title: Reduction of hexavalent chromium: photocatalysis and photochemistry and their application in wastewater remediation.
abstract: Hexavalent chromium present in wastewater discharge of galvanic industries is toxic to most microorganisms and potentially harmful to human health. This work examines the photochemical reduction of Cr(VI) with ethanol under ultraviolet (UV) and visible radiation, and photocatalytic reduction of Cr(VI) with TiO2 in the presence of ethanol under UV radiation. By means of different experimental designs, this study investigates the influence of the initial pH, ethanol amount, catalyst concentration and initial Cr(VI) concentration on total Cr(VI) reduction. The results obtained showed that photochemistry with ethanol under UV radiation (96.10%) was more efficient than photochemistry with ethanol under visible light (48.07%). Furthermore, photocatalysis with TiO2 in the presence of ethanol under UV radiation showed high values of total Cr(VI) reduction: 94.15%, under the optimal conditions established by the experimental design. Finally, experiments were carried out with wastewater discharge from an electroplating plant in its original concentration, and higher values of total Cr(VI) reduction were observed.
authors.affiliation: Chemical Engineering Department, Federal University of Rio Grande do Sul Rua Engenheiro Luiz Englert s/n - CEP: 90040-040 - Porto Alegre, RS - Brazil E-mail: tiele@enq.ufrgs.br.
authors.forename: Tiele Caprioli
authors.initials: TC
authors.lastname: Machado
authors.affiliation: Chemical Engineering Department, Federal University of Rio Grande do Sul Rua Engenheiro Luiz Englert s/n - CEP: 90040-040 - Porto Alegre, RS - Brazil E-mail: tiele@enq.ufrgs.br.
authors.forename: Marla Azário
authors.initials: MA
authors.lastname: Lansarin
authors.affiliation: Chemical Engineering Department, Federal University of Rio Grande do Sul Rua Engenheiro Luiz Englert s/n - CEP: 90040-040 - Porto Alegre, RS - Brazil E-mail: tiele@enq.ufrgs.br.
authors.forename: Natália
authors.initials: N
authors.lastname: Matte
mesh_terms: D002384:Catalysis; D002857:Chromium / Q000302:isolation & purification*; D004595:Electroplating; D052918:Environmental Restoration and Remediation; D000431:Ethanol / Q000737:chemistry; D006863:Hydrogen-Ion Concentration; D055668:Photochemical Processes; D014025:Titanium / Q000737:chemistry; D014466:Ultraviolet Rays; D014865:Waste Disposal, Fluid / Q000379:methods*; D062065:Wastewater; D014874:Water Pollutants, Chemical / Q000302:isolation & purification*; D018508:Water Purification / Q000379:methods
chemical_list: D002857:Chromium; D000431:Ethanol; D014025:Titanium; D062065:Wastewater; D014874:Water Pollutants, Chemical; C009495:titanium dioxide; C074702:chromium hexavalent ion