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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.
21

Regenerable Adsorbents for Removal of Arsenic from Contaminated Waters and Synthesis and Characterization of Multifunctional Magnetic Nanoparticles for Environmental and Biomedical Applications

Verdugo Gonzalez, Brenda January 2011 (has links)
The present work is divided into two sections. The first section deals with the synthesis of regenerable adsorbents for the removal of arsenic from contaminated waters. An adsorbent based on carboxymethylated polyethylenimine grafted agarose gels was synthesized and characterized as a regenerable synthetic ferric oxide adsorbent with high capacity for arsenate ions at pH 3.0. Similarly, four metal ion chelating adsorbents based on dipicolylamine were synthesized and characterized with respect to their Cu(II), Fe(III) and As(V) adsorption capacities. The most efficient adsorbents were Nov-PEI-DPA and Nov-TREN-DPA. Additionally, a commercial ion exchange resin was modified with permanganate to oxidize arsenite into arsenate. A complete oxidation-adsorption system was proposed in which a column packed with the oxidation resin was connected in series with an adsorbent column composed of the polyethylenimine grafted agarose gels.The second section involved work with magnetic nanoparticles. First, composite adsorbents consisting of magnetic particles encapsulated within agarose beads with and without grafted iminodiacetic acid (IDA) chelating groups were synthesized. The adsorption capacity of the adsorbents for Cu(II), Fe(III) and As(V) at different concentrations was investigated. Batch experiments were carried out to determine the Fe(III) and As(V) adsorption isotherms for the magnetic Novarose-IDA. Regenerability of the adsorbent was achieved with a pH change of the inlet solution, without affecting its magnetic or adsorption properties.Magnetic composite particles were synthesized for biomedical applications. First, magnetic nanoparticles were coated with silica and then used for gold nanoshell production. These nanoshells were functionalized with a Brij S10 derivative, containing carboxylic groups, using dodecanethiol as a bridging agent to incorporate a fluorescent biomolecule.Finally, magnetic and gold particles were encapsulated in PLGA nanoparticles. Docetaxel was loaded on these multifunctional nanoparticles and released studies were performed at 37°C. The presence of magnetite, colloidal gold and gold nanoshells in the PLGA nanoparticles was revealed by the coloration acquired by the polymeric nanoparticles. The release of drug from the polymeric nanoparticles showed a biphasic behavior with an initial burst followed by a prolonged slow release. There was no effect of the presence of magnetic or metallic particles on docetaxel release.
22

Avaliação do potencial de adsorventes de baixo custo para purificação de biodiesel etílico e estabelecimento das condições operacionais por metodologia de superfície de resposta / Assessing the potential of low cost adsorbents for ethyl biodiesel and establishment the operational conditions by response surface methodology

Santos, Flávia Danielle dos 15 February 2016 (has links)
O presente estudo tem como objetivo avaliar o processo de purificação do biodiesel por adsorção, utilizando adsorventes alternativos de baixo custo, comparando a eficiência dos adsorventes selecionados com o método de purificação convencional (lavagem aquosa). Para tanto, foram realizados testes de triagem de materiais provenientes de resíduos industriais, avaliando a capacidade desses materiais na remoção de glicerol e recuperação mássica. Dentre os adsorventes testados, a cinza da casca de arroz e a argila chamo-te apresentaram melhores resultados, juntamente com a resina comercial Amberlite BD10DRY, utilizada como parâmetro de comparação nos ensaios de purificação por via seca. Por meio de planejamento experimental composto de face centrada 22, foi avaliado o efeito da concentração de cada adsorvente selecionado (2, 5 e 8% m/v) e a temperatura (30, 40 e 50 °C) nas variáveis respostas: percentuais de recuperação mássica e adsorção de glicerol. De acordo com a análise estatística foi possível estabelecer as condições operacionais para cada adsorvente que maximizam as variáveis respostas. As condições ótimas estabelecidas foram: concentração de adsorventes (3,7; 2,4 e 2,1% m/v) e temperatura (30, 45 e 30 °C) para a resina Amberlite BD10DRY, argila chamote e cinza de casca de arroz, respectivamente. Tais condições maximizaram a remoção de glicerol (entre 76 - 80%) sem ocasionar perdas elevadas de massa do adsorvato (3,0 - 6,5%). Para validar a metodologia de purificação por via seca, o procedimento foi testado em amostra de biodiesel etílico obtido em escala de laboratório, a partir de óleo de palmiste utilizando como catalisador óxido de nióbio impregnado com sódio. A purificação do biodiesel por adsorção foi realizada adotando as condições otimizadas, adotando a técnica de lavagem aquosa como método de comparação. Todos os métodos de purificação foram eficientes quanto à remoção de glicerol (abaixo do limite estipulado de 0,02% em massa) e todas as amostras purificadas apresentaram elevados teores de ésteres etílicos (EE%) variando entre 99,18% e 99,71% e valores de viscosidade cinemática (3,0-6,0 mm2/s) e densidade (850-900 kg/m3) dentro dos limites especificados pelas normas de qualidade estabelecidas pela Agência Nacional do Petróleo, Gás natural e Biocombustíveis (ANP) Resolução 45/2014. Entretanto, apenas as amostras purificadas por via seca utilizando argila chamote e cinza de casca de arroz apresentaram teores de monoacilglicerol e diacilglicerol dentro dos valores estipulados (0,70% para MAG e 0,20% para DAG). Estudos complementares da estrutura e composição dos adsorventes Cinza de casca de arroz e Argila Chamote foram efetuados para melhor compreender suas propriedades como agentes de adsorção. A capacidade de adsorção desses materiais está relacionada com o elevado conteúdo de sílica, como demonstrado pela difração de raios-x e análises de espectroscopia no infravermelho. Desta forma, resíduos de baixo custo e de elevada disponibilidade como argila chamote e cinza de casca de arroz, podem ser considerados como materiais promissores para serem usados em processos de purificação de biodiesel por via seca. / The present study aims at assessing the purification of ethyl biodiesel by dry washing using alternative low-cost sorbents, taking the efficiency demonstrated by a conventional purification method (wet washing) as a control parameter. Screening tests carried out with different sorbents (commercial and industrial wastes) revealed that rice husk ash and chamotte clay showed better results, along with the commercial resin Amberlite BD10DRY, used here as standard sorbent for dry washing. For the selected sorbents, a combined effect of sorbent concentration (2, 5, and 8 wt%) and temperature (30, 40 and 50° C) on the mass recovered and glycerol removal was studied using the response surface methodology. A 22 full-factorial central composite design was employed for the experimental design and analysis of the results. According to the statistical analysis it was possible to establish the operating conditions for each sorbent that maximize both responses. The optimum conditions were established at: concentration of sorbent (3.7; 2.4 and 2.1% m/v) and temperature (30, 45 and 30° C) for the resin Amberlite BD10DRY, chamotte clay and rice husk ash, respectively. Such conditions maximized the removal of glycerol (between 76-80%) and minimized the loss of the adsorbate mass (3.0-6.5%). Under optimal conditions, the sorbents were used for purifying ethyl biodiesel samples obtaining at laboratory scale from palm kernel oil using as catalyst niobium oxide impregnated with sodium. Both procedures (dry and wet washing) were quite efficient in removing glycerol (below the required limit of 0.02%) and all the purified samples showed high percentages of ethyl esters (EE%) ranging from 99.18% and 99.71% and values of kinematic viscosity (3.0-6.0 mm2/s) and density (850-900 kg/m3) within the limits specified by the quality standards established by the National Agency of Petroleum, Natural Gas and Biofuels (ANP) Resolution 45/2014. However, only the alternatives sorbents (chamotte clay and rice husk ash) were also able to remove monoacylglycerols (MG) and diacylglycerols (DG), thus their structures and compositions were further analyzed to better understand their properties as sorbents. The adsorption capacity of these sorbents is related to their high silica contents, as it was demonstrated by the X-ray diffraction and infrared spectroscopy analyses. Thus low-cost wastes such as chamotte clay and rice husk ash with high-availability features can be considered as a promising materials to be used in biodiesel purification processes by wet washing.
23

Estudo da magnetita como material adsorvedor de íons uranilo / Study of magnetite as adsorbent material of uranyl ions

Leal, Roberto 24 March 2006 (has links)
A magnetita, também chamada de ferrita de ferro, é um minério conhecido como imã natural e encontrada em depósitos de ferro. Além desse comportamento intrínseco, a magnetita possui a capacidade de remover os íons metálicos do meio aquoso por fenômenos de adsorção. O seu caráter fortemente magnético a distingue de outros tipos de adsorventes, visto que, é facilmente removida da solução por separação magnética. Neste trabalho estudou-se a adsorção de urânio(VI), na forma de íons UO22+, de solução nítrica pela magnetita sintética. Esta foi preparada por precipitação simultânea adicionando-se uma solução de NaOH à solução contendo os íons Fe2+ e Fe3+. A magnetita sintética, na forma de um pó preto, exibiu uma resposta magnética de atração intensa na presença de um campo magnético, sem contudo tornar-se magnética, um comportamento típico de material superparamagnético constatado por medidas de magnetização. Estudou-se a influência dos parâmetros de adsorção de íons UO22+ tais como o pH, a dose do adsorvente, tempo de contato e a isoterma de equilíbrio. A máxima adsorção de urânio foi encontrada no intervalo de pH entre 4 e 5. Verificou-se que quanto maior a dose de magnetita menor a capacidade de adsorção e maior a remoção de U. Da relação entre adsorção e tempo de contato verificou-se que a remoção aumentou rapidamente com o tempo e atingiu-se a condição de equilíbrio em 30 min. Os resultados da isoterma de equilíbrio apresentaram maior concordância com o modelo de Langmuir, o qual permitiu a determinação da capacidade teórica de saturação da magnetita para o urânio. A interação entre os íons UO22+ e a magnetita foi caracterizada como uma adsorção química e espontânea. / Magnetite, also known as iron ferrite, is a mineral iron and a natural magnet found in iron deposits. In addition to its magnetic intrinsic behavior, the magnetite has the capacity to remove the metallic ions from aqueous medium by adsorption phenomena. The strong magnetic character of magnetite distinguishes it from other adsorbent types, which it allows to be readily removed from solution by magnetic separation. In this work, uranium (VI) adsorption, as UO22+ ions, from nitric solution by synthetic magnetite was investigated. It was prepared by simultaneous precipitation process, adding a NaOH solution into a solution containing Fe2+ and Fe3+ ions. The synthetic magnetite, a black powder, has exhibited a strong magnetic response in presence of a magnetic field, without nevertheless becomes magnetic. This typical superparamagnetic behavior was confirmed by magnetization measurements. Adsorption parameters of UO22+ ions such as pH. the adsorbent dose, contact time and equilibrium isotherm were evaluated. Maximum uranium adsorption was observed in the pH 4.0-5.0 range. It was noticed that increase in magnetite dose increased the percent removal of uranium, but decreased the adsorption capacity of the magnetite. It was observed from the relation between adsorption and contact time that the removal has increased very fast with time, and achieved the equilibrium within 30 minutes. The results of equilibrium isotherm agreed well with the Langmuir model, and so the theorical saturation capacity of the magnetite was determined for uranyl ions. The interaction between UO22+ ions and the magnetite was defined as a spontaneous chemical adsorption.
24

Estudo da magnetita como material adsorvedor de íons uranilo / Study of magnetite as adsorbent material of uranyl ions

Roberto Leal 24 March 2006 (has links)
A magnetita, também chamada de ferrita de ferro, é um minério conhecido como imã natural e encontrada em depósitos de ferro. Além desse comportamento intrínseco, a magnetita possui a capacidade de remover os íons metálicos do meio aquoso por fenômenos de adsorção. O seu caráter fortemente magnético a distingue de outros tipos de adsorventes, visto que, é facilmente removida da solução por separação magnética. Neste trabalho estudou-se a adsorção de urânio(VI), na forma de íons UO22+, de solução nítrica pela magnetita sintética. Esta foi preparada por precipitação simultânea adicionando-se uma solução de NaOH à solução contendo os íons Fe2+ e Fe3+. A magnetita sintética, na forma de um pó preto, exibiu uma resposta magnética de atração intensa na presença de um campo magnético, sem contudo tornar-se magnética, um comportamento típico de material superparamagnético constatado por medidas de magnetização. Estudou-se a influência dos parâmetros de adsorção de íons UO22+ tais como o pH, a dose do adsorvente, tempo de contato e a isoterma de equilíbrio. A máxima adsorção de urânio foi encontrada no intervalo de pH entre 4 e 5. Verificou-se que quanto maior a dose de magnetita menor a capacidade de adsorção e maior a remoção de U. Da relação entre adsorção e tempo de contato verificou-se que a remoção aumentou rapidamente com o tempo e atingiu-se a condição de equilíbrio em 30 min. Os resultados da isoterma de equilíbrio apresentaram maior concordância com o modelo de Langmuir, o qual permitiu a determinação da capacidade teórica de saturação da magnetita para o urânio. A interação entre os íons UO22+ e a magnetita foi caracterizada como uma adsorção química e espontânea. / Magnetite, also known as iron ferrite, is a mineral iron and a natural magnet found in iron deposits. In addition to its magnetic intrinsic behavior, the magnetite has the capacity to remove the metallic ions from aqueous medium by adsorption phenomena. The strong magnetic character of magnetite distinguishes it from other adsorbent types, which it allows to be readily removed from solution by magnetic separation. In this work, uranium (VI) adsorption, as UO22+ ions, from nitric solution by synthetic magnetite was investigated. It was prepared by simultaneous precipitation process, adding a NaOH solution into a solution containing Fe2+ and Fe3+ ions. The synthetic magnetite, a black powder, has exhibited a strong magnetic response in presence of a magnetic field, without nevertheless becomes magnetic. This typical superparamagnetic behavior was confirmed by magnetization measurements. Adsorption parameters of UO22+ ions such as pH. the adsorbent dose, contact time and equilibrium isotherm were evaluated. Maximum uranium adsorption was observed in the pH 4.0-5.0 range. It was noticed that increase in magnetite dose increased the percent removal of uranium, but decreased the adsorption capacity of the magnetite. It was observed from the relation between adsorption and contact time that the removal has increased very fast with time, and achieved the equilibrium within 30 minutes. The results of equilibrium isotherm agreed well with the Langmuir model, and so the theorical saturation capacity of the magnetite was determined for uranyl ions. The interaction between UO22+ ions and the magnetite was defined as a spontaneous chemical adsorption.
25

Avaliação do potencial de adsorventes de baixo custo para purificação de biodiesel etílico e estabelecimento das condições operacionais por metodologia de superfície de resposta / Assessing the potential of low cost adsorbents for ethyl biodiesel and establishment the operational conditions by response surface methodology

Flávia Danielle dos Santos 15 February 2016 (has links)
O presente estudo tem como objetivo avaliar o processo de purificação do biodiesel por adsorção, utilizando adsorventes alternativos de baixo custo, comparando a eficiência dos adsorventes selecionados com o método de purificação convencional (lavagem aquosa). Para tanto, foram realizados testes de triagem de materiais provenientes de resíduos industriais, avaliando a capacidade desses materiais na remoção de glicerol e recuperação mássica. Dentre os adsorventes testados, a cinza da casca de arroz e a argila chamo-te apresentaram melhores resultados, juntamente com a resina comercial Amberlite BD10DRY, utilizada como parâmetro de comparação nos ensaios de purificação por via seca. Por meio de planejamento experimental composto de face centrada 22, foi avaliado o efeito da concentração de cada adsorvente selecionado (2, 5 e 8% m/v) e a temperatura (30, 40 e 50 °C) nas variáveis respostas: percentuais de recuperação mássica e adsorção de glicerol. De acordo com a análise estatística foi possível estabelecer as condições operacionais para cada adsorvente que maximizam as variáveis respostas. As condições ótimas estabelecidas foram: concentração de adsorventes (3,7; 2,4 e 2,1% m/v) e temperatura (30, 45 e 30 °C) para a resina Amberlite BD10DRY, argila chamote e cinza de casca de arroz, respectivamente. Tais condições maximizaram a remoção de glicerol (entre 76 - 80%) sem ocasionar perdas elevadas de massa do adsorvato (3,0 - 6,5%). Para validar a metodologia de purificação por via seca, o procedimento foi testado em amostra de biodiesel etílico obtido em escala de laboratório, a partir de óleo de palmiste utilizando como catalisador óxido de nióbio impregnado com sódio. A purificação do biodiesel por adsorção foi realizada adotando as condições otimizadas, adotando a técnica de lavagem aquosa como método de comparação. Todos os métodos de purificação foram eficientes quanto à remoção de glicerol (abaixo do limite estipulado de 0,02% em massa) e todas as amostras purificadas apresentaram elevados teores de ésteres etílicos (EE%) variando entre 99,18% e 99,71% e valores de viscosidade cinemática (3,0-6,0 mm2/s) e densidade (850-900 kg/m3) dentro dos limites especificados pelas normas de qualidade estabelecidas pela Agência Nacional do Petróleo, Gás natural e Biocombustíveis (ANP) Resolução 45/2014. Entretanto, apenas as amostras purificadas por via seca utilizando argila chamote e cinza de casca de arroz apresentaram teores de monoacilglicerol e diacilglicerol dentro dos valores estipulados (0,70% para MAG e 0,20% para DAG). Estudos complementares da estrutura e composição dos adsorventes Cinza de casca de arroz e Argila Chamote foram efetuados para melhor compreender suas propriedades como agentes de adsorção. A capacidade de adsorção desses materiais está relacionada com o elevado conteúdo de sílica, como demonstrado pela difração de raios-x e análises de espectroscopia no infravermelho. Desta forma, resíduos de baixo custo e de elevada disponibilidade como argila chamote e cinza de casca de arroz, podem ser considerados como materiais promissores para serem usados em processos de purificação de biodiesel por via seca. / The present study aims at assessing the purification of ethyl biodiesel by dry washing using alternative low-cost sorbents, taking the efficiency demonstrated by a conventional purification method (wet washing) as a control parameter. Screening tests carried out with different sorbents (commercial and industrial wastes) revealed that rice husk ash and chamotte clay showed better results, along with the commercial resin Amberlite BD10DRY, used here as standard sorbent for dry washing. For the selected sorbents, a combined effect of sorbent concentration (2, 5, and 8 wt%) and temperature (30, 40 and 50° C) on the mass recovered and glycerol removal was studied using the response surface methodology. A 22 full-factorial central composite design was employed for the experimental design and analysis of the results. According to the statistical analysis it was possible to establish the operating conditions for each sorbent that maximize both responses. The optimum conditions were established at: concentration of sorbent (3.7; 2.4 and 2.1% m/v) and temperature (30, 45 and 30° C) for the resin Amberlite BD10DRY, chamotte clay and rice husk ash, respectively. Such conditions maximized the removal of glycerol (between 76-80%) and minimized the loss of the adsorbate mass (3.0-6.5%). Under optimal conditions, the sorbents were used for purifying ethyl biodiesel samples obtaining at laboratory scale from palm kernel oil using as catalyst niobium oxide impregnated with sodium. Both procedures (dry and wet washing) were quite efficient in removing glycerol (below the required limit of 0.02%) and all the purified samples showed high percentages of ethyl esters (EE%) ranging from 99.18% and 99.71% and values of kinematic viscosity (3.0-6.0 mm2/s) and density (850-900 kg/m3) within the limits specified by the quality standards established by the National Agency of Petroleum, Natural Gas and Biofuels (ANP) Resolution 45/2014. However, only the alternatives sorbents (chamotte clay and rice husk ash) were also able to remove monoacylglycerols (MG) and diacylglycerols (DG), thus their structures and compositions were further analyzed to better understand their properties as sorbents. The adsorption capacity of these sorbents is related to their high silica contents, as it was demonstrated by the X-ray diffraction and infrared spectroscopy analyses. Thus low-cost wastes such as chamotte clay and rice husk ash with high-availability features can be considered as a promising materials to be used in biodiesel purification processes by wet washing.
26

Brine treatment using natural adsorbents

Mabovu, Bonelwa January 2011 (has links)
The current study investigated application of natural adsorbents in brine treatment. Brines are hypersaline waters generated in power stations and mining industries rich in Mg2+, K+, Ca2+, Na+, SO4 2- , Cl- and traces of heavy metals, thus there is a need for these brines to be treated to recover potable water and remove problematic elements. Natural adsorbents have been successfully used in waste water treatment because of their high surface area and high adsorptive properties when they are conditioned with acid or base. The investigation of pH showed that natural adsorbents did not perform well at low pH of 4 and 6. The adsorbents were able to work efficiently at the natural pH of 8.52 of the brine solution. These results show that natural adsorbents hold great potential to remove cationic major components and selected heavy metal species from industrial brine wastewater. Heterogeneity of natural adsorbents samples, even when they have the same origin, could be a problem when wastewater treatment systems utilizing natural clinoptilolite and bentonite are planned to be developed. Therefore, it is very important to characterize the reserves fully in order to make them attractive in developing treatment technologies.
27

Hollow fiber sorbents for the desulfurization of pipeline natural gas

Bhandari, Dhaval Ajit 04 November 2010 (has links)
Pipeline natural gas is the primary fuel of choice for distributed fuel cell-based applications. The concentration of sulfur in odorized natural gas is about 30 ppm, with acceptable levels being <1 ppm for catalyst stability in such applications. Packed bed technology for desulfurization suffers from several disadvantages including high pressure drop and slow regeneration rates that require large unit sizes. We describe a novel Rapid Temperature Swing Adsorption (RTSA) system utilizing hollow fibers with polymer 'binder', impregnated with high loadings of sulfur selective sorbent 'fillers'. Steam and cooling water can be utilized to thermally swing the sorbent during the regeneration cycles. An impermeable, thin polymer barrier layer on the outside of fiber sorbents allows only thermal interactions with the regeneration media, thereby promoting consistent sorption capacity over repeated cycles. A simplified flow pattern minimizes pressure drop, porous core morphology maximizes sorption efficiencies, while small fiber dimensions allows for rapid thermal cycles.
28

Brine treatment using natural adsorbents

Mabovu, Bonelwa January 2011 (has links)
The current study investigated application of natural adsorbents in brine treatment. Brines are hypersaline waters generated in power stations and mining industries rich in Mg2+, K+, Ca2+, Na+, SO4 2- , Cl- and traces of heavy metals, thus there is a need for these brines to be treated to recover potable water and remove problematic elements. Natural adsorbents have been successfully used in waste water treatment because of their high surface area and high adsorptive properties when they are conditioned with acid or base. The investigation of pH showed that natural adsorbents did not perform well at low pH of 4 and 6. The adsorbents were able to work efficiently at the natural pH of 8.52 of the brine solution. These results show that natural adsorbents hold great potential to remove cationic major components and selected heavy metal species from industrial brine wastewater. Heterogeneity of natural adsorbents samples, even when they have the same origin, could be a problem when wastewater treatment systems utilizing natural clinoptilolite and bentonite are planned to be developed. Therefore, it is very important to characterize the reserves fully in order to make them attractive in developing treatment technologies.
29

IMPACTO DA AFLATOXINA B1, MONTMORILONITA E β-GLUCANA NA FERMENTAÇÃO RUMINAL In vitro / IMPACT OF AFLATOXIN B1, MONTMORILLONITE AND β-GLUCAN ON RUMINAL FERMENTATION In vitro

Pozzo, Marcelo Dal 27 February 2015 (has links)
Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / The effects of aflatoxin B1 (AFB1) (1μg/mL) were evaluated and sorbents β-glucans derived from Saccharomyces cerevisae with 65% of active ingredient (β-glu) (1mg/mL) and montmirillonite (MMT) (5mg/mL) under ruminal fermentation. Two in vitro assays were conducted. On the first assay the objectives were to determine the production of short chain fatty acids, the production of ammonia during 24-h in vitro. While on the second assay the production of methane (CH4) and kinetic parameters based on gas production date were determined (GPmax= maxim gas production in t time; Lag= lag phase before gas production commenced; S=gas production rate (h-1)) during 72-h in vitro incubation. In each assay six repetitions were made for the following treatments: CONT: control (without AFB1 or sorbents); AF: AFB1 (1μg/mL); β-glu (1mg/mL); β-glu + AF: (1mg/mL of β-glu + 1μg/mL of AFB1); MMT: (5mg/mL); MMT + AF: (5mg/mL of MMT + 1μg/mL of AFB1). The amount of AGCC produced by the β-glu (67,7 mM) treatment was significantly higher about CONT (57,72 mM) and MMT (53,3 mM). treatments. On the other hand, MMT clay reduced the production of NH3 (9,6 mM) about CONT (11,4 mM), AF (12,6 mM) and β-glu (12,2 mM). The amount of GPmax by the β-glu treatment was 103,4 mL, significantly higher about produced CONT (89,0 mL) e MMT (91,6 mL). There was also higher gas production rate by the β-glu treatment. The montmorilonite raised the lag phase and reduced the CH4 production. The results of this study suggest that AFB1 (1μg/mL) has no toxic effect on ruminal fermentation. Whereas the β-glu impacts the ruminal fermentation by increase the AGCC produced. The montmorilonite can delay the bacterial colonization but does t effect the quantity of AGCC produced. / Foram avaliados os efeitos da aflatoxina B1 (AFB1) (1μg/mL) e os adsorventes β-glucanas devivadas de Saccharomyces cerevisae com 65% de princípio ativo (β-glu) (1mg/mL) e montmorilonita (MMT) (5mg/mL) sobre a fermentação ruminal. Foram conduzidos dois ensaios in vitro, no primeiro ensaio o propósito foi determinar a produção de ácidos graxos de cadeia curta, a produção de amônia em 24h de incubação. Enquanto no segundo ensaio determinou-se a produção de metano (CH4) e os parâmetros da cinética da produção de gases (Vf = volume final de gás (ml) no tempo t; L = tempo de colonização; S = taxa de degradação (h-1)) no período de 72h de incubação. Em cada ensaio seis repetições foram realizadas para os seguintes tratamentos: CONT: controle (sem AFB1 ou adsorventes); AF: AFB1 (1μg/mL); β-glu (1mg/mL); β-glu + AF: (1mg/mL de β-glu + 1μg/mL de AFB1); MMT: (5mg/mL); MMT + AF: (5mg/mL de MMT + 1μg/mL de AFB1). A quantidade produzida de AGCC foi significativamente maior no tratamento β-glu (67,7 mM) em relação aos tratamentos CONT (57,72 mM) e MMT (53,3 mM). A MMT reduziu significativamente a produção de NH3 (9,6 mM) em relação aos tratamentos CONT (11,4 mM), AF (12,6 mM) e β-glu (12,2 mM). O tratamento β-glu produziu maior volume de gás (103, 4 mL) em relação aos tratamentos CONT (89,0 mL) e MMT (91,6 mL). Também o tratamento β-glu teve maior taxa de degradação em relação aos demais tratamentos. A montmorilonita aumentou o tempo de colonização e reduziu a produção de CH4. Os resultados deste estudo sugerem que a AFB1 (1μg/mL) não é tóxica a fermentação ruminal. Enquanto, o uso do β-glu impacta a fermentação ruminal, aumentando a produção de AGCC. O uso de montmorilonita pode retardar a colonização bacteriana no alimento porém, não interfere significativamente na quantidade total de AGCC produzidos.
30

Desenvolvimento de um absorvedor inorganico solido para reduzir a emissao de fluoreto na industria ceramica

CARVALHO, ELITA F.U. de 09 October 2014 (has links)
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