title: Electrochemical oxidation of synthetic tannery wastewater in chloride-free aqueous media.
abstract: The electrochemical treatment of a synthetic tannery wastewater, prepared with several compounds used by finishing tanneries, was studied in chloride-free media. Boron-doped diamond (Si/BDD), antimony-doped tin dioxide (Ti/SnO(2)-Sb), and iridium-antimony-doped tin dioxide (Ti/SnO(2)-Sb-Ir) were evaluated as anode. The influence of pH and current density on the treatment was assessed by means of the parameters used to measure the level of organic contaminants in the wastewater; i.e., total phenols, chemical oxygen demand (COD), total organic carbon (TOC), and absorbance. Results showed that faster decrease in these parameters occurred when the Si/BDD anode was used. Good results were obtained with the Ti/SnO(2)-Sb anode, but its complete deactivation was reached after 4h of electrolysis at 25 mA cm(-2), indicating that the service life of this electrode is short. The Ti/SnO(2)-Sb-Ir anode is chemically and electrochemically more stable than the Ti/SnO(2)-Sb anode, but it is not suitable for the electrochemical treatment under the studied conditions. No significant changes were observed for electrolyses performed at different pH conditions with Si/BDD, and this electrode led to almost complete mineralization after 4h of electrolysis at 100 mA cm(-2). The increase in current density resulted in faster wastewater oxidation, with lower current efficiency and higher energy consumption. Si/BBD proved to be the best electrodic material for the direct electrooxidation of tannery wastewaters.
authors.affiliation: Departamento de Química, Faculdade de Filosofia, Ciências e Letras de Ribeirão Preto, Universidade de São Paulo, CEP 14040-901, Ribeirão Preto, SP, Brazil.
authors.forename: Carla Regina
authors.initials: CR
authors.lastname: Costa
authors.forename: Francisco
authors.initials: F
authors.lastname: Montilla
authors.forename: Emilia
authors.initials: E
authors.lastname: Morallón
authors.forename: Paulo
authors.initials: P
authors.lastname: Olivi
mesh_terms: D002712:Chlorides / Q000737:chemistry*; D004563:Electrochemistry; D007220:Industrial Waste; D010084:Oxidation-Reduction; D013633:Tanning; D014867:Water; D014874:Water Pollutants, Chemical / Q000737:chemistry*
chemical_list: D002712:Chlorides; D007220:Industrial Waste; D014874:Water Pollutants, Chemical; D014867:Water