51,062 research outputs found

    Treatment of saline wastewater amended with endocrine disruptors by aerobic granular sludge: assessing performance and microbial community dynamics

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    An aerobic granular sludge (AGS) sequencing batch reactor (SBR) adapted to salinity (12gL-1 NaCl) was operated under alternating anaerobic-aerobic conditions for the treatment of synthetic saline wastewater containing endocrine-disrupting chemicals (EDCs), namely 17estradiol (E2), 17ethinylestradiol (EE2) and bisphenol-A (BPA). The SBR was intermittently fed with the EDCs at 2mgL-1 of each compound. E2 was completely biodegraded, with 60% to 80% removal attained anaerobically and the remaining quickly consumed under aeration. EE2 was sorbed onto the granular sludge biomass in the anaerobic period, but it was desorbed in subsequent cycles even when the compound was not supplied to the reactor. BPA removal was poor but improved after bioaugmentation with an EDCs degrading bacteria. EDCs shock loads did not significantly affect the COD removal nor the activity of ammonium- and nitrite-oxidizing bacteria (AOB and NOB, respectively). In contrast, the activity of phosphate-accumulating organisms (PAOs) was affected, implying a decrease in P removal within the aerobic phase. AGS core microbiome grouped most bacteria belonging to the phylum Proteobacteria, followed by Bacteroidetes. The microbial profile showed that the introduction of the EDCs mixture increased the relative abundance of Chryseobacterium and Flavobacterium. AOB and NOB species were detected in the AGS biomass, with the latter showing lower relative abundance. Different PAOs, such as Rhodocyclus, Tetrasphaera and Gemmatimonas, were also part of the microbial community, but the addition of EDCs decreased significantly the relative abundance of Rhodocyclus. High microbial diversity was sustained over reactor operation, with the main bacterial groups responsible for nutrients and EDCs removal preserved in the AGS system. The results pointed to the maintenance of a core microbiome over reactor operation that may be related to the stability of the AGS process during EDCs loading.This study was supported in part by the Coordena√ß√£o de Aperfei√ßoamento de Pessoal de N√≠vel Superior (CAPES/Brasil) ‚Äď Finance Code 001 and the other part was financed by National Funds from Funda√ß√£o para a Ci√™ncia e a Tecnologia (FCT/Portugal) - through the project AGeNT - PTDC/BTA-BTA/31264/2017 (POCI-01-0145-FEDER 031264)and the project CBQF - UID/Multi/50016/2019info:eu-repo/semantics/publishedVersio

    Modelado de las etapas de reacción y separación en la producción de nopol

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    El presente trabajo se enfoca en el modelado y dimensionamiento de las etapas de reacci√≥n y separaci√≥n para la producci√≥n de nopol mediante un proceso catal√≠tico con Sn-MCM-41. La simulaci√≥n din√°mica del reactor se realiz√≥ en Simulink¬ģ, mientras que la destilaci√≥n de la mezcla reaccionante se propuso como una etapa en continuo, simulada con el software Aspen Plus¬ģ. La simulaci√≥n muestra que se alcanza una conversi√≥n de ő≤-pineno del 88 % despu√©s de 9 horas de reacci√≥n y que la destilaci√≥n de la mezcla resultante permite la recuperaci√≥n de una corriente de nopol de aproximadamente 100 % de pureza con 7 etapas de equilibrio. Los resultados de la simulaci√≥n evidencian la factibilidad t√©cnica del procesoDepartamento Administrativo de Ciencia, Tecnolog√≠a e Innovaci√≥n [CO] Colciencias5507-543-31904Programa: Bioprospecci√≥n y desarrollo de ingredientes naturales para las industrias cosm√©tica, farmac√©utica y de productos de aseo con base en la biodiversidad colombianan

    Fermentação de gás de síntese usando sistemas pressurizados

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    Tese de doutoramento em Chemical and Biological EngineeringOne of the major drawbacks of syngas fermentation is the limited gas-liquid mass transfer that generally limits productivities. Most research has been focusing in increasing the kLa (volumetric gas-liquid mass transfer coefficient), investigating different reactor typologies and gas dispersion devices. However, the driving force for mass transfer can also be increased, for instance, by operating at increased pressure. This thesis aims to explore the effect of increased pressure in syngas fermentation to improve the gas solubility, evaluating the effect on the biocatalysts and on the process itself. The starting point of this work was to use an adapted culture (from a syngas converting reactor) as inoculum. This culture was able to mainly produce methane and acetate from syngas. Methane was not produced directly from CO, but via the conversion of acetate and H2 by the bacteria present in the mixed culture (Acetobacterium and Sporomusa species). Later on, this culture was subsequentially transferred with syngas, originating an enriched culture mainly composed by Acetobacterium and Methanospirillum species that, besides acetate and methane, was able to produce propionate from syngas. From that highly enriched culture a new strain of Acetobacterium wieringae, strain JM, was isolated and characterized. This highly enriched culture was tested in an axial agitation reactor (AAR) with different initial syngas (CO, H2 and CO2 (60:30:10 %, v/v)) pressures, from 100 kPa to 600 kPa. No substrate inhibition was observed, even at the highest pressure and an increase of 45 % in titres (of acetate and propionate) were obtained. Moreover, the increase of pressure resulted in a shift in the metabolic pathways from acetate towards propionate, which is an uncommon product of syngas fermentation. The effect of pressure on the conversion of syngas by anaerobic mixed sludge was then studied using two different reactor typologies, AAR and GLR (gas-lift reactor). Initial syngas pressures of 100 kPa, 300 kPa and 500 kPa were tested. Overall, the GLR showed better performance in terms of CO consumption rates and product titres. The main product obtained was methane and the results showed, for the first time, that methanogenic activity was not inhibited with initial syngas pressures up to 500 kPa, achieving methane yields of 75 % for the GLR, and 92 % for the AAR. At 300 kPa and 500 kPa, volatile fatty acids were also produced, namely acetate, proprionate and n-butyrate. Propionate was the most abundant acid produced, reaching 4.4 mM at 300 kPa and 4.8 mM at 500 kPa in the AAR. Overall, the use of moderate pressures in syngas fermentation was shown beneficial, as it resulted in better productivities and titres without having significant detrimental effects on cell growth. The increase of pressure also did not inhibit methanogenesis. Moreover, higher pressures seem to induce the production of different chemicals, broadening the product spectrum of syngas fermentation. In this way, these findings could be the basis of new developments in the industrialization of syngas fermentation to produce platform chemicals and/or for biomethanation processes.Um dos principais desafios da fermenta√ß√£o do g√°s de s√≠ntese √© a limita√ß√£o na transfer√™ncia de massa g√°s-l√≠quido que geralmente limita a produtividade. A maioria das pesquisas t√™m-se concentrado no aumento do kLa (coeficiente de transfer√™ncia de massa g√°s-l√≠quido volum√©trico), investigando diferentes tipologias de reatores e dispositivos de dispers√£o de g√°s. No entanto, a for√ßa motriz para a transfer√™ncia de massa tamb√©m pode ser aumentada, por exemplo, operando sistemas pressurizados. Esta tese tem como objetivo explorar o efeito do aumento da press√£o na fermenta√ß√£o de g√°s de s√≠ntese para melhorar a solubilidade do g√°s, avaliando o efeito nos biocatalisadores e no pr√≥prio processo. O ponto de partida deste trabalho foi a utiliza√ß√£o de uma cultura adaptada (de um reator de convers√£o de g√°s de s√≠ntese) como in√≥culo. Essa cultura foi capaz de produzir principalmente metano e acetato a partir do g√°s de s√≠ntese. O metano n√£o foi produzido diretamente do CO, mas atrav√©s da convers√£o de acetato e H2 pelas bact√©rias presentes na cultura mista (esp√©cies dos g√©neros Acetobacterium e Sporomusa). Essa cultura foi consecutivamente transferida usando g√°s de s√≠ntese como substrato, originando uma cultura enriquecida composta principalmente por esp√©cies de Acetobacterium e de Methanospirillum que, al√©m de acetato e metano, foi capaz de produzir propionato a partir de g√°s de s√≠ntese. A partir dessa cultura altamente enriquecida, uma nova strain de Acetobacterium wieringae, strain JM, foi isolada e caracterizada. Esta cultura altamente enriquecida foi testada num reator de agita√ß√£o axial (AAR) com diferentes press√Ķes de g√°s de s√≠ntese (CO, H2 e CO2 (60:30:10%, v/v)), de 100 kPa a 600 kPa. N√£o foi observada qualquer inibi√ß√£o pelo substrato, mesmo na press√£o mais elevada e obteve-se um aumento de 45 % na produ√ß√£o final de acetato e propionato. Al√©m disso, o aumento da press√£o originou um desvio metab√≥lico de acetato para propionato, que √© um produto incomum da fermenta√ß√£o do g√°s de s√≠ntese. O efeito da press√£o na convers√£o de g√°s de s√≠ntese utilizando biomassa anaer√≥bia foi tamb√©m estudado usando duas tipologias de reatores diferentes, AAR e GLR (reator gas-lift). Foram testadas as seguintes press√Ķes iniciais de g√°s de s√≠ntese: 100 kPa, 300 kPa e 500 kPa. O GLR apresentou melhor desempenho em termos de taxas de consumo de CO e de concentra√ß√£o final de produtos. O principal produto obtido foi o metano e os resultados mostraram, pela primeira vez, que a atividade metalog√©nica n√£o foi inibida com press√Ķes iniciais de syngas de at√© 500 kPa, atingindo rendimentos de metano de 75 % para o GLR e 92 % para o AAR. A 300 kPa e 500 kPa, tamb√©m foram produzidos √°cidos gordos vol√°teis, nomeadamente, acetato, propionato e n-butirato. O propionato foi o √°cido mais abundante produzido, atingindo 4,4 mM a 300 kPa e 4,8 mM a 500 kPa no AAR. No geral, o uso de press√Ķes moderadas na fermenta√ß√£o do g√°s de s√≠ntese mostrou-se ben√©fico, pois resultou em melhores produtividades e concentra√ß√Ķes finais de produto sem ter efeitos prejudiciais significativos no crescimento celular. O aumento da press√£o tamb√©m n√£o inibiu a metanog√©nese. Al√©m disso, press√Ķes mais altas parecem induzir a produ√ß√£o de diferentes produtos qu√≠micos, ampliando o espectro de produtos da fermenta√ß√£o do g√°s de s√≠ntese. Desta forma, estas descobertas podem ser a base de novos desenvolvimentos na industrializa√ß√£o da fermenta√ß√£o do g√°s de s√≠ntese para a produ√ß√£o de produtos qu√≠micos e/ou para processos de biometana√ß√£o

    Catalizadores avanzados para la síntesis directa de dimetil éter

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    Fecha de lectura de Tesis Doctoral: 10 de diciembre 2019.n esta Tesis Doctoral se estudia la preparaci√≥n de catalizadores eficientes para la s√≠ntesis directa de dimetil √©ter (DME). Esta tesis est√° dividida en siete cap√≠tulos. El cap√≠tulo uno es una introducci√≥n general, en ella se introduce el tema y se repasa el estado actual del arte, as√≠ como los antecedentes bibliogr√°ficos. El cap√≠tulo dos se centra en los procedimientos experimentales seguidos en el desarrollo de esta Tesis Doctoral. En el tercero, se estudia la preparaci√≥n y caracterizaci√≥n de catalizadores de base carbonosa y su uso como catalizadores eficientes en la reacci√≥n de deshidrataci√≥n de metanol para producir DME. En este trabajo se prepararon carbones activados mediante dos procesos diferentes de activaci√≥n y, posteriormente, se impregnaron con diferentes cantidades de Zr. El cap√≠tulo cuatro presenta un estudio cin√©tico de la deshidrataci√≥n selectiva de metanol hacia DME sobre el catalizador de base carbonosa que mejor rendimiento catal√≠tico mostr√≥ en el cap√≠tulo tres. En el cap√≠tulo cinco se estudia la s√≠ntesis directa de DME, a partir de gas de s√≠ntesis, usando catalizadores de base carbonosa. El cap√≠tulo seis aborda la preparaci√≥n de materiales fibrilares de ZrO2-zeolita nanoestructurados en con morfolog√≠a tipo ‚Äúcore-shell‚ÄĚ, de una forma simple y directa, mediante el uso de la t√©cnica del electrohilado, y su aplicaci√≥n como catalizadores en la reacci√≥n de deshidrataci√≥n de metanol a DME y para la s√≠ntesis directa de DME a partir de syngas. En el cap√≠tulo siete, se aborda la preparaci√≥n, caracterizaci√≥n y aplicaci√≥n de catalizadores fibrilares para la s√≠ntesis de metanol y la s√≠ntesis directa de DME. En este cap√≠tulo se llev√≥ a cabo un estudio param√©trico de la s√≠ntesis directa de DME en un reactor de lecho fijo. Finalmente se recogen las conclusiones m√°s relevantes derivadas de esta Tesis doctoral

    Estudo exploratório do processo de co-pirólise de biomassa e plástico

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    A co-pir√≥lise √© um processo de melhoria da qualidade do bio-√≥leo e tamb√©m uma alternativa que pode contribuir para a gest√£o dos res√≠duos florestais e alguns res√≠duos urbanos como os pl√°sticos. Neste trabalho, processou-se a co-pir√≥lise de biomassa (derivada de pinheiro) e pl√°stico (HDPE), num reator de leito fixo, com o objetivo de analisar os efeitos dos par√Ęmetros que influenciam o processo, como a temperatura (450¬ļC;500¬ļC;550¬ļC), taxa de aquecimento (10¬ļC/min; 20¬ļC/min) e adi√ß√£o de HDPE (12.5% m/m e 25% m/m) na composi√ß√£o da alimenta√ß√£o. Os resultados colhidos mostram que o rendimento m√©dio mais alto do g√°s de pir√≥lise √© 32.2% (m/m) bs obtido a 550¬ļC, 20 ¬ļC/min com adi√ß√£o de 25% de HDPE, do carbonizado √© 32.5% (m/m) bs obtido a 450¬ļC, 20 ¬ļC/min com adi√ß√£o de 12.5% de HDPE, e do bio-√≥leo √© 57.8 % (m/m) bs obtido a 450¬ļC, nas taxas 10¬ļC/min e 20¬ļC/min, sem adi√ß√£o de HDPE. Recolheram-se amostras de g√°s de pir√≥lise de cada condi√ß√£o de opera√ß√£o com objetivo de determinar a sua composi√ß√£o qu√≠mica e o poder calorifico inferior (PCI). A introdu√ß√£o de HDPE no processo causou um aumento nos valores do PCI do g√°s, sendo o valor m√°ximo de PCI igual a 15.2 MJ/m3PTN (Press√£o (1.013√ó105 Pa) e Temperatura (273K) normal), obtido a 550 ¬ļC com adi√ß√£o de 25% de HDPE, a 10 ¬ļC/min de taxa de aquecimento. Por√©m, a adi√ß√£o de HDPE promoveu a gera√ß√£o de ceras que causaram problemas operat√≥rios nos sistemas de condensa√ß√£o de vapores de pir√≥lise para a gera√ß√£o de bio-√≥leo, como por exemplo, entupimentos. Consequentemente, tentou-se melhorar o processo de modo a ultrapassar os problemas causados pelas ceras. Para o efeito, utilizou-se uma resist√™ncia el√©trica para aumentar a temperatura do escoamento dos vapores entre a sa√≠da do reator de pir√≥lise e o sistema de condensa√ß√£o dos vapores. Contudo, apesar de algumas melhorias observadas, o problema n√£o foi totalmente resolvido e √© um assunto a que se deve dar aten√ß√£o em trabalhos futuros.Co-pyrolysis is a process to improve the quality of bio-oil and an alternative that can contribute to the management of forestry residues and some urban residues such as plastics. In this work, the co-pyrolysis of biomass (derived from pine) and plastic (HDPE) was carried out in a fixed-bed reactor, to analyse the effects of parameters that influence the process, such as the temperature (450¬ļC;500¬ļC;550¬ļC), the heating rate (10¬įC/min; 20¬įC/min) and the addition of HDPE (12.5% wt. and 25% wt.) in the feed composition. The results show that the highest average yield of the pyrolysis gas is 32.2% wt. db obtained at 550¬ļC, 20¬ļC/min, and with the addition of 25% wt. of HDPE. The highest average yield of the char is 32.5% wt. db obtained at 450¬įC, 20¬įC/min, and with the addition of 12.5 wt. of HDPE. The highest average yield of the bio-oil is 57.8% wt. db obtained at 450¬įC, at the heating rates of 10¬įC/min and 20¬įC/min, without adding HDPE. Pyrolysis gas samples were collected from each operating condition to determine its chemical composition and lower heating value (LHV). The introduction of HDPE into the feed mixture caused an increase in the LHV of the gas samples, the maximum LHV of the pyrolysis gas is 15.2 MJ/m3SPT (Standard Pressure (1.013√ó105 Pa) and Temperature (273K)), obtained at 550 ¬įC with 25% Wt. of HDPE, at 10 ¬įC/min of heating rate. However, the addition of HDPE promoted the generation of waxes that caused operating problems in the condensation systems of pyrolysis vapors, such as clogging. Consequently, it was made an attempt to improve the process and to overcome the problems caused by the waxes. For this purpose, an electrical resistance was used to increase the temperature of the gas stream between the exit of the pyrolysis reactor and the condensation system of pyrolysis vapors. However, despite some improvements, the problem has not been fully solved and is an issue that should be addressed in future work.Mestrado em Engenharia Qu√≠mic

    Alternative carbon dioxide utilization in dimethyl carbonate synthesis and comparison with current technologies

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    Dimethyl carbonate (DMC) has recently gained popularity due to its environmentally friendly status and multiple applications in which it is able to replace more toxic chemicals. Among its several commercial synthesis production routes, the ethylene carbonate (EC) transesterification shines as a CO2 consuming process. However, other factors such as the high emitting synthesis of EC precursors hinder its environmental capabilities. Methanol oxycarbonylation is a mature DMC non-CO2 consuming synthesis route with the potential to indirectly utilize the greenhouse gas throughout the synthesis of its intermediates. In this work, we propose a DMC production superstructure using the methanol oxycarbonylation route with the aim of consuming CO2 in both the synthesis gas (syngas) and methanol synthesis stages. Results show that the integration of methanol and syngas synthesis with the DMC production process vastly decreases both the cost and emission with respect to the unintegrated case. However, the addition of a Reverse Water Gas Shift (RWGS) reactor further decreases the emission down to a minimum of 1.019. kg CO2-eq/kg DMC, resulting in a 54 % decrease in the indicator compared with the direct CO2 utilization route. In comparison with other routes, utilization of this DMC in blends with gasoline manages to reduce the GWP of using the fuel mix to a potential 16 %.The authors gratefully acknowledge financial support from the project PROMETEO2020/064. The authors would also like to thank ¬ęGeneralitat Valenciana: Conselleria de Educaci√≥n, Investigaci√≥n, Cultura y Deporte¬Ľ for the Ph.D grant (ACIF/2016/ 062)

    Desenvolvimento de uma formulação de um adesivo-selante híbrido transparente

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    Os adesivos-selantes baseados em pol√≠meros modificados com silanos, MSP, apresentam caracter√≠sticas interessantes tais uma boa ades√£o a v√°rios substratos e serem amigos do ambiente. Neste sentido, o objetivo desta disserta√ß√£o que foi realizada em ambiente empresarial na empresa PECOL-Sistemas de Fixa√ß√£o, SA, centrou-se no desenvolvimento de uma formula√ß√£o de um adesivo-selante h√≠brido transparente baseado num poliuretano modificado com silano. Numa primeira fase prepararam-se oito formula√ß√Ķes, partindo de uma formula√ß√£o padr√£o, E-1, constitu√≠da pelo pol√≠mero, plastificante, dessecante, promotor de ades√£o, modificador reol√≥gico e pelo catalisador. Para tal, variou-se a quantidade de alguns aditivos, nomeadamente, do dessecante e do promotor de ades√£o e em algumas formula√ß√Ķes tamb√©m se adicionaram cargas, um antioxidante e um estabilizador UV. A mistura foi realizada num reator PARR sob v√°cuo, a 60 ¬ļC e a 100 rpm, durante 45 min. De seguida, efetuou-se um estudo comparativo entre um produto comercial e as formula√ß√Ķes produzidas analisando-se a viscosidade, o tempo de forma√ß√£o de pel√≠cula, a rigidez e a apar√™ncia visual do filme obtido, verificando-se desde logo que as formula√ß√Ķes E-3, E-6, E-7 n√£o cumprem com o prop√≥sito, uma vez que os filmes produzidos apresentaram uma cor branca e s√£o opacas devido √†s cargas utilizadas. Posteriormente, para um melhor conhecimento das suas caracter√≠sticas, recorreu-se √† an√°lise mec√Ęnica din√Ęmica (DMA), √† calorimetria diferencial de varrimento (DSC) e √† an√°lise termogravim√©trica (TGA) para avaliar as propriedades t√©rmicas e termomec√Ęnicas e verificou-se que as amostras apresentaram um comportamento semelhante. Realizou-se tamb√©m a an√°lise por difra√ß√£o de raios-X (DRX) para conhecer as fases cristalinas do produto comercial e das amostras, verificando-se que o produto comercial apresenta um car√°ter amorfo e que as formula√ß√Ķes que cont√™m cargas na sua constitui√ß√£o apresentam alguma cristalinidade. As propriedades mec√Ęnicas s√£o das mais importantes neste tipo de produtos, tendo-se realizado ensaios de tra√ß√£o. As formula√ß√Ķes E-6 e E-7 destacaram-se nestes ensaios, o que se conclui que as cargas s√£o essenciais na incorpora√ß√£o dos adesivos-selantes. Posto isto, conclui-se que as formula√ß√Ķes que mais se destacaram foram a E-2 e a E-5, uma vez que apresentam propriedades mec√Ęnicas semelhantes e uma apar√™ncia visual melhor, no entanto ainda se encontram longe das propriedades do produto comercial sendo ainda necess√°rio otimizar as suas composi√ß√Ķes.Sealant-adhesives based on polymers modified with silanes, MSP, present interesting characteristics such as having good adhesion to various substrates and being environmentally-friendly. In this sense, the objective of this dissertation, which was carried out in a business environment at the company PECOL-Sistemas de Fixa√ß√£o, SA, focused on the development of a formulation of a transparent hybrid adhesive-sealant based on a polyurethane modified with silane. On a first phase, eight formulations were prepared, starting from a standard formulation, E-1, consisting of the polymer, plasticizer, desiccant, adhesion promoter, rheological additive and catalyst. To this end, the amount of some additives was varied, namely the desiccant and the adhesion promoter, and in some formulations a filler, an antioxidant and a UV stabilizer were also added. The mixtures were prepared in a PARR reactor under vacuum, at 60¬įC and at 100 rpm, for 45 min. Then, a comparative study was carried out between a commercial product and the formulations produced, analyzing the viscosity, the film formation time, the rigidity and the color of the film obtained, verifying immediately that the E-3, E-6 and E-7 formulations do not fulfill the purpose because the obtained films showed a white color and are opaque due to the fillers used. Subsequently, for a better understanding of their characteristics, dynamic mechanical analysis (DMA), differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA) were used to assess the thermomechanical and thermal properties and it was found that the samples showed a similar behavior. Analysis by X-ray diffraction (XRD) were also performed to know the crystalline phases of the commercial product and of samples, verifying that the commercial product has an amorphous character and that the formulations that contain charges in their constitution present some crystallinity. The mechanical properties are one of the most important in this type of products, having been carried out tensile tests. Formulations E-6 and E-7 stood out in these tests, which allows to conclude that fillers are essential for the incorporation on sealant-adhesives. That said, it‚Äôs concluded that the formulations that most stood out were E-2 and E-5, as they have similar mechanical properties and a better color requirements. However, the formulations still remain far from the properties of the commercial product and their compositions still need to be optimized.Mestrado em Engenharia Qu√≠mic

    Influência das características da biomassa na produção de bio-óleo por pirólise

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    As elevadas emiss√Ķes de gases efeito de estufa, para a atmosfera, e consequentes impactes torna urgente a cria√ß√£o e a ado√ß√£o de solu√ß√Ķes para a sua redu√ß√£o. A pir√≥lise de biomassa florestal residual consiste numa alternativa aliciante, dado o seu cariz sustent√°vel, a sua elevada disponibilidade nacional de biomassa e o seu potencial associado √† produ√ß√£o de produtos s√≥lidos, gasosos e l√≠quidos e respetivas potenciais aplica√ß√Ķes. Ainda que exista conhecimento cient√≠fico sobre o processo, √© necess√°rio aprofundar o estudo da produ√ß√£o e composi√ß√£o da fra√ß√£o l√≠quida, tendo em vista o seu elevado teor em √°gua. O trabalho experimental consistiu na pir√≥lise interm√©dia de diferentes de biomassas florestais residuais ‚Äď eucalipto, ac√°cia, tojo e canas ‚Äď num reator descontinuo de leito fixo. As vari√°veis do processo foram a temperatura de pico (450 e 550ňöC), a taxa de aquecimento (10, 20 e 30ňöC/min) e o tamanho de part√≠cula (entre 2 e 4mm e superiores a 4mm). Foi realizada, tamb√©m, a an√°lise da influ√™ncia do catalisador Fe-Mn, in-situ, no rendimento dos produtos, teor de humidade do bio-√≥leo e na composi√ß√£o do g√°s n√£o-condens√°vel. O aumento da temperatura do processo, da taxa de aquecimento (apenas para as canas e para o tojo) e do tamanho de part√≠cula resultaram na redu√ß√£o do rendimento do carbonizado e aumento do rendimento de bio-√≥leo. Na rela√ß√£o entre as biomassas foi verificada a varia√ß√£o entre 30,6 e 34,9% m/m bs para o rendimento dos produtos s√≥lido, entre 42,1 a 45,0% m/m bs para o rendimento do bio-√≥leo e de 21,6 a 27,4% m/m bs para o rendimento do g√°s. Sendo que os rendimentos m√°ximos de carbonizado, bio-√≥leo e g√°s s√£o relativos √†s biomassas eucalipto, tojo e canas, respetivamente A an√°lise das amostras de carbonizados, das biomassas, apresentou teores de carbono superiores a 70% m/m bs, e poderes calor√≠ficos inferiores entre 24,4 e 27,6 MJ/kg. O bio-√≥leo apresentou teores de humidade entre 61,0 e 91,4%, verificando a sua redu√ß√£o com o aumento da temperatura do processo e do tamanho de part√≠cula. A utiliza√ß√£o do catalisador n√£o fomentou varia√ß√Ķes nos rendimentos de produ√ß√£o dos produtos. Por√©m observou-se um aumento em 16% da humidade do bio-√≥leo, e aumento do poder calor√≠fico inferior para 13,3 MJ/kg.The increasing emission of greenhouse gases, into the atmosphere, and the consequent impacts, becomes imperative to create and adopt solutions to reduce them. The pyrolysis of residual forest biomass is an attractive alternative, because of its sustainable nature, high national availability of biomass and the potential associated with the production of solid, gaseous and liquid products and their respective potential applications. Although the scientific knowledge about the process, it is necessary to further study the production and composition of the liquid fraction, considering its higher water content. The experimental work consisted of the intermediate pyrolysis of different residual forest biomass ‚Äď eucalyptus, acacia, gorse and reeds ‚Äď in a discontinuous fixed-bed reactor. The process variables were the peak temperature (450 and 550ňöC), heating rate (10, 20 and 30ňöC/min) and particle size (between 2 and 4mm and greater than 4mm). It was also carried out the analysis of the influence of the Fe-Mn catalyst, in-situ, on the yield of the products, moisture content of the bio-oil and on the composition of the non-condensable gas. The increase in the process temperature, the heating rate (only for the reeds and for the gorse) and the particle size resulted in a reduction in the biochar yield and an increase in the bio-oil yield. In the relationship between biomass, a variation between 30,6 and 34,9% m/m bs was verified for the yield of solid products, between 42.1 to 45.0% m/m bs for the yield of bio-oil and of 21.6 to 27.4% m/m bs for gas yield. Since the maximum yields of biochar, bio-oil and gas are related to biomass eucalyptus, gorse and reeds, respectively. The analysis of biochar samples showed carbon contents near by 70% m/m bs, and low heating values between 24.4 and 27.6 MJ/kg. Bio-oil presented moisture contents between 61.0 and 91.4%, verifying its reduction with the increase in process temperature and particle size. The use of the catalyst did not promote variations in the production yields of the products. However, there was an increase of 16% in the moisture of the bio-oil, and an increase in the lower calorific value to 13.3 MJ/kg.Mestrado em Engenharia do Ambient

    Microplasma-driven, atomic layer deposition of flexible electronic and photonic nanofilms

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    Atomic Layer Deposition (ALD) of aluminum oxide (Al2O3), gallium oxide (Ga2O3) and Zirconium oxide (ZrO2), driven by arrays of microcavity plasmas (MALD), has been demonstrated. Microplasma has been drawn attention due to its unique characteristics such as high electron density (>1016 cm-3), low temperature (electron and ion temperature are ~ 5 and 0.1 eV, respectively) and plasma ignition at atmospheric pressure. Especially, the higher electron density of microplasma is directly related to gas dissociation such as oxygen and ammonia which are co-reactants of semiconductor thin film deposition. The ratio of the local electric field strength to the gas number density (E/N) in microplasma is also increased significantly relative to conventional (macroscopic) plasmas, resulting in higher dissociation of co-reactant. A compact ALD system with reduced volume by at least a factor of five was achievable due to the miniaturized microplasma source operating in a lower frequency AC waveform. Due to the complete reaction between precursors, the stoichiometric value of films presented ~ 1.5 in the crystalline state of Al2O3 and Ga2O3, indicating the presence of negligible levels of impurities and oxygen vacancy, which was verified from EDX, RBS and SIMs analysis. The thin films were grown at 300 K by dissociating oxygen in an array of microcavity plasmas with a reactor back pressure of 5 Torr. Metal-oxide semiconductor capacitors (MOSCAP) fabricated from Al2O3 ¬¨film deposited on p-Si by MALD with Al top ohmic contact and Au bottom electrodes exhibited breakdown electric field strength of 6.1 MV/cm and a hysteresis width of < 1 mV, indicating near-zero trap charges in the film. In addition, dielectric constant of Al2O3 ¬¨film, őĶ_ox, can be derived from the C-V accumulation region. The measured őĶ_ox of MOSCAP is 9.7 and this value is enough for MOS structures application in drastic conditions, in particular, the high thermal conductivity, high chemical stability, high radiation resistance, and low permeability to alkali impurities. These values along with Al2O3 film having 30 nm thickness are higher than conventional values in MOSCAP. This result is noticeable in that MALD process in room temperature is enabled to produce high-quality film with uniformity and conformality. Furthermore, area-selective deposition at specific locations on a surface with uniform and conformal Al2O3 thin film were attainable by MALD due to the room temperature process. A general limitation of lift-off area-selective ALD (AS-ALD) is that the deposition process requires low temperature (< 50 ¬įC) to avoid the passivation layer damage by thermal energy and plasma source. Since MALD operation is completely room temperature deposition without irregular discharge, which causes damage on fragile substrates such as PMMA and PR. Based on this technique use, the lateral dimension 1 - 10 ¬Ķm of Al2O3 film was uniformly deposited with ~ 68 nm thickness. Thus, all of results show that how well the MALD process can be compatible to semiconductor area-selective patterning with narrow lateral dimension through simple lithography and lift-off. E-beam lithography was used to achieve ~ 250 nm dimension structure without the etching process. Furthermore, amorphous Ga2O3 (a-Ga2O3) was deposited on Si, quartz, and PET substrate. Since Ga2O3 is a high bandgap semiconductor material, its crystallinity has been analyzed after post-annealing above 800 ¬įC by X-ray diffraction (XRD) and transmission electron microscopy (TEM). Due to the deposition of a-Ga2O3 on PET substrate, a flexible deep ultraviolet (DUV) photodetector was successfully fabricated. Based on the Tauc law calculation with transmittance of grown film as a function of wavelength, a-Ga2O3 bandgap was measured ~ 5.35 eV, indicating higher photo response at 222 nm UV illumination then typical 254 nm. By increasing surface to volume ratio of a-Ga2O3 surface with etching-free patterning process, photocurrent was half-orders of magnitude increased with the same applied bias voltage on the flat surface DUV photodetector. Furthermore, the optical parametric oscillator (OPO) laser was utilized to measure the fastest response time of a-Ga2O3/PET and a-Ga2O3/Si DUV detector. The rise and fall times of a-Ga2O3/PET detector were 0.34 ¬Ķs and 11.84 ¬Ķs, and a-Ga2O3/Si were recorded 0.38 ¬Ķs and 9.98 ¬Ķs, respectively. Finally, optical filters based on alternating layers of zirconium dioxide (ZrO2) and Al2O3 dielectric distributed Bragg reflector (DDBR) structure were fabricated. These ZrO2/Al2O3 multi-layers have been successfully deposited on the quartz substrate in order to realize the bandpass with different central wavelengths in UV range. Depending on the design method of the optical filter, the central passband of transmittance spectra varied from 222 nm to 300 nm. Theses DDBR structures have good periodicity, which was verified by scanning electron microscope (SEM) and secondary ion mass spectrometry (SIMs). As a proof of concept, a krypton chloride (KrCl) excimer lamp, having dominant emission at 222 nm wavelength was used to verify the suitability of the wavelength-window-selection of the optical filter.U of I OnlyAuthor requested U of Illinois access only (OA after 2yrs) in Vireo ETD syste

    Kinetics of the formation and destruction of PCDD/Fs in a laboratory tubular furnace

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    A kinetic model has been developed for the formation of selected congeners of PCDD/Fs during the thermal decomposition of different wastes in a horizontal reactor. Previously published data on the decomposition of wastes have been correlated using a kinetic model that only considers process parameters, such as the presence of different amounts of oxygen in the atmosphere of reaction, chlorine and metals in the waste. The effect of both chlorine and metals is modelled through an equation assuming a ‚Äúsaturation effect‚ÄĚ, i.e., that a certain amount of each substance produces the maximum rate, and that higher amounts do not increase the rate. The presence of oxygen is modelled by a destruction reaction over part of the PCDD/Fs produced. The model, which uses data from more than 64 experiments, correlated the emissions of three selected congeners: 1,2,3,6,7,8-HxCDD, OCDF and 2,3,7,8-TCDF, which are enough to estimate the total amount and toxicity of an emission
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