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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.
81

Composite carbon membranes for the desalination of water

Chamier, Jessica 03 1900 (has links)
Thesis (MSc (Chemistry and Polymer Science))--University of Stellenbosch, 2007. / Electrodialysis is a method of water desalination which involves the separation of TDS through an ion-exchange membrane under a potential gradient. In this study it was attempted to reverse engineer the composite carbon ion-exchange membrane used in a prototype plant and electrochemically evaluate a prototype desalination cell. The influence of applied potential on the capacitance of the various electrode surfaces and possible electrode reactions was investigated. A model was also suggested to describe the conductivity through the membrane. The composition of composite carbon membranes were determined by compositional analysis using various analytical tools. Elemental analysis, done with PIXE and EDS, showed that the membranes contained chloride, fluoride, oxygen, carbon, and possibly hydrogen. With LC-MS and IR it was established that the membranes consisted of two polymers with no carbonyl or aromatic functional groups. After further thermal analysis the following possible compounds remained: hexafluoropropylene tetrafluoroethylene copolymer, polychlorotrifluoroethylene (PCTFE), polyoxyethylene oxide (PEO) and polyethylene glycol (PEG). This assessment is in good agreement with the contents of US patent 4,153, 661, which describes the composite membrane.
82

FLUID FILTRATION FROM CAPILLARY NETWORKS (MICROCIRCULATION, MATHEMATICAL MODELING).

FLEISCHMAN, GREGORY JOSEPH. January 1985 (has links)
A mathematical model has been developed which describes the fluid exchange from a capillary network of realistic topology, and calculates the spatial distribution of extravascular pressure. In this model, the capillaries are represented by a superposition of sources and sinks, resulting from a D'Arcy's Law description of flow in tissue of uniform fluid conductivity. The combination of this representation and Starling's Hypothesis, which relates the forces influencing transmural fluid exchange, yields an integral equation of the second kind which is solved numerically for the source strength distribution. Two important features of this approach are that: (i) it allows for interaction between the local tissue pressure field and fluid exchange (the model is called, therefore, the tissue pressure interaction model); and (ii) complex network morphologies are easily modeled. In single capillaries, this interaction, which decreases the predicted fluid exchange, increases with the magnitude of the ratio of capillary wall to extravascular fluid conductivities. For multiple capillaries, in addition to the "self" interaction of a capillary with the local extravascular pressure field, there is the possibility of interaction between capillaries ("capillary-capillary" interaction). The ratio of conductivities, and the additional factors of intercapillary distance and the number of capillaries, also affect interaction in capillary networks. Although interaction is only a weak function of intercapillary distance, it depends strongly on the number of capillaries. The major result from this work is that for the entire physiological range of conductivity ratios, interaction cannot be neglected in predicting fluid exchange. Although tissue pressure interaction affects the magnitude of fluid exchange, it does not greatly alter the pattern of extravascular flow. Therefore, previous models which neglected interaction are not invalidated by the present findings. The effect of interaction on planar capillary networks within a semi-infinite tissue space was also investigated. Flow boundary conditions were imposed at opposed planar boundaries, parallel with the capillary network. Interaction was found to decrease with decreasing distance between the boundary and plane of the capillaries. It still exerted a large effect, however, for distances greater than one-fourth the reference capillary length.
83

Techno-Economic Study of CO<sub>2</sub> Capture from Natural Gas Based Hydrogen Plants<br><br>

Tarun, Cynthia January 2006 (has links)
As reserves of conventional crude oil are depleted, there is a growing need to develop unconventional oils such as heavy oil and bitumen from oil sands. In terms of recoverable oil, Canadian oil sands are considered to be the second largest oil reserves in the world. However, the upgrading of bitumen from oil sands to synthetic crude oil (SCO) requires nearly ten times more hydrogen (H<sub>2</sub>) than the conventional crude oils. The current H<sub>2</sub> demand for oil sands operations is met mostly by steam reforming of natural gas. With the future expansion of oil sands operations, the demand of H<sub>2</sub> for oil sand operations is likely to quadruple in the next decade. As natural gas reforming involves significant carbon dioxide (CO<sub>2</sub>) emissions, this sector is likely to be one of the largest emitters of CO<sub>2</sub> in Canada. <br> <br>In the current H<sub>2</sub> plants, CO<sub>2</sub> emissions originate from two sources, the combustion flue gases from the steam reformer furnace and the off-gas from the process (steam reforming and water-gas shift) reactions. The objective of this study is to develop a process that captures CO<sub>2</sub> at minimum energy penalty in typical H<sub>2</sub> plants. <br> <br>The approach is to look at the best operating conditions when considering the H<sub>2</sub> and steam production, CO<sub>2</sub> production and external fuel requirements. The simulation in this study incorporates the kinetics of the steam methane reforming (SMR) and the water gas shift (WGS) reactions. It also includes the integration of CO<sub>2</sub> capture technologies to typical H<sub>2</sub> plants using pressure swing adsorption (PSA) to purify the H<sub>2</sub> product. These typical H<sub>2</sub> plants are the world standard of producing H<sub>2</sub> and are then considered as the base case for this study. The base case is modified to account for the implementation of CO<sub>2</sub> capture technologies. Two capture schemes are tested in this study. The first process scheme is the integration of a monoethanolamine (MEA) CO<sub>2</sub> scrubbing process. The other scheme is the introduction of a cardo polyimide hollow fibre membrane capture process. Both schemes are designed to capture 80% of the CO<sub>2</sub> from the H<sub>2</sub> process at a purity of 98%. <br> <br>The simulation results show that the H<sub>2</sub> plant with the integration of CO<sub>2</sub> capture has to be operated at the lowest steam to carbon (S/C) ratio, highest inlet temperature of the SMR and lowest inlet temperatures for the WGS converters to attain lowest energy penalty. H<sub>2</sub> plant with membrane separation technology requires higher electricity requirement. However, it produces better quality of steam than the H<sub>2</sub> plant with MEA-CO<sub>2</sub> capture process which is used to supply the electricity requirement of the process. Fuel (highvale coal) is burned to supply the additional electricity requirement. The membrane based H<sub>2</sub> plant requires higher additional electricity requirement for most of the operating conditions tested. However, it requires comparable energy penalty than the H<sub>2</sub> plant with MEA-CO<sub>2</sub> capture process when operated at the lowest energy operating conditions at 80% CO<sub>2</sub> recovery. <br> <br>This thesis also investigates the sensitivity of the energy penalty as function of the percent CO<sub>2</sub> recovery. The break-even point is determined at a certain amount of CO<sub>2</sub> recovery where the amount of energy produced is equal to the amount of energy required. This point, where no additional energy is required, is approximately 73% CO<sub>2</sub> recovery for the MEA based capture plant and 57% CO<sub>2</sub> recovery for the membrane based capture plant. <br> <br>The amount of CO<sub>2</sub> emissions at various CO<sub>2</sub> recoveries using the best operating conditions is also presented. The results show that MEA plant has comparable CO<sub>2</sub> emissions to that of the membrane plant at 80% CO<sub>2</sub> recovery. MEA plant is more attractive than membrane plant at lower CO<sub>2</sub> recoveries.
84

Desenvolvimento de um processo de reúso do efluente de refinaria baseado em sistema de osmose reversa combinado com precipitação. / Process development for reuse the refinary wastewater based on reverse osmosis system combined with precipitation.

Moreira, Ramon Heleno 12 December 2016 (has links)
O processo de osmose reversa produz um permeado com elevada pureza, pois a membrana é praticamente uma barreira absoluta para partículas sólidas, coloides, íons e orgânicos. No entanto, alguns parâmetros devem ser controlados para proteger a membrana de oxidações por cloro, incrustações por partículas metálicas, compostos orgânicos e por sais concentrados acima ou próximos da supersaturação. Este processo é consolidado em aplicações de dessalinização e desmineralização para geração de água de nobre, porém requer maior avanço conceitual e prático em tratamento de efluentes em função das características particulares em termos de contaminantes para cada tipo de efluente. A presença de sais de metais alcalinos terrosos pode formar inscrustação (scaling) por precipitados indesejados, tais como: sulfato de bário (BaSO4), sulfato de estrôncio (SrSO4), carbonato de estrôncio (SrCO3), carbonato de cálcio (CaCO3) e hidróxido de magnésio (Mg(OH)2), além de sílica (SiO2). Para redução do potencial de scaling, podem ser aplicados na água compostos anti-incrustantes, bem como soluções para ajuste de pH para dissolução de cristais de certos compostos incrustantes, porém estas aplicações são dependentes do estudo de impacto nos processos e equipamentos (JANG et al., 2002). Este estudo foi realizado com o efluente de uma refinaria no Brasil após ser tratado pela ETAC (Estação de tratamento de águas contaminadas). Este efluente foi submetido a um novo processo de remoção de sais dissolvidos baseado em sistema de osmose reversa integrado com precipitação. Foram também analisados os índices de saturação dos sais dissolvidos nas correntes de alimentação e de rejeito do sistema de osmose reversa, de modo a verificar a incrustação de sais nas membranas e dimensionar adequadamente a unidade sem a adição de anti-incrustantes. Também foi verificado o atendimento da qualidade da água de permeado do sistema de osmose reversa com os requisitos de qualidade de água recomendados pela ASME (American Society of Mechanical Engineers) para caldeiras a vapor. Neste estudo foi identificado que, mediante uma dosagem que eleve o pH da solução para o valor de 9,5 no precipitador, é possível precipitar 90% dois íons presentes e que em valores de pH maiores (maiores dosagens) essa eficiência de precipitação diminui. Nesta condição, o consumo de reagentes Na2CO3 e Na2SO4 foi de 3,23 mmol e para o MgCl2 foi de 0,16 mmol por litro de efluente bruto a ser tratado. O pré-tratamento de precipitação antes do sistema de osmose reversa pode reduzir a precipitação de sais superfície das membranas. Nas condições aplicadas neste estudo, foram atingidas as reduções de sais de barita em 96%,de sílica em 91,6% e complexos de apatita em 99,97%. Esta melhoria reflete diretamente na vida útil das membranas visto que a precipitação de barita e de sílica são os maiores complicadores de remoção nas membranas mesmo que seja realizada a limpeza química. Para avaliação do custo de investimento e de consumo de químicos, também foi desenvolvido um estudo de implantação de uma unidade de capacidade de tratamento de 150 m3/h. Esta vazão foi definida como referência com base no estudo de produção de efluentes pelas refinarias no Brasil. O custo de implantação e de operação foi aplicado na avaliação de três cenários distintos que poderiam haver a necessidade de implantação do sistema de reúso na refinaria, tais como: implantação em uma refinaria nova em local com baixa disponibilidade de água para captação ou com grande variação sazonal do aquífero, expansão da refinaria sem alterar as plantas com sistema de tratamento água e tratamento de água desmineralizada existentes e de expansão da refinaria com a possibilidade de implantação de novos sistemas de tratamento de água e tratamento de água desmineralizada. Os resultados apresentam que os cenários estudados foram favoráveis a iniciativa de implantar o sistema de reúso nas refinarias. / The reverse osmosis process produces a permeate with high purity because the membrane is almost an absolute barrier to solid particles, colloids, and organic ions. However, some parameters must be controlled to protect the membrane from oxidation by chlorine, inlays for metal particles, organic compounds and salts above concentrated or near supersaturation. This process is consolidated in desalination and demineralization applications for boiler water generation, but requires more conceptual and practical advances in wastewater treatment according to the particular characteristics in terms of contaminants for each type of wastewater. The presence of alkaline earth metal salts may form unwanted precipitates such as barium sulfate (BaSO4), strontium sulfate (SrSO4), strontium carbonate (SrCO3), calcium carbonate (CaCO3) and magnesium hydroxide (Mg(OH)2) and silica (SiO2). This phenomenon of fouling salts is also known as \"scaling\". To reduce the scaling potential is usual to apply anti-fouling compounds, as well as pH adjustment to dissolve crystals of certain fouling compounds, but these applications are dependent upon impact study on processes and equipment (Jang et al., 2002). This study was conducted with the wastewater of a refinery in Brazil after being treated by ETAC (Wastewater Treatment Plant). The wastewater was subjected to a new process for removal of dissolved salts based on reverse osmosis system integrated with precipitation. The saturation index of the dissolved salt was also analyzed in the feed and concentrate streams of the reverse osmosis system, in order to verify salts fouling the membranes and properly sizing the unit without the addition of antifoulants. It was also checked the water quality in the permeate of the reverse osmosis with the quality requirements of water recommended by the ASME (American Society of Mechanical Engineers) for steam boilers. In this study it was identified through a dose that raise the pH to a value of 9.5, that it is possible to precipitate 90% of the ions dissolved in the wastewater and at higher pH (higher doses) this precipitation efficiency decreases. In this condition, the consumption of reagents Na2CO3 and Na2SO4 was 3.23 mmol and MgCl2 was 0.16 mmol per liter of raw wastewater to be treated. The pre-treatment with precipitation before the reverse osmosis system can reduce the precipitation on the surface of the membranes of barite salts in 96%, 91.6% to silica, and for complex apatite mineral of 99.97%. This improvement directly reflects the life-time of the membranes since the precipitation of barite and silica are the most complicating particles to the membranes even if chemical cleaning is applied. To evaluate the cost of investment and consumption of chemicals, it has also developed a study of deployment of a unit treatment capacity of 150 m3/h. This flow was defined as a reference based on the study of production of wastewater by refineries in Brazil. The cost of deployment and operation was applied in the evaluation of three different scenarios that could be a need to reuse the water in the refinery, such as: implementation of a new refinery in location with low water availability for pickup or large variation seasonal aquifer, refinery expansion without changing the plants water treatment system, and demineralized water treatment and existing refinery expansion with the possibility of developing new water treatment systems and treatment of demineralized water. The results show that the scenarios studied were favorable to initiative of introducing the system of reuse in refineries.
85

Tratamento de água para abastecimento público por sistema de separação por membrana de ultrafiltração: estudo de caso na ETA Alto da Boa Vista (São Paulo, SP). / Drinking water treatment by ultrafiltration: case study at Alto da Boa Vista WTP(São Paulo- SP).

Oliveira, Thiago Forteza de 28 April 2010 (has links)
Os processos de separação por membranas, especialmente a microfiltração e a ultrafiltração, são tecnologias emergentes para o tratamento de águas de abastecimento pela possibilidade de obtenção de águas com melhor qualidade em estações de tratamento mais compactas, de fácil automação, com menor geração de lodo e custo competitivo em relação ao sistema convencional de tratamento. A presente pesquisa avaliou o desempenho do processo de ultrafiltração no tratamento de água na ETA Alto da Boa Vista, que se utiliza do processo convencional tratando água do Reservatório Guarapiranga, manancial degradado da Região Metropolitana de São Paulo, sob os pontos de vista do desempenho operacional de produção de água e remoção de contaminantes. Tendo como água bruta, a água decantada da ETA ABV, o sistema operou por 2995 horas e 40 minutos, de agosto de 2009 a janeiro de 2010, produzindo com fluxo médio normalizado de 24,3 ± 2,2 L.h-1.m-2, pressão transmembrana de 94,2 ± 6,6 kPa e recuperação de 90,6 ± 0,9%. Foram analisados 13 pares de amostras de alimentação e permeado que indicaram a rejeição de COT de 11,2±8,6% (permeado=2,18±0,20 mg.L-1) , cor aparente 57,5±15,4% (permeado=2±2 mg.L-1 Pt- Co), condutividade elétrica 2,2±1,3% (permeado=138,2±17,8 S.cm-1), turbidez 92,7±4,5% (permeado=0,040±0,010 uT) e substâncias com absorção de radiação UV em 254nm 19,7±8,2% (permeado=0,025±0,008 cm-1). Em uma única amostra analisada, a rejeição a coliformes totais foi de 100%. Não foram detectados coliformes termotolerantes. Em 22/01/2010 foram coletadas amostras de alimentação e permeado para análise segundo Portaria 518 do Ministério da Saúde que indicou rejeição da contagem de bactérias heterotróficas de 98,98%, fluoretos de 36,49%, trihalometanos totais de 30,91%, alumínio total de 100%, cloretos de 20,29%, manganês total de 14,29% e sódio total de 0,81%. Em comparação com a água de abastecimento produzida na ETA ABV, a água do permeado da ultrafiltração apresentou qualidade melhor especialmente em relação à turbidez. / Membrane processes, specially microfiltration and ultrafiltration, are emerging technologies for drinking water treatment due the possibility for producing high quality water through compact treatment plants that are easier to automate with reduced sludge production and cost competitive compared with conventional processes. In this research it had been evaluated the ultrafiltration performance for water treatment at Alto da Boa Vista Water Treatment Plant that runs with conventional process, in São Paulo Metropolitan Region, from the viewpoints of water production and contaminants removal. An UF pilot plant was operated during 2995 hours and 40 minutes from August 2009 to January 2010 treating water from sedimentation tanks outlet. The UF pilot plant was able to operate with normalized flux of 24,3 ± 2,2 L.h- 1.m-2, transmembrane pressure of 94,2 ± 6,6 kPa and water recovery of 90,6 ± 0,9%. A total of 13 pairs of samples from feed and permeate were analyzed. The results were TOC rejection of 11,2±8,6% (permeate=2,18±0,20 mg.L-1), apparent color of 57,5±15,4% (permeate=2±2 mg.L-1 Pt-Co), conductivity of 2,2±1,3% (permeate=138,2±17,8 S.cm-1), turbidity 92,7±4,5% (permeate=0,040±0,01 uT) and UV 254nm 19,7±8,2% (permeate=0,025±0,008 cm-1). In an unique sample analysed for total coliforms, the rejection was 100%. Faecal coliforms were not detected in this sample. A sample of feed and permeate was collected at 01/22/2010 for analyses according to Portaria 518 (Brazilian drinking water regulations) that resulted in heterotrophic bacteria rejection of 98,98%, fluoride of 36,49%, total THM of 30,91%, total aluminium of 100%, chloride of 20,29%, total manganese of 14,29% and total sodium of 0,81%. In comparison with drinking water produced at Alto da Boa Vista WTP, the permeate of UF pilot plant was better in quality specially in terms of turbidity.
86

Montagem e caracterização de unidade de eletrodiálise em escala de laboratório para tratamento de soluções salinas. / Assembly and characterization of unit electrodialysis in laboratory scale for treatment of saline solutions.

Galuchi, Thales Pires Dias 06 August 2010 (has links)
A escassez de água nos grandes centros urbanos deve se agravar nos próximos anos. Novas fontes de água são necessárias para suprir a demanda. Nas cidades não há disponibilidade de terrenos para construção de estações de tratamento de águas e esgotos convencionais. Por isso, são necessários novos processos de tratamento. Processos de separação por membranas como osmose reversa e eletrodiálise são usados na dessalinização de águas e efluentes. Para a realização do estudo foi montada unidade de eletrodiálise em escala de laboratório. Na montagem selecionaram-se equipamentos que fossem resistentes à salinidade das soluções. As bombas magnéticas deveriam, ainda, superar a perda de cargas causada pelas membranas. As membranas foram adquiridas no exterior; os equipamentos, no mercado local. Os experimentos foram realizados em duas etapas: exploratória e comparativa. Eles seguiram os planejamentos de fatorial e do tipo Doehlert, respectivamente. Estudou-se a dessalinização de soluções aquosas unitárias (NaCl, Na2SO4, MgCl2 e KCl), com salinidade similar à água marinha (3,5%). Obtiveram-se como respostas os fluxos de sal, de água e consumo de energia em função dos fatores envolvidos no processo. Análises estatísticas propiciaram relacionar os fatores estudados com os resultados empíricos. Os fluxos salinos são proporcionais às densidade de corrente aplicadas e não apresentaram diferenças significativas entre si. Observou-se que o fluxo de água é relevante pelo mecanismo de solvatação de íons removidos e pela osmose. O consumo de energia é proporcional à densidade de corrente e maior para os sais bivalentes. / Water shortage in urban centers is expected to get worse in the next years. New water sources are necessary to meet demand. At urban area there are no available lands to build conventional water and sewage treatment plants. Therefore, new treatment processes are needed. Membrane processes like reverse osmosis and electrodialysis are used in water and wastewater desalination. A lab-scale electrodialysis unit was assembled for the study, based on a stack of electrodialysis membranes and support components that are capable of resisting solution salinity. The membrane stack was imported; the other equipment, obtained locally. The experiments were divided in two phases: exploratory and comparative. The experiments followed factorial and Doehlert designs, respectively. The desalination of aqueous solutions containing different inorganic salts (NaCl, Na2SO4, MgCl2 e KCl) in seawater salinity (3.5% mass) was studied. The responses were the salt and water fluxes and energy consumption in function of the processes variables selected. By means of a statistical analysis, it was possible to obtain the correlations for the studied factors based on the experimental results. The salt fluxes are proportional to the applied current density and they are not significantly different for the salts included in the study. It was observed that the water fluxes are relevant due to solvation of removed ions and osmosis. The energy consumption is proportional to current density and is larger for bivalent salts.
87

Fracionamento das proteínas do soro de leite por meio de agregação proteica combinada com processos de separação por membranas

Oliveira, Alisson de January 2017 (has links)
O soro de leite é o coproduto da produção de queijos e contém proteínas com excelentes propriedades nutricionais e tecnológicas. Dentre essas proteínas, as majoritárias são a β-lactoglobulina (BLG) e a α-lactalbumina (ALA). Embora o soro do leite já seja aproveitado pelas indústrias para a produção de isolados e concentrados proteicos, esses produtos consistem em uma mistura de diversas proteínas e atualmente há um grande interesse em realizar o seu fracionamento a fim de aproveitar melhor as suas propriedades individuais. Entretanto, fracionar essas proteínas é um grande desafio devido às suas massas molares próximas, e uma combinação de diferentes abordagens baseadas nas suas características se torna necessária para possibilitar uma boa separação. A ALA apresenta uma capacidade de formar agregados proteicos em meio ácido e ausência de cálcio, sendo uma estratégia interessante para combinar com processos de separação por membranas. Diante disso, o objetivo deste trabalho foi realizar o fracionamento da BLG e da ALA a partir da agregação proteica combinada com processos de separação por membranas. O ajuste do pH para 4 e adição de citrato de sódio como agente complexante do íon cálcio possibilitou a formação de agregados proteicos da solução de isolado proteico do soro de leite 6 %, porém ao determinar a pressão de operação dessa solução utilizando membranas cerâmicas de microfiltração (MF) de 0,8 e 0,05 μm para reter os agregados proteicos, o fluxo de permeado foi baixo. O mesmo procedimento foi utilizado para a solução de soro do leite em pó 6 % e membrana de 0,8 μm, resultando, também, em um fluxo de permeado baixo durante a determinação da pressão de operação. Ao combinar a centrifugação com a ultrafiltração (UF), o sobrenadante, contendo a fração que não formou agregados proteicos, apresentou maiores fluxos de permeado em pH 7 e 10, e baixos fluxos em pH 3 e 4. A purificação do sobrenadante em pH 10 com membrana cerâmica de 5 kDa apresentou fluxo de permeado elevado e, quando a diafiltração foi realizada, o fluxo de permeado apresentou um comportamento ascendente e menor tendência ao fouling, variando entre 56,5 e 64,6 %. O sedimentado ressolubilizado em pH 10 também apresentou um fluxo de permeado elevado, porém com comportamento mais estável durante a diafiltração, e tendência ao fouling entre 81,4 e 84,6 %. Contudo, a agregação proteica precisa ser mais bem avaliada para separar as proteínas, bem como a retenção da membrana de 5 kDa, x a qual permitiu a passagem de parte das proteínas tanto do sobrenadante como do sedimentado ressolubilizado, sendo, ainda, verificado um pH mais elevado nos concentrados do que nos permeados e livre passagem dos demais íons mediante análise de condutividade elétrica. Os resultados demonstraram que o ajuste do pH para 10 possibilitou melhorar a performance do fluxo de permeado, provavelmente devido à menor interação proteína-proteína e proteína-membrana, além de ser uma estratégia interessante para minimizar os fatores limitantes em processos de separação por membranas. / Whey is the co-product of cheese production and contains proteins with excellent nutritional and technological properties. Among these proteins, β-lactoglobulin (BLG) and α-lactalbumin (ALA) are the main ones. Although whey is already used by industries to produce protein isolates and concentrates, these products consist of a mixture of several proteins and currently there is a great interest in their fractionation in order to take better advantage of their individual properties. However, fractionating whey proteins is a great challenge because of their similar molecular weight. Due to this, a combination of different approaches based on characteristics of each of these proteins becomes necessary to enable a good separation. ALA has the ability to form protein aggregates in an acidic media and absence of calcium, providing an interesting condition to combine with membrane separation processes. In view of this, the aim of this work was to fractionate BLG and ALA using a combination of protein aggregation procedure and membrane separation processes. Adjustment of pH to 4 and addition of sodium citrate as complexing agent of calcium ion allowed the formation of protein aggregates in whey protein isolate solution, but when microfiltration was carried out with ceramic membranes of 0.8 and 0.05 μm to retain the protein aggregates formed, permeate flux was low during the determination of the operating pressure of the process. The same procedure was used with whey powder solution and 0.8 μm membrane, also resulting in a low permeate flux when determining the operating pressure. By combining centrifugation with ultrafiltration, the supernatant containing the fraction that did not form protein aggregates showed higher permeate flux at pH 7 and 10, and lower permeate flux at pH 3 and 4. Purification of the supernatant at pH 10 with 5 kDa ceramic membrane showed high permeate flux and, when the diafiltration was performed, the permeate flux presented an upward behavior and lower fouling tendency, varying between 56.5 and 64.6 %. The resolubilized sediment at pH 10 also showed a higher permeate flux, but with a more stable behavior during diafiltration and fouling tendency between 81.4 and 84.6 %. Nevertheless, protein aggregation procedure needs to be better evaluated to separate the proteins as well as the retention of the 5 kDa membrane, which allowed passage of part of the proteins of the supernatant and the resolubilized sediment solutions and showed a higher pH in the xii concentrates than in the final permeate and free passage of the other ions evaluated by electrical conductivity analysis. The results showed that adjusting the pH to 10 allowed to improve the perfomance of permeate flux, probably due to the lower protein-protein and protein-membrane interactions, besides being an interesting strategy to minimize the limiting factors in PSM.
88

Tratamento de água para abastecimento público por sistema de separação por membrana de ultrafiltração: estudo de caso na ETA Alto da Boa Vista (São Paulo, SP). / Drinking water treatment by ultrafiltration: case study at Alto da Boa Vista WTP(São Paulo- SP).

Thiago Forteza de Oliveira 28 April 2010 (has links)
Os processos de separação por membranas, especialmente a microfiltração e a ultrafiltração, são tecnologias emergentes para o tratamento de águas de abastecimento pela possibilidade de obtenção de águas com melhor qualidade em estações de tratamento mais compactas, de fácil automação, com menor geração de lodo e custo competitivo em relação ao sistema convencional de tratamento. A presente pesquisa avaliou o desempenho do processo de ultrafiltração no tratamento de água na ETA Alto da Boa Vista, que se utiliza do processo convencional tratando água do Reservatório Guarapiranga, manancial degradado da Região Metropolitana de São Paulo, sob os pontos de vista do desempenho operacional de produção de água e remoção de contaminantes. Tendo como água bruta, a água decantada da ETA ABV, o sistema operou por 2995 horas e 40 minutos, de agosto de 2009 a janeiro de 2010, produzindo com fluxo médio normalizado de 24,3 ± 2,2 L.h-1.m-2, pressão transmembrana de 94,2 ± 6,6 kPa e recuperação de 90,6 ± 0,9%. Foram analisados 13 pares de amostras de alimentação e permeado que indicaram a rejeição de COT de 11,2±8,6% (permeado=2,18±0,20 mg.L-1) , cor aparente 57,5±15,4% (permeado=2±2 mg.L-1 Pt- Co), condutividade elétrica 2,2±1,3% (permeado=138,2±17,8 S.cm-1), turbidez 92,7±4,5% (permeado=0,040±0,010 uT) e substâncias com absorção de radiação UV em 254nm 19,7±8,2% (permeado=0,025±0,008 cm-1). Em uma única amostra analisada, a rejeição a coliformes totais foi de 100%. Não foram detectados coliformes termotolerantes. Em 22/01/2010 foram coletadas amostras de alimentação e permeado para análise segundo Portaria 518 do Ministério da Saúde que indicou rejeição da contagem de bactérias heterotróficas de 98,98%, fluoretos de 36,49%, trihalometanos totais de 30,91%, alumínio total de 100%, cloretos de 20,29%, manganês total de 14,29% e sódio total de 0,81%. Em comparação com a água de abastecimento produzida na ETA ABV, a água do permeado da ultrafiltração apresentou qualidade melhor especialmente em relação à turbidez. / Membrane processes, specially microfiltration and ultrafiltration, are emerging technologies for drinking water treatment due the possibility for producing high quality water through compact treatment plants that are easier to automate with reduced sludge production and cost competitive compared with conventional processes. In this research it had been evaluated the ultrafiltration performance for water treatment at Alto da Boa Vista Water Treatment Plant that runs with conventional process, in São Paulo Metropolitan Region, from the viewpoints of water production and contaminants removal. An UF pilot plant was operated during 2995 hours and 40 minutes from August 2009 to January 2010 treating water from sedimentation tanks outlet. The UF pilot plant was able to operate with normalized flux of 24,3 ± 2,2 L.h- 1.m-2, transmembrane pressure of 94,2 ± 6,6 kPa and water recovery of 90,6 ± 0,9%. A total of 13 pairs of samples from feed and permeate were analyzed. The results were TOC rejection of 11,2±8,6% (permeate=2,18±0,20 mg.L-1), apparent color of 57,5±15,4% (permeate=2±2 mg.L-1 Pt-Co), conductivity of 2,2±1,3% (permeate=138,2±17,8 S.cm-1), turbidity 92,7±4,5% (permeate=0,040±0,01 uT) and UV 254nm 19,7±8,2% (permeate=0,025±0,008 cm-1). In an unique sample analysed for total coliforms, the rejection was 100%. Faecal coliforms were not detected in this sample. A sample of feed and permeate was collected at 01/22/2010 for analyses according to Portaria 518 (Brazilian drinking water regulations) that resulted in heterotrophic bacteria rejection of 98,98%, fluoride of 36,49%, total THM of 30,91%, total aluminium of 100%, chloride of 20,29%, total manganese of 14,29% and total sodium of 0,81%. In comparison with drinking water produced at Alto da Boa Vista WTP, the permeate of UF pilot plant was better in quality specially in terms of turbidity.
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Produção e caracterização de membranas de microfiltração e ultrafiltração pelo método de inversão de fases, utilizando polisulfona como matéria-prima. / Production and characterization of microfiltration and ultrafiltration membranes via phase inversion process employing polysulfone as raw material.

Pucca, Paulo Tadeu Pimentel 08 October 2010 (has links)
A presente pesquisa consistiu em produzir membranas sintéticas pelo processo de inversão de fases via precipitação por imersão e levantar dados operacionais relativos ao preparo das soluções poliméricas e respectivos espalhamentos sobre um suporte inerte, de forma a obter-se membranas uniformes, livres de imperfeições que possam afetar seu desempenho. Tal uniformidade requer a produção de soluções poliméricas homogêneas, sem a presença de bolhas, isentas de sólidos em suspensão e com viscosidade adequada, para que o filme espalhado com espessura controlada se mantenha íntegro até o momento da solidificação do polímero, que formará as membranas propriamente ditas. Para condução dos experimentos utilizou-se a polisulfona como polímero, a N-metil- 2 pirrolidona como solvente, não-tecido em poliéster como suporte inerte e água desmineralizada como não-solvente. As soluções foram preparadas com concentrações de cerca de 15 %, 20 % e 25 % em massa de polímero e imersas em banhos de coagulação contendo água desmineralizada a temperaturas de aproximadamente 23°C, 40°C e 50°C. As membranas obtidas após precipitação foram enxaguadas em água desmineralizada morna e então avaliadas morfologicamente através de microscopia eletrônica de varredura, bem como submetidas a alguns outros testes como o ensaio de permeabilidade e o ensaio de tração e de ângulo de contato. Partindo-se de alguns poucos parâmetros encontrados em literatura, procurou-se obter um maior número de dados que permitam definir um procedimento de preparação de membranas através do processo mencionado. Os ensaios indicaram que a utilização de matérias-primas com um grau de pureza elevado, preparo da solução em temperatura, velocidade de rotação, umidade relativa e tempo de agitação adequados, além de filtração, se necessário, são condições muito importantes para a obtenção de soluções homogêneas. A utilização de equipamento aplicador de filme com ajuste de espessura, controles de velocidade de espalhamento e temperatura, e o controle da umidade da atmosfera são essenciais para a obtenção de um filme bem definido, garantindo a reprodutibilidade da síntese de membranas com a qualidade desejada. A utilização de não-tecido adequado como suporte inerte, de superfície lisa e homogênea é de fundamental importância para se obter uma camada polimérica bem homogênea e com espessura uniforme, garantindo condições morfológicas adequadas para a obtenção de níveis de produtividade e seletividade, compatíveis com os processos onde tipicamente se empregam membranas. / The proposal of this research is to produce synthetic membranes through the process of phase inversion via immersion precipitation, and obtain some operational data relating to the preparation of the polymeric solution and its casting on an inert support layer, in order to obtain uniform membranes, free from flaws which might affect its performance. Such uniformity requires the production of homogeneous polymer solutions, free from bubbles or suspended solids and with a suitable viscosity, in order to avoid loss of thickness until the solidification of polymer occurs. Polysulfone was employed as polymer, N-methyl-2 pyrrolidone as a solvent, nonwoven polyester as inert support and demineralized water as non-solvent. The solutions were prepared with concentrations of polymer of approximately 15%, 20% and 25% and, after casting, immersed in a coagulation bath containing demineralized water at approximately 23°C, 40°C and 50°C. The membranes obtained after precipitation were rinsed in demineralized water and evaluated through scanning electron microscopy, and some other tests, as the permeability, the mechanical and contact angle tests. Taking a few parameters found in the literature, we intended to obtain additional data to define a procedure for the preparation of membranes using the afore mentioned process. The tests indicated that the use of high purity raw materials and proper solution preparation parameters as temperature, speed, relative humidity and stirring time are very important to obtain an homogeneous solution. Besides, the use of motorized film application equipment with adjustments for film thickness, casting speed, temperature, and controlled water content in air are essential in obtaining a good film definition, and ensuring the reproducibility in the synthesis of membranes with a desired quality. The use of suitable non-woven fabric as a inert support with smooth and homogeneous surface is very important in order to obtain uniform polymer layers, ensuring morphological conditions suitable for achieving levels of productivity and selectivity, compatible with processes where typically membranes are employed.
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Fouling mechanisms in the membrane filtration of single and binary protein solutions

Chan, Robert, Chemical Engineering & Industrial Chemistry, UNSW January 2002 (has links)
In this study the fouling mechanisms of various microfiltration and ultrafiltration membranes were studied when subjected to crossflow filtration using various protein solutions. Experimentation was carried out using controlled flux experiments and fouling phenomena was investigated via the monitoring of the transmembrane pressure (TMP) and rejection. Electron microscopy was employed to study fouling on microfiltration membranes when single protein solutions were filtered while a novel method involving Matrix-Assisted Laser Desorption Ionisation Mass Spectrometry (MALDI-MS) was developed to qualitatively and quantitatively analyse mixed proteins fouled on ultrafiltration membranes. An apparent critical flux was identified whereby fouling was shown to occur at fluxes where there was no increase in TMP. TMP increase is one of the common indicators of fouling in controlled flux operation. Microfiltration experiments showed that the imposition of the apparent critical flux is accompanied by rapid increases in hydraulic resistance and the membrane wall concentration. Pore blockage and narrowing occurred at somewhat higher fluxes as indicated by increases in the observed rejection. Fouling was not influenced greatly by the addition of electrolytes for microfiltration membranes but observed transmissions were found to be greater than 100% when ultrafiltration membranes were employed. For all membranes used, the actual value of the apparent critical flux was shown to be independent of the salt concentration but dependent on pH. Sub apparent-critical constant flux microfiltration showed the existence of an aggregation/deposition time lag after which the membrane experiences a rapid increase in resistance due to protein aggregates blocking a majority of pores. This phenomenon was shown to be dependent on pH and ionic strength and was concluded to be the product of a balance between electrostatic, solubility and hydrophobic interactions.

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