Ambiente e Sustentabilidade | Artigos em revistas internacionais / Papers in international journals
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Browsing Ambiente e Sustentabilidade | Artigos em revistas internacionais / Papers in international journals by Author "Alves, M. Madalena"
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- Bioelectrochemical energy storage in a microbial redox flow cellPublication . Santos, Márcia S. S.; Peixoto, Luciana; Mushtaq, Kashif; Ferreira, Célia; Mendes, Adélio; Alves, M. MadalenaBioelectrochemical systems (BESs) can be used to transform the electrochemical energy of fuels in electricity in Microbial Fuel Cells (MFC). However, this generated bioenergy can be captured by external loads or dissipated as heat, instead of being utilized or stored. A Microbial Redox Flow Cell (MRFC) is here presented, which demonstrates the integration of a BESs with a Redox Flow Cell (RFC); it is an innovative approach to store the energy released by the electroactive bacteria into storable electrochemical energy (electrochemical fuels) easily and effciently convertible into electricity. The MRFC uses Geobacter sulfurreducens as biocatalyst: (i) operating as Exoelectrogenic Bacteria for the reduction of the redox pair anthraquinone-2,6-disulfonate (2,6-AQDS) in anthrahydroquinone-2,6-disulfonate (2,6-AQDSH2) (BESs as bioanode of MRFC) and (ii) operating as Electrotrophic Bacteria for oxidation of the redox pair ferrocyanide ([Fe(CN)6] 4−) to ferricyanide ([Fe(CN)6] 3−) (BESs as biocathode of MRFC). In the reduction of 2,6-AQDS, current density of 0.048 mA cm−2 was recorded with a bioconversion to 2,6-AQDSH2 of ca. 27%. As for the oxidation of [Fe(CN)6] 4−, 35.7% was oxidized to [Fe(CN)6] 3−. The bio-converted electrochemical fuels were introduced in a RFC, 2,6-AQDSH2 as negalyte and ferricyanide ([Fe(CN)6] 3−) as posilyte. An MRFC, operating with 29 cycles reached Coulombic effciencies of ca. 99% and Energy effciencies of ca. 55%. The concept of a MRFC is successfully demonstrated.
- Microbially-charged electrochemical fuel for energy storage in a redox flow cellPublication . Santos, Márcia S. S.; Peixoto, Luciana; Azevedo, João; Monteiro, Ricardo A. R.; Ferreira, Célia; Alves, M. Madalena; Mendes, AdélioA Bioelectrochemical System (BES) is used for charging an electrochemical fuel to be used in a Redox Flow Cell (RFC), demonstrating the first proof of concept of a microbially-charged electrochemical fuel. Geobacter sulfurreducens, electroactive bacteria, was used to charge anthraquinone-2,6-disulfonate (2,6-AQDS) producing current densities of ca. 200–500 mA m 2 and maximum power densities of ca. 33 mW m 2 . The microbially-charged electrochemical fuel and potassium ferricyanide, K3[Fe(CN)6] were introduced in a RFC producing a potential difference of 0.62 V, with a ca. 80% energy conversion efficiency. The use of a BES for charging the posilyte of a RFC is now envisioned. The bio-conversion of waste biomass energy into electrochemical fuels (microbiallycharged electrochemical fuel for negalyte and posilyte) for later use in a RFC to produce electricity is a promising approach of converting biomass into storable and easy to use energy.