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Removal of methylene blue from aqueous solutions using an Fe2+ catalyst and in-situ H2O2 generated at gas diffusion cathodes

Removal of methylene blue from aqueous solutions using an Fe2+ catalyst and in-situ H2O2 generated at gas diffusion cathodes
Removal of methylene blue from aqueous solutions using an Fe2+ catalyst and in-situ H2O2 generated at gas diffusion cathodes
Textile industries generate large volumes of wastewater containing organic dyes, which may be hazardous to the environment and human health. In this work, the oxidation of 100 mg dm-3 of methylene blue (MB) in aqueous solutions was studied using H2O2 (formed in-situ) at gas diffusion electrodes (GDEs) in the presence of 1 × 10-3 mol dm-3 Fe2+ catalyst, to create hydroxyl radicals to facilitate Fenton oxidation. The influence of applied potential (-0.5 to -1.3 V vs. Ag/AgCl) at different oxygen flow rates to the GDE (0.15 – 0.45 cm3 min-1) and different counter electrode materials (Pt mesh, Ni mesh, RVC) was investigated. MB was completely degraded to a residual concentration below the detection limit of 0.5 mg dm-3. The rate and degree of mineralisation were significantly influenced by the applied potential. A maximum mineralisation of 88.2% was achieved at -1.0 V vs. Ag/AgCl. The oxygen flow rate to the GDE did not influence the degradation of MB under the experimental conditions. The counter electrode material affected the degree of mineralisation in the order Pt mesh > reticulated vitreous carbon (RVC) > Ni mesh. The apparent first order rate decay constant for MB degradation and MB mineralisation was calculated to have a maximum value of 0.0182 min-1 for MB mineralisation at a potential of -1.0 V vs. Ag/AgCl.
electrochemical oxidation, electro-Fenton process, gas diffusion electrode, methylene blue.
0013-4686
45-53
Lacasa, Engracia
b600711a-d713-45ea-90fe-51e70460b90e
Cañizares, Pablo
586ce278-f529-43b3-a9d0-ffef7b94dbe1
Walsh, Frank C.
309528e7-062e-439b-af40-9309bc91efb2
Rodrigo, Manuel A.
60f5b735-d515-487e-b3b1-19f0e6f85002
Ponce De Leon, Carlos
508a312e-75ff-4bcb-9151-dacc424d755c
Lacasa, Engracia
b600711a-d713-45ea-90fe-51e70460b90e
Cañizares, Pablo
586ce278-f529-43b3-a9d0-ffef7b94dbe1
Walsh, Frank C.
309528e7-062e-439b-af40-9309bc91efb2
Rodrigo, Manuel A.
60f5b735-d515-487e-b3b1-19f0e6f85002
Ponce De Leon, Carlos
508a312e-75ff-4bcb-9151-dacc424d755c

Lacasa, Engracia, Cañizares, Pablo, Walsh, Frank C., Rodrigo, Manuel A. and Ponce De Leon, Carlos (2019) Removal of methylene blue from aqueous solutions using an Fe2+ catalyst and in-situ H2O2 generated at gas diffusion cathodes. Electrochimica Acta, 308, 45-53. (doi:10.1016/j.electacta.2019.03.218).

Record type: Article

Abstract

Textile industries generate large volumes of wastewater containing organic dyes, which may be hazardous to the environment and human health. In this work, the oxidation of 100 mg dm-3 of methylene blue (MB) in aqueous solutions was studied using H2O2 (formed in-situ) at gas diffusion electrodes (GDEs) in the presence of 1 × 10-3 mol dm-3 Fe2+ catalyst, to create hydroxyl radicals to facilitate Fenton oxidation. The influence of applied potential (-0.5 to -1.3 V vs. Ag/AgCl) at different oxygen flow rates to the GDE (0.15 – 0.45 cm3 min-1) and different counter electrode materials (Pt mesh, Ni mesh, RVC) was investigated. MB was completely degraded to a residual concentration below the detection limit of 0.5 mg dm-3. The rate and degree of mineralisation were significantly influenced by the applied potential. A maximum mineralisation of 88.2% was achieved at -1.0 V vs. Ag/AgCl. The oxygen flow rate to the GDE did not influence the degradation of MB under the experimental conditions. The counter electrode material affected the degree of mineralisation in the order Pt mesh > reticulated vitreous carbon (RVC) > Ni mesh. The apparent first order rate decay constant for MB degradation and MB mineralisation was calculated to have a maximum value of 0.0182 min-1 for MB mineralisation at a potential of -1.0 V vs. Ag/AgCl.

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Accepted/In Press date: 31 March 2019
e-pub ahead of print date: 1 April 2019
Published date: 10 June 2019
Keywords: electrochemical oxidation, electro-Fenton process, gas diffusion electrode, methylene blue.

Identifiers

Local EPrints ID: 431412
URI: http://eprints.soton.ac.uk/id/eprint/431412
ISSN: 0013-4686
PURE UUID: 2e9bb94b-ab95-41c7-8ef2-b7aa05e2ed8e
ORCID for Carlos Ponce De Leon: ORCID iD orcid.org/0000-0002-1907-5913

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Date deposited: 31 May 2019 16:30
Last modified: 07 Oct 2020 06:42

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