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(Reference retrieved automatically from Web of Science through information on FAPESP grant and its corresponding number as mentioned in the publication by the authors.)

The role of reactive oxygen species in sulfamethazine degradation using UV-based technologies and products identification

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Author(s):
Batista, Ana Paula S. [1] ; Pires, Flavio Chiquetto C. [1] ; Teixeira, Antonio Carlos S. C. [1]
Total Authors: 3
Affiliation:
[1] Univ Sao Paulo, Dept Chem Engn, Sch Engn, BR-05508010 Sao Paulo - Brazil
Total Affiliations: 1
Document type: Journal article
Source: JOURNAL OF PHOTOCHEMISTRY AND PHOTOBIOLOGY A-CHEMISTRY; v. 290, p. 77-85, SEP 15 2014.
Web of Science Citations: 17
Abstract

Sulfamethazine (SMT) is an emerging pollutant continuously delivered into water bodies that has attracted growing attention due to its recalcitrant behavior in the environment. Although UV-based technologies have been investigated for the treatment of both water and wastewater containing SMT, photosensitization of the target compound is not usually examined during photo-induced oxidation processes. It is not our intention to propose processes for water treatment, only to understand the phenomena induced by the interactions between UV radiation and pollutant molecule. In this way, the photo-initiated and photo-induced oxidation processes are compared in terms of changes in SMT degradation rates and photoproducts formed. A tubular photochemical reactor with a concentric low pressure mercury vapor lamp emitting at 254 nm was used and SMT concentrations were determined by ultra-fast liquid chromatography analysis. Hydrogen peroxide consumption was monitored spectrophotometrically and the photoproducts were analyzed by LCMS-IT-TOF. To characterize samples we used three spectroscopic methods based on: (1) UV-Vis absorption; (2) excitation-emission matrix (EEM) fluorescence; and (3) phosphorescence. Our results suggest that photolysis and photosensitization played an important role in sulfamethazine degradation during irradiation at 254 nm. The reaction with singlet oxygen and radical species promotes sulfamethazine degradation during a photosensitized process occurring simultaneously with direct photolysis. The photo-initiated oxidation process was advantageous over the photo-induced oxidation in terms of SMT degradation rates, achieving concentration below the detection limit after 47 min of irradiation. Compounds originated from the cleavage of the C S and N-S bonds of the SMT molecule were detected as common transformation products during photo-initiated and photo-induced oxidation processes, whereas a degradation product resulting from the electrophilic addition of hydroxyl radicals to the aromatic ring was detected for the H2O2/UV system. The high efficiency of the photo-initiated oxidation process on the photodegradation of the recalcitrant sulfamethazine was verified, suggesting the formation of acidic subproducts probably from the oxidative cleavage of hydroxylated aromatic rings. (C) 2014 Elsevier B.V. All rights reserved. (AU)

FAPESP's process: 12/14889-7 - STUDY OF THE DEGRADATION OF ANTIBIOTICS AT TRACE CONCENTRATION BY PHOTO-OXIDATIVE PROCESSES
Grantee:Ana Paula dos Santos Batista
Support type: Scholarships in Brazil - Post-Doctorate