title: Influence of pH and ozone dose on sulfaquinoxaline ozonation.
abstract: Sulfaquinoxaline (SQX) is an antimicrobial of the sulfonamides class. Usually employed in veterinary medicine, this contaminant of emerging concern has been found in superficial and groundwater and its consequences for the environment and human health are not completely known. In this study, SQX (C0= 500 μg L-1, 1 L) degradation by an ozonation process at pH 3, 7, and 11 was evaluated. Ozonation was effective in degrading SQX: efficiency exceeding 99% was obtained applying an ozone dose of 2.8 mg L-1at pH 3. Assays were performed according to a 22design of experiments (DOE) with star points and three central points for statistical validity. Minimum and maximum levels were set at 3 and 11 for pH, and 0 and 11.5 mg L-1for applied ozone dose. There was no significant interaction between these variables, and the pH value played the most important role in terms of contaminant degradation. In relation to toxicity, samples ozonated at pH 3 did not inhibit the luminescence of the bacteria, even though different intermediates were formed and identified by mass spectra. At pH 7, inhibition of luminescence remained almost constant (at around 30%) according to ozonation time or ozone dose. However, the hydroxyl radical, the major oxidant at pH 11, was responsible for the formation of toxic intermediates.
authors: School of Civil Engineering, Architecture and Urban Design, University of Campinas, P.O. Box 6143, 13083-889, Campinas, Brazil.
authors: Vanessa Ribeiro
authors: VR
authors: Urbano
authors: School of Civil Engineering, Architecture and Urban Design, University of Campinas, P.O. Box 6143, 13083-889, Campinas, Brazil.
authors: Milena Guedes
authors: MG
authors: Maniero
authors: Escola d'Enginyeria de Barcelona Est, EEBE, Chemical Engineering Department, UPC, BARCELONATECH, Comte d'Urgell 187, 08036, Barcelona, Spain.
authors: Montserrat
authors: M
authors: Pérez-Moya
authors: School of Civil Engineering, Architecture and Urban Design, University of Campinas, P.O. Box 6143, 13083-889, Campinas, Brazil. Electronic address: jorober@fec.unicamp.br.
authors: José Roberto
authors: JR
authors: Guimarães
mesh_terms: D006863:Hydrogen-Ion Concentration; D017665:Hydroxyl Radical; D010084:Oxidation-Reduction; D010126:Ozone; D013428:Sulfaquinoxaline; D014874:Water Pollutants, Chemical
chemical_list: D014874:Water Pollutants, Chemical; D017665:Hydroxyl Radical; D010126:Ozone; D013428:Sulfaquinoxaline
keywords: Advanced oxidation processes; Microtox; Molecular ozone; Sulfonamides; Toxicity assays