Hydrogen production from water splitting is a widely used technique and hematite is one of the most used semiconductors in these processes due to its favorable characteristics such as: adequate band gap, visible light absorption, high chemical stability, abundance in nature, among others. Research on hydrogen fuel production from ammonia instead of water is still very limited. Ammonia is a contaminant normally found in wastewater and annualy tons of ammonia or effluents containing this contaminant are thrown into the environment, making it an ideal reagent to produce hydrogen in a clean environmental process. Based on this knowledge, this work proposes the comparison of the photoelectrochemical performance of hematite doped with structural cations (zinc, copper, cobalt, and nickel) in the molecular fragmentation of water and ammonia to produce hydrogen. A structural characterization of the materials used and tests for PEC activity were performed. Pure hematite doped with ammonia as a substrate presented higher electrical current and it was not activated by visible light. When under visible light hematite‐Co presented a discrete increase in the electrical current and, consequently, a small increase in the hydrogen production from water, whereas in the tests with ammonia, the copper‐doped hematite was responsible for a slight increase in the electrical current.
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There is a growing number of studies related to computational fluid dynamics for the construction and optimization of equipment, machines, and systems. In this work, the main knowledge needed to perform an analysis of computational fluid dynamics in airlift-type bioreactors for ethanol production will be addressed.
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Biofuels are present in the global scenario as an energy source derived from organic biomass, representing an economic and environmental alternative. They are a renewable source of energy with low rates of pollutants emissions and, consequently, less carbon dioxide is released into the atmosphere. The obtaining of bioethanol is originated from a fermentation process, in which a multi-component mix is generated and the anhydrous bioethanol is separated. To obtain such compounds, some operations are required, such as extractive distillation, where solvents are added in order to "break" the ethanol-water azeotrope. In the present work two solvents were used: Glycerol and the ionic liquid [BMIM][BF4]. Starting from a multi-component mixture composed by ethanol, water, acetic acid and isoamyl alcohol, the bioethanol purification process was simulated using the computational tool Aspen Plus® simulator. Through a comparative analysis, it was possible to determine which solvent presented the best performance, where operational parameters such as the reflux ratio, distillate rate and the solvent flow were analyzed. The purity degree of 99.7% in mass and an approximate production of 2764 kg/h of anhydrous bioethanol were fixed and the results showed that glycerol was the solvent that presented greater economic and environmental viability for the process, considering the operational parameters mentioned above.
The discovery of the environmental impacts caused by petroleumbased polymers has led to the use of natural polymers gaining more and more space. Naturally occurring polymers, also known as biopolymers, are chemical compounds produced by living things or raw materials from renewable energy sources. Their main advantage is decomposition, while polymers from fossil and non-renewable energies can take hundreds of years to decompose, biopolymers have significantly shorter life cycles. In this study, a study of the application of the biomass of the microalgae Spirulina platensis in biodegradable films with corn starch was conducted, aiming for the development of a functional film with rapid degradability. Approximately 48 biofilms were produced in varying concentrations (w/v), where the visual characteristics of each were observed and the ones that presented the greatest resemblance to conventional plastics were selected, being Trial 4 (T4) and Trial 46 (T46), composed of 2 and 70% v/v of microalgae, respectively. The other tries were discarded due to cracking, high fragility, and very gelatinous or very rigid appearance. The morphological characteristics of T4 and T46 biofilms were analyzed by Scanning Electron Microscopy (SEM) and compared to those of a conventional plastic bag and a commercially available biodegradable plastic bag, where it was possible to prove that the biofilms produced presented good morphological structure. The Fourier Transform Infrared Spectroscopy (FTIR) analysis provided structural information, proving the presence of polyhydroxyalkanoate in the biofilms produced. Two degradability tests were performed with satisfactory results obtained, proving the rapid degradation of the biopolymers produced. It was possible to prove that the biofilms under study present great potential for replacing conventional polymers.
A produção de resíduos sólidos urbanos apresenta grandes disparidades, variando tanto no nível dos vários países do mundo, como, dentro de cada país, de região para região onde a assimetria é evidente e requer um processo de gerenciamento com protocolos e técnicas nem sempre cumpridos. A decomposição dos resíduos confinados em aterros ou dispersos pelo ambiente emite gases relacionados às alterações atmosféricas. No presente estudo foram usadas duas metodologias para estimar a geração de biogás e gás metano, a recomendada pela Agência de Proteção Ambiental dos Estados Unidos e a do Painel Intergovernamental sobre Mudanças Climáticas, bem como foi realizada a amostragem e composição gravimétrica dos resíduos sólidos urbanos conforme a metodologia simplificada indica pela FEAM de 2015 e a ABNT NBR 10.007;2004. Como metodologia foi proposto um estudo de caso no Aterro de Resíduos Sólidos Urbanos do Município de Ribeirão das Neves-MG e o levantamento gravimétrico dos RSU municipais. A descrição da ação microbiana frente a significativa e farta quantidade de resíduos depositados nos aterros é de fundamental importância para o monitoramento, a avaliação decompositora e suas característica específicas. A determinação do mecanismo de ação das bactérias metanogênicas é um campo que ainda necessita de estudos e elaboração de experimentos específicos para cada aterro, sanitário ou controlado, principalmente no que refere-se a adequação de técnicas para inoculação deste tipo de microorganismos com o objetivo de potencializar a geração de biogás através da decomposição dos RSU com rigoroso monitoramento e controle. PALAVRAS-CHAVE: Archaea; biogás; aproveitamento energético; metano
<p><em>O biodiesel vem sendo amplamente utilizado no mercado atual como uma alternativa de substituição aos combustíveis fósseis finitos. No final de sua produção, 10% da corrente de saída do processo é composta de glicerol. A conversão deste glicerol em hidrogênio é uma alternativa que visa agregar valor econômico a este subproduto. Sendo assim, este trabalho apresenta um estudo da reforma em fase aquosa de glicerol, subproduto de um processo de produção de biodiesel, utilizando catalisador de platina suportados em Al<sub>2</sub>O<sub>3</sub> para produção de hidrogênio. Para isto, os balanços de massa e energia foram analisados, onde os resultados mostraram uma corrente final constituída de hidrogênio e 4,66% de CO<sub>2</sub>,</em> <em>impactando em baixos gastos energéticos e gerando resíduos menos poluentes se comparados as rotas de reforma mais tradicionais empregadas na indústria</em><em>.</em></p><p><em> </em></p><p><em>Abstract</em></p><p><em> Biodiesel is being widely used in the current market in place of fossil fuels. At the end of its production process, 10% of the output stream is comprised of glycerol. The conversion of this glycerol into hydrogen is an alternative that can add economic value to the by-product. This paper presents a study of the aqueous-phase reforming of glycerol, by product of a biodiesel production process, over platinum catalysts supported on Al<sub>2</sub>O<sub>3</sub> for hydrogen production. For this, the mass and energy balances were analyzed, where the results showed a final current constituted of hydrogen and only 4.66% of CO<sub>2</sub>, impacting on low energy costs and the generation of less polluting residues when compared to the used in industry.</em></p>
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