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Common carbon-blacks have shown insufficient stability as cathodic catalyst supports for proton exchange membrane fuel cells (PEMFCs). In this regard, alternative supports have been proposed and, specifically graphene or reduced graphene oxide (rGO), have attracted special attention. Herein, a set of electrocatalysts using reduced graphene oxide (rGO) as support is synthetized by a modified polyol method. The influence of Pt loading on the support is studied and compared with conventional supports, considering Pt particle morphologies and oxygen reduction reaction (ORR) performance in rotating disk electrode (RDE). Despite Pt average particle size typically increases with the Pt loading, 30 wt% of Pt on rGO is the optimal Pt loading, yielding the highest ORR activity among the rGO-supported electrocatalysts. These results show that both Pt loading and type of support greatly impact on the morphology and electrochemical performance of Pt nanoparticles.

Humidity is one of the main environmental factors that limits performance and stability of perovskite solar cells (PSC); it plays a critical role during the preparation of the perovskite film, influencing the crystal growth. In this work, it is investigated the effect of the relative humidity (RH) and type of atmosphere (nitrogen vs air) used during the deposition of both perovskite layer and hole extraction layer (HEL). While humidity and oxygen seem not to affect the HEL deposition step, the perovskite layer is notoriously influenced by the RH and by the presence of oxygen during its deposition. Until 10% of RH, the performance of devices prepared with a triple-cation perovskite layer deposited under a nitrogen environment was mostly unaffected, whilst for devices deposited in air that limit is lower. On the other hand, for high RH values (above 30%), devices prepared with a triple-cation perovskite layer deposited under N2 presented slightly better stability over time than the ones prepared under air. The best-performing device was prepared with a triple-cation perovskite layer deposited under dry air, presenting a power conversion efficiency of 16.7%. These results are of critical value when designing a plant for fabricating PSC showing that the perovskite layer may be deposited under a simple dry air atmosphere (RH

CNPq - Conselho Nacional de Desenvolvimento Científico e Tecnológico O uso de catalisadores bifuncionais para a captura de dióxido de carbono (CO2) concomitante à reação de reforma a vapor de hidrocarbonetos tem sido proposto como uma possível opção para melhorar o rendimento de hidrogênio (H2) e diminuir as emissões de CO2. Neste trabalho, o desempenho dos catalisadores bifuncionais de Ni suportados em CaO, CaO-CaZrO3 e CaO-Ca2SiO4 foi testado em ciclos de carbonatação e regeneração e de reforma a vapor do propano com captura de CO2. Os catalisadores foram sintetizados pelo método sol-gel e caracterizados usando técnicas de Difratometria de Raios-X ex situ e in situ, Microscopia Eletrônica de Varredura e Espectroscopia de Absorção de Raios-X in situ. Os testes de carbonatação mostraram que os catalisadores contendo ZrO2 e SiO2 foram mais estáveis termicamente. Esta melhora pode ser atribuída à minimização da sinterização do CaO, em decorrência da maior estabilidade térmica agregada pela formação do CaZrO3 e Ca2SiO4 e por ambos evitarem o contato entre as partículas de CaO. O catalisador contendo sílica, apesar de possuir menor percentual de CaO livre, e portanto um menor período antes de atingir a saturação em termos da captura de CO2 (pre-breakthrough), produziu H2 com maior pureza, tanto no pre-breakthrough quanto no post-breakthrough, com purezas próximas a 95 e 80%, respectivamente. Já o catalisador contendo zircônia apresentou melhor captura de CO2 desde o 2º ciclo de carbonatação, quando comparado ao catalisador de Ni/CaO, além de tempo de pre-breakthrough estável e em torno de 50 minutos. A formação dos óxidos mistos CaZrO3 e Ca2SiO4 favoreceu a estabilidade térmica dos catalisadores tanto durante os testes de carbonatação, quanto durante os testes reacionais. Os testes de análise termogravimétrica (ATG) após os ciclos reacionais também mostraram que provavelmente a presença dos óxidos mistos CaZrO3 e Ca2SiO4 nos catalisadores minimizou a formação de coque na superfície dos catalisadores, passando de 3,6 para 1,3 e 1,5 mgC/gcat/h, para os catalisadores de Ni/Ca, Ni/CaZr e Ni/CaSi, respectivamente. The use of bifunctional catalysts to carbon dioxide (CO2) capture with concomitant hydrocarbon steam reform has been proposed as a possible option to improve hydrogen yield (H2) and decrease CO2 emissions. In this study, the performance of bifunctional catalysts of Ni over CaO, CaO-CaZrO3 and CaO-Ca2SiO4 were tested in CO2 capture and sorption-enhanced steam propane reforming cycles. The catalysts were synthesized by sol-gel technique and characterized by X-ray Diffraction (XRD) ex situ and in situ, Scanning Electron Microscopy (SEM), and X-Ray Absorption Spectroscopy (XAS) in situ. Both tests confirmed a significant improvement in the thermal stability of the catalysts containing ZrO2 and SiO2. The reason is the minimization of CaO sintering due to the higher thermal stability added by the formation of CaZrO3 and Ca2SiO4 and avoiding contact between the CaO particles. The catalyst containing silica, although it has a lower percentage of free CaO, and a shorter period before saturation in terms of CO2 capture (pre-breakthrough), produced a higher purity H2, both in pre-breakthrough and post-breakthrough, with purities close to 95 and 80%, respectively. On the other hand, the catalyst containing zirconia showed better CO2 capture since the second cycle than Ni/Ca catalyst and stable pre-breakthrough time, around 50 minutes. The formation of the mixed oxides CaZrO3 and Ca2SiO4 favored the thermal stability of the catalysts both in the carbonation and reaction tests. The thermogravimetric (TGA) tests, after the reaction cycles, also showed that presence of the mixed oxides CaZrO3 and Ca2SiO4 in the catalysts probably minimized formation of coke on catalysts surface, from 3.6 to 1.3 and 1.5 mgC/gcat/h, for the Ni/Ca, Ni/CaZr, and Ni/CaSi catalysts, respectively. Dissertação (Mestrado)

Perovskite solar cells are by far the photovoltaic technology with the fastest efficiency evolution, reaching now the astonishing power conversion efficiency (PCE) of 25.2%. Their advantages cover also color and transparency, extremely low thickness, low cost, simple fabrication methods and versatile designs. Nevertheless, since it is a young technology, there are still several challenges that need to be overcome for making its commercialization feasible. For making perovskite solar modules, the back-contact plays a critical job since it drives and deliveries the low energy electrons to the p contact of the cell. In n-i-p configuration cells, gold is normally used as back-contact, which is expensive and rare. In this work, several commercial carbon papers and application procedures were investigated. The best performing system produced 89% of the PCE obtained with standard gold back-contact. Besides having a much simpler and cheaper application method, other features such as low cost, great chemical and mechanical stability and low electrical resistivity proved carbon papers potential for commercialization. Moreover, when a gold interlayer of 5 nm was applied, the relative PCE increased up to 92%.

A highly efficient copper-catalyst (noble-metal free) was developed for the electrochemical reduction of CO2 (ERCO2) to methanol. Due to the nanowire structure of the catalyst, a remarkable ERCO2 selectivity was achieved, while the competing H2 evolution reaction (HER) was significantly suppressed for the overall range of potential tested. The developed copper-catalyst (CuO NWs) outperforms the single metal Cu-catalysts in aqueous environment. Under atmospheric conditions, methanol was produced at an overpotential of 410 mV with a faradaic efficiency (FE) of 66%, and 1.27 × 10−4 mol m−2 s−1 of production yield; which represents a 6.7% improvement over the previously reported value of 1.19 × 10−4 mol m−2 s−1. Interestingly, when the developed CuO NWs was used as a gas diffusion electrode (GDE) in a filter-press cell (more real industrial configuration), methanol remained as the major ERCO2 product with the same FE (66%). Azenha, C., is grateful to the Portuguese Foundation for Science and Technology (FCT) for the doctoral grant (refer- ence SFRH/BD/128768/2017 ). This work was performed under the project “SunStorage - Harvesting and storage of solar energy”, with reference POCI-01-0145-FEDER-016387, funded by European Regional Development Fund (ERDF), through COMPETE 2020 - Operational Programme for Competitiveness and internationalisation (OPCI), and by national funds, through FCT - Fundação para a Ciência e a Tecnologia I.P. The authors are thankful to POCI-01- 0145-FEDER-006939 (Laboratory for Process Engineering, Environ- ment, Biotechnology and Energy – UID/EQU/00511/2013) funded by the European Regional Development Fund (ERDF), through COM- PETE2020 - Programa Operacional Competitividade e Internacional- ização (POCI) and by national funds, through FCT - Fundação para a Ciência e a Tecnologia and NORTE-01-0145-FEDER-0 0 0 0 05 –LEPABE-2-ECO-INNOVATION, supported by North Portugal Regional Operational Programme (NORTE 2020), under the Portugal 2020 Partnership Agreement, through the European Regional Develop- ment Fund (ERDF).

Flow batteries exhibit relatively low power density owing to ohmic and concentration overpotentials, which leads to higher system costs. In this work, a phenomenological model of a vanadium redox flow battery (VRFB) equipped with an anion exchange membrane (AEM) was developed and validated. The model is used to assess the concentration overpotential during charge-discharge cycling at different operating conditions and a method to determine the mass transfer coefficient is presented. Also, a strategy to reduce the concentration overpotential is proposed. The simulated charge-discharge curve displays the lowest relative error reported in the literature for VRFB equipped with an AEM; the results reveal that the mass transfer coefficient is overestimated in most models in the literature. It is demonstrated that the concentration overpotentials during charging and discharging steps are not equal owing to a mismatch between the state of charge and the state of discharge. Also, the current density has a greater impact on this overpotential than the flow rate. Higher overpotentials were found near the membrane since the electronic conductivity is higher than the ionic conductivity. The simulation results show that positioning the distribution channels close to the membrane allows a reduction of the concentration overpotential up to 3.9%.

ZrAl materials with different compositions have been synthesized by the hydrothermal method and used as supports of Cu catalysts for hydrogen production from methanol steam reforming (MSR). The effect of the support composition, Zr/Al ratio, on the physicochemical and catalytic properties of CuZrAl catalysts was studied. The characterization results show that there is an optimal support composition (Zr/Al ratio of 0.4), allowing to achieve the highest methanol conversion due to enhanced dispersion and reducibility of copper. Zr-rich catalysts displayed low MSR activity, which is likely due to the segregation and crystallization of zirconia, resulting in the formation of large copper particles with lowered dispersion and reducibility. The catalyst with the optimal Zr/Al ratio shows the highest methanol conversion, enhanced selectivity and good long term stability, rendering this catalyst a promising material for the production of high purity H2 from MSR.

CAPES - Coordenação de Aperfeiçoamento de Pessoal de Nível Superior CNPq - Conselho Nacional de Desenvolvimento Científico e Tecnológico FAPEMIG - Fundação de Amparo a Pesquisa do Estado de Minas Gerais VALE S. A. A produção de hidrogênio por via biológica é uma alternativa sustentável, pois demanda baixa quantidade de energia e tem a capacidade da utilização de matérias primas renováveis como os substratos. A conversão de compostos orgânicos a hidrogênio no processo de fotofermentação, tem atraído interesse na sua utilização, por apresentar altos rendimentos teóricos de conversão de substrato. A combinação de grupos diferentes de bactérias cultivadas em um único biorreator apresenta como vantagens a simples manipulação, a redução de tempo de fermentação e taxas altas de rendimento. No presente trabalho, o objetivo foi estudar a produção de hidrogênio por fotofermentação, utilizando a bactéria Enterobacter cloacae e as bactérias fotossintetizantes púrpuras não sulfurosas: Rhodobacter capsulatus e Rhodopseudomonas palustris. As fontes de carbono utilizadas foram glicose P.A. e o permeado de soro de queijo em pó (70% lactose), que é um subproduto agroindustrial. Os ensaios foram realizados em reator operando em batelada alimentada, verificando a influência de: meio de cultivo, fonte de açúcar, presença de luminosidade, gás inerte e formas de alimentação do substrato para a produção de hidrogênio. Verificou-se que o microrganismo Enterobacter cloacae apresentou resultados promissores para a produção de hidrogênio, utilizando nitrogênio ou argônio como gases inertes, na presença ou não de luminosidade, caracterizando a sua capacidade de metabolizar os substratos em diferentes condições. Avaliando a influência dos meios de cultivos no sistema de co-cultura, o meio reacional caldo nutriente alcançou uma produtividade máxima de 201,15 mmol H2/L.dia, com a Enterobacter cloacae e Rhodobacter capsulatus (permeado de soro de queijo em pó), visto que, a sua composição oferece a quantidade de carbono e nitrogênio total, provenientes dos reagentes extrato de carne e peptona, presentes na composição do meio, impactando diretamente na produção de hidrogênio. Os ensaios com alimentação alternada da fonte de carbono ao meio reacional, promoveram a maior produtividade de hidrogênio. O valor máximo de produtividade obtido foi de 319,35 mmol H2/L.dia no tempo de 180 horas. Os metabólitos formados durante o processo fermentativo, foram obtidos em quantidades significativas, com destaque para os ácidos butírico, lático e acético, predominantes nas rotas metabólicas de produção de hidrogênio. Hydrogen production by biological is a sustainable alternative because it demands a low amount of energy for its production and has the capacity to use renewable raw materials as substrates. The conversion of organic compounds to hydrogen in the photofermentation process has attracted interest in their use, as it presents high theoretical substrate conversion yields. Combining different groups of bacteria grown in a single bioreactor provides advantages of simple handling, reduced fermentation time and high yield rates. In this present study, the objective was study the production of hydrogen by photofermentation using Enterobacter cloacae bacteria and photosynthetic purple non-sulfur bacteria: Rhodobacter capsulatus and Rhodopseudomonas palustris. The carbon sources used were glucose P.A. and the whey permeate (70 % lactose), that is an agroindustrial residue. The assays were carried out in fed batch reactor, checking the influence of: culture medium, sugar source, light, inert gas and substrate feeding forms. The Enterobacter cloacae microorganism showed satisfactory results for hydrogen production, using nitrogen or argon as inert gases, with or without the presence of light, characterizing its ability to metabolize under different conditions. Evaluating the culture media in the co-culture system, the nutrient broth reaction medium reached a maximum productivity of 201.15 mmol H2/L.day, with Enterobacter cloacae and Rhodobacter capsulatus (whey permeate), since its composition offers the amount of carbon and total nitrogen, derived from meat extract and peptone reagents, present in the medium composition, directly impacting the hydrogen production. In the tests with the alternation feeding of the carbon source to the reaction medium, promoted the highest hydrogen productivity, being the maximum of 319.35 mmol H2/L.day in the 180 hours time. The metabolites formed during the fermentation process were obtained in significant quantities, especially butyric, lactic and acetic acid, predominating the metabolic pathways of hydrogen production. Tese (Doutorado) 2022-10-28

Hermetic encapsulation protects perovskite solar cells (PSCs) from degradations induced by humidity and oxygen. A novel dual laser beam glass frit sealing process is developed and optimized to hermetically encapsulate PSCs. A 3D transient phenomenological model of the laser-assisted encapsulation is developed, validated and used to optimize the glass sealing procedure. During the laser-sealing process, the cells are subjected to 65 +/- 5 degrees C for a short time of

Os processos de reforma de hidrocarbonetos para a produção de hidrogênio são bastante estudados e o gás liquefeito de petróleo (GLP) pode ser uma matéria-prima promissora para esses processos, uma vez que possui grande facilidade de armazenamento e transporte e ampla rede de distribuição. Em vista disto, o objetivo deste trabalho foi estudar a reforma a vapor e oxidativa do GLP utilizando catalisadores derivados de hidrotalcita e suportados em aluminato de magnésio. Os catalisadores de hidrotalcita foram sintetizados pelo método de co-precipitação com relação molar para a formação de hidrotalcitas M3+/(M2++M3+) igual a 0,25, sendo M2+ íons de Ni2+ e Mg2+ e M3+ íons de Al3+. Os catalisadores de níquel suportados em aluminato de magnésio (10, 15 e 20% de Ni) foram sintetizados pela técnica de coprecipitação (suporte) e impregnação a seco (Ni). A caracterização dos catalisadores foi realizada através de análises de fluorescência de raios X (FRX), área específica BET, difração de raios X em temperatura ambiente, redução à temperatura programada (RTP), análise termogravimétrica (ATG) e térmica diferencial (DTA), difração de raios X in situ (DRX in situ) e espectroscopia de absorção de raios X (XAS). Para os catalisadores derivados de hidrotalcita quanto maior foi a substituição de Mg2+ por Ni2+ menor foi a temperatura necessária para a redução do catalisador devido a uma menor estabilidade térmica da estrutura pela menor formação da solução sólida NiO-MgO. Estes resultados foram observados nas análises de RTP e DRX in situ redução. Observou-se também que foi possível sintetizar catalisadores com 47,5% de teor de Ni com uma dispersão de 33,1%. Em relação aos catalisadores de Ni suportados em aluminato de magnésio, observou-se que a técnica de coprecipitação permitiu a formação da estrutura do suporte (MgAl2O4). Após a redução observou-se que os catalisadores suportados apresentaram menores dispersões com o aumento do teor de Ni. Durante o período reacional todos os catalisadores apresentaram a formação dos mesmos produtos para a reforma a vapor: H2, CO, CH4 e CO2. Os catalisadores derivados de hidrotalcita apresentaram conversões para o GLP entre 70 e 30%, e o catalisador Ni1,64Mg1,36Al que apresentou a maior conversão (em torno de 70%) e menor desativação por deposição de coque entre as amostras estudadas após as 24 horas de reação. No processo de reforma oxidativa com o catalisador Ni1,64Mg1,36Al observou-se que a adição de oxigênio na mistura reacional ocasionou um aumento no depósito de carbono em torno de 7%, apresentando também menor estabilidade, provavelmente devido à oxidação da fase ativa. Na reforma oxidativa com catalisadores suportados em aluminato de magnésio observou que a adição de oxigênio no sistema ocasionou a oxidação do leito catalítico e deposição de carbono, levando à desativação dos catalisadores. O estudo das reações de reforma em temperaturas mais elevadas (1073 e 1173 K) foi realizado para o catalisador Ni1,64Mg1,36Al que apresentou maior atividade catalítica. O aumento da temperatura na presença ou não de oxigênio resultou em maiores conversões do GLP, maior formação de H2 e menor formação de depósitos de coque. The reform of hydrocarbons for hydrogen production has been widely studied, and liquefied petroleum gas (LPG) may be a promising raw material for these processes, since it is easy to store and it has a vast transportation and broad distribution network. Therefore, the objective of this work was to study the steam reforming and oxidative of LPG using catalysts derived from hydrotalcite-type structure and supported on magnesium aluminate. The catalysts derived from the hydrotalcite-type structure were synthesized by coprecipitation with molar ratio to form hydrotalcites M3+/(M2++ M3+) equals to 0.25. Nickel catalysts supported on magnesium aluminate (10, 15 and 20 wt% of Ni) were synthesized by coprecipitation technique (support) and dry impregnation (Ni). The characterization of the catalysts was performed by fluorescence analysis X-ray (XRF), BET surface area, X-ray diffraction at room temperature, temperature programmed reduction (TPR), thermogravimetric analysis (TGA) and differential thermal (DTA), in situ X-ray diffraction (in situ XRD) and X-ray absorption (XAS) spectroscopy. For hydrotalcite derived catalysts the higher the substitution of Mg2+ by Ni2+, the lowest was the temperature for the reduction of the precursor. This was probably due to the lower thermal stability of the structure. These results were observed in the analysis of TPR and in situ XRD reduction. It was also observed that it was possible to synthesize catalysts with 47.5% of Ni content with dispersion of 33.1%. Regarding the Ni catalysts supported on magnesium aluminate, it was found that coprecipitation technique allowed the formation of the support structure (MgAl2O4). After of the reduction it was observed that the supported catalysts showed lower dispersions with increasing nickel content. During the reaction period all catalysts showed the formation of the same products for steam reforming: H2, CO, CH4 and CO2. Catalysts derivatived from hydrotalcite-type structure showed conversions of LPG between 70 and 30%, and the catalyst Ni1.64Mg1.36Al presented the highest conversion (around 70%) and lower deactivation by coke deposition among all the samples studied. In the oxidative reforming process, for the catalyst Ni1.64Mg1.36Al, a decrease in the stability and a slight increase of carbon accumulation (~ 7%) was observed. In the oxidative reforming for the samples supported on magnesium aluminate both the oxidation of the catalyst bed and carbon deposition were observed, leading to deactivation of the catalysts. The study of reforming reactions at higher temperatures (1073 and 1173 K) was performed for the Ni1.64Mg1.36Al sample, which showed higher catalytic activity. The increase of temperature in the presence or absence of oxygen resulted in higher conversions of LPG, an increase in H2 formation and smaller coke deposits. Tese (Doutorado)

In the field of gas separation and purification, membrane technologies compete with conventional purification processes on the basis of technical, economic and environmental factors. In this context, there is a growing interest in the development of carbon molecular sieve membranes (CMSM) due to their higher permeability and selectivity and higher stability in corrosive and high temperature environments. However, the industrial use of CMSM has been thus far hindered mostly by their relative instability in the presence of water vapor, present in a large number of process streams, as well as by the high cost of polymeric precursors such as polyimide. In this context, cellulosic precursors appear as very promising alternatives, especially targeting the production of CMSM for the separation of O2/N2 and CO2/CH4. For these two gas separations, cellulose-based CMSM have demonstrated performances well above the Robeson upper bound and above the performance of CMSM based on other polymeric precursors. Furthermore, cellulose is an inexpensive bio-renewable feed-stock highly abundant on Earth. This article reviews the major fabrication aspects of cellulose-based CMSM. Additionally, this article suggests a new tool to characterize the membrane performance, the Robeson Index. The Robeson Index, θ, is the ratio between the actual selectivity at the Robeson plot and the corresponding selectivity—for the same permeability—of the Robeson upper bound; the Robeson Index measures how far the actual point is from the upper bound.

CNPq - Conselho Nacional de Desenvolvimento Científico e Tecnológico Os hidrociclones são equipamentos utilizados em processos de separação sólido-líquido e líquido-líquido, possuem tamanho reduzido e baixo custo de aquisição e manutenção. Diversos estudos vêm sendo desenvolvidos na busca por melhorar o desempenho desses equipamentos, garantindo um processo mais eficiente e com menores gastos energéticos. Neste âmbito, pesquisadores da FEQUI/UFU desenvolveram hidrociclones filtrantes. A proposta deste trabalho foi avaliar o desempenho de hidrociclones cilíndrico-filtrantes otimizados por Salvador (2017) frente a hidrociclones convencionais sob os mesmos parâmetros geométricos e operacionais. Para isso, variaram-se em três níveis a concentração volumétrica de sólidos na alimentação, o diâmetro de underflow e a queda de pressão nos equipamentos. Para o caso de máxima eficiência total, a maior eficiência foi para o equipamento filtrante com 5 mm de diâmetro de underflow, operando a 1,77 bar e com uma suspensão de quartzito com concentração volumétrica de 1%, sendo de 88,55%. O aumento da concentração de sólidos na alimentação prejudicou a eficiência de separação. No segundo caso de otimização (mínima razão de líquido), os menores valores encontrados para a razão de líquido foram para os hidrociclones na condição mais diluída, chegando a 0,57% para uma modalidade convencional e 0,65% para uma filtrante. Para manter baixos valores de razão de líquido e valores de eficiência mais altos, foi necessário trabalhar com uma suspensão mais diluída. Já no terceiro caso de otimização, cujo objetivo era minimizar o número de Euler, o equipamento filtrante com 5 mm de diâmetro de underflow, em uma concentração volumétrica de alimentação de 5,5% exibiu menor número de Euler, sendo de 578. O acréscimo no percentual de sólidos causou uma diminuição do gasto energético para esses equipamentos. Por fim, as equações de projeto e as curvas de eficiência para os hidrociclones cilíndrico-filtrantes foram levantadas com um ajuste satisfatório. Hydrocyclones are devices used in solid-liquid and liquid-liquid separation processes, having a small size and low acquisition and maintenance cost. Several studies have been developed to increase the performance of these equipment, guaranteeing a more efficient process with lower energy costs. In this context, researchers from FEQUI / UFU developed filtering hydrocyclones. The purpose of this paper was to evaluate the performance of cylindrical-filtering hydrocyclones optimized by Salvador (2017) towards conventional hydrocyclones with the same geometric and operational parameters. Thereunto, the volumetric concentration of solids in the feed, the underflow diameter and the pressure drop in the equipment were varied in three levels. For the case of maximum total efficiency, the highest efficiency was obtained for the filtering equipment with 5 mm of underflow diameter, operating at 1.77 bar and with a quartzite suspension with volumetric concentration of 1%, being 88.55%. The increase of feed’s solids concentration impaired the separation efficiency. In the second case of optimization (minimum underflow-to-throughput ratio), the lowest values found were obtained for the hydrocyclones in the most diluted condition, reaching 0.57% for a conventional modality and 0.65% for a filtering one. To maintain lower net ratios and higher efficiency values, it was necessary to work with a more diluted suspension. In the third optimization case, whose objective was to minimize Euler number, the filtering equipment with 5 mm of underflow diameter, in a volumetric feed concentration of 5.5% showed a smaller Euler number, being 578. The increment in the percentage of solids caused a decrease on the energy cost for these devices. Finally, the project equations and efficiency curves for the cylindrical-filtering hydrocyclones were raised with satisfactory adjusts. Dissertação (Mestrado)

The recognition of the effects of fossil fuel consumption resulted in several agreements, legislation, and projects focusing on the minimization of impacts caused. Biomass is a versatile energy source. Eucalyptus is a fast-growing crop, mainly used by the pulp and paper industry. Torrefaction is a thermochemical conversion process that can improve biomass fuel properties, enabling its use in the energy sector. However, correct management of biomass is crucial for the sustainability of this process. Torrefaction can also be used to eliminate some elements that can hinder subsequent conversion processes. One example is chlorine, which, during combustion or gasification processes, can form hydrochloric acid that leads to corrosion of metal surfaces. In this context, this research aimed to determine the temperature at which chlorine is eliminated during torrefaction process. For this purpose, several tests were performed at different temperatures and residence times. All samples were analyzed before and after the process, and were characterized by proximate and elemental analysis, calorimetry, and chlorine titration. The analysis showed that, even for the lowest torrefaction temperature used, chlorine content was already below the detection value, showing that, even at lower temperatures, thermal treatment is an efficient technique for the elimination of chlorine from biomass.

CAPES - Coordenação de Aperfeiçoamento de Pessoal de Nível Superior CNPq - Conselho Nacional de Desenvolvimento Científico e Tecnológico FAPEMIG - Fundação de Amparo a Pesquisa do Estado de Minas Gerais O uso contínuo dos combustíveis fósseis para fins de transporte, eletricidade e aquecimento, tem levado a uma crescente busca por fontes alternativas e renováveis de energia como a eólica, solar e a energia proveniente das biomassas. Estudos de processos de conversão como a pirólise que produzem energia transportável e estocável a partir da biomassa têm se destacado no meio acadêmico. Na pirólise catalítica (in situ e ex situ) os catalisadores têm sido aplicados para melhorar a composição química do bio-óleo produzido. No método catalítico ex situ catalisador e biomassa encontram-se em reatores distintos e facilitam o reuso dos catalisadores, caracterizando uma das vantagens deste método. Isto posto, o objetivo principal deste trabalho foi estudar a pirólise solar catalítica ex situ da microalga Chlamydomonas reinhardtii usando o catalisador hidrotalcita, com a finalidade de produzir carvão, bio-óleo e gás. A metodologia de superfície de resposta foi usada para avaliar a influência das variáveis massa de biomassa, tempo de reação e porcentagem de catalisador no rendimento dos produtos e qualidade do bio-óleo. Um estudo de otimização foi realizado visando à obtenção de máximo rendimento de líquido, e o valor alcançado foi de 47,59%. Os bio-óleos obtidos na pirólise catalítica apresentaram hidrocarbonetos de cadeias longas e menor quantidade de compostos oxigenados, evidenciando a atuação do catalisador na melhoria da qualidade dos produtos líquidos. A função desejabilidade foi utilizada para identificar as condições das variáveis independentes que maximizavam simultaneamente o rendimento de líquido e seu conteúdo de hidrocarbonetos. O teste experimental realizado nas condições ótimas mostrou que foi possível obter rendimento de líquido de 38,55% com teor de hidrocarbonetos de 32,65%, e os valores experimentais mostraram boa conformidade com os valores preditos. A caracterização dos carvões foi realizada e os valores de poder calorífico superior (PCS) foram condizentes com os reportados na literatura para carvões derivados da pirólise de microalgas. Na avaliação do reuso do catalisador realizaram-se 3 ciclos consecutivos de pirólise solar que revelaram a boa estabilidade estrutural da hidrotalcita. Além disso, seu desempenho pouco se alterou ao longo dos ciclos de pirólise. Assim, este estudo evidenciou que em determinadas condições é possível obter bons rendimentos de bio-óleo e melhorar sua qualidade do mesmo através do processo de pirólise catalítica ex situ de microalgas usando energia solar. The continued use of fossil fuels for transportation, electricity and heating purposes has led to a growing search for alternative and renewable sources of energy such as wind, solar and energy from biomass. Studies of conversion processes such as pyrolysis that produce transportable and stockpile energy from biomass have been highlighted in academia. In catalytic pyrolysis (in situ and ex situ), catalysts have been applied to improve the chemical composition of the bio-oil produced. In the ex situ catalytic method, catalyst and biomass are found in different reactors and facilitate the reuse of catalysts, characterizing one of the advantages of this method. Thus, the main objective of this work was to study the ex situ catalytic solar pyrolysis of the microalgae Chlamydomonas reinhardtii using the hydrotalcite catalyst, with the purpose of producing coal, bio-oil and gas. The response surface methodology was used to assess the influence of the variables biomass mass, reaction time and percentage of catalyst on product yield and quality of bio-oil. An optimization study was carried out aiming to obtain maximum liquid yield, and the value reached was 47.59%. The bio-oils obtained in the catalytic pyrolysis showed long-chain hydrocarbons and a lower amount of oxygenated compounds, showing the role of the catalyst in improving the quality of liquid products. The desirability function was used to identify the conditions of the independent variables that simultaneously maximized the liquid yield and its hydrocarbon content. The experimental test performed under the optimum conditions showed that it was possible to obtain a liquid yield of 38.55% with a hydrocarbon content of 32.65%, and the experimental values showed good compliance with the predicted values. The charcoal characterization was performed and the values of superior calorific power (PCS) were consistent with those reported in the literature for coals derived from microalgae pyrolysis. In the evaluation of the reuse of the catalyst, 3 consecutive cycles of solar pyrolysis were performed, which revealed the good structural stability of the hydrotalcite. In addition, their performance has hardly changed over the course of pyrolysis cycles. Thus, this study showed that under certain conditions it is possible to obtain good yields of bio-oil and improve its quality through the process of ex situ catalytic pyrolysis of microalgae using solar energy. Tese (Doutorado)

Phenol was detected for the first time in the mononitrobenzene production process by benzene adiabatic nitration, supporting the theory that proposes phenol as the precursor of nitrophenols, unwanted byproducts. For that, analytical procedures (based in liquid and gas chromatographic techniques) have been developed and improved that aim to detect these chemical species both in the industrial nitration process as well as in laboratory tests at different reaction conditions. The obtained results confirmed the proposed and accepted mechanism for the nitrophenols formation during benzene nitration, showing that phenol is indeed the nitrophenolic byproducts precursor. Moreover, it is shown the phenol's high reactivity even at smooth reaction conditions (namely low temperature and low sulfuric acid concentration), which explains the difficulty of detecting this compound within the reaction medium using the analytical techniques applied for monitoring benzene nitration process. In this study, it was also discovered that 4-mononitrophenol had higher affinity into the aqueous acid phase when compared to the other nitrophenolic byproducts (2-mononitrophenol; 2,4-dinitrophenol; 2,6-dinitrophenol; and 2,4,6-trinitrophenol) that have more affinity into the organic phase. Phenol distribution between both reaction phases was found to be similar to the majority of the nitrophenols, i.e., it is present in higher concentration in the organic phase.

This is the first review presenting and discussing Burkholderia sacchari as a bacterial chassis. B. sacchari is a distinguished polyhydroxyalkanoates producer strain, with low biological risk, reaching high biopolymer yields from sucrose (0.29 g/g), and xylose (0.38 g/g). It has great potential for integration into a biorefinery using residues from biomass, achieving 146 g/L cell dry weight containing 72% polyhydroxyalkanoates. Xylitol (about 70 g/L) and xylonic acid [about 390 g/L, productivity 7.7 g/(L.h)] are produced by the wild-type B. sacchari. Recombinants were constructed to allow the production and monomer composition control of diverse tailor-made polyhydroxyalkanoates, and some applications have been tested. 3-hydroxyvalerate and 3-hydroxyhexanoate yields from substrate reached 80% and 50%, respectively. The genome-scale reconstruction of its metabolic network, associated with the improvement of tools for genetic modification, and metabolic fluxes understanding by future research, will consolidate its potential as a bioproduction chassis.

A series of TiO 2 composites loaded with 0.5–4 wt.% of reduced graphene oxide (rGO) was prepared through a combined sol-gel method and solvothermal treatment. The composites were characterized by scanning electron microscopy (SEM), Raman spectroscopy, X-ray diffraction (XRD), thermogravimetric analysis (TGA), the Brunauer-Emmett-Teller (BET) method and diffuse reflectance spectroscopy (DRS). The photocatalytic performance of the prepared materials was evaluated by methylene blue discoloration in aqueous medium. The TiO 2 -rGO 1% composite led to an increase of ca. 11% in the pseudo-first-order rate constant, however, further increasing in rGO contents led to a decrease in the photocatalytic activity. When present in a high content, reduced graphene oxide can act as a recombination center, rather than providing a pathway for charge transfer and preventing recombination of electron-hole pairs. Subsequently, the TiO 2 -rGO 1% was immobilized in a vinyl-base paint and evaluated for the purification of air containing 1 ppm v of nitrogen oxide (NO). The results showed that the NO conversion was 25% and the selectivity for the transformation of NO into nitrates and nitrites was 50%. The same paint containing bare TiO 2 presented an NO conversion of 35% and selectivity of 40%. Although, the abatement of NO by the composite was lower, the selectivity for ionic compounds was higher, indicating that the presence of rGO is important for the decomposition of NO under more oxidized compounds.

CAPES - Coordenação de Aperfeiçoamento de Pessoal de Nível Superior Com o aumento das emissões de gases estufa, combustíveis alternativos como o hidrogênio (H2) são cada vez mais necessários. O H2 possui elevado potencial energético, porém, sua obtenção gera subprodutos que necessitam ser separados para alcançar a pureza necessária para sua utilização. A purificação através de membranas de paládio surge como uma alternativa, graças à sua elevada eficiência e baixo consumo de energia. No entanto, o alto custo do metal exige estudos em torno da diminuição da espessura da membrana de paládio, geralmente através da deposição de uma fina camada do metal sobre suportes porosos. A redução da rugosidade das superfícies destes suportes também auxilia na deposição de camadas ultrafinas de paládio, além de diminuir a chance de defeitos que possam reduzir a seletividade. O óxido de grafeno (OG) é um composto carbônico de elevada resistência mecânica capaz de formar filmes de baixa espessura, sendo assim, o presente trabalho realizou o estudo da influência de revestimentos de óxido de grafeno visando reduzir a rugosidade da camada externa de fibras ocas de alumina para a deposição de membranas de paládio seletivas ao H2. Para isso, foram produzidas fibras ocas de alumina com mesoporosidade controlada, que foram revestidas com camadas óxido de grafeno, produzido através do método de Hummer modificado, seguido da deposição de membranas de paládio através de electroless plating. As fibras puras e revestidas foram caracterizadas através de microscopia eletrônica de varredura, permeabilidade de água e nitrogênio e rugosidade de suas superfícies externas. Os testes de permeação de H2 foram realizados nas temperaturas de 300 a 450 °C em pressões de 40 a 200 kPa. A seletividade foi avaliada através da permeação de nitrogênio (N2). Para os revestimentos testados, foi observada a diminuição de aproximadamente 13,5% da rugosidade da superfície externa da fibra oca de alumina. A membrana produzida sem camada intermediária de OG (M1) apresentou espessura de 1,56 µm, permeabilidade ao H2 de 2x10-7 mol s-1m-2kPa-1 e seletividade infinita. Entre as membranas produzidas com camada de OG, destacaram-se M3 e M4, com espessuras de cerca de 1 µm e permeabilidades ao H2 de 24x10-7 e 11x10-7 mol s-1m-2kPa-1, respectivamente. Através das análises realizadas, foi possível verificar que os revestimentos de óxido de grafeno foram capazes de proporcionar a deposição de camadas ultrafinas de paládio de seletividade infinita, reduzindo o custo de produção. With the increase of greenhouse gases emission, alternative fuels such as hydrogen (H2) are increasingly needed. H2 has a high-energy potential; however, its production generates byproducts that need to be separated in order to achieve high purity. Palladium membrane purification is an alternative separation method due to its high efficiency and low energy consumption. However, the high cost of the metal requires studies around the reduction of the palladium membrane thickness, usually by depositing of thin layer of the metal on porous supports. Decreasing surface roughness of these supports also assists the deposition of ultra-thin palladium layers and decreases the chance of defects that may reduce selectivity. Graphene oxide (GO) is a carbonic compound with high mechanical strength capable of forming single layer films with low thickness, in this sense, the present work studied the influence of graphene oxide coatings to reduce the roughness of alumina hollow fibers for the deposition of H2 selective palladium membranes. For this purpose, alumina hollow fibers with controlled mesoporosity were produced, and were coated with graphene oxide layers, produced by the modified Hummer method, followed by the deposition of palladium membranes by electroless plating technique. The pure and coated fibers were characterized by scanning electron microscopy, water and nitrogen permeability and the roughness of their external surfaces. H2 permeation tests were performed at temperatures from 300 to 450 °C at pressures from 40 to 200 kPa. For the tested coatings, approximately 13.5% reduction in surface roughness was observed. The membrane produced without intermediate layer of OG (M1) presented a thickness of 1.6 µm, H2 permeability of 2x10-7 mol s-1m-2kPa-1 and infinite selectivity. Among the membranes produced with OG layer, M3 and M4 stood out, with thicknesses of approximately 1.0 µm and H2 permeabilities of 24x10-7 and 11x10-7 mol s-1m-2kPa-1, respectively. Through the analyzes carried out, it was verified that the graphene oxide coatings were able to provide the deposition of infinite selectivity palladium ultra-thin layers, reducing the production cost. Dissertação (Mestrado)

Highly ordered anodic hafnium oxide (AHO) nanoporous or nanotubes were synthesized by electrochemical anodization of Hf foils. The growth of self-ordered AHO was investigated by optimizing a key electrochemical anodization parameter, the solvent-based electrolyte using: Ethylene glycol, dimethyl sulfoxide, formamide and N-methylformamide organic solvents. The electrolyte solvent is here shown to highly affect the morphological properties of the AHO, namely the self-ordering, growth rate and length. As a result, AHO nanoporous and nanotubes arrays were obtained, as well as other different shapes and morphologies, such as nanoneedles, nanoflakes and nanowires-agglomerations. The intrinsic chemical-physical properties of the electrolyte solvents (solvent type, dielectric constant and viscosity) are at the base of the properties that mainly affect the AHO morphology shape, growth rate, final thickness and porosity, for the same anodization voltage and time. We found that the interplay between the dielectric and viscosity constants of the solvent electrolyte is able to tailor the anodic oxide growth from continuous-to-nanoporous-to-nanotubes.

This study aimed to evaluate the synthesis and application of heterogeneous catalysts based on heteropolyacids for 5-hydroxymethylfurfural (HMF) production from glucose. Initially, assays were carried out in order to establish the most favorable catalyst synthesis conditions. For such purpose, calcination temperature (300 or 500 °C), type of support (Nb2O5 or Al2O3), and active phase (H3PW12O40—HPW or H3PMo12O40—HPMo) were tested and combined based on Taguchi’s L8 orthogonal array. As a result, HPW-Nb2O5 calcined at 300 °C was selected as it presented optimal HMF production performance (9.5% yield). Subsequently, the reaction conditions capable of maximizing HMF production from glucose using the selected catalyst were established. In these experiments, different temperatures (160 or 200 °C), acetone-to-water ratios (1:1 or 3:1 v/v), glucose concentrations (50 or 100 g/L), and catalyst concentrations (1 or 5% w/v) were evaluated according to a Taguchi’s L16 experimental design. The conditions that resulted in the highest HMF yield (40.8%) consisted of using 50 g/L of glucose at 160 °C, 1:1 (v/v) acetone-to-water ratio, and catalyst concentration of 5% (w/v). Recycling tests revealed that the catalyst can be used in four runs, which results in the same HMF yield (approx. 40%).

The current work assesses the transport properties of BaCe0·9Y0·1O3-d (BCY10) in oxidising atmospheres as a function of water vapour partial pressure (pH2O = ∼10−7 – 0.1 atm) in the intermediate temperature range 350–600 °C. From these data and those measured under similar conditions in H2, from literature data, the transport numbers of this material in both reducing and oxidising conditions are compared. Contrary to that observed in reducing atmospheres, where feeding with nominally dry hydrogen-based atmospheres was sufficient to provide high levels of protonic conductivity, in oxidising conditions the material can only exhibit significant protonic conductivity by externally imposing more elevated pH2O values (10−5 – 10−4 atm). From this knowledge, the current article provides the first detailed clarification of the limiting conditions of operation of BCY10 under low humidity values and, subsequently, highlights the relevance of this finding to cell efficiency and membrane stability in the intermediate temperature range.

Summary Photoelectrochemical (PEC) water splitting offers an elegant approach for solar energy conversion into hydrogen fuel. Large-scale hydrogen production requires stable and efficient photoelectrodes and scalable PEC cells that are fitted for safe and cost-effective operation. One of the greatest challenges is the collection of hydrogen gas from millions of PEC cells distributed in the solar field. In this work, a separate-cell PEC system with decoupled hydrogen and oxygen cells was designed for centralized hydrogen production, using 100 cm2 hematite (α-Fe2O3) photoanodes and nickel hydroxide (Ni(OH)2)/oxyhydroxide (NiOOH) electrodes as redox mediators. The operating conditions of the system components and their configuration were optimized for daily cycles, and ten 8.3 h cycles were carried out under solar simulated illumination without additional bias at an average short-circuit current of 55.2 mA. These results demonstrate successful operation of a decoupled PEC water splitting system with separate hydrogen and oxygen cells.

Industrial hydrogen-rich waste streams hold promises in their upgrading to feed fuel cell stacks. As in the ammonia synthesis process, a stream of up to 180–240 Nm3 per ton of ammonia is purged to keep the inert gases concentration below a threshold value; this stream contains large hydrogen quantities, which could be recovered. In the current work, a four-column PSA unit has been used to produce a high-purity hydrogen stream for fuel cell applications from a synthetic mixture with a molar composition of 58% H2, 25% N2, 15% CH4 and 2% Ar, based on ammonia purge gas. Firstly, a comparative performance of four commercially adsorbents was accomplished to obtain the adsorption isotherms of H2, N2, CH4, and Ar, leading to the selection of 5A zeolite adsorbent. Then, the dynamic behavior of a packed bed was studied by single and multicomponent breakthrough experiments and simulated using Aspen Adsorption®. The results, simulations and experimental, indicate that after H2 the first impurity to break thought the column is Ar, followed by N2 and finally by CH4. Then, a design-of-experiments (DoE) methodology was used to select the best operating conditions of the experimental cyclic PSA unit to reach different target hydrogen product concentrations; the overall PSA performance was evaluated in terms of purity and recovery of H2 product. According to the results, the four-column PSA unit running at 9 bar produced a stream with hydrogen concentration of 99.25% and 99.97% of H2, with a recovery of 75.3% and 55.5%, respectively, where the impurities were mostly Ar and N2. In addition to the technical performance, the economic assessment concluded that the cost to compress, transport and purify waste hydrogen to a concentration of 99.97% using a small-scale PSA unit from ammonia plants has been estimated in the range of 1.17–1.39 € kg H2−1, depending on the dispensing pressure of 350 or 700 bar, respectively. These assessments offer a cost-effective solution to produce high-purity H2 as low cost transportation, allowing hydrogen penetration into the mass markets. This research was supported by the projects CTQ2015-66078-R (MINECO/FEDER) and SOE1/P1/E0293 (INTERREG SUDOE /FEDER, UE), “Energy Sustainability at the Sudoe Region: Red PEMFC-Sudoe”. Adélio Mendes and Frederico Relvas acknowledge to projects UID/EQU/00511/2019 funded by national funds through FCT/MCTES (PIDDAC); and “LEPABE-2-ECO-INNOVATION” – NORTE‐01‐0145‐FEDER‐000005, funded by Norte Portugal Regional Operational Programme (NORTE 2020), under PORTUGAL 2020 Partnership Agreement, through the European Regional Development Fund (ERDF). Frederico Relvas also acknowledges NORTE-08-5369-FSE-000028 supported by NORTE 2020, under the Portugal 2020 Partnership Agreement and the European Social Fund (ESF).

The aim of this investigation is to evaluate the influence of glycerol (a nontoxic additive) on Zn-Mn coatings formed by electrochemical deposition. The influence of glycerol (GLY) on the electrodeposition of Zn-Mn alloys on Pt from acid baths was studied by cyclic voltammetry. The coatings were analyzed by scanning electron microscopy (SEM) and X-ray diffraction (XRD). The Zn-Mn alloys prepared in the absence or presence of this additive showed similar voltammograms except when using GLY and boric acid (BA) concentrations at 0.63 and 0.24 M, respectively. The current efficiency of the Zn-Mn electrodeposition process ranged from 5 to 41%, due to the lowest and highest concentrations of GLY and BA, respectively. SEM images of deposits obtained at -1.53 V from baths containing 0.08-0.48 M GLY were dendritic, while those formed in the presence of 0.63 M GLY showed that GLY acted as a brightener at this concentration. The XRD analysis showed that the electrodeposits contained Zn, Mn, oxides as well as alloys of various compositions. GLY acted as a grain refiner and inhibited the codeposition of Zn with Mn and the formation of oxides.

Seeking renewable energy sources has been a very important aspect in the development of human society, with many authors regarding hydrogen as a rather promising energy source. There are several forms of obtaining hydrogen, including steam reforming of hydrocarbons, alcohols, and ethers. Some characteristics of methanol, such as processing at mild temperatures from 250 to 350 o C under atmospheric pressure and production from biomass – no competition for food production – have distinguished it from other alcohols for steam reforming. The great disadvantage of this technology when applied in proton exchange membrane (PEM) fuel cells is that the process of methanol steam reforming involves not only hydrogen and carbon dioxide, but also the production of a small amount of carbon monoxide, which is sufficient to affect the functionality of the fuel cells. This work presents the characterization of the catalyst HiFUEL R120 and shows how water/methanol molar ratio in the feed stream of an integral methanol steam reforming reactor influenced the conversion and the hydrogen selectivity in relation to carbon monoxide. This made it possible to identify the best operational conditions for lowering carbon monoxide content in the reactor effluent, avoiding the use of a CO purification unit.

A interesterificacao permite a obtencao de esteres livre de glicerol, com a producao da triacetina, que pode ainda ser utilizada como aditivo ao biocombustivel. A fim de potencializar a producao de esteres e triacetina a insercao de aditivos a reacao tem sido abordada. O presente estudo teve como objetivo avaliar o efeito de adicionar solucao aquosa de acido acetico 26% (SA 26% ) em 5 e 10% (em relacao a massa de oleo) sobre o rendimento em esteres e teor de triacetina, bem como verificar seu efeito sobre os esteres individuais, variando a temperatura da reacao de 300 a 325 ° C e tempo de residencia entre 10 a 30 minutos. Para a maioria das reacoes conduzidas com SA (26%) a 300 ° C houve maior producao de esteres, se comparadas as reacoes sem o aditivo (p

Hollow fiber membrane contactors with microporous polypropylene (PP) and composite polytetrafluoroethylene/polyethersulfone (PTFE/PES) were used for carbon dioxide (CO2) removal from a gas mixture. The composite membranes exhibited higher efficiency than the microporous membranes, which was related to prevention of pore wetting due to the PTFE present in the top layer of the membrane. For both type of contactors, it was investigated the influence of liquid flow rate, temperature and kind of absorbent on the CO2 removal. A better performance of CO2 transfer into the liquid phase was observed by increasing the liquid flow rate, by using a reacting absorbent (sodium hydroxide) and by decreasing the liquid temperature.

FAPEMIG - Fundação de Amparo a Pesquisa do Estado de Minas Gerais O açaí é um fruto proveniente da palmeira Euterpe oleracea Martius, nativa da região amazônica, que apresenta diversas propriedades funcionais, nutricionais e elevado valor energético. Apesar de inúmeras pesquisas científicas relacionarem o consumo regular de açaí com diversos benefícios à saúde, as atuais práticas de produção da polpa em condições higiênico-sanitárias insatisfatórias têm preocupado os órgãos de saúde pública, uma vez que surtos recentes do Mal de Chagas podem estar relacionados ao consumo de açaí contaminado com o microrganismo transmissor da doença. A pasteurização do produto visa à destruição de microrganismos transmissores de diversas doenças, entre as quais, o Mal de Chagas, e além disso inativa enzimas que causam alterações sensoriais indesejáveis. Dentre estas enzimas, a peroxidase (POD) e polifenoloxidase (PPO) oxidam diversos compostos orgânicos, produzindo substâncias escuras, que prejudicam a cor e o sabor da polpa. Uma vez que são mais termorresistentes que a maioria dos microrganismos presentes, a inativação de peroxidase e polifenoloxidase garante um produto com boa qualidade microbiológica. Diante disto, este trabalho é direcionado ao estudo do processo de pasteurização contínua da polpa de açaí. Primeiramente são apresentados os métodos e os resultados de determinação do comportamento reológico e das propriedades físicas densidade, coeficiente de expansão térmico-volumétrico, calor específico, condutividade térmica e difusividade térmica do açaí. Posteriormente, apresentam-se os estudos cinéticos de degradação térmica de antocianinas e das enzimas peroxidase e polifenoloxidase. As antocianinas seguiram uma cinética de degradação de primeira ordem e mostraram boa estabilidade térmica, com tempos de meia-vida entre 10,7 a 28,6 horas para a faixa de temperatura de 40 a 80°C, sendo portanto, resistentes aos processos de pasteurização convencionais que utilizam temperaturas de aproximadamente 80 a 90°C por 1 a 10 minutos. As cinéticas de inativação da POD e PPO foram representadas de acordo com o modelo de primeira ordem contendo duas isoenzimas com diferentes estabilidades térmicas. A peroxidase apresentou maior resistência a temperaturas de pasteurização, tendo sidos estimados os parâmetros de redução decimal, D1 = 7,10 s e D2 = 254 s para as isoformas menos termorresistente e mais termorresistente, respectivamente, a uma temperatura de referência de 89°C. Os parâmetros Z1 e Z2 foram estimados em 4,3°C e 2,4°C, respectivamente. A fluidodinâmica computacional foi aplicada na simulação numérica do processo de pasteurização contínua em um pasteurizador de escala de laboratório, dotado de um trocador de calor a placas (TCP) contendo as seções de aquecimento e resfriamento do produto, intercalados por um tubo de retenção. Distribuições de temperatura e atividade residual da peroxidase foram obtidos para escoamento contracorrente em série e em série-paralelo nos TCP para até quatro diferentes vazões de polpa de açaí (15, 20, 25 e 30 L/h). Ensaios também foram conduzidos em um pasteurizador experimental e os resultados foram comparados. Os dados da distribuição de temperatura obtidos experimentalmente foram melhor representados para as simulações com escoamento em série. No entanto, os resultados da atividade residual da POD obtidos nos ensaios experimentais divergiram razoavelmente dos obtidos por CFD. O tratamento térmico contínuo comprovou os resultados dos ensaios cinéticos das enzimas, tendo sido observado maior estabilidade da peroxidase em relação à polifenoloxidase. O processo foi mais eficiente quando realizado com escoamento em série. Nesta condição, quando a polpa de açaí foi experimentalmente processada a 15 L/h, 89,9% da POD foi inativada. A simulação numérica nesta condição mostrou uma redução de mais de 99,9% da atividade desta enzima. Açai-berry is a fruit from Euterpe oleracea Martius palm tree, native from the Amazon, and it is known to feature several functional properties and have high energetic and nutritional value. Despite many scientific studies have shown that regular consumption of açai may provide health benefits, current bad manufacturing practices during its pulp extraction processing have warned the public health agencies, mainly because current outbreaks of Chagas Disease may be related to the consumption of açai contaminated with the microorganism that transmits this illness. A suitable pasteurization of this açai pulp destroys the microorganisms that transmit several diseases, including Chagas and also, inactivates enzymes that cause undesirable changes in sensory aspects. Among these enzymes, peroxidase (POD) and polyphenoloxidase (PPO) reacts with many organic compounds, producing dark-brown substances, which spoils the colour and flavor of the pulp. Once the heat resistance of these enzymes is higher than the resistance of most vegetative cells of microorganisms, inactivating peroxidase and polyphenoloxidase assure a product with good microbiological quality. Based on it, this work is focused on the study of the pasteurization process of açai-berry pulp. Firstly, the methods and results of determination of rheological behavior and physical properties, density, volumetric thermal expansion coefficient, specific heat, thermal conductivity and thermal diffusivity of açai are shown. Afterward, the kinetics study of thermal degradation of anthocyanin and the enzymes peroxidase and polyphenoloxidase is presented. Anthocyanin followed a first-order kinetic degradation and showed good thermal stability, presenting half-life times between 10.7 to 28.6 hours for the temperature range from 40 to 80°C. Therefore, they are stable against conventional pasteurization processes, which applies temperatures from about 80 to 90°C during 1 to 10 minutes. Thermal inactivation of enzymes POD and PPO were represented according to the first-order kinetic model, considering that there are two different enzyme fractions with different thermal stabilities. Among the two enzymes, peroxidase has shown higher resistance against pasteurization temperatures, and decimal reduction parameters were estimated in D1 = 7.10 s and D2 = 254 s for the thermolabile and thermostable fractions, respectively, at a reference temperature of 89°C. Parameters Z1 and Z2 were estimate as 4.3°C and 2.4°C, respectively. Computational fluid dynamics was applied in the numerical simulation of the continuous pasteurization process in a lab-scale pasteurizer, containing a plate heat exchanger (PHE) with a heating and cooling sections, separated by a holding tube. Distributions of temperature and residual activity of peroxidase were obtained for a series and series-parallel flows in the PHE for up to four açai pulp flow-rates (15, 20, 25 and 30 L/h). Tests were also carried out in an experimental pasteurizer and the results were compared. Experimental data of temperature distribution were better represented by the CFD simulations for the series-flow. Nevertheless, the experimental results of the residual activity of POD diverged from those achieved by CFD. The continuous thermal processing of açai pulp confirmed the results obtained in the kinetics experiments of enzyme degradations, showing that the thermal stability of peroxidase is higher than polyphenoloxidase. Pasteurization was more effective when the pulp was processed in a series-flow arrangement. In this situation, when açai pulp was experimentally processed at 15 L/h, 89.9% of POD was inactivated. CFD simulations of these conditions showed a reduction in more than 99.9% of this enzyme activity. Tese (Doutorado)

CAPES - Coordenação de Aperfeiçoamento de Pessoal de Nível Superior UFU - Universidade Federal de Uberlândia O potássio (K) configura entre os principais nutrientes do solo, devido tanto a sua participação no crescimento vegetal quanto no desempenho de atividades fisiológicas, como absorção de água e circulação de outros nutrientes nas plantas. Entretanto, no Brasil este se torna escasso devido à elevada acidez e lixiviação nos solos tropicais e, por isso, é massivamente utilizado pelas indústrias de fertilizantes em corretivos, juntamente com nitrogênio (N) e fósforo (P). Na contramão de sua importância na agricultura, a única fonte em larga escala de potássio nacional se resume à mina de Taquari Vassouras/SE, que corresponde à produção de cerca de apenas 10% da demanda brasileira. Neste contexto, o potássio torna-se um elemento estratégico e a busca por fontes alternativas é cada vez maior. Entre as fontes alternativas no país, destaca-se a rocha silicatada denominada Verdete, com reserva localizada em Cedro do Abaeté/MG. O Verdete in natura apresenta teores totais de K2O entre 7 e 14%, porém distribuídos em estruturas minerais não absorvíveis por vegetais. Esse trabalho propõe a caracterização física e mineralógica do Verdete, assim como a aplicação de tratamentos hidrotermais utilizando CaCl2.2(H2O), MgCl2.6(H2O), H2SO4 e CaCO3 calcinado para extração de íons K+ desse minério. O Verdete foi caracterizado por análise granulométrica, fluorescência de raios X (FRX) e difração de raios X (DRX). Comprovou-se que o minério é enriquecido em potássio (teor aproximado de 11%) e composto por quartzo, micas e feldspatos potássicos. Os produtos obtidos dos tratamentos hidrotermais foram analisados por fotometria de chama e os resultados indicaram maior extração do potássio quando utilizados como reagentes o H2SO4 (máximo de 24% da massa de potássio alimentada) e o CaCO3 calcinado (máximo de 39% da massa de potássio alimentada). A análise de DRX dos produtos mostrou que a conversão obtida a partir da reação com H2SO4 foi resultante da formação de sulfatos solúveis, enquanto a reação entre hidróxido de cálcio e glauconita, mineral componente do Verdete, promoveu a liberação de íons potássio durante o tratamento realizado com CaCO3 calcinado. Potassium (K) is one of the main nutrients in the soil due to its participation in plant growth and in the performance of physiological activities, such as water absorption and circulation of other nutrients in the plant. However, in Brazil, the concentration of K in the soil is scarce due to the high levels of acidity and leaching in the tropical soil and, because of that, it is massively used by the fertilizers industries in its correctives along with nitrogen (N) and phosphorus (P). Contrary to its importance in agriculture, the only potash-producing plant is located in the Taquari-Vassouras Mine, in Sergipe, corresponding to the production of only about 10% of the domestic demand. In this context, potassium has become a strategic element and the pursuit of alternative sources has increased in the last few years. Among the alternative sources in our country, the silicate rock called Verdete stands out, with its reserve located in Cedro de Abaeté/MG and surroundings. Natural Verdete presents contents from 7% to 14% of K2O, which are however, distributed into mineral structures not directly absorbed by the plants. This paper proposes the physical and mineralogical characterization of Verdete as well as the application of hydrothermal treatments using CaCl2.2(H2O), MgCl2.6(H2O), H2SO4 and calcinated CaCO3 in order to extract K+ ions from this mineral. The “Verdete” rock was characterized by granulometric analysis, X-rays fluorescence (XRF) and X-rays diffraction (XRD). It was demonstrated that the rock is enriched with potassium (a content of approximately 11%) and composed by quartz, micas and potassium feldspars. The products obtained from the hydrothermal treatments were analyzed through flame photometry and the results indicated a higher extraction of potassium when reagents such as H2SO4 (maximum of 24% of the fed potassium mass) and the calcinated CaCO3 (maximum of 39% of the fed potassium mass) were used. The XRD analysis of the products showed that the obtained conversion from the reaction with H2SO4 was due to the formation of soluble sulphates, while the reactions between the calcium hydroxide and glauconite, a mineral component of Verdete, promoted the liberation of potassium ions during the treatment carried out with calcinated CaCO3. Dissertação (Mestrado)

O presente trabalho teve por objetivo estudar a cinética de secagem em estufa através da obtenção de dados de secagem de suas curvas e aplicação dos modelos matemáticos aplicados à secagem de polpas de hidróxido de magnésio preparadas a partir da hidratação de duas fontes distintas de magnésia cáustica e de uma polpa de hidróxido de magnésio p.a., a título de comparação. As polpas preparadas a partir das fontes de magnésia cáustica foram obtidas por hidratação do óxido de magnésio em um sistema híbrido reator-moinho de bolas após 5 horas de reação. Para caracterização físico-química das amostras, foram utilizadas as técnicas de fluorescência de raios X e análise granulométrica por difração a laser. Os resultados mostraram alta velocidade de secagem das polpas com a etapa de secagem à taxa constante como sendo a controladora do processo, com transferência de calor e massa predominantemente a partir da superfície, apresentando um melhor ajuste ao modelo de Lei de Resfriamento de Newton. ABSTRACTThe aim of the present work was to study the kinetics of drying in stove by obtaining drying data of its curves and applying the mathematical models applied to the drying of magnesium hydroxide pulps prepared from the hydration of two different sources of caustic magnesia and one magnesium hydroxide pulp, for comparison purposes. The pulps prepared from the sources of caustic magnesia were obtained by hydration of the magnesium oxide in a reactor-ball mill hybrid system after 5 hours of reaction. For the physicochemical characterization of the samples, the techniques of X-ray fluorescence and granulometric analysis by laser diffraction were used. The results showed a high drying rate of the pulps with the drying step at constant rate as the process controller, with heat transfer and mass predominantly from the surface, presenting a better fit to the Newton Cooling Law model.

A novel quadruple spinneret to produce dual-layer hollow fiber membranes by simultaneous spinning of two polymer solutions, using the dual precipitation bath technique is proposed. Hollow fibers aimed at gas separation processes were prepared in extrusion system specifically designed and built for this purpose. A polyurethane polymer was selected as the selective layer (outer-layer), while polyethersulfone was defined as the support (inner-layer). Activated carbon powder was added into the PU solution for further improvement of the transport properties. The hollow fibers showed good adhesion between the polymer layers and a defect-free selective layer. Representative results include a CO2/N2 selectivity of 43.

The optimization of hydraulic retention time (HRT) and initial organic matter concentration for dissolved organic carbon (DOC) abatement of wastewater from a fish canning industry of northern Portugal by activated sludge was investigated using response surface methodology (RSM). The two parameters were chosen since it was found that the treatment efficiency is mainly influenced by them. The experimental data on DOC removal were fitted into a quadratic polynomial model using factorial design and RSM. The optimum process conditions were determined by analyzing the response surface of a three-dimensional plot and by solving the regression model equation. The obtained results showed a HRT of 6.4. h and an initial DOC of 406.2. mg/L as the best treatment conditions. Under these conditions, the maximum predicted DOC removal was 88.0%, confirming the feasibility and the reliability of fish canning wastewater treatment by activated sludge for organic content removal. (c) 2015 The Authors.

Bark from Eucalyptus globulus, a side-stream of pulp and paper industry, is a source of bioactive polyphenols that are extractable with 80/20 (v/v) ethanol/water. In this work, downstream processing of this extract was performed by ultrafiltration (UF) assessing for the first time (i) the influence of membrane type and transmembrane pressure (TMP) on the flux and permeate composition; (ii) the analysis of flux and resistances using the resistance-in-series model; (iii) permeate flux and cake build up modeling; and finally (iv) the feasibility of concentration by UF. Four membranes were selected: polyamide composite GE – 1 kDa (GE 1), polyethersulfone PLEAIDE – 5 kDa (P 5), polyvinylidenefluoride JW – 30 kDa (JW 30), and polysulfone EW – 60 kDa (EW 60). The effect of TMP on the permeation flux was evaluated, and total solids (TS), total phenolic compounds (TPC), proanthocyanidins (Pac) and formaldehyde condensed tannins (fcT) were quantified in the permeates. Data analysis showed that the experiments were performed in a region not controlled by pressure. P 5 and JW 30 membranes are more susceptible to fouling than the GE 1 and EW 60. In spite of the lowest cut-off of GE 1 membrane, it presented the lowest retention to TS, TPC and Pac, demonstrating that membrane material plays a significant role in separation. Finally, a model using classical cake-filtration theory and the surface-renewal concept successfully predicted the permeate flux and cake build up. A trade-off between permeate flux, the resistance and the retentions to TPC and Pac was established. The selected TMP was 3 bar for EW 60 (retentions: TPC 14%, Pac 30%) and 5 bar for JW 30, P 5 and GE 1 (retentions: TPC 66%, 66% and 58%; Pac 87%, 88% and 58%, respectively).

CAPES - Coordenação de Aperfeiçoamento de Pessoal de Nível Superior A β-galactosidase é uma hidrolase que catalisa a reação de hidrólise da lactose. Essa enzima tem se destacado cada vez mais no âmbito industrial, apresenta grande potencial para aplicação na indústria de laticínios, pela sua ação é possível elaborar produtos isentos de lactose, voltados para intolerantes, além de aumentar a digestibilidade de lácteos e melhorar as características dos mesmos. Além disso, a β-galactosidase atua na produção de galacto-oligossacarídeos, que possuem efeitos prebióticos e ajudam na manutenção da flora intestinal. A lactose, principal carboidrato do leite, está presente em alta quantidade no soro de leite, designado como subproduto da indústria de laticínios, nesse sentindo a β-galactosidase apresenta potencial significativo para hidrólise da lactose do soro de leite com possibilidade de desenvolvimentos de novos produtos e tecnologias. A enzima β-galactosidase têm sido imobilizada com intuito de expandir e melhorar sua aplicação nos processos. Assim, vários métodos de imobilização vêm sendo aplicados, um deles é a adsorção física, método simples que envolve apenas ligações fracas. Dentre os suportes utilizados as resinas de troca iônica apresentam grande potencial. Neste trabalho a β-galactosidase foi produzida a partir da levedura Kluyveromyces marxianus e imobilizada em resina de troca iônica Duolite® A-568. A produção foi realizada por fermentação submersa, utilizando como fonte de carbono a lactose presente no permeado do soro de leite. Em seguida, a enzima foi caracterizada quanto sua estabilidade térmica, ao pH e ao armazenamento. Após a caracterização da enzima livre, esta foi imobilizada em resina Duolite® A-568. Realizaram-se testes preliminares variando tempo, concentração de enzima e utilização de enzima liofilizada na imobilização. Na sequência foi realizado uma otimização das condições por meio de um Planejamento Composto Central com as variáveis pH, concentração do tampão e atividade ofertada na imobilização. Para todas as imobilizações definiu-se a atividade recuperada. Foram realizados testes de reticulação com glutaraldeído em diferentes concentrações. A enzima também passou por um processo com duas imobilizações, visando aumentar a atividade recuperada. Como resultados obtidos, a enzima livre apresentou maior estabilidade térmica a 30 °C e estabilidade ao pH 7,3, além de reter 80% da atividade inicial durante sete semanas de armazenamento sob refrigeração, tanto em sua forma solúvel como liofilizada. Os testes preliminares de imobilização definiram a atividade ofertada como 27 U e o tempo de uma hora de imobilização, a atividade recuperada da imobilização com a enzima não liofilizada e liofilizada não apresentou diferenças. Na otimização as faixas ótimas obtidas no planejamento foram de 6,9 a 7,3 para o pH, 0,4 a 0,8 M para concentração do tampão e 24 a 31 U para atividade ofertada. Os testes de reticulação mostraram que o aumento da concentração da solução de glutaraldeído implicou em uma redução da atividade do biocatalisador imobilizado. A imobilização em série foi importante para aumentar a atividade do biocatalisador imobilizado. De forma geral a enzima produzida se apresentou eficiente para imobilização em resina de troca iônica Duolite® A-568, levando em consideração que mais variáveis devem ser otimizadas para melhora da imobilização. β-galactosidase is a hydrolase that catalyzes the hydrolysis reaction of lactose. This enzyme has been increasingly highlighted in the industrial field, presents great potential for application in the dairy industry, by its action it is possible to produce lactose-free products, aimed at intolerants, in addition to increasing the digestibility of dairy products and improving their characteristics. In addition, β-galactosidase acts in the production of galacto-oligosaccharides, which have prebiotic effects and help in maintaining the intestinal flora. Lactose, the main carbohydrate in milk, is present in high amounts in whey, designated as a by-product of the dairy industry, in which β-galactosidase presents significant potential for hydrolysis of whey lactose with the possibility of new product developments and technologies. The β-galactosidase enzyme has been immobilized in order to expand and improve its application in the processes. Thus, several methods of immobilization have been applied, one of them is the physical adsorption, simple method involving only weak links. Among the substrates used ion exchange resins have great potential In this work β-galactosidase was produced from yeast Kluyveromyces marxianus and immobilized on Duolite® A-568 ion exchange resin. The production was carried out by submerged fermentation, using lactose present in the permeate of the whey as the carbon source. The enzyme was then characterized as to its thermal stability, pH and storage. After characterization of the free enzyme, it was immobilized on Duolite® A-568 resin. Preliminary tests were performed varying time, enzyme concentration and use of lyophilized enzyme in the immobilization. In the sequence an optimization of the conditions was carried out by means of a Central Composite Planning with the variables pH, buffer concentration and activity offered in the immobilization. For all immobilizations the recovered activity was defined. Glutaraldehyde crosslinking tests were performed at different concentrations. The enzyme also underwent a process with two immobilizations, aiming to increase the recovered activity. As results obtained, the free enzyme presented greater thermal stability at 30 ° C and stability at pH 7.3, besides retaining 80% of the initial activity during seven weeks of storage under refrigeration, both in its soluble and lyophilized form. Preliminary immobilization tests defined the activity offered as 27 U and the one-hour immobilization time, the activity recovered from immobilization with the non-lyophilized and lyophilized enzyme did not present differences. In the optimization, the optimum ranges obtained in the planning were 6.9 to 7.3 for the pH, 0.4 to 0.8 M for the buffer concentration and 24 to 31 U for the offered activity. Crosslinking tests showed that increasing the concentration of the glutaraldehyde solution implied a reduction in the activity of the immobilized biocatalyst. Serial immobilization was important to increase the activity of the immobilized biocatalyst. In general, the enzyme produced was efficient for immobilization in Duolite® A-568 ion exchange resin, taking into account that more variables should be optimized for immobilization improvement. Dissertação (Mestrado)

CAPES - Coordenação de Aperfeiçoamento de Pessoal de Nível Superior O consumo de bebidas e alimentos funcionais tem crescido no mundo nos últimos anos principalmente devido ao aumento da preocupação das pessoas com a saúde e o bem estar. As folhas da planta Camellia sinensis são tradicionalmente utilizadas para o preparo de infusões e, além disso, devido à alta concentração de compostos bioativos em seus extratos, essa erva tem chamado a atenção de pesquisadores e das indústrias alimentícia e farmacêutica. Os processos de filtração por membranas podem ser utilizados para clarificação, purificação e concentração de diversos produtos. Nessa perspectiva, este trabalho teve como objetivo o processamento do chá verde incluindo a caracterização das folhas, a extração, a clarificação e a purificação dos polifenóis presentes no chá usando água como solvente, pré-tratamentos macroscópicos para a clarificação (centrifugação e adição de agentes coagulantes - quitosana e sementes de Moringa oleífera) e, sequencialmente, filtração por membranas para purificação dos extratos. Inicialmente fez-se a moagem, o peneiramento e a classificação granulométrica das folhas de chá verde. A influência da granulometria na extração foi analisada em uma extração aquosa conduzida a 80ºC por 30 min a uma razão chá-água de 50 g L-1 utilizando folhas de chá com granulometria na faixa de 0,05-2,83 mm e também folhas de chá não moídas. A melhor granulometria para extração de polifenóis encontrada foi para a faixa de partículas de 0,15-0,74 mm e essa foi utilizada em todos os experimentos de extração convencional e com ultrassom subsequentes. O impacto da razão chá-água foi avaliado variando-a de 10 a 120 g L-1 para extrações a 80ºC por 30 min. Para a verificação do melhor tempo e da melhor temperatura na extração convencional, o preparo do chá foi realizado com uma razão chá-água de 50 g L-1, variando-se o tempo de 10 a 120 min e a temperatura de 40 a 90°C. A extração ultrassônica foi feita em duas etapas, na primeira etapa foi feito um planejamento composto central (PCC), com três réplicas no ponto central, com alfa de ortogonalidade igual a 1,3531, a um nível de significância de 95%. Para bateladas de 30 min variou-se a temperatura de 22 a 83ºC, a razão chá-água de 12 a 73 g L-1 e a amplitude de 23 a 77%. Na segunda etapa da extração ultrassônica, utilizou-se a razão chá-água de 50 g L-1, a melhor amplitude encontrada na primeira etapa (77%) e, similarmente à extração convencional, avaliou-se o efeito da temperatura em função do tempo variando-se o tempo de 10 a 120 min e a temperatura de 40 a 90ºC. A melhor condição de extração encontrada nesse trabalho foi a extração convencional a 80ºC, 50 g L-1 por 60 min utilizando partículas de chá na faixa (0,15-0,74 mm). Em seguida, avaliou-se como pré-tratamentos: centrifugação (8000 rpm, 20 min), adição de quitosana (0-2000 mg L-1) e adição de sementes de Moringa oleífera (SMO) (0-10.000 mg L-1). As microfiltrações foram feitas a 0,8 bar utilizando como alimentação o extrato centrifugado. Para tal empregou-se uma membrana plana de éster de celulose de 0,22 μm e um cartucho de membranas cerâmicas do tipo fibra-oca sem revestimento polimérico fabricado em laboratório. A microfiltração através das membranas do tipo fibra-oca sem revestimento apresentaram menor retenção de polifenóis (2,33%), maior retenção de sólidos (4,23%), maior redução da turbidez (89,91%) e maior fluxo estabilizado (19,37 L h-1m-2) em relação à membrana comercial plana de 0,22 μm. Posteriormente à microfiltração fez-se uma filtração sequencial empregando um cartucho com membranas de alumina do tipo fibra-oca com revestimento polimérico a 1,5 bar. Para esse processo obteve-se um fluxo estabilizado de 3,51 L h-1m-2, uma redução de 9,17% de polifenóis, 12,89% de sólidos, 80,65% da turbidez e 16,92% de sólidos solúveis (ºbrix). Os fluxos obtidos nas filtrações foram utilizados para calcular o mecanismo de fouling e para calcular as resistências das membranas. O mecanismo de fouling predominante (n) e o valor da resistência dos poros (RP) encontrados para a membrana plana de 0,22 µm, para a fibra oca sem revestimento e para fibra oca com revestimento foram bloqueio interno dos poros (n=1,5) e (RP = 0,7 x 10-13), formação de torta (n=0) e (Rc = 2,80 x 10-13) e bloqueio intermediário dos poros (n=1) e (RP = 7,38 x 10-13), respectivamente. Avaliou-se a estabilidade do extrato de alimentação e dos permeados das filtrações, quando armazenados por 30 dias à 5ºC, tomando como referência os parâmetros concentração de polifenóis, turbidez e formação de tea cream. Observou-se que apenas o permeado obtido através da filtração pela fibra oca revestida (S5) apresentou estabilidade (turbidez menor que 4 NTU) e sem a formação de tea cream ao longo dos 30 dias de armazenamento à 5ºC. Assim, este trabalho encontrou as melhores condições de extração de polifenóis presentes em folhas de chá verde e evidenciou a utilização de centrifugação para clarificação e a aplicação filtração com membranas de alumina do tipo fibra oca sem e com revestimento polimérico para purificação do extrato de chá de chá verde. O resultado final foi a produção do chá verde como uma bebida mais clarificada e estável. The consumption of functional beverages and food has increased in the last years mainly due to people concerning about their health and well-being. Camellia sinensis leaves are traditionally used for infusion preparations. Furthermore, considering the high bioactive compounds concentration in its extracts, this herb has been catching the attention of researchers as well as of the food and pharmaceutical industries. Membrane filtration processes may be used for clarification, purification, and concentration of several products. From this point of view, this study focused on the green tea processing, including leaves characterization, extraction, clarification, and purification of polyphenols. In this sense, water was used as a solvent for extraction; macroscopic pre-treatments was applied for clarification (centrifugation and addition of coagulants agent, such as chitosan and Moringa oleífera seeds) and sequentially, a membrane filtration was employed for purification. Initially, the tea was ground, sifted and classified granulometrically. Then, different parameters were evaluated in order to find the best polyphenol extraction condition from tea leaves. The influence of the tea particle was analysed at 80ºC for 30 min for a water-to-tea ratio 50 g L-1 and a tea particle size (0.05-2.83 mm) besides unground leaves. The best tea particle size for polyphenols extraction was 0.15-0.74 mm and it was then used for all further conventional and ultrasound assisted extraction experiments. The optimum ratio was determined by extractions at 80ºC for 30 min with a tea-to-water ratio ranging from 10 to 120 g L-1. The impact of time and temperature on the conventional extraction of polyphenols was evaluated at 50 g L-1 tea-to-water ratio by ranging the time and the temperature from 10 to 120 min and from 40 to 90ºC respectively. Ultrasound-assisted extraction (UAE) consisted of two steps. In the first step of UAE, an experimental design using Response Surface Methodology (RSM) was performed with three replicates at the central point, orthogonality alpha of 1.3531 and at a significance level of 95%. For extraction time of 30 min, temperature, tea-to-water ratio, and amplitude ranged from 22 to 83ºC, 12 to 73 g L-1, 23 to 77% respectively. In the second step of UAE, using the best amplitude determined in step one (77%) and for a water-to-tea ratio 50 g L-1, similarly to conventional extraction, time and temperature varied from 10 to 120 min and from 40 to 90ºC respectively. The optimum extraction condition found in this study was 80ºC, 50 g L-1 for 60 min and a particle size (0.15-0.74 mm). Sequentially, the pre-treatments were performed: centrifugation (8000 rpm, 20 min), chitosan addition (0-2000 mg L-1) and Moringa oleífera seeds addition (0-10.000 mg L-1). Microfiltration processes were carried out at 0.8 bar applying a flat membrane of 0.22 µm and hollow fibres without coating coupled in a home-made cartridge. Microfiltration through hollow fibres without coating presented less polyphenol retention (2.33%), greater solids removal (4.23%), greater turbidity reduction (89.91%) and the greatest steady-state flux (19.37 L h-1m-2) comparatively to flat membrane of 0.22 μm. After the microfiltration processes, a sequential filtration was executed at 1.5 bar employing a home-made cartridge using hollow fibres with a polymeric coating. This sequential process achieved a steady-stead flux of 3.51 L h-1m-2 and a reduction of 9.17% of polyphenols, 12.89% de solids, 80.65% of turbidity and 16.92% of soluble solids (ºbrix). The obtained flux in each filtration process was used to calculate the fouling mechanism and the membrane resistance. In this way, fouling mechanisms (n) and pore resistance values (RP) found for flat membrane of 0.22 µm, hollow fibre without coating and for hollow fibre with coating were internal pore blocking (n=1.5) e (RP = 0.7 x 10-13), cake formation (n=0) e (Rc = 2.80 x 10-13) and intermediary pore blocking (n=1) e (RP = 7.38 x 10-13) respectively. Extract and permeates stability, stored at 5ºC for 30 days, were evaluated using as reference the parameters polyphenols concentration, turbidity and tea cream formation. Only the permeate obtained through filtration by the coated hollow fibre (S5) presented stability (turbidity value less than 4 NTU) and no formation of tea cream during the 30 days of storage at 5ºC. In conclusion, this study found the best polyphenol extraction conditions and proposed the utilisation of centrifugation for clarification followed by filtration through hollow fibres membranes without and with coating for green tea extract purification. Dissertação (Mestrado)

The increasing concern over the spread of diseases has lead to a high consumption of antimicrobial additives in the medical and industrial fields. Since these particles can lixiviate from loaded materials, the contact between this additive and mammalian cells can occur during manufacture, use and disposal of the products. Silver on fumed silica (AgNP_SiO2) and titanium dioxide (TiO2) can be used as antimicrobial additives that are applied in polymeric formulation. While these additives can inhibit bacteria, fungus and virus proliferation; they may also be harmful to humans. Standard toxicological studies were undertaken using the MTT (3-(4,5-dimethylthiazol-2-yl)-2,5 diphenyltetrazolium bromide), CBPI (cytokinesis-block proliferation index) and micronucleus assay using different sets of additive concentrations. The nanosize of the samples evaluated was confirmed by transmission electronic microscopy. No significant micronucleus frequency increase or cell viability reduction were observed with the exposure of L-929 murine fibroblast cells to AgNP_SiO2 and TiO2 particles at any of the tested concentrations. The non toxic effect of the analyzed particles can be explained by considering its agglomeration tendency, composition, and crystalline form. Further investigations should be done to understand the interference of agglomeration and how it affects the toxicological study.

The flow in a Confined Impinging Jets (CIJs) mixer was studied with Planar Laser Induced Fluorescence. Two key aspects influencing the flow regimes and mixing quality were studied: the impact of the jets' Reynolds number (Re) in the range 50 < Re < 600; and the effect of the jets' flow imbalance, maintaining the flow rate of one of the injectors fixed and varying the other. Mixing mechanisms and scales are studied from the acquired flow images, and the mixing degree is quantified from the calculation of the Intensity of Segregation (Danckwerts, 1952). In balanced flow conditions, i.e., equal volumetric feeding rates, when the best mixing performance is observed, three flow regimes are observed: for Re < 103 the flow is steady with complete segregation of the two feeding jet streams; for Re = 104 the flow tends to an oscillatory periodic laminar flow regime; for Re > 104 the flow evolves to a self-sustained chaotic laminar regime with strong mixing dynamics. With the increase of Re it is observed the formation of smaller mixing scales in the flow and an increase on the mixing quality. The visualized mixing scales are compared with theoretical models existing in the literature for the estimation of the striation thickness, leading to the conclusion that, in the studied flow regimes, the statistical theory of turbulent diffusion does not provide a realistic physical description of the flow. Furthermore, the jets' mass flow imbalance is shown to always influence negatively the mixing quality. This is observed even when the flow imbalance results in the increase of the flow rate of one of the jets, increasing the amount of energy supplied to the system for dissipation. Results of this work show that the mechanism of eddy engulfment promoted by the two chaotically oscillating impinging jets, in the laminar regime, is a key aspect in mixing by CIJs.

CNPq - Conselho Nacional de Desenvolvimento Científico e Tecnológico O uso de microalgas e cianobactérias como fonte de produção de bicombustíveis e outros produtos químicos de interesse comercial tem sido largamente reportada como uma tecnologia sustentável promissora. Em decorrência desse fato, as fontes de energia renováveis, como a biomassa, têm papel fundamental no contexto energético, ambiental e sócioeconômico. Uma vez que as microalgas estão entre os microorganismos fotossintéticos de crescimento mais rápido, além de terem a capacidade de se adaptar facilmente a várias condições climáticas e alta eficiência na fixação de CO2. A Spirulina maxima é considerada uma potencial matéria-prima para pirólise rápida, pois é uma cianobactéria que possui baixo teor de lipídios e alta quantidade de proteínas. Os hidrocarbonetos aromáticos, largamente empregados na indústria são os principais derivados da pirólise de proteínas. Neste estudo, análises termogravimétricas foram realizadas e os parâmetros cinéticos referentes à degradação térmica da biomassa foram identificados segundo três metodologias; dentre elas dois modelos globais isoconversionais (Friedman e Flynn-Wall-Ozawa) e um de energia de ativação distribuída (Miura-Maki). Observou-se concordância entre os resultados de energia de ativação obtidos pelas três metodologias, ou seja, 132,62, 143,77 e 130,04 kJ/mol, respectivamente para os modelos de Flynn-Wall-Ozawa, Friedman e Miura-Maki . Foram realizadas análises de micropirólise para biomassa pura em três diferentes temperaturas de reação (450, 550 e 650°C); assim, a composição dos vapores formados foi avaliada. As análises realizadas a 650°C apresentaram o maior rendimento de hidrocarbonetos aromáticos além de uma redução de compostos oxigenados. Variou-se também a taxa de aquecimento em 1, 5, 10, 15, e 20ºC/ms; ao analisar a composição dos vapores pôde-se observar que não houve mudanças significativas ao variar a taxa de aquecimento. Outro parâmetro analisado foi o tempo de reação, sendo realizadas análises em três diferentes tempos de reação (10, 20 e 30 s); assim analisou-se a composição dos vapores gerados. Com o aumento de tempo de reação houve uma diminuição dos compostos oxigenados, entretanto não houve mudanças significativas nos compostos aromáticos. Foi realizada também a micropirólise catalítica da Spirulina maxima com adição de dois tipos de catalisadores ácidos: zeolita (ZSM-5) e nióbio (HY-340). Nas condições estudadas, a Spirulina maxima adicionada de zeólita apresentou resultados expressivos para a seletividade de hidrocarbonetos aromáticos, para a razão biomassa/catalisador de 1:10, a produção foi aumentada em mais de cinco vezes em relação à biomassa pura. O catalisador à base de nióbio (HY-340) não apresentou efeito catalítico significativo em relação à produção de aromáticos. O nióbio é pouco explorado como catalisador para pirólise de biomassas, mas é promissor para estudos, pois apresenta alta acidez e um custo significativamente menor que as zeólitas comerciais. É importante ressaltar que os dados coletados no trabalho em questão podem ser útei para projetos de reatores. The use of microalgae and cyanobacteria as an important source for biofuels and value-added chemicals has been widely reported as a promising sustainable technology. As a result of this fact, renewable energy sources, such as biomass, have a fundamental importance in the energy, environment and socioeconomic context. Due to they are among the fastest growing photosynthetic microorganisms, they also have the ability to easily adapt to various climatic conditions and have high efficiency in fixing CO2. A Spirulina maxima is considered a potential raw material for fast pyrolysis due to its low lipid and high protein contents. Aromatic hydrocarbons, which are widely used in industry, are the main derivatives of protein pyrolysis. In this study, thermogravimetric analyses were performed and the activation energy values for biomass thermal degradation were identified using three methodologies: the Friedman and the Flynn-Wall-Ozawa isoconversional methods, and the Miura-Maki distributed activation energy model. The three methodologies resulted in similar mean values of activation energy, namely, 132.2, 143.77 and 130.04 kJ/mol, respectively, for the Flynn-Wall-Ozawa, Friedman and Miura-Maki models. The micropyrolysis of the pure biomass was analyzed at three different reaction temperatures (450, 550 and 650°C) and the composition of the vapor products was evaluated. The micropyrolysis performed at 650°C presented the highest yield of aromatic hydrocarbons and a decrease in oxygenated compounds. In addition, the heating rate was also varied in 1, 5, 10, 15, and 20 ° C / ms, and the composition of the vapors products was evalueted, it can be observed that there were no significant changes when the heating rate varied. Another parameter analyzed was the reaction time, analyzes were performed at three different reaction times (10, 20 and 30). So the composition of the vapors products generated was analyzed, with the increase of reaction time there was a decrease of the oxygenated compounds, however, there were no significant changes in the aromatic compounds. A Spirulina maxima was also subjected to catalytic micropyrolysis by the addition of two types of acid catalysts: zeolite ZSM-5 and niobic acid (HY-340). Under the conditions of this study, the addition of zeolite to microalgae yielded significant results in the production of aromatic hydrocarbons, i.e., the production volume was more than five-fold greater with the biomass-to-catalyst ratio of 1:10 than with the pure biomass. The catalytic effect of the niobium-based catalyst (HY-340) on the production of aromatic compounds was negligible. The niobium is little explored as a catalyst for biomass’s pyrolysis, but it is promising for studies, due to the niobium present high acidity and a significantly lower cost than the commercial zeolites. It is important to emphasize that the data collected in this work can be useful for reactor projects. Dissertação (Mestrado)

CAPES - Coordenação de Aperfeiçoamento de Pessoal de Nível Superior FAPEMIG - Fundação de Amparo a Pesquisa do Estado de Minas Gerais O hidrogênio é considerado como um dos portadores de energia mais promissores, o que se deve à sua alta eficiência de conversão em energia. Neste sentido, a investigação intensiva da produção sustentável de hidrogênio atrai cada vez mais pesquisadores. No presente trabalho, estudou-se o potencial produtor de hidrogênio das bactérias Enterobacter aerogenes e Enterobacter cloacae variando-se parâmetros operacionais. As fermentações realizadas em batelada avaliaram a influência da luz e das fontes de carbono, glicose e permeado do soro de leite. Além disso, também foi verificada a influência dos gases inertes nitrogênio e argônio na fermentação clara para as bactérias produtoras de hidrogênio. Na primeira etapa deste trabalho, os ensaios realizados ocorreram em reatores de 50 mLcom duração de 108 horas. Para a E. aerogenes, o substrato foi a variável que mais influenciou a fermentação. O volume de hidrogênio obtido utilizando glicose como substratofoi superior à fermentação com permeado de soro de queijo, sendo que as melhores condições fermentação dos respectivos substratos geraram 3,18 e 0,86 mmol de H2. Verificou-se também que a incidência de luz gerou resultados positivos, sendo o rendimento da fermentação com glicose na presença e ausência de luz foi de 1,51 e 0,94 mols H2/mol de hexose, respectivamente. Entretanto, para E. cloacae, a influência do substrato e da iluminação foram menos expressivas. Na fermentação escura os rendimentos para glicose e lactose foram de 1,60 e 1,39 mols H2/mol de hexose, respectivamente. Enquanto que, na fermentação clara o rendimento foi equivalente para a glicose e superior em 33% para a lactose, quando comparados a situação escura. Em relação a substituição do gás inerte nitrogênio por argônio, apenas a E. cloacae apresentou melhora nos resultados, o que foi observado para ambos os substratos em estudo. O rendimento na presença do gás argônio foi superior em 47% e 37% para glicose e lactose, respectivamente, quando comparados a mesma condição com o gás nitrogênio. Este melhor resultado indica uma mudança na rota metabólica do microrganismo, sendo uma possibilidade a utilização da enzima nitrogenase para a síntese de H2. Verificando melhores resultados para a E. cloacae, o microrganismo foi avaliado na condição de sistema híbrido, em reator de 50 mL. O sobrenadante gerado na fermentação escura pela E.cloacae foi utilizado na pela mesma bactéria na fase clara, o que gerou um rendimento de 2,01 mols de H2/mol de hexose. O aumento na escala de fermentação para um reator de tanque agitado de 1,50 L foi empregado para E. cloacaena condição escura. Neste sistema, a fermentação escura ocorreu por 432 horas, período em que foi observado a produção de biogás. A produtividade máxima obtida com o sistema foi de 110,09 mmol H2/L·dia e o rendimento de 2,16 mols H2 mol/mol hexose. A produção de ácidos orgânicos e etanol também foi verificada, sendo o ácido butírico o metabólico com maior expressão no meio. De forma geral, foi verificado que a E.cloacae se mostrou mais promissora à produção de hidrogênio utilizando tanto glicose como lactose como fonte de carbono, sendo os resultados deste microrganismo otimizados na presença do gás inerte argônio. Hydrogen is considered one of the most promising energy carriersdue its high energy conversion efficiency. In this way, the intensive investigation of the sustainable production of hydrogen attracts more and more researchers. In the present work, the potential hydrogen producer by the bacteria Enterobacter aerogenes and Enterobacter cloacae was studied for for different parameters. The batch fermentations evaluated the influence of light and sources of carbon, glucose and whey permeate. In addition, the influence of inert gases nitrogen and argon in the light fermentation for hydrogen producing bacteria was also verified. The tests were carried out in 50 mL reactors during 108 hours. In the case of E. aerogenes the substrate was the variable that most influenced the fermentation. The volume of hydrogen obtained using glucose as substrate was higher than the fermentation with cheese whey permeate, and the best fermentation conditions of the respective substrates generated 3.18 and 0.86. It was also verified that the influence of the light got positive results, being the fermentation yield with glucose in the presence and absence of light of 0.94 and 1.51 mols H2/mol of hexose, respectively. However, the influence of E. cloacae in the substrate and illumination was less expressive. In the dark fermentation the yields for glucose and lactose were 1.60 and 1.39 mols H2/mol of hexose, respectively. While in the light fermentation the yield was equivalent to glucose and 33% higher for lactose when compared to the dark situation. About the inert gas, only the E. cloacae showed improvement in the results. The yield in the presence of argon gas and was higher by 47% and 37% for glucose and lactose, respectively, when compared to the same condition with nitrogen gas. Verifying better results for E. cloacae, the microorganism was evaluated in the hybrid system condition in a 50 mL reactor. The effluent generated in the dark fermentation was used in the light phase, which generated a yield of 2.01 mols H2/mol hexose. The increase in fermentation scale for a stirred tank reactor of 1.5 L was proposed for E. cloacae. In this system, the dark fermentation happened for 432 hours while the biogas production was verified, obtaining a maximum yield of 110.09 mmol H2/L·day and yield of 2.16 mols H2 mol/mol hexose. In general, E.cloacae showed to be more promising for the production of hydrogen using both glucose and lactose as carbon source, and the results of this microorganism were optimized in the presence of inert gas argon. Dissertação (Mestrado)

A pectina é um polissacarídeo complexo, que atua como agente geleificante, espessante e estabilizante na composição de diversos produtos. A casca do maracujá possui elevado nível de pectina, cujo método convencional de extração é a ebulição utilizando ácidos fortes. O presente estudo objetivou explorar um novo método de extração utilizando ácidos fracos. Buscando esse propósito, a pectina da casca de maracujá foi obtida por meio de extração assistida por ultrassom, utilizando solução de ácido cítrico. Os experimentos foram conduzidos visando avaliar o efeito das variáveis experimentais (razão amostra:solvente, temperatura e tempo) no rendimento de pectina. Os resultados demonstraram que a extração conduzida com razão amostra:solvente de 1:50 (m/v), temperatura de 50 °C e tempo de 90 min proporcionou a obtenção de 26,45% de pectina. Nessas mesmas condições experimentais a pectina foi extraída por método convencional para efeito comparativo, o qual permitiu a obtenção de 21,06% de pectina. Portanto, o uso do ultrassom promoveu a obtenção de melhores resultados, visto que proporcionou o aumento de 25% no rendimento. O grau de esterificação foi determinado apenas para amostras obtidas por ultrassom, as quais foram classificadas com alto grau de metoxilação (81,93%).ABSTRACTPectin is a complex polysaccharide, which acts as a gelling agent, thick and stabilizing in the composition of various products. The passion fruit peel has a high level of pectin, whose conventional method of extraction is boiling using strong acids. The present study aimed to explore a new extraction method with the weak acids. For this purpose, a pectin from the passion fruit peel was obtained by ultrasound-assisted extraction, using citric acid solution. The experiments were conducted with the objective of evaluating the effect of experimental variables (analysis procedure: solvent, temperature and time) on pectin yield. The results demonstrated that the extraction was carried out on the basis of a solvent criterion of 1:50 (m/v) at a temperature of 50 °C and the time of 90 minutes provided a yield of 26.45% pectin. In these same experimental conditions the pectin was extracted by conventional method for comparative effect, which allowed a obtainment of 21.06% pectin. Consequently, the use of the product was promoted to obtain better results, which gave rise to a 25% of increase in yield. The degree of esterification was determined only for samples obtained by ultrasound, which were classified with high degree of methoxylation (81.93%).

The goal of this work was to study the adsorption equilibrium of ions Zn 2+ and Cd 2+ using bovine bone char in fixed bed columns. Dynamic tests were performed with upstream flow fixed bed column, at 30 o C and average particle diameter of 0.08 mm. Initially, the optimal operating flow rate was determined, which was 4 mL min. -1 for both metals. The dynamic isotherms, obtained by mass balance in the breakthrough curves, were fitted to the Langmuir and Freundlich models. Simulations of the dynamics of ion adsorption provided satisfactory results, wherein the mass transfer coefficient was directly affected by the inflow concentration of ions, within the range of the study.

n-Decane is a saturated long-chain hydrocarbon, belonging to the family of the volatile organic compounds (VOCs), which is persistently present in indoor air of several industrial closed facilities. Due to the VOCs environmental impact, all efforts that have been made during the last decades to degrade this kind of air pollutants are extremely important. Accordingly, the present paper reports n-decane photooxidation studies carried out in an annular photoreactor under simulated solar irradiation and employing a catalytic bed made of cellulose acetate monoliths coated with a photocatalytic paint. The influence of the feed flow rate, n-decane concentration, relative humidity, and incident irradiance on the n-decane degradation kinetics was assessed. Within this work, n-decane photodegradations higher than 90% were achieved, depending on the experimental conditions. Additionally, a phenomenological reaction rate model of the n-decane photocatalytic oxidation was proposed and assessed. The proposed model assumes that n-decane and water molecules compete for different active sites on the catalyst surface. Finally, despite the high n-decane photodegradation achieved, reaction by-products were identified and, based on these compounds, a reaction mechanism was formulated.

In this paper, the use of Automated Bonding Evaluation System (ABES) for evaluation of bonding strength of wood adhesives is presented. A simple reactive model is proposed, which considers the phenomena involved during resin cure: formation of wood-resin-wood bonds. In the present study, experimental data of a standard urea-formaldehyde (UF) resin using different catalysts, phosphoric acid and ammonium sulphate, are presented and discussed. The proposed can be applied to wood adhesives, namely formaldehyde-based resins under different temperatures. The model fits well to experimental data, presenting high determination coefficient values.

Nowadays, the production of hydrogen has received increased attention due to its important industrial applications and to its promising potential as an alternative energy source. The use of hydrogen in fuel cell applications requires a high purity. In this work, hydrogen purification from mixtures that also contain CO2, CO, CH4, and N2 was performed by Pressure Swing Adsorption (PSA) with CuBTC as adsorbent (supplied by KRICT). The equilibrium adsorption of each pure gas was measured and fixed-bed adsorption experiments were carried out. The same column, employed for the fixed-bed breakthrough curves, was used to carry out experiments of a 4-step PSA cycle. A mathematical model of multicomponent adsorption in fixed bed was developed. This model was validated against the results obtained in breakthrough experiments and PSA tests, presenting a good prediction of the experimental data. Therefore, this model can be used as a base for the design of optimized PSA cycles.

Carbon materials with distinct morphological and chemical characteristics, namely activated carbons, carbon nanotubes, glycerol-based carbon materials and carbon xerogels, were tested for the removal of 2-nitrophenol (2-NP) in aqueous solutions, either by pure adsorption or by catalytic wet peroxide oxidation (CWPO). The results obtained in adsorption experiments carried out at pH 3, T = 323 K, adsorbent load of 0.1 g L−1 and 2-NP concentration of 100 mg L−1, show that, in general, the activated carbons have superior adsorption performances compared to the other carbon materials tested, exhibiting removals of 2-NP up to 316 mg g−1 after 150 min of adsorption. In the CWPO experiments, whilst the activated carbons and carbon xerogels were not able to improve the removal of 2-nitrophenol, in comparison with the removals observed in pure adsorption experiments performed at the same conditions, the use of carbon nanotubes (CNT) and a glycerol-based carbon material (GBCM) resulted in increments in the removal of 2-NP as high as 83% and 56%, respectively. Removals of about 80% after only 30 min and higher than 90% after 150 min of reaction (equivalent to 929 mg g−1) are reached when using CNT as catalysts. The leaching of Fe (present as impurity in the CNT) at the end of the CWPO experiment was found to be negligible. The opposite was observed for classical iron supported on activated carbons, with catalytic activities resulting from the homogeneous contribution of Fe that is leached to the liquid phase. The superior performances found for CNT, makes this catalyst a promising system for CWPO.

This article studies the incorporation of sucrose in amino polymers produced by the strongly acid process and its role on the physico-mechanical properties and aldehyde emission of the resulting particleboards. The incorporation of sucrose at different pH environments was studied and differences on molecular weight of resins were analyzed by gel permeation chromatography/size exclusion chromatography (GPC/SEC) and characteristic chemical bands by Raman spectroscopy. A reaction mechanism was proposed to explain the observed differences in GPC/SEC chromatograms and was supported by Raman spectra. It was observed that small amounts of sucrose incorporated in polymeric matrix are sufficient to improve the physico-mechanical properties of particleboards; the sucrose addition protocol plays a key role on these improvements.

Advanced oxidation processes (AOPs) have been increasingly applied to emergent pollutants degradation. Although, homogeneous reaction by classical Fenton enables amoxicillin degradation, high iron catalyst concentrations are needed, raising environmental concerns. This work proposed an innovative and cheap solution to degrade amoxicillin by combining microwave with Fenton’s reaction. The main operational parameters were optimized step-by-step (hydrogen peroxide and ferrous ion concentration and microwave power). Amoxicillin oxidation was significantly improved over classical Fenton’s reaction. In fact, in less than 5 min (P = 162 W, [H2O2]0 = 2.35 mg L−1, [Fe2+]0 = 95 μg L−1) amoxicillin was no longer detected in the reaction system. A semi-empirical kinetic model was proposed to predict the two-stage decay curves at any conditions within the studied parameters and the adequacy of the model was statistically evaluated.

Adsorption equilibrium isotherms for propane and propylene on a new 13X zeolite from CECA were measured at three temperatures (323, 373, 423 K) up to 5 bar. Maximum capacities of 3.47 and 3.08 mol/kg were found for propylene and propane, respectively. These values are significantly higher than those reported in literature. Adsorption isotherms were fitted with Toth equation. Heats of adsorption were calculated as a function of loading from experimental data with Van’t Hoff equation leading to 53 kJ/mol and 35 kJ/mol for propylene and propane, respectively; values were also obtained from fitting with Toth equation. Single and binary breakthrough curves were measured and simulated with a mathematical model for fixed bed adsorbers. A 5-step VSA cycle was also simulated to produce 99.5% propylene from a 25:75 propane/propylene mixture; experimental validation confirms a good prediction. Propylene was obtained with a purity of 99.54%, a recovery of 85% and a productivity of 1.46 molC3H6/kgads/h.

Adequate water management is crucial to increase stability and durability of Polymer Electrolyte Membrane Fuel Cells. In this paper, a test rig suitable for water balance and nitrogen crossover studies was built around a hydrogen‐air segmented cell and used to indirectly assess flooding or drying conditions in specific zones of the active cell area. In particular, the anode of the segmented cell was operated in recirculation mode with continuous water removal. Current density distribution (CDD) diagrams were obtained for different anode operating parameters, namely, the recirculated gas flow rate, anode pressure, and time between purges. Water accumulation at the electrodes was assessed from CDD diagrams and confirmed using water balance and flow‐patterns calculations. It was concluded that lower recirculation flow rates led to flooding due to decreased water removal capabilities at the anode. For higher recirculation flow rates, drying was observed in one zone of the cell but homogeneous CDD in the other. Finally, the use of partially segment bipolar plates was proposed to increase the in‐plane electrical resistance between adjacent segments. The partial segmentation increased the segment to segment in‐plane electrical resistance between 14 and 21% and decreased the through‐plane to in‐plane resistance ratio by 17%.

Neste trabalho avaliou-se a aplicação do processo oxidativo avançado (POA) de foto-peroxidação (UV/H2O2) na degradação do azocorante têxtil comercial Azul Reativo 5G. Foram preparadas soluções sintéticas contendo o corante e tratadas através do respectivo POA, sendo a eficiência do tratamento avaliada através dos seguintes parâmetros: descoloração, redução da demanda química de oxigênio (DQO) e ecotoxicidade com sementes de Lactuca sativa. Após 30 minutos de tratamento em condições otimizadas na presença de peróxido de hidrogênio e radiação ultravioleta, foi observada descoloração na ordem de 91,8% sem redução significativa da DQO (1,8%), além de diminuição da ecotoxicidade da solução, indicando a viabilidade da aplicação do processo UV/H2O2 para tratamento de resíduos líquidos contendo este azocorante.ABSTRACTIn the present paper was evaluated the application of advanced oxidation process (AOP) photo-peroxidation (UV/H2O2) applied to degradation of the commercial textile azo dye Reactive Blue 5G. Synthetic solutions were prepared containing the dye, treated through the respective AOP and the efficiency of the treatment evaluated by the following parameters: discoloration, reduction of chemical oxygen demand (COD) and ecotoxicity with Lactuca sativa seeds. After 30 minutes of treatment in optimized conditions in the presence of hydrogen peroxide and ultraviolet radiation, discoloration was observed in order of 91.8% without significant reduction of COD (1.8%), but decrease in the ecotoxicity of the solution, indicating feasibility of the process UV/H2O2 for treating liquid wastes containing this azo dye.