title: Degradation of tyrosol by a novel electro-Fenton process using pyrite as heterogeneous source of iron catalyst.
abstract: Tyrosol (TY) is one of the most abundant phenolic components of olive oil mill wastewaters. Here, the degradation of synthetic aqueous solutions of 0.30 mM TY was studied by a novel heterogeneous electro-Fenton (EF) process, so-called EF-pyrite, in which pyrite powder was the source of Fe(2+) catalyst instead of a soluble iron salt used in classical EF. Experiments were performed with a cell equipped with a boron-doped diamond anode and a carbon-felt cathode, where TY and its products were destroyed by hydroxyl radicals formed at the anode surface from water oxidation and in the bulk from Fenton's reaction between Fe(2+) and H2O2 generated at the cathode. Addition of 1.0 g L(-1) pyrite provided an easily adjustable pH to 3.0 and an appropriate 0.20 mM Fe(2+) to optimize the EF-pyrite treatment. The effect of current on mineralization rate, mineralization current efficiency and specific energy consumption was examined under comparable EF and EF-pyrite conditions. The performance of EF-pyrite was 8.6% superior at 50 mA due to self-regulation of soluble Fe(2+) by pyrite. The TY decay in this process followed a pseudo-first-order kinetics. The absolute rate constant for TY hydroxylation was 3.57 × 10(9) M(-1) s(-1), as determined by the competition kinetics method. Aromatic products like 3,4-dihydroxyphenylethanol, 4-hydroxyphenylacetic acid, 4-hydroxybenzoic acid, 3,4-dihydroxybenzoic acid and catechol, as well as o-benzoquinone, were identified by GC-MS and reversed-phase HPLC. Short-chain aliphatic carboxylic acids like maleic, glycolic, acetic, oxalic and formic were quantified by ion-exclusion HPLC. Oxalic acid was the major and most persistent product found. Based on detected intermediates, a plausible mineralization pathway for TY by EF-pyrite was proposed.
authors.affiliation: Unité de Recherche d'Electrochimie et Environnement, Ecole Nationale d'Ingénieurs de Sfax, BPW 3038 Sfax, Tunisia; Institut Supérieur des Études Technologiques de Gabès, Université de Gabès, 6027 Gabès, Tunisia.
authors.forename: Salah
authors.initials: S
authors.lastname: Ammar
authors.affiliation: Université Paris-Est, Laboratoire Géomatériaux et Environnement, EA 4508, UPEM, 5 Bd Descartes, 77454 Marne-la-Vallée, Cedex 2, France.
authors.forename: Mehmet A
authors.initials: MA
authors.lastname: Oturan
authors.affiliation: Département de chimie, Faculté des Sciences de Gabès, Cité Erriadh, Université de Gabès, 6027 Gabès, Tunisia.
authors.forename: Lazhar
authors.initials: L
authors.lastname: Labiadh
authors.affiliation: Institut Supérieur des Études Technologiques de Gabès, Université de Gabès, 6027 Gabès, Tunisia.
authors.forename: Amor
authors.initials: A
authors.lastname: Guersalli
authors.affiliation: Unité de Recherche d'Electrochimie et Environnement, Ecole Nationale d'Ingénieurs de Sfax, BPW 3038 Sfax, Tunisia.
authors.forename: Ridha
authors.initials: R
authors.lastname: Abdelhedi
authors.affiliation: Université Paris-Est, Laboratoire Géomatériaux et Environnement, EA 4508, UPEM, 5 Bd Descartes, 77454 Marne-la-Vallée, Cedex 2, France.
authors.forename: Nihal
authors.initials: N
authors.lastname: Oturan
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: D001895:Boron / Q000737:chemistry; D002244:Carbon / Q000737:chemistry; D002384:Catalysis; D018130:Diamond / Q000737:chemistry; D055664:Electrochemical Techniques; D004566:Electrodes; D006861:Hydrogen Peroxide / Q000737:chemistry*; D006863:Hydrogen-Ion Concentration; D017665:Hydroxyl Radical / Q000737:chemistry; D007501:Iron / Q000737:chemistry*; D007700:Kinetics; D010626:Phenylethyl Alcohol / Q000031:analogs & derivatives* / Q000737:chemistry; D013440:Sulfides / Q000737:chemistry*; D014874:Water Pollutants, Chemical / Q000737:chemistry
chemical_list: C045076:Fenton's reagent; D013440:Sulfides; D014874:Water Pollutants, Chemical; C011342:pyrite; C011867:4-hydroxyphenylethanol; D017665:Hydroxyl Radical; D002244:Carbon; D018130:Diamond; D006861:Hydrogen Peroxide; D007501:Iron; D010626:Phenylethyl Alcohol; D001895:Boron
keywords: Electro-Fenton; Heterogeneous catalysis; Hydroxyl radicals; Pyrite; Tyrosol; Wastewater treatment