Applications of hydrogen peroxide in electrochemical technology
Applications of hydrogen peroxide in electrochemical technology
It is demonstrated that hydrogen peroxide can be produced with a current efficiency of 40-70% by the cathodic reduction of oxygen at a reticulated vitreous carbon electrode in a divided flow-cell using catholytes consisting of aqueous chloride or sulphate media, pH ≈2. The supporting electrolyte does not influence either the current efficiency for H2O2 or its rate of production. The current efficiency for H2O2 is not a strong function of the potential and this suggests that 2e- or 4e- reduction of oxygen occurs in parallel at different sites on the carbon surface.
Voltammetry experiments showed that (a) the I-E response for oxygen reduction at pH ≈ 2 is a function of the electrode surface and/or the supporting electrolyte; (b) both H2 evolution and oxygen reduction are retarded on carbon with increasing ionic strength; (c) the presence of ferrous ions leads to the homogeneous decomposition of H2O2 away from the cathode surface, but their effectiveness as a catalyst for this decomposition depends on their speciation in solution which changes during an electrolysis.
The use of a three-dimensional electrode fabricated from reticulated vitreous carbon allows Fenton's reagent to be electroproduced at a practical rate which makes possible the removal of organics in slightly acidic aqueous media. A wide range of highly toxic organic molecules (phenol, catechol, hydroquinone, p-benzoquinone, oxalic acid, aniline, cresol and amaranth) have been oxidised in mild conditions and a significant fraction of the organic carbon is evolved as CO2. In all cases studied the initial chemical oxygen demand (COD) was depleted to levels higher than 85%, indicating a complete mineralisation of the organic pollutants.
The life-time of the reticulated vitreous carbon cathode was demonstrated to be over 1000 hours during two and a half years of experiments. During this time the cathode performance was very good, leading to reproducible results and indicating that under the experimental conditions studied the reticulated vitreous carbon cathode and the cell components were chemically and electrochemically stable.
University of Southampton
Alvarez-Gallegos, Alberto Armando
1998
Alvarez-Gallegos, Alberto Armando
Alvarez-Gallegos, Alberto Armando
(1998)
Applications of hydrogen peroxide in electrochemical technology.
University of Southampton, Doctoral Thesis.
Record type:
Thesis
(Doctoral)
Abstract
It is demonstrated that hydrogen peroxide can be produced with a current efficiency of 40-70% by the cathodic reduction of oxygen at a reticulated vitreous carbon electrode in a divided flow-cell using catholytes consisting of aqueous chloride or sulphate media, pH ≈2. The supporting electrolyte does not influence either the current efficiency for H2O2 or its rate of production. The current efficiency for H2O2 is not a strong function of the potential and this suggests that 2e- or 4e- reduction of oxygen occurs in parallel at different sites on the carbon surface.
Voltammetry experiments showed that (a) the I-E response for oxygen reduction at pH ≈ 2 is a function of the electrode surface and/or the supporting electrolyte; (b) both H2 evolution and oxygen reduction are retarded on carbon with increasing ionic strength; (c) the presence of ferrous ions leads to the homogeneous decomposition of H2O2 away from the cathode surface, but their effectiveness as a catalyst for this decomposition depends on their speciation in solution which changes during an electrolysis.
The use of a three-dimensional electrode fabricated from reticulated vitreous carbon allows Fenton's reagent to be electroproduced at a practical rate which makes possible the removal of organics in slightly acidic aqueous media. A wide range of highly toxic organic molecules (phenol, catechol, hydroquinone, p-benzoquinone, oxalic acid, aniline, cresol and amaranth) have been oxidised in mild conditions and a significant fraction of the organic carbon is evolved as CO2. In all cases studied the initial chemical oxygen demand (COD) was depleted to levels higher than 85%, indicating a complete mineralisation of the organic pollutants.
The life-time of the reticulated vitreous carbon cathode was demonstrated to be over 1000 hours during two and a half years of experiments. During this time the cathode performance was very good, leading to reproducible results and indicating that under the experimental conditions studied the reticulated vitreous carbon cathode and the cell components were chemically and electrochemically stable.
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Published date: 1998
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Local EPrints ID: 463528
URI: http://eprints.soton.ac.uk/id/eprint/463528
PURE UUID: b190fb47-ad88-4590-885e-6ce71249ec1f
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Date deposited: 04 Jul 2022 20:53
Last modified: 04 Jul 2022 20:53
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Author:
Alberto Armando Alvarez-Gallegos
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