Kinetic and mechanistic analysis of azo dyes decolorization by ZVI-assisted Fenton systems: pH-dependent shift in the contributions of reductive and oxidative transformation pathways

The chemical decolorization of the azo-dye Acid Black 1 (AB1) by ZVI-assisted Fenton systems was investigated for assessing the relative importance of reductive and oxidative pathways. To this end, system evolution was followed by UV–vis, HPLC, CG–MS, TOC and toxicity measurements. The effects of re...

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Detalles Bibliográficos
Autores principales: Donadelli, Jorge Andrés, Carlos, Luciano, Arques, Antonio, García Einschlag, Fernando Sebastián
Formato: Articulo Preprint
Lenguaje:Inglés
Publicado: 2018
Materias:
Química
Advanced oxidation processes
Azo Dyes
pH dependent mechanism
Wastewater treatment
Zvi-assisted Fenton
Acceso en línea:http://sedici.unlp.edu.ar/handle/10915/97419
https://ri.conicet.gov.ar/11336/88801
Aporte de:
SEDICI (UNLP) de Universidad Nacional de La Plata
id I19-R120-10915-97419
record_format dspace
institution Universidad Nacional de La Plata
institution_str I-19
repository_str R-120
collection SEDICI (UNLP)
language Inglés
topic Química
Advanced oxidation processes
Azo Dyes
pH dependent mechanism
Wastewater treatment
Zvi-assisted Fenton
spellingShingle Química
Advanced oxidation processes
Azo Dyes
pH dependent mechanism
Wastewater treatment
Zvi-assisted Fenton
Donadelli, Jorge Andrés
Carlos, Luciano
Arques, Antonio
García Einschlag, Fernando Sebastián
Kinetic and mechanistic analysis of azo dyes decolorization by ZVI-assisted Fenton systems: pH-dependent shift in the contributions of reductive and oxidative transformation pathways
topic_facet Química
Advanced oxidation processes
Azo Dyes
pH dependent mechanism
Wastewater treatment
Zvi-assisted Fenton
description The chemical decolorization of the azo-dye Acid Black 1 (AB1) by ZVI-assisted Fenton systems was investigated for assessing the relative importance of reductive and oxidative pathways. To this end, system evolution was followed by UV–vis, HPLC, CG–MS, TOC and toxicity measurements. The effects of reaction conditions including initial pH, oxidants (O2 and H2O2) concentrations, ZVI loading, and the presence of SO42− were studied. Mechanistic issues were addressed by following H2O2, Fe(II), Fe(III) and pH profiles, as well as by performing experiments in the presence of iron-complexing agents (o-phenanthroline and EDTA) or reactive species scavengers (2-propanol and DMSO). Results show that AB1 reduction occurs through heterogeneous processes with moderate to low pH dependent rates, whereas AB1 oxidation is ruled by the Fenton reaction with significantly pH dependent rates. Mechanistic studies demonstrated that AB1 decolorization in ZVI-assisted Fenton systems involves both oxidative and reductive pathways, whose relative contributions significantly change as the initial pH is raised from 3 to 5. In acidic media, AB1 is mostly transformed by oxidative pathways linked to H2O2 consumption. In contrast, in circumneutral media, a rather inefficient H2O2 consumption leads to similar contributions of oxidative and reductive AB1 transformation pathways. A detailed analysis of the pH dependence of the key reactions involved suggests that the overall system behavior is ruled by a shift in the oxidation mechanism of Fe(II) species, as a consequence of the development of a thigh corrosion layer onto ZVI particles at circumneutral pH values.
format Articulo
Preprint
author Donadelli, Jorge Andrés
Carlos, Luciano
Arques, Antonio
García Einschlag, Fernando Sebastián
author_facet Donadelli, Jorge Andrés
Carlos, Luciano
Arques, Antonio
García Einschlag, Fernando Sebastián
author_sort Donadelli, Jorge Andrés
title Kinetic and mechanistic analysis of azo dyes decolorization by ZVI-assisted Fenton systems: pH-dependent shift in the contributions of reductive and oxidative transformation pathways
title_short Kinetic and mechanistic analysis of azo dyes decolorization by ZVI-assisted Fenton systems: pH-dependent shift in the contributions of reductive and oxidative transformation pathways
title_full Kinetic and mechanistic analysis of azo dyes decolorization by ZVI-assisted Fenton systems: pH-dependent shift in the contributions of reductive and oxidative transformation pathways
title_fullStr Kinetic and mechanistic analysis of azo dyes decolorization by ZVI-assisted Fenton systems: pH-dependent shift in the contributions of reductive and oxidative transformation pathways
title_full_unstemmed Kinetic and mechanistic analysis of azo dyes decolorization by ZVI-assisted Fenton systems: pH-dependent shift in the contributions of reductive and oxidative transformation pathways
title_sort kinetic and mechanistic analysis of azo dyes decolorization by zvi-assisted fenton systems: ph-dependent shift in the contributions of reductive and oxidative transformation pathways
publishDate 2018
url http://sedici.unlp.edu.ar/handle/10915/97419
https://ri.conicet.gov.ar/11336/88801
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