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Author(s): Francisca C. Moreira
Sergi Garcia-Segura
Vítor J. P. Vilar
Rui A. R. Boaventura
Enric Brillas
Title: Decolorization and mineralization of Sunset Yellow FCF azo dye by anodic oxidation, electro-Fenton, UVA photoelectro-Fenton and solar photoelectro-Fenton processes
Issue Date: 2013
Abstract: The decolorization and mineralization of 100 mL of 290 mg L-1 Sunset Yellow FCF (SY) azo dye at pH 3.0 were studied by anodic oxidation with electrogenerated H2O2 (AO-H2O2), electro-Fenton (EF), UVA photoelectro-Fenton (PEF) and solar photoelectro-Fenton (SPEF). Trials were performed in a one-compartment cell equipped with a boron-doped diamond (BDD) anode and a carbon-PTFE air-diffusion cathode. Organics were removed by hydroxyl radical ((OH)-O-center dot) formed: (i) at the BDD anode from water oxidation, (ii) in the bulk from Fenton's reaction between added Fe2+ and generated H2O2 at the cathode and (iii) from the photolysis of Fe(OH)(2+) species by UV light. The most powerful method was SPEF, achieving an almost total mineralization more rapidly than PEF due to the higher UV intensity of sunlight, which quickly photolyzes Fe(III)-carboxylate complexes that cannot be destroyed by (OH)-O-center dot in EF. However, SY was completely decolorized at similar rate by EF, PEF and SPEF. The little oxidation action of (OH)-O-center dot at the BDD anode yielded a slow decolorization and mineralization in AO-H2O2. The effect of current density on all treatments was examined. The azo dye decay always followed a pseudo-first-order reaction. It was more rapidly removed than decolorized, indicating that colored aromatic products are involved in the decolorization process. A total of 14 aromatic products and 34 hydroxylated derivatives, including benzenic, naphthalenic and phthalic acid compounds, were detected by LC-MS. Generated carboxylic acids like tartronic, oxalic, formic and oxamic were identified by ion-exclusion HPLC. The viability of SPEF at industrial scale was demonstrated using a solar pre-pilot plant with a Pt/carbon-PTFE air-diffusion cell coupled with a compound parabolic collectors (CPCs) photoreactor. In this plant, the treatment of 101 of 290 mg L-1 SY at pH 3.0 between 33.2 and 77.6 mA cm(-2) gave total decolorization and 91-94% mineralization in short time. A plausible general reaction sequence for SY mineralization involving all oxidation products detected was proposed.
Subject: Ciências Tecnológicas, Ciências da engenharia e tecnologias
Technological sciences, Engineering and technology
Scientific areas: Ciências da engenharia e tecnologias
Engineering and technology
Related Information: info:eu-repo/grantAgreement/FCT - Fundação para a Ciência e Tecnologia/Programa de Financiamento Plurianual de Unidades de I&D/PEst-C/EQB/LA0020/2011/Projeto Estratégico-LA 20 - 2011-2012/LA 20
Document Type: Artigo em Revista Científica Internacional
Rights: restrictedAccess
Appears in Collections:FEUP - Artigo em Revista Científica Internacional

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