Biotratamento de vinhaça sintética e geração de eletricidade utilizando uma célula a combustível microbiana

Avanços Científicos e Tecnológicos em BioprocessosO Brasil é um dos maiores produtores de etanol no mundo, no entanto, durante o processo de obtenção deste combustível, elevadas quantidades de vinhaça são geradas, em média, para cada litro de etanol produzido são gerados 13 litros deste resíduo. A vinhaça possui propriedades físicas e químicas que podem desencadear efeitos nocivos à biota, deste modo, existe um interesse crescente em identificar novas tecnologias para o seu tratamento. A utilização de células a combustível microbianas (CCMs) apresenta um enorme potencial, uma vez que, pode promover simultaneamente o tratamento deste resíduo e a biogeração de energia elétrica, pela conversão da energia química disponível nesses substratos biodegradáveis diretamente em eletricidade, por meio da ação catalítica de bactérias eletrogênicas aderidas ao eletrodo. Neste contexto, o presente estudo avaliou a utilização de uma CCM de câmara dupla no tratamento de vinhaça sintética. Durante a operação deste reator foi detectada uma máxima densidade de potência de 330 mW·m-2 e uma redução na demanda química de oxigênio (DQO) em 58,8% após 28 dias. Diante destes resultados preliminares, a tecnologia CCM pode ser considerada promissora no tratamento da vinhaça, contudo, estudos a respeito da configuração, tipo de inóculo e formas de operação da CCM são necessários para que amplie sua eficiência.Brazil is one of the largest producers of ethanol in the world, however, during the process of obtaining ethanol, high quantities of vinasse are generated, on average, for each liter of ethanol produced, 13 liters of this residue is generated. Vinasse has physical and chemical properties that can trigger harmful effects on biota, so there is a growing interest in identifying new technologies for its treatment. The use of microbial fuel cells (CCMs) presents a very high potential, since it can simultaneously promote the treatment of this residue and the biogeneration of electric energy, by converting the available chemical energy in these biodegradable substrates and directly into electricity, by means of the action of electrogenic bacteria adhered to the electrode. In this context, the present study evaluated the use of a double chamber CCM in the treatment of synthetic vinasse. During the operation of this reactor, a maximum power density of 330 mW m-2 and a reduction in chemical oxygen demand (COD) was detected at 58.8% after 28 days. Considering these preliminary results, CCM technology may be considered promising in the treatment of vinasse, however, studies regarding the configuration, type of inoculum and forms of CCM operation are necessary to increase its efficiency.info:eu-repo/semantics/publishedVersio

Pseudocapacitance Properties of Co3O4 Nanoparticles Synthesized Using a Modified Sol-Gel Method

<div><p>This work reports the synthesization of nanoparticles cobalt oxide (Co3O4) with no secondary phase by a modified sol-gel method and its structural morphological and electrochemical characterizations. FTIR, XRD and Raman analysis showed the formation of spinel cobalt oxide with no secondary phase. TEM images revealed that an undefined morphology with average crystallite size estimated by Scherrer's equation was found to be 30 nm. Experiments of cyclic voltametric, galvanostatic charge-discharge and impedance spectroscopy were evaluated at 1 mol L-1 KOH and revealed an intrinsic pseudocapacitance. The studies of complex capacitance and complex power revealed the resistive and capacitive characteristics with a specific capacitance of 120 F g-1.</p></div

Ethanol electro-oxidation in an alkaline medium using Pd/C, Au/C and PdAu/C electrocatalysts prepared by electron beam irradiation

Carbon-supported Pd, Au and bimetallic PdAu (Pd:Au 90:10, 50:50 and 30:70 atomic ratios) electrocatalysts were prepared using electron beam irradiation. The obtained materials were characterized by energy dispersive X-ray analysis (EDX), X-ray diffraction (XRD) and transmission electron microscopy (TEM), and their catalytic activities toward ethanol electro-oxidation were evaluated in an alkaline medium using electrochemical techniques, in situ attenuated total reflectance Fourier transformed infrared spectroscopy (ATR-FTIR) analysis and a single alkaline direct ethanol fuel cell (ADEFC). EDX analyses showed that the actual Pd: Au atomic ratios were very similar to the nominal ones. X-ray diffractograms of PdAu/C electrocatalysts evidenced the presence of Pd-rich (fcc) and Au-rich (fcc) phases. TEM analysis showed a homogeneous dispersion of nanoparticles on the carbon support, with an average size in the range of 3-5 nm and broad size distributions. Cyclic voltammetry (CV) and chronoamperometry (CA) experiments revealed the superior ambient activity toward ethanol electro-oxidation of PdAu/C electrocatalysts with Pd: Au ratios of 90:10 and 50:50. In situ ATR-FTIR spectroscopy measurements have shown that the mechanism for ethanol electro-oxidation is dependent on catalyst composition, leading to different reaction products, such as acetaldehyde and acetate, depending on the number of electrons transferred. Experiments on a single ADEFC were conducted between 50 and 900 C, and the best performance of 44 mW cm-2 in 2.0molL-1 ethanol was obtained at 850C for the Pd:Au 90:10 catalysts. This superior performance is most likely associated with enhancement of ethanol adsorption on Pd, oxidation of the intermediates, the presence of gold oxide-hydroxyl species, low mean particle diameters and better distribution of particles on the support. © 2013 Elsevier Ltd. All rights reserved

Microbial fuel cell-induced production of fungal laccase to degrade the anthraquinone dye Remazol Brilliant Blue R

The anthraquinone dye Remazol Brilliant Blue R is largely used in the textile industry. However, its removal from wastewaters is costly and complex. Many methods have been tested to solve this ecological problem, but there is still a need for efficient methods. We propose here an alternative use of a two-chambered microbial fuel cell (MFC), fuelled with domestic wastewater in the anodic chamber, to degrade a simulated textile dye effluent made of Remazol Brilliant Blue R inoculated with an immobilised fungal strain, Pleurotus ostreatus URM 4809, as a laccase producer, in the cathodic chamber. The MFC showed continuous synthesis of laccase in the cathodic chamber, which, in turn, promoted the rapid decolourisation, of more than 86\% of the textile dye effluent. The yield was further increased by the addition of glycerol. Electrochemical monitoring also indicated an increase in power density and current density. After 20 days of MFC operation, 62.1\\% of organic matter was removed in the anodic compartment, thus leaving the effluent with a much lower toxicity.Authors would like to acknowledge the technician and fnancial support of Programa Novos Talentos provided by the Instituto de Pesquisa Tecnológica do Estado de São Paulo (IPT) and Instituto de Estudos Avançados do Mar (IEAMar).info:eu-repo/semantics/publishedVersio

Neotropical freshwater fisheries : A dataset of occurrence and abundance of freshwater fishes in the Neotropics

The Neotropical region hosts 4225 freshwater fish species, ranking first among the world's most diverse regions for freshwater fishes. Our NEOTROPICAL FRESHWATER FISHES data set is the first to produce a large-scale Neotropical freshwater fish inventory, covering the entire Neotropical region from Mexico and the Caribbean in the north to the southern limits in Argentina, Paraguay, Chile, and Uruguay. We compiled 185,787 distribution records, with unique georeferenced coordinates, for the 4225 species, represented by occurrence and abundance data. The number of species for the most numerous orders are as follows: Characiformes (1289), Siluriformes (1384), Cichliformes (354), Cyprinodontiformes (245), and Gymnotiformes (135). The most recorded species was the characid Astyanax fasciatus (4696 records). We registered 116,802 distribution records for native species, compared to 1802 distribution records for nonnative species. The main aim of the NEOTROPICAL FRESHWATER FISHES data set was to make these occurrence and abundance data accessible for international researchers to develop ecological and macroecological studies, from local to regional scales, with focal fish species, families, or orders. We anticipate that the NEOTROPICAL FRESHWATER FISHES data set will be valuable for studies on a wide range of ecological processes, such as trophic cascades, fishery pressure, the effects of habitat loss and fragmentation, and the impacts of species invasion and climate change. There are no copyright restrictions on the data, and please cite this data paper when using the data in publications