Please use this identifier to cite or link to this item: http://repositorio.unicamp.br/jspui/handle/REPOSIP/243760
Type: Artigo de periódico
Title: Remediation Of 17-alpha-ethinylestradiol Aqueous Solution By Photocatalysis And Electrochemically-assisted Photocatalysis Using Tio2 And Tio2/wo3 Electrodes Irradiated By A Solar Simulator
Author: Oliveira
Haroldo G.; Ferreira
Leticia H.; Bertazzoli
Rodnei; Longo
Claudia
Abstract: TiO2 and TiO2/WO3 electrodes, irradiated by a solar simulator in configurations for heterogeneous photocatalysis (HP) and electrochemically-assisted HP (EHP), were used to remediate aqueous solutions containing 10 mg L-1 (34 mu mol L-1) of 17-alpha-ethinylestradiol (EE2), active component of most oral contraceptives. The photocatalysts consisted of 4.5 mu m thick porous films of TiO2 and TiO2/WO3 (molar ratio W/Ti of 12%) deposited on transparent electrodes from aqueous suspensions of TiO2 particles and WO3 precursors, followed by thermal treatment at 450 degrees C. First, an energy diagram was organized with photoelectrochemical and UV-Vis absorption spectroscopy data and revealed that EE2 could be directly oxidized by the photogenerated holes at the semiconductor surfaces, considering the relative HOMO level for EE2 and the semiconductor valence band edges. Also, for the irradiated hybrid photocatalyst, electrons in TiO2 should be transferred to WO3 conduction band, while holes move toward TiO2 valence band, improving charge separation. The remediated EE2 solutions were analyzed by fluorescence, HPLC and total organic carbon measurements. As expected from the energy diagram, both photocatalysts promoted the EE2 oxidation in HP configuration; after 4 h, the EE2 concentration decayed to 6.2 mg L-1 (35% of EE2 removal) with irradiated TiO2 while TiO2/WO3 electrode resulted in 45% EE2 removal. A higher performance was achieved in EHP systems, when a Pt wire was introduced as a counter-electrode and the photoelectrodes were biased at +0.7 V; then, the EE2 removal corresponded to 48 and 54% for the TiO2 and TiO2/WO3, respectively. The hybrid TiO2/WO3, when compared to TiO2 electrode, exhibited enhanced sunlight harvesting and improved separation of photogenerated charge carriers, resulting in higher performance for removing this contaminant of emerging concern from aqueous solution. (C) 2014 Elsevier Ltd. All rights reserved.
Subject: Waste-water
Degradation
Films
Wo3
17-alpha-ethynylestradiol
Photodegradation
Photolysis
Estrogens
Hormones
Estrone
Country: OXFORD
Editor: PERGAMON-ELSEVIER SCIENCE LTD
Rights: fechado
Identifier DOI: 10.1016/j.watres.2014.08.042
Address: http://www.sciencedirect.com/science/article/pii/S0043135414006095
Date Issue: 2015
Appears in Collections:Unicamp - Artigos e Outros Documentos

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