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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
51

Development of chitosan nanocomposite coatings for visible-light photocatalytic antiviral applications / Framställning av kitosan-nanokompositbeläggningar för fotokatalytiska antivirala applikationer i synligt ljus

Neuman, Michael January 2023 (has links)
During the global pandemic of coronavirus, the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) outbreak, the world was desperately searching for simpler yet more effective solutions to stop the spread of coronavirus (COVID-19). Since no one was prepared for the fast spread of such a contagious virus, there was a shortage of proper protective solutions to stop the spread. Large quantities of alcohol-based disinfectant and hand sanitizers were used, but it led to global shortages. It is desired to have a water-based, easily applied, low-cost and long-lasting disinfectant that can prevent the spread of coronavirus on any surface, without the issue of skin allergies or skin-drying as often found while using alcohol. Inspired by nature, chitosan (CS), a natural biopolymer with well-known antimicrobial and film-forming properties, was tested in this study for the preparation of coatings spread onto various surfaces and the antiviral effect was evaluated. Zinc oxide (ZnO), a material generally recognized as safe (GRAS) by the US Food and Drug Administration (FDA), is a photocatalyst that was embedded in chitosan to enhance the antimicrobial and antiviral performance of the coatings. In order to apply water-based chitosan formulation on hydrophobic polypropylene (PP) surgical mask and polyethylene terephthalate (PET) surface, the plastics were treated with either oxygen plasma or corona plasma to improve the surface hydrophilicity. The corona plasma treatment decreased the water contact angle (WCA) of the surgical mask from approximately 125° to 101° and drastically reduced WCA of the PET film from approximately 100° to 29°. The PET film was coated with CS – ZnO nanocomposite, which contains 1% chitosan and 5 wt.% (w.r.t weight of chitosan) ZnO nanoparticles. The capability of photocatalytic degradation of CS – ZnO coating was demonstrated during the degradation of methylene blue dye molecules. Additionally, we evaluated the antiviral effect of the CS – ZnO nanocomposite coating on PET plastic films under typical room lighting conditions by measuring the inactivation of lentivirus. This approach utilizes the pseudotype system, which is a reliable tool to study under conventional biosafety conditions, particularly for certain pathogenic strains of coronaviruses (CoVs) which have a strong pathogenicity. / Under den globala coronapandemin, utbrottet av allvarligt akut respiratoriskt syndrom coronavirus 2 (SARS-CoV-2), sökte världen desperat efter enklare men ändå mer effektiva lösningar för att stoppa spridningen av coronaviruset (COVID-19). Eftersom ingen var förberedd på en så smittsam sjukdom uppstod en brist på lämpliga skyddsmetoder för att stoppa spridningen. Stora mängder alkoholbaserade desinfektionsmedel och handdesinfektionsmedel användes, vilket skapade en global brist. Det önskades en vattenbaserad, lättapplicerad, kostnadseffektiv och långvarig desinfektionsmedel som kunde förhindra spridningen av coronaviruset på vilken yta som helst, utan problem med allergiska reaktioner eller uttorkning av huden som ofta uppstår vid användning av alkohol. Med inspiration från naturen testades kitosan, en naturlig biopolymer med välkända antimikrobiella och film-formande egenskaper, för att göra beläggningar på olika ytor och testa deras antivirala effekt. Zinkoxid (ZnO), ett material som allmänt erkänns som säkert (GRAS) av US Food and Drug Administration (FDA), är en fotokatalysator och användes i kitosanbeläggningen för att förbättra den antimikrobiella och antivirala effekten. För att applicera den vattenbaserade kitosanformuleringen på hydrofoba ytor på en kirurgisk mask av polypropen (PP) och en plastfilm av polyetylentereftalat (PET), behandlades plasterna med antingen O2 eller corona plasma för att förbättra ytornas hydrofilicitet. Behandlingen av corona plasma minskade vattenkontaktvinkeln på den kirurgiska masken från cirka 125° till 101° och för PET-filmen från cirka 100° till 29°. PET-filmen belades med CS – ZnO nanokomposit, som innehåller 1% kitosan och 5 wt.% (med avseende på vikten av kitosan) ZnO nanopartiklar. Förmågan till fotokatalytisk nedbrytning av CS – ZnO-beläggningen demonstrerades genom att bryta ned metylenblå färgmolekyler. Dessutom utvärderades vi den antivirala effekten av CS – ZnO nanokompositbeläggningen på PET-filmer i normal rumsbelysning genom att mäta dess förmåga att inaktivera lentivirus. Denna metod använder pseudotypsystemet, vilket är ett tillförlitligt verktyg för att studera under konventionella biosäkerhetsförhållanden, särskilt för vissa patogena stammar av coronavirusen (CoVs) som har en hög patogenicitet.
52

Modelling and simulation of membrane bioreactors for wastewater treatment

Janus, Tomasz January 2013 (has links)
The work presented in this thesis leads to the formulation of a dynamic mathematical model of an immersed membrane bioreactor (iMBR) for wastewater treatment. This thesis is organised into three parts, each one describing a different set of tasks associated with model development and simulation. In the first part, the Author qualitatively and quantitatively compares various published activated sludge models, i.e. models of biochemical processes associated with bacterial growth, decay, lysis and substrate utilisation in activated sludge systems. As the thesis is focused on modelling membrane bioreactors (MBRs) which are known to experience membrane fouling as a result of adsorption of biopolymers present in the bulk liquid onto and within the membrane, all activated sludge models considered in this thesis are able to predict, with various levels of accuracy, the concentrations of biopolymeric substances, namely soluble microbial products (SMP) and extracellular polymeric substances (EPS). Some of the published activated sludge models dedicated to modelling SMP and EPS kinetics in MBR systems were unable to predict the SMP and EPS concentrations with adequate levels of accuracy, without compromising the predictions of other sludge and wastewater constituents. In other cases, the model equations and the assumptions made by their authors were questionable. Hence, two new activated sludge models with SMP and EPS as additional components have been formulated, described, and simulated. The first model is based on the Activated Sludge Model No. 1 (ASM1) whereas the second model is based on the Activated Sludge Model No. 3 (ASM3). Both models are calibrated on two sets of data obtained from a laboratory-scale system and a full-scale system and prove to be in very good agreement with the measurements. The second part of this thesis explains the development of two membrane fouling models. These models are set to describe the loss of membrane permeability during filtration of various solutions and suspensions. The main emphasis is placed on filtration of activated sludge mixtures, however the models are designed to be as general as feasibly possible. As fouling is found to be caused by a large number of often very complex processes which occur at different spatial as well as temporal scales, the two fouling models developed here have to consider a number of significant simplifications and assumptions. These simplifications are required to balance the model's accuracy, generality and completeness with its usability in terms of execution times, identifiability of parameters and ease of implementation in general purpose simulators. These requirements are necessary to ascertain that long term simulations as well as optimisation and sensitivity studies performed in this thesis either individually on fouling models or on the complete model of a MBR can be carried out within realistic time-scales. The first fouling model is based on an idea that fouling can be subdivided into just two processes: short-term reversible fouling and long-term irreversible fouling. These two processes are described with two first order ordinary differential equations (ODEs). Whilst the first model characterises the membrane filtration process from an observer's input-output point of view without any rigorous deterministic description of the underlying mechanisms of membrane fouling, the second model provides a more theoretical and in-depth description of membrane fouling by incorporating and combining three classical macroscopic mechanistic fouling equations within a single simulation framework. Both models are calibrated on a number of experimental data and show good levels of accuracy for their designated applications and within the intended ranges of operating conditions. In the third part, the first developed biological model (CES-ASM1) is combined with the behavioural fouling model and the links between these two models are formulated to allow complete simulation of a hollow fibre (HF) immersed membrane bioreactor (iMBR). It is assumed that biological processes affect the membrane through production of mixed liquor suspended solids (MLSS), SMP and EPS which cause pore blockage, cake formation, pore diameter constriction, and affect the specific cake resistance (SCR). The membrane, on the other hand, has a direct effect on the bulk liquid SMP concentration due to its SMP rejection properties. SMP are assumed to be solely responsible for irreversible fouling, MLSS is directly linked to the amount of cake depositing on the membrane surface, whereas EPS content in activated sludge affects the cake's SCR. Other links provided in the integrated MBR model include the effects of air scouring on the rate of particle back-transport from the membrane surface and the effects of MLSS concentration on oxygen mass transfer. Although backwashing is not described in great detail, its effects are represented in the model by resetting the initial condition in the cake deposition equation after each backwash period. The MBR model was implemented in Simulink® using the plant layout adopted in the MBR benchmark model of Maere et al. [160]. The model was then simulated with the inputs and operational parameters defined in [36, 160]. The results were compared against the MBR benchmark model of Maere et al. [160] which, contrary to this work, does not take into account the production of biopolymers, the membrane fouling, nor any interactions between the biological and the membrane parts of an MBR system.
53

Investigations into the Pilot Scale Separation of Protein and Starch Biopolymers from Oat Cereal

Macdonald, Rebecca Joanne January 2010 (has links)
Cereals contain naturally occurring biopolymers (for example proteins and starches) that can be used as renewable raw materials in a variety of speciality chemical applications. The separation of protein and starch biopolymers from wheat is well established and relies on a group of proteins called glutens that have a unique network-forming functionality. Oat and other cereals do not naturally contain these gluten proteins and typically rely on chemical-based separation techniques which alter the chemical and physical structures and damage the inherent natural functionality of the biopolymers. This research study investigated the separation of the protein and starch fractions from cereals using the Al-Hakkak Process, a new aqueous process. This process involves adding water and wheat gluten protein to cereals that do not contain gluten. The wheat gluten interacts with the cereal proteins, facilitating the separation of the starch and protein fractions whilst retaining their inherent natural functionality. The aim of this research project was to investigate and optimise the pilot scale separation performance of the Al-Hakkak Process using oat flour. As very little prior research had been carried out, the focus was to characterise the oat starch and protein separation performance and gain an understanding of the mechanisms involved. A variety of techniques were employed. Large scale deformation rheology was used to gain an understanding of the oat-gluten dough rheology and establish the relationship between the rheology and the separation performance. Confocal scanning laser microscopy was used to investigate the structure of the oat-gluten protein network. The molecular interactions between the oat and gluten proteins were studied using gel electrophoresis. The network-forming functionality of the new oat-gluten protein was explored. The influence of various processing parameters on the pilot scale separation performance was investigated and the results compared with other data collected through the study to identify key processing parameters. This research programme has resulted in interesting, encouraging and some unexpected outcomes and these are discussed in detail in the thesis. It was concluded that an insoluble protein network formed in the oat-gluten dough and both kneading and extraction processes were found to contribute to the formation of this. A key conclusion was that the changes that took place in the oat-gluten dough were similar to, but not identical to, the changes that occur in wheat dough. It was proposed that the mechanism for the development of a protein network in oat-gluten dough differed from wheat dough for two main reasons: a) the presence of the oat flour disrupted the normal wheat gluten behaviour, and b) components in the oat flour altered the activity of the gluten proteins. The research identified key processing parameters for the Al-Hakkak Process including kneading time, gluten content, and sodium chloride content of the oat-gluten dough as well as sodium chloride concentration, pH, and temperature of the extract liquor. An important discovery was that the oat and gluten proteins interacted at a molecular level through reducible, covalent, bonding (most likely disulphide linkages) to form the insoluble protein network in the oat-gluten dough. It was concluded that these reducible bonds coupled the individual protein subunits to form new hybrid oat-gluten protein molecules (a combination of oat proteins and gluten proteins). Both insoluble and soluble proteins in the oat and gluten flour were involved in the formation of the insoluble protein network in the oat-gluten dough. This outcome has applications beyond the Al-Hakkak Process, as this new knowledge can be applied to the wider dough processing industry. It was concluded that the wheat gluten was the source of the protein network-forming functionality of the hybrid oat-gluten protein and that the oat proteins had a diluting effect. It was proposed that oat-gluten protein flour from the Al-Hakkak Process could be reused to replace the commercial wheat gluten flour in subsequent production batches. During spray drying of the starch stream, the soluble biopolymers in the extract liquor were found to act as an adhesive and glued individual starch granules together to form spherical agglomerates. Acidification of the extract liquor was found to enhance this agglomeration. It was proposed the acidified starch granules were sticker during spray drying due to the partial acid hydrolysis of the starch granule suface which enhanced the agglomeration.
54

Contribution à l'étude de la structure et de la texture du PLA : Effet de la dégradation hydrothermale / Contribution to the study of the structure and the texture of the PLA : Effect of the hydrothermal degradation

Sambha'a, Lionel 24 February 2011 (has links)
Le risque d'épuisement de ressources naturelles fossiles à partir desquelles nombres d'oléfines sont fabriqués, a permis le développement de nouveaux matériaux polymères, 100% renouvelables dénommés biopolymères. L'acide poly lactique est sans doute le plus prometteur d'entre eux. D'origine naturelle, ce polyester est synthétisé à partir d'aliments riches en amidon tels que le maïs, la betterave ou la pomme de terre. Son caractère biodégradable lui offre un large éventail d'applications dans les domaines aussi variés et divers que la médecine, le bâtiment, l'industrie automobile, le biomédicale ou encore le textile habillement. Ce travail consiste à étudier la structure et la texture de l'isomère mixte (PDLA) et de déterminer l'incidence de sa morphologie sur les propriétés mécaniques et tinctoriales requises pour des applications textiles. Nous avons par des méthodes spectrales, caractérisé le polymère afin d'en déterminer entre autre, la composition massique, et la stéréorégularité, paramètres très importants ayant une forte influence sur les propriétés mécaniques du polymère, notamment la stabilité thermique ou la résistance à l'hydrolyse. Nos expériences menées sur la stabilité thermique du polymère révèlent que le polymère est susceptible de s'hydrolyser sous l'action combinée de l'eau, de la température et du pH, entraînant ainsi une diminution de la masse moléculaire, donc, une perte de propriétés mécaniques de la fibre.Le PLA est également un polymère qui supporte mal la teinture, et seuls les colorants dispersés sont susceptibles de teinte cette fibre sous certaines conditions. L'étude de la cinétique de fixation de trois colorants dispersés sur la fibre de PLA à permis d'établir une relation entre la structure du colorant et ses propriétés tinctoriales. / The risk of exhaustion of fossil natural resources from which count of polymers are made, allowed the development of new polymer materials, renewable 100 % were called biopolymer. The poly acid lactic is doubtless the most promising of them. Of natural origin, this polyester is synthetized from food rich in starch such as the corn, the beet or the potato. His biodegradable character offers him a wide range of applications in many field as medicine, building, car industry, biomedical or textile clothing. This work consists in studying the structure and the texture of the mixed isomer (PDLA) and to determine the incidence of its morphology on the mechanical properties required for textiles applications.We have by spectral methods, characterized the polymer ,in arder to determine, the molecular weight,composition, and monomers distribution, very important parameter, having a strong influence on the mechanical properties of the polymer, in particular the thermal stability or the resistance in the hydrolysis. Our experiments led on the thermal stability of the polymer reveal that the polymer may hydrolyser under the combined effect of temperature, moisture and by the pH, then, a decrease of the molecular weight, thus, a Joss ofmechanical properties of the fiber.The PLA is also a polymer which can be dye only with certain disperses dyes under particulars conditions.The study of the kinetics of fixation of three disperses dyes scattered on PLA fiber permit to establish a relation between the structure of the disperses dyes and its dyeing properties.
55

Processo contínuo de produção de polihidroxialcanoatos de cadeia média (PHAMCL) sob limitação múltipla de nutrientes. / Medium-chain-length polyhydroxylkanoates production in chemostat culture under multiple nutrient limitation.

Taciro, Marilda Keico 07 August 2008 (has links)
A produção de PHAMCL por Pseudomonas putida IPT 046 em cultivo contínuo sob limitação múltipla de nutrientes foi estudada, utilizando glicose e frutose como fontes de carbono. O estudo da limitação em nitrogênio, fósforo e simultânea de nitrogênio e fósforo para indução de acúmulo de polihidroxialcanoato, apontou que maiores valores de polímero foram acumulados quando fósforo foi o nutriente limitante (70%). Limitação em nitrogênio resultou no máximo em 40% de polímero. A limitação simultânea de nitrogênio e fósforo resultou em 68% de polímero, menor consumo de oxigênio para gerar células e maior fator de conversão de fonte de carbono em polímero (0,19 g/g) quando comparado com a limitação em fósforo, 0,16 g/g, ou à limitação em nitrogênio, 0,10 g/g. Oxigênio utilizado para manutenção das células não dependeu do tipo de limitação e dos valores das vazões específicas de alimentação. Um modelo metabólico foi proposto, ajustando aos dados experimentais na condição de limitação em nitrogênio. / Multiple nutrient limited growth of Pseudomonas putida IPT 046 was studied in chemostat culture from glucose and fructose as carbon source. Nitrogen, phosphorus and both nitrogen and phosphorus limitation was performed in order to accumulate medium-chain-length polhydroxyalkanoate. Phosphorus limitation resulted in higher polymer content accumulated (70%). Nitrogen limited assays achieved only 40% of polymer. Nitrogen and phosphorus simultaneous limitation resulted in 68 % polymer content, less oxygen demand to synthesize cells and best yields of carbon into polymer (0,19 g/g) when compared with 0,16 g/g on phosphorus limitation and 0,10 g/g on nitrogen limitation. Oxygen demand for maintenance is the same, independent of limitation strategy or dilution rate performed. A metabolic pathway model was proposed and fitted with nitrogen limited experimental data.
56

Biopolímero de Fibrina como arcabouço biológico para células-tronco mesenquimais como potencial produtor osteogênico

Lima, Patricia Rodrigues de January 2019 (has links)
Orientador: Rui Seabra Ferreira / Resumo: Desenvolvido em 1990 por um grupo de pesquisadores do Centro de Estudo de Venenos e Animais Peçonhentos (CEVAP), no Estado de São Paulo, Brasil, o Biopolímero de Fibrina (BPF) possuía o principal objetivo de ser um adesivo à base de fibrina sem o uso de sangue humano, a fim de evitar a transmissão de doenças infecciosas por meio deste insumo. Após diversas pesquisas com o BPF, comprovou-se não somente sua capacidade adesiva, como também sua ação coagulante, sua ação como auxiliar no reparo ósseo e cartilaginoso e sua função como arcabouço para células-tronco mesenquimais (CTMs), devido ao fato de que o BPF possui uma estrutura tridimensional adequada. Em estudos recentes e ao exercer essa função, tal material não afetou o microambiente biológico das células, ou seja, permitiu a adesão, proliferação e diferenciação celular, e aderência e crescimento destas. Tais características, apresentadas pelo BPF, são desejáveis na maioria dos biopolímeros utilizáveis, o que ressalta a importância do aprofundamento das pesquisas com BPF e suas interações em experimentos in vivo. Assim, no capítulo 1 realizamos uma ampla revisão na literatura sobre biopolímeros de fibrina, células-tronco e reparação de tecido ósseo. No capítulo 2 é apresentado o artigo científico “Arcabouço de fibrina para células-tronco mesenquimais como potencial osteogênico”. / Abstract: Developed in 1990 by a group of researchers from the Center for the Study of Venomous and Poisonous Animals (CEVAP) in the State of São Paulo, Brazil, the Fibrin Biopolymer (GMP) had the main objective of being a fibrin-based adhesive without the use of human blood in order to avoid the transmission of infectious diseases by means of this input. After several investigations with BPF, it was verified not only its adhesive capacity, but also its coagulant action, its action as an aid in bone and cartilage repair and its function as a framework for mesenchymal stem cells (MSCs), due to the fact that the BPF has an adequate three-dimensional structure. In recent studies and in carrying out this function, such material did not affect the biological microenvironment of the cells, that is, it allowed cell adhesion, proliferation and differentiation, and adhesion and growth of these cells. These characteristics, presented by BPF, are desirable in most usable biopolymers, which underscores the importance of deepening GMP research and its interactions in in vivo experiments. Thus, in Chapter 1 we conducted a broad review in the literature on biopolymers of fibrin, stem cells and repair of bone tissue. In chapter 2 the scientific paper "Fibrin scaffold for mesenchymal stem cells as osteogenic potential" is presented. / Doutor
57

Obtenção de nanocompósitos a base de bentonita, amido e quitosana. / Obtaining nanocomposites based on bentonite, starch and chitosan.

Cleide dos Anjos Bastos 09 March 2012 (has links)
Novos materiais obtidos a partir de polímeros biodegradáveis são uma alternativa para a redução do impacto ambiental causado pelo uso excessivo de polímeros derivados do petróleo. Atualmente, vários estudos têm sido realizados na busca de matéria-prima para o desenvolvimento de filmes biodegradáveis, com boa viabilidade técnica e econômica. Dentre estas matérias-primas, destacam-se as que são provenientes de fontes renováveis, de baixo custo e que tenham grande importância econômica e ambiental, como, por exemplo, o amido, as argilas, e a quitosana. Nos filmes que preparamos, adicionamos como plastificante a glicerina, um subproduto do biodiesel, e que contribui para maior estabilidade térmica dos filmes, em conjunto com o amido. O propósito deste trabalho foi o preparo de um biopolímero a base de quitosana e argila com propriedades de nanocompósitos, pois estes materiais costumam exibir propriedades físico-químicas diferenciadas em relação a outros materiais, devido à redução no seu tamanho. Sendo assim, através do estudo e comparação de duas argilas esmectíticas sódicas naturais, Bentogel e Corral, pôde-se observar o comportamento dos filmes formados em presença de amido e glicerina. Os filmes obtidos, através do método de dispersão em solução do polímero, foram caracterizados através das técnicas de DRX, MEV, IV, TG e DSC. Os resultados obtidos mostraram a formação de filmes nanocompósitos esfoliados de boa estabilidade térmica. / New materials made from biodegradable polymers are an alternative to reducing the environmental impact caused by excessive use of polymers derived from petroleum. Currently, several studies have been conducted in search of raw material for the development of biodegradable films, with good technical and economic feasibility. Among these materials, we highlight those that are from renewable resources, low cost and have great economic and environmental importance, such as, starch, clays, and chitosan. In preparing films, we added glycerol as a plasticizer, a byproduct of biodiesel, and contributes to better thermal stability of the films, together with starch. The purpose of this study was the preparation of a biopolymer based on chitosan and clay nanocomposites properties, because these materials tend to display different physico-chemical properties compared to other materials because of the reduction in size. Thus, through the study and comparison of two natural sodium smectite clays, Bentogel and Corral, it was observing the behavior of films formed in the presence of starch and glycerol. The films obtained by the method of dispersion in the polymer solution, were characterized by techniques of XRD, SEM, FTIR, TG and DSC. The results obtained showed the formation of exfoliated nanocomposites films and good thermal stability.
58

Produção e caracterização de filmes biodegradáveis ativos de amido de semente de jaca / Production and characterization of jackfruit seed starch biodegradable active films

Campos, Natália di Loreto 21 September 2017 (has links)
O uso indiscriminado dos plásticos tem gerado graves problemas ambientais de acúmulo de material na natureza, poluição das águas, além de ser proveniente do petróleo, um recurso não renovável. Isso tem causado preocupação e, portanto, os cientistas e indústrias vêm buscando alternativas ao uso desses materiais, como por exemplo o emprego de materiais naturais e/ou biodegradáveis e o aproveitamento de subprodutos desperdiçados. O amido é um polímero natural que tem aspectos que o tornam promissor, como sua biodegradabilidade, baixo custo e disponibilidade. Para prolongar a vida útil dos alimentos, investigou-se o amido como matéria prima para a produção de filmes biodegradáveis e revestimentos comestíveis ativos. Além de atuar como barreira a gases e como proteção mecânica, as embalagens também podem carrear substâncias ativas como antioxidantes, antimicrobianos, entre outros. Foi estudado o efeito da incorporação de (0,3; 0,5 e 1,0) g de α-tocoferol/100 g de dispersão filmogênica nas propriedades morfológicas, mecânicas, ópticas, de superfície, de barreira ao vapor d\'água e à luz UV/Visível e antioxidantes dos filmes de amido de semente de jaca. A adição de α-tocoferol aumentou a resistência à tração e o módulo de elasticidade nos filmes com até 0,5% de α-tocoferol. Também aumentou a barreira ao vapor d\'água, possivelmente devido à natureza hidrofóbica do α-tocoferol e ao efeito de tortuosidade causado por ele na matriz polimérica, embora a solubilidade em água não tenha diferido significativamente entre os filmes. O α-tocoferol proporcionou aumento na barreira contra a luz UV, especialmente nos comprimentos de onda entre (200 e 310) nm. A opacidade e o parâmetro de cor b* aumentaram significativamente, o que significa que a incorporação de α-tocoferol tornou os filmes mais opacos e amarelados. A hidrofobicidade da superfície aumentou significativamente (p < 0,05) com adição de α-tocoferol, principalmente no filme com 0,5% de α-tocoferol. A capacidade antioxidante aumentou significativamente com adição de até 0,5% de α-tocoferol. O filme controle (sem α-tocoferol) não apresentou capacidade antioxidante. Concluiu-se que o material de amido de semente de jaca incorporado de α-tocoferol tem potencial para ser usado como revestimento ativo para alimentos com alto teor de gordura. Entre as formulações produzidas, a de 0,5% de α-tocoferol foi a melhor, porque apresentou atividade antioxidante tão boa quanto o filme 1,0% de α-tocoferol e propriedades mais interessantes, como a microestrutural, mecânica, óptica e de superfície. / Indiscriminate use of plastics has been generating environmental problems, like accumulation of materials, water pollution, as well as depleting a non-renewable resource (crude oil). This has been causing concern, therefore scientists and industries are seeking alternatives for these materials, for example, the employment of natural and/or biodegradable materials and the reuse of wasted byproducts. Starch is a natural polymer with many promising aspects, like its biodegradability, low cost and availability. Aiming at prolonging shelf-life of food products, starch has been investigated as a feedstock for development of edible active films and coatings. Besides acting as a barrier against gases and as mechanical protection, packages also may carry active substances (antioxidants, antimicrobials, etc.). The effects of the incorporation of (0.3; 0.5 and 1.0) g α-tocopherol/100 g filmogenic dispersion on the morphological, mechanical, optical, surface, water vapor permeability, barrier to UV/Visible light and antioxidant properties of jackfruit seed starch films were studied. Addition of α-tocopherol increased the tensile strength and the elastic modulus up to 0.5%. It also increased the water vapor barrier, possibly due to α-tocopherol\'s hydrophobic nature and because it caused a tortuosity effect in the polymer matrix, although the film solubility was not significantly affected. α-tocopherol improved the UV light barrier, especially in the wavelengths between (200 and 310) nm. The opacity and the color parameter b* increased significantly, which means that films with α-tocopherol became more opaque and yellowish. Surface hydrophobicity increased with the incorporation of α-tocopherol, especially for the 0.5% α-tocopherol film. The antioxidant activity increased significantly up to 0.5% α-tocopherol. The film without α-tocopherol presented no antioxidant capacity. Therefore, jackfruit seed starch films incorporated with α-tocopherol have potential to be used as edible active coatings for high fat content foods. Between the formulations produced, the one with 0.5% of α-tocopherol was the best, because it presented an antioxidant activity similar to the film with 1.0% of α-tocopherol and superior characteristics, like microstructural, mechanical, optical and surface properties.
59

Tratamento físico químico da vinhaça de destilaria de etanol com biopolímero à base de cálcio / Physical chemical treatment of distillery vinasse of ethanol with calcium-based biopolymer

Sapla, Rudner Brancalhoni 06 June 2012 (has links)
Este presente trabalho teve como objetivo a investigação do desempenho de um biopolímero experimental à base de cálcio, desenvolvido e fornecido por uma empresa americana, na coagulação, floculação e sedimentação da vinhaça bruta como tratamento físico-químico na remoção de carga orgânica e na concentração de compostos fertilizantes no lodo. O estudo do tratamento da vinhaça por meio da aplicação deste biopolímero possibilitaria, hipoteticamente, uma redução significativa da carga orgânica como tratamento inicial da vinhaça, além de concentrar os nutrientes presentes na vinhaça no lodo gerado para uso fertilizante. Foram realizados ensaios com coagulantes convencionais (sulfato ferroso, cloreto férrico e óxido de cálcio) para efeito de comparação entre estes e o biopolímero. Os ensaios de coagulação, floculação e sedimentação foram realizados em escala de laboratório com uso do equipamento Jar Test. Os ensaios foram divididos em três etapas. Na primeira etapa foram realizados ensaios aplicando-se determinadas dosagens de biopolímero e variando-se os tempos de coagulação, velocidades de rotação, além de realizar ou não a mistura lenta após a etapa de coagulação, a fim de verificar se estes parâmetros poderiam otimizar o processo de tratamento com o aplicação do biopolímero. Para segunda etapa do procedimento experimental foram realizados ensaios com os outros coagulantes: óxido de cálcio, sulfato férrico e cloreto férrico. Os ensaios com o cloreto férrico e o sulfato férrico foram realizados nas seguintes condições: velocidade de mistura rápida de 200 rpm por um período de tempo de 30 segundos e velocidade de mistura lenta de 80 rpm por um período de 20 minutos. Já os ensaios com óxido de cálcio foram realizados com apenas velocidade de mistura rápida de 200 rpm variando os períodos de tempo em 1, 5 e 10 minutos. O tempo de sedimentação para separação dos flocos formados foi de 2 horas para todas as etapas. O tratamento com biopolímero experimental apresentou resultados de remoção de matéria orgânica abaixo dos valores esperados, que era na faixa de 60% a 80%. Os resultados limitaram-se a valores de 10% a 35% de remoção de DQO. Porém, a remoção de turbidez atingiu valores elevados, próximos a 90%. Para os compostos relacionados à fertilização NPK (nitrogênio, fósforo e potássio), o tratamento com biopolímero experimental obteve as melhores eficiências de remoção de fósforo (48,3%) e de NTK (17,2%) em relação aos demais coagulantes, porém não apresentou remoção de potássio. Não houve diferença significativa na eficiência de remoção de DQO quando se alteram as condições operacionais de velocidade de agitação. Já o aumento no tempo de agitação diminui a eficiência de remoção de DQO. / This work aimed to investigate the performance of an experimental biopolymer calcium-based, developed and supplied by an American company, on gross vinasse coagulation, flocculation and sedimentation as a physical chemical treatment on organic load removal and on fertilizer compounds concentration in sludge. The study of the vinasse treatment through the application of this biopolymer would allow, hypothetically a significant reduction of the organic load as vinasse initial treatment, besides concentrating the vinasse found nutrients in the sludge created for fertilizer use. Assays were performed with conventional coagulants (ferrous sulfate, ferric chloride and calcium oxide) for comparison between them and the biopolymer. Tests of coagulation, flocculation and sedimentation were carried out in laboratory scale using Jar Test equipment. The experiments were divided in three stages. In the first stage assays were performed applying certain dosages of biopolymer and varying the clotting time, rotational speeds in addition to performing or not performing the slow mixture after the clotting stage in order to check if these parameters could optimize the treatment process with the biopolymer application. For the second stage of the experimental procedure tests were developed with other coagulants: calcium oxide, ferric sulphate and ferric chloride. Tests with ferric chloride and ferric sulphate were performed under the following conditions: fast mixing speed of 200 rpm for a period of 30 seconds and slow mixing speed of 80 rpm for a period of 20 minutes. Considering the assays with calcium oxide, they were carried out using only rapid mixing speed of 200 rpm by varying the time periods at 1, 5 and 10 minutes. The sedimentation time to the formed flakes separation was two hours for all stages. Treatment with experimental biopolymer presented results of removal of organic matter below the expected values, which was in the range 60% to80%. The results limited to values of 10% to 35% of COD clearance. However, the removal of turbidity reached high values near 90%. For compounds related to NPK (nitrogen, phosphorus and potassium) fertilization, the treatment with experimental biopolymer obtained the best efficiency of phosphorus removal (48,3) and TKN removal (17.2%) in comparison with the other coagulants, but showed no removal of potassium. There was no significant difference in COD removal efficiency when the operating conditions of agitation speed are changed. Regarding to the increase in the agitation time, it reduces the efficiency of COD removal.
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O plástico \"verde\" e o mercado brasileiro de etanol / The green plastic and the Brazilian ethanol market

José Jorge Marques 01 March 2011 (has links)
Com o consumo de etanol superando o de gasolina desde 2008, o Brasil é único país do mundo onde domina o combustível renovável, e o fóssil é o \"alternativo\". O foco deste trabalho é apresentar o projeto para produção do plástico verde, um biopolímero produzido com etanol da cana. O etanol destaca-se como uma alternativa à nafta (do petróleo). O eteno de origem fóssil, que provém da nafta, responde por 90% a 95% dos custos totais da cadeia de suprimento dos plásticos. No Brasil, a cana-deaçúcar e o etanol mostram-se mais competitivos que a nafta, \"grosso modo\", sempre que o barril do petróleo supera US$ 55. Quando comparado com o plástico da nafta, em torno de 4,5 kg de CO2 não são adicionados à atmosfera no processo para produção de 1,0 kg do plástico verde. Essa pode ser categorizada como mudança tecnológica \"empurrada\" no primeiro momento (anos 60) e \"puxada\" no momento atual (DOSI, 1982). Trata-se de uma ideia pré-existente na organização que foi novamente aplicada (HARGADON; SUTTON, 2000) e uma variação do processo genérico de desenvolvimento de produto proposto por Ulrich e Eppinger (2004). Contribui com o modelo de fatores que impactam no sucesso do produto sugerido por Brown e Eisenhardt (1995) ao agregar o fator \"processo tecnológico\" ao modelo. Este estudo também busca analisar implicações no mercado brasileiro de etanol mediante o movimento de inserção do álcool na cadeia produtiva petroquímica (alcoolquímica). A análise de mercado no curto prazo (2011) aponta uma demanda tímida para a alcoolquímica de cerca de 2% ou 700 milhões de litros/ano do total da demanda prevista de 33 bilhões de litros de etanol. Serão necessárias em torno de 688,5 milhões de toneladas de cana para suprir o mercado interno e externo de álcool e açúcar, que ocuparão cerca de 8,3 milhões de hectares (2,4% das terras aráveis brasileiras). Chama a atenção o crescente aumento da frota flex fuel brasileira, que poderá demandar cerca de 55 bilhões de litros de etanol até 2020, salvo desequilíbrio no preço do álcool versus o preço da gasolina e o potencial do mercado externo de 39 bilhões de litros. Estudo da ABIQUIM (2007), BNDES Setorial 2009 aponta a possibilidade de déficit de capacidade de eteno e propeno em 2020. Hoje, o País produz 70% do que consome de nafta (a produção de nafta representa apenas 8% dos derivados produzidos no País). Com a demanda global de eteno, em 2005, de 105 milhões de toneladas (CMAI, 2005 apud HORTA NOGUEIRA, 2008), com uma penetração de apenas 10% do etanol em v substituição a outros insumos, tem-se um mercado de 23 bilhões de litros de etanol, o que pode ser um desafio para a produção brasileira. / With ethanol consumption exceeding that of gasoline since 2008, Brazil is only country in the world where it dominates the renewable fuel, and the fossil is the alternative. The focus of this paper is to present the project for production of green plastic, a biopolymer produced ethanol from sugarcane. Ethanol stands out as an alternative to naphtha (petroleum). The ethylene produced from fossil fuels, which comes from naphtha accounts for 90% to 95% of the total supply chain of plastics. In Brazil, sugar cane and ethanol show to be more competitive than naphtha, \"roughly\" where a barrel of oil exceeds US$ 55. When compared with plastic naphtha, about 4,5 kg of CO2 are not added to the atmosphere in the process to produce 1,0 kg of green plastic. This can be categorized as technological change \"pushed\" at first (60) and \"pull\" at the present time (DOSI, 1982). This is an idea to pre-existing organization that was reapplied (HARGADON, SUTTON, 2000) and a variation of the general process of product development proposed by Ulrich and Eppinger (2004). Contributes to the model of factors that impact the success of the product suggested by Brown and Eisenhardt (1995) by adding the factor \"process technology\" to the model. This study also seeks to analyze the implications of the Brazilian ethanol market by the movement of insertion of alcohol in the petrochemical production chain. The market in the short term (2011) points to a demand for Ethanol timid about 2% or 700 million liters / year of total projected demand of 33 billion liters of ethanol. Will be needed around 688,5 million tons of sugarcane to supply the domestic and foreign alcohol and sugar, which occupy about 8,3 million hectares (2,4% of arable land in Brazil). Draws attention to the increasing Brazilian flex-fuel fleet, which will require about 55 billion liters of ethanol by 2020 unless imbalance in the price of ethanol versus gasoline prices and the potential foreign market of 39 billion liters. Study ABIQUIM (2007), BNDES Sector 2009 suggests the possibility of capacity shortage of ethylene and propylene in 2020. Today the country produces 70% of its consumption of naphtha (naphtha production accounts for only 8% of products produced in the country). With global demand for ethylene in 2005 was 105 million tons (CMAI, 2005 apud HORTA NOGUEIRA, 2008), with a penetration of only 10% of ethanol to substitute other inputs, has a market of 23 billion liters of ethanol, which can be a challenge for the brazilian production.

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