Domestic wastewater treatment using Pt,Ni-RE (rare earth) electrodes

Eurico Moutinho; Daniele Macciò; Adriana Saccone; Margarida Mateus; Diogo Santos; Eurico Moutinho; Daniele Macciò; Adriana Saccone; Margarida Mateus; Diogo Santos

doi:10.3934/energy.2016.6.894

AIMS Energy

2016, Volume 4, Issue 6: 894-905. doi: 10.3934/energy.2016.6.894

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Domestic wastewater treatment using Pt,Ni-RE (rare earth) electrodes

1.
Materials Electrochemistry Group, CeFEMA, Instituto Superior Técnico, Universidade de Lisboa, 1049-001 Lisbon, Portugal
2.
Università di Genova, Dipartimento di Chimica e Chimica Industriale, I-16146 Genova, Italy
3.
Raw Materials Group, CERENA, Instituto Superior Técnico, Universidade de Lisboa, 1049-001 Lisbon, Portugal

Received: 25 August 2016 Accepted: 27 October 2016 Published: 02 November 2016

Electrochemical technologies can be used for the treatment of domestic wastewaters, by eliminating their organic pollutants. They have advantages over conventional methods, such as environmental compatibility, versatility, energy efficiency, safety and cost. The organic compounds degradation process is based on the production of OH radicals, formed during water electrolysis, which oxidize the organic molecules to CO₂. At the same time, hydrogen (H₂) is produced through reduction of the water in the effluent, which can be later used in a fuel cell. Present study seeks to find effective electrocatalysts to produce H₂ by electrolysis, using domestic wastewaters as the hydrogen source, with or without the addition of supporting electrolyte. Herein KOH is used as the supporting electrolyte, as the extra hydroxide can be used to degrade the organic matter. Nine different electrode materials are evaluated as cathodes for the hydrogen evolution reaction (HER) in a domestic wastewater. The tested materials include platinum (Pt) and platinum-rare earth (Pt-RE) binary alloys, and nickel (Ni) and Ni-RE alloys, with the REs being cerium (Ce), samarium (Sm), dysprosium (Dy), and holmium (Ho). Linear scan voltammetry measurements are conducted at temperatures ranging from 25 to 85 ºC. Several kinetic parameters are calculated, such as the Tafel slopes, charge transfer coefficients and exchange current densities. The data obtained at the different electrode materials is compared and it is clear that Pt-RE alloys show superior activity for the HER. It is also noticeable that the wastewater effluent containing the supporting electrolyte leads to significantly better HER performances.
- domestic wastewater treatment,
- platinum,
- nickel,
- rare-earth alloys,
- hydrogen evolution reaction
Citation: Eurico Moutinho, Daniele Macciò, Adriana Saccone, Margarida Mateus, Diogo Santos. Domestic wastewater treatment using Pt,Ni-RE (rare earth) electrodes[J]. AIMS Energy, 2016, 4(6): 894-905. doi: 10.3934/energy.2016.6.894

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Abstract

Electrochemical technologies can be used for the treatment of domestic wastewaters, by eliminating their organic pollutants. They have advantages over conventional methods, such as environmental compatibility, versatility, energy efficiency, safety and cost. The organic compounds degradation process is based on the production of OH radicals, formed during water electrolysis, which oxidize the organic molecules to CO₂. At the same time, hydrogen (H₂) is produced through reduction of the water in the effluent, which can be later used in a fuel cell. Present study seeks to find effective electrocatalysts to produce H₂ by electrolysis, using domestic wastewaters as the hydrogen source, with or without the addition of supporting electrolyte. Herein KOH is used as the supporting electrolyte, as the extra hydroxide can be used to degrade the organic matter. Nine different electrode materials are evaluated as cathodes for the hydrogen evolution reaction (HER) in a domestic wastewater. The tested materials include platinum (Pt) and platinum-rare earth (Pt-RE) binary alloys, and nickel (Ni) and Ni-RE alloys, with the REs being cerium (Ce), samarium (Sm), dysprosium (Dy), and holmium (Ho). Linear scan voltammetry measurements are conducted at temperatures ranging from 25 to 85 ºC. Several kinetic parameters are calculated, such as the Tafel slopes, charge transfer coefficients and exchange current densities. The data obtained at the different electrode materials is compared and it is clear that Pt-RE alloys show superior activity for the HER. It is also noticeable that the wastewater effluent containing the supporting electrolyte leads to significantly better HER performances.

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