_list: D013425:Sulfanilic Acids; D014874:Water Pollutants, Chemical; D013193:Stainless Steel; C100016:4-sulfanilic acid; D018130:Diamond; D001895:Boron