title: Microwave-enhanced UV/H2O2 degradation of an azo dye (tartrazine): optimization, colour removal, mineralization and ecotoxicity.
abstract: This study optimizes two factors, pH and initial [H2O2], in the ultraviolet (UV)/H2O2/microwave (MW) process through experimental design and assesses the effect of MWs on the colour removal of an azo-dye (tartrazine) solution that was favoured by an acidic pH. The estimated optimal conditions were: initial [H2O2] = 2.0 mmol L(-1) and pH = 2.6, at 30 +/- 2 degrees C. We obtained colour removals of approximately 92% in 24 min of irradiation (EDL, 244.2 W), following zero order kinetics: k = (3.9 +/- 0.52) x 10(-2) a.u. min(-1) and R2 = 0.989. Chemical and biological oxygen demand were significantly removed. On the other hand, the carbon content, biodegradability and ecotoxicity (Lactuca sativa) remained approximately the same. The UV/H2O2/MW process was shown to be eight times faster than other tested processes (MW, H2O2, H2O2/MW, and UV/MW).
authors.affiliation: Chemistry and Molecular Physics Department, Institute of Chemistry of São Carlos, University of Sãão Paulo (USP), São Carlos/SP, Brazil.
authors.forename: Fernanda
authors.initials: F
authors.lastname: Parolin
authors.forename: Ulisses Magalhães
authors.initials: UM
authors.lastname: Nascimento
authors.forename: Eduardo Bessa
authors.initials: EB
authors.lastname: Azevedo
mesh_terms: D057919:Biological Oxygen Demand Analysis; D006861:Hydrogen Peroxide / Q000737:chemistry*; D006863:Hydrogen-Ion Concentration; D008872:Microwaves; D010084:Oxidation-Reduction; D010782:Photolysis; D013645:Tartrazine / Q000737:chemistry* / Q000302:isolation & purification / Q000378:metabolism / Q000528:radiation effects*; D014466:Ultraviolet Rays; D014874:Water Pollutants, Chemical / Q000737:chemistry* / Q000302:isolation & purification / Q000378:metabolism / Q000528:radiation effects*
chemical_list: D014874:Water Pollutants, Chemical; D006861:Hydrogen Peroxide; D013645:Tartrazine