title: Cr(VI) reduction in wastewater using a bimetallic galvanic reactor.
abstract: The electrochemical reduction of Cr(VI)-Cr(III) in wastewater by iron and copper-iron bimetallic plates was evaluated and optimized. Iron has been used as a reducing agent, but in this work a copper-iron galvanic system in the form of bimetallic plates is applied to reducing hexavalent chromium. The optimal pH (2) and ratio of copper to iron surface areas (3.5:1) were determined in batch studies, achieving a 100% reduction in about 25 min. The Cr(VI) reduction kinetics for the bimetallic system fit a first order mechanism with a correlation of 0.9935. Thermodynamic analysis shows that the Cr(VI) reduction is possible at any pH value. However, at pH values above 3.0 for iron and 5.5 for chromium insoluble species appear, indicating that the reaction will be hindered. Continuous column studies indicate that the bimetallic copper-iron galvanic system has a reduction capacity of 9.5890 mg Cr(VI) cm(-2) iron, whereas iron alone only has a capacity of 0.1269 mg Cr(VI) cm(-2). The bimetallic copper-iron galvanic system is much more effective in reducing hexavalent chromium than iron alone. The exhausted plates were analyzed by SEM, EDS, and XRD to determine the mechanism and the surface effects, especially surface fouling.
authors.affiliation: Centro Conjunto de Investigación en Química Sustentable UAEM-UNAM. Universidad Autónoma del Estado de México. Facultad de Química. Paseo Colón intersección Paseo Tollocan S/N. C.P. 50120, Toluca, Estado de México, Mexico.
authors.forename: Violeta
authors.initials: V
authors.lastname: Lugo-Lugo
authors.forename: Carlos
authors.initials: C
authors.lastname: Barrera-Díaz
authors.forename: Bryan
authors.initials: B
authors.lastname: Bilyeu
authors.forename: Patricia
authors.initials: P
authors.lastname: Balderas-Hernández
authors.forename: Fernando
authors.initials: F
authors.lastname: Ureña-Nuñez
authors.forename: Víctor
authors.initials: V
authors.lastname: Sánchez-Mendieta
mesh_terms: D002857:Chromium / Q000737:chemistry*; D003300:Copper; D055664:Electrochemical Techniques; D006863:Hydrogen-Ion Concentration; D007220:Industrial Waste / Q000517:prevention & control*; D007501:Iron; D007700:Kinetics; D010084:Oxidation-Reduction; D014874:Water Pollutants, Chemical / Q000737:chemistry*
chemical_list: D007220:Industrial Waste; D014874:Water Pollutants, Chemical; D002857:Chromium; C074702:chromium hexavalent ion; D003300:Copper; D007501:Iron