title: Comparative electrochemical degradation of salicylic and aminosalicylic acids: Influence of functional groups on decay kinetics and mineralization.
abstract: Solutions of 100 mL with 1.20 mM of salicylic acid (SA), 4-aminosalicylic acid (4-ASA) or 5-aminosalicylic acid (5-ASA) have been comparatively degraded by anodic oxidation with electrogenerated H2O2 (AO-H2O2), electro-Fenton (EF) and photoelectro-Fenton (PEF). Trials were carried out with a stirred tank reactor with a BDD anode and an air-diffusion cathode for continuous H2O2 production. A marked influence of the functional groups of the drugs was observed in their decay kinetics, increasing in the order SA < 5-ASA < 4-ASA in AO-H2O2 and 5-ASA < SA < 4-ASA in EF and PEF, due to the different attack of OH generated at the BDD surface and in the bulk from Fenton's reaction, respectively. This effect was clearly observed when varying the current density between 16.7 and 100 mA cm(-2). The relative mineralization power of the processes always followed the sequence: AO-H2O2 < EF < PEF. The three drugs underwent analogous mineralization abatement up to 88% by AO-H2O2 at 100 mA cm(-2). The mineralization rate in EF and PEF grew in the order: 4-ASA < 5-ASA < SA. The most powerful process was PEF, attaining >98% mineralization for all the drugs at 100 mA cm(-2). Oxalic and oxamic acids were detected as final short-linear aliphatic carboxylic acids by ion-exclusion HPLC, allowing the fast photolysis of their Fe(III) complexes by UVA light to justify the high power of PEF.
authors.affiliation: Laboratori d'Electroquímica dels 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: Xavier
authors.initials: X
authors.lastname: Florenza
authors.affiliation: Laboratori d'Electroquímica dels Materials i del Medi Ambient, Departament de Química Física, Facultat de Química, Universitat de Barcelona, Martí i Franquès 1-11, 08028 Barcelona, Spain. Electronic address: sergigarcia@ub.edu.
authors.forename: Sergi
authors.initials: S
authors.lastname: Garcia-Segura
authors.affiliation: Laboratori d'Electroquímica dels 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: Francesc
authors.initials: F
authors.lastname: Centellas
authors.affiliation: Laboratori d'Electroquímica dels Materials i del Medi Ambient, Departament de Química Física, Facultat de Química, Universitat de Barcelona, Martí i Franquès 1-11, 08028 Barcelona, Spain. Electronic address: brillas@ub.edu.
authors.forename: Enric
authors.initials: E
authors.lastname: Brillas
mesh_terms: D000636:Aminosalicylic Acids / Q000737:chemistry*; D002264:Carboxylic Acids / Q000032:analysis*; D002851:Chromatography, High Pressure Liquid; D004566:Electrodes; D006861:Hydrogen Peroxide / Q000737:chemistry*; D007501:Iron / Q000737:chemistry; D007700:Kinetics; D019815:Oxalic Acid / Q000032:analysis*; D010072:Oxamic Acid / Q000032:analysis*; D010084:Oxidation-Reduction; D010782:Photolysis; D020156:Salicylic Acid / Q000737:chemistry*; D062065:Wastewater / Q000032:analysis / Q000737:chemistry*; D014874:Water Pollutants, Chemical / Q000737:chemistry*
chemical_list: D000636:Aminosalicylic Acids; D002264:Carboxylic Acids; D006861:Hydrogen Peroxide; D007501:Iron; D019815:Oxalic Acid; D010072:Oxamic Acid; D020156:Salicylic Acid; D062065:Wastewater; D014874:Water Pollutants, Chemical
keywords: 4-Aminosalicylic acid; 5-Aminosalicylic acid; Anodic oxidation; Electro-Fenton; Photoelectro-Fenton; Salicylic acid