Submitted by Automa??o e Estat?stica (sst@bczm.ufrn.br) on 2016-12-29T16:22:07Z No. of bitstreams: 1 LidianeAlvesDeMorais_TESE.pdf: 2444711 bytes, checksum: 23f2b53145f8389d4a45f7f7c2040146 (MD5) / Approved for entry into archive by Arlan Eloi Leite Silva (eloihistoriador@yahoo.com.br) on 2017-01-02T17:55:19Z (GMT) No. of bitstreams: 1 LidianeAlvesDeMorais_TESE.pdf: 2444711 bytes, checksum: 23f2b53145f8389d4a45f7f7c2040146 (MD5) / Made available in DSpace on 2017-01-02T17:55:19Z (GMT). No. of bitstreams: 1 LidianeAlvesDeMorais_TESE.pdf: 2444711 bytes, checksum: 23f2b53145f8389d4a45f7f7c2040146 (MD5) Previous issue date: 2016-05-16 / Coordena??o de Aperfei?oamento de Pessoal de N?vel Superior (CAPES) / Um dos materiais que atualmente est? em destaque s?o os compostos de ni?bio, por apresentarem caracter?sticas como acidez, propriedades oxidativas e fotocatal?ticas e por ser um dos metais mais abundantes do pa?s, sendo o Brasil o maior produtor mundial. Este trabalho avaliou a efici?ncia da fotocat?lise heterog?nea de materiais de ni?bio na oxida??o de metanol e na inativa??o do microrganismo Escherichia Coli. Foram sintetizados catalisadores a base de ni?bio Nb2O5 e foram feitas imobiliza??es (coating) utilizando ?xido de ni?bio. Diante das caracteriza??es, foi poss?vel verificar a forma??o de esp?cies de ?xido de ni?bio e niobatos de s?dio dependendo da metodologia de s?ntese adotada. Esses materiais foram avaliados na oxida??o de metanol em diferentes concentra??es de catalisadores e apresentaram uma efici?ncia na forma??o do formalde?do proveniente da oxida??o, esta efici?ncia est? diretamente relacionada com a concentra??o dos catalisadores, sendo o material de niobato de s?dio o que apresentou maior efici?ncia, devido as suas propriedades texturais, ?pticas, sendo este um material promissor no ramo da fotocat?lise. Para os sistemas de imobiliza??o (coating), verificou-se que o revestimento ideal ? obtido com tr?s imobiliza??es, estes materiais foram analisados na oxida??o de metanol e na inativa??o de microrganismo Escherichia Coli. Estes sistemas (coating) mostram uma boa atividade na oxida??o de metanol, apesar de apresentar resultados inferiores quando comparados aos materiais em suspens?o de ?xido de ni?bio, por?m a grande vantagem dos sistemas imobilizados em rela??o ao de suspens?es s?o a sua reutiliza??o. Em rela??o ? inativa??o da Escherichia Coli, foi verificado que os sistemas imobilizados n?o s?o muitos ativos e que o microrganismo ? bastante dependendo do meio em que se encontra. / One of the materials that is currently highlighted are the compounds of niobium, because they have features like acidity, oxidative and photocatalytic properties and for being one of the most abundant metals in the country, Brazil is the world's largest producer. In this scenario, the work has to evaluate the efficiency of heterogeneous photocatalysis niobium materials in the oxidation of methanol and the inactivation of Escherichia coli using immobilization systems ?coating? and suspension. Commercial niobium oxide (Nb2O5) was evaluated in suspension and immobilization in different systems (tubes and rings) for photocatalytic processes for water treatment (methanol oxidation and inactivation of Escherichia coli). From the results of the commercial Nb2O5 characterizations was observed the presence of an amorphous structure with heat thermal treatment at temperatures above 550 ?C becomes crystalline phases, however, this fact produce a significant aggregation of the particles which reduced the specific area and the photocatalytic activity. The not calcined Nb2O5 material showed a higher activity, for both oxidation of methanol as for the inactivation of bacterial tests, the latter being very sensitive to the chemical composition water. Immobilization of the photocatalyst reactor walls prevents the need for removal of Nb2O5 particles after treatment, but significantly reduction its activity. In contrast, immobilization in a fixed-bed (rings) led to a moderate reduction in activity, which is counteracted by improvement in the long-term stability of the material. Niobium catalysts were synthesized using a refluxing method with and without the use of NaOH in different conditions of synthesis and characterized by different techniques in order to verify the phase formation of niobium. From the results of X-ray diffraction for the synthesized materials were recorded forming of species niobium oxide and sodium niobates depending on the adopted synthesis methodology. The catalytic activity of these materials was evaluated in the oxidation of methanol in relation to the amount of catalyst in which the activities have different behaviors have been dependent on the structure, surface and morphological parameters. Materials with sodium niobate structure have a lineal tendency of activity in relation to the mass of catalysts, while the materials niobium oxide structure have an abrupt loss of their catalytic activity at higher catalyst concentrations, indicating that the dispersion of the light is higher in these catalysts as increases the amount of particles in suspension. Among the materials synthesized and analyzed in the oxidation of methanol, which was more efficient, was the material of sodium niobate NaNbO3 to their textural properties, optical, which is a promising material for photocatalysis.

Made available in DSpace on 2014-12-17T15:01:50Z (GMT). No. of bitstreams: 1 OtideneRSR_DISSERT.pdf: 1647726 bytes, checksum: 2a45d120fb2b82e3a84f67c77eff85a3 (MD5) Previous issue date: 2010-09-01 / Conselho Nacional de Desenvolvimento Cient?fico e Tecnol?gico / The petroleum industry deals with problems which are difficult to solve because of their relation to environmental issues. This is because amounts of residue are generated which vary in type and danger level. The soil contamination by non aqueous liquid phase mixtures, specifically hydrocarbon petroleum has been a reason for great concern, mainly the aromatic and polycyclic aromatic, which present risk to human health due to its carcinogenic and mutagenic character. The Advanced Oxidative Processes (AOP) are efficient technologies for destruction of organic compounds of difficult degradation and, often, they are present in low concentrations. They can be considered clean technologies, because there is no formation of solid by-products or the transfer of pollutor phases. This work focuses on the study of the degradation of petroleum industrial waste, by Advanced Oxidation Processes. Treatments tackling petroleum residues, contaminated soil, and water occurring in the production of petroleum reached the following Polycyclic Aromatic Hydrocarbons (PAH) degradation levels: solid residues 100% in 96 treatment hours; water residue - 100% in 6 treatment hours; soil contamination (COT degradation) - 50.3% in 12 treatment hours. AOP were effective in dealing with petroleum residues thus revealing themselves to be a promising treatment alternative / A ind?stria de petr?leo lida com problemas de dif?cil solu??o em rela??o ?s atividades voltadas para a prote??o ambiental, devido ? gera??o de res?duos de diversos tipos e n?veis de periculosidade. A contamina??o do solo por compostos de fase l?quida n?o aquosa, especificamente os hidrocarbonetos de petr?leo tem sido motivo de preocupa??o, principalmente os arom?ticos e poliarom?ticos, apresentam risco ? sa?de humana devido a seu car?ter carcinog?nico e mutag?nico. Os Processos Oxidativos Avan?ados (POA) s?o tecnologias eficientes para destrui??o de compostos org?nicos de dif?cil degrada??o biol?gica e, muitas vezes, presentes em baixas concentra??es. Podem ser consideradas tecnologias limpas, pois n?o h? a forma??o de subprodutos s?lidos e nem a transfer?ncia de fase dos poluentes. O objetivo desse trabalho foi estudar a degrada??o de res?duos da ind?stria de petr?leo, por Processos Oxidativos Avan?ados. Foram realizados tratamentos de borra de petr?leo, solo contaminado com petr?leo e ?gua de produ??o de petr?leo alcan?ando uma degrada??o de Hidrocarbonetos Polic?clicos Arom?ticos (HPA) de 100 % em 96 horas de tratamento para a borra, 100% em 6 horas de tratamento para ?gua de produ??o de petr?leo e uma degrada??o de Carbono Org?nico Total (COT) de 50,3% em 12 horas de tratamento para o solo contaminado com petr?leo. Os POA foram eficientes no tratamento de res?duos de petr?leo apresentando-se como uma alternativa promissora no tratamento desses res?duos

Submitted by Automa??o e Estat?stica (sst@bczm.ufrn.br) on 2017-02-02T12:10:54Z No. of bitstreams: 1 MaiteMedeirosDeSantanaESilva_DISSERT.pdf: 2765135 bytes, checksum: 2308e88f6d7f78d3c63e10b06eee531d (MD5) / Approved for entry into archive by Arlan Eloi Leite Silva (eloihistoriador@yahoo.com.br) on 2017-02-07T16:43:25Z (GMT) No. of bitstreams: 1 MaiteMedeirosDeSantanaESilva_DISSERT.pdf: 2765135 bytes, checksum: 2308e88f6d7f78d3c63e10b06eee531d (MD5) / Made available in DSpace on 2017-02-07T16:43:25Z (GMT). No. of bitstreams: 1 MaiteMedeirosDeSantanaESilva_DISSERT.pdf: 2765135 bytes, checksum: 2308e88f6d7f78d3c63e10b06eee531d (MD5) Previous issue date: 2016-08-26 / Coordena??o de Aperfei?oamento de Pessoal de N?vel Superior (CAPES) / Este trabalho descreve o planejamento experimental 2? com triplicata no ponto central para produ??o do molibdato de estr?ncio (SrMoO4) atrav?s do m?todo de complexa??o combinado EDTA/Citrato onde investigou-se a influ?ncia do pH (6, 7,5 e 9), tempo de calcina??o (3, 4 e 5h) e taxa de aquecimento (5, 7 e 10?C.min-1) em alguns de seus par?metros qu?micos e f?sicos. Com base na curva de termogravim?trica os p?s de SrMoO4 foram calcinados a 650?C.Os materiais sintetizados foram caracterizados por TG/DSC, DRX, EDX, MEV e ERD. Os par?metros de rede da estrutura cristalina foram obtidos com base no m?todo de refinamento Rietveld. Todos os padr?es de DRX foram indexados segundo a ficha JCPDS 01-085-0586, com estrutura tetragonal e grupo espacial I41/a e o par?metro residual do refinamento da estrutura variou entre 1,035 a 1,292, n?o sendo identificadas fases secund?rias e impurezas. Constatou-se a exist?ncia de diferen?as entre as intensidades relativas m?dias dos picos de difra??o de raios-x. Atrav?s de ferramentas estat?sticas, concluiu-se que a taxa de aquecimento foi a vari?vel independente que demonstrou maior influ?ncia nessa diferen?a. As analises de EDX mostraram a presen?a de desvios entre a composi??o te?rica e experimental para os elementos estr?ncio e molibd?nio; o desvio percentual variou de 0,027 a 3,67% em fun??o das condi??es de s?ntese. De acordo com as micrografias obtidas por MEV, os p?s sintetizados s?o compostos de aglomerados de part?culas, com morfologia esf?ricas irregulares e bipiramidais. De acordo com a an?lise do planejamento experimental, tendo como vari?vel dependente a energia de bandgap, os menores valores obtidos (4,18 e 4,17 eV para pH 6 e 9, respectivamente) foram as amostras calcinadas por 3h com taxa de aquecimento igual a 10?C.min-1 em compara??o aos materiais calcinados nas demais condi??es de s?nteses e os modelos estat?sticos gerados se mostraram capazes de descrever os fen?menos observados. Testes explorat?rios na fotodegrada??o da solu??o sint?tica do corante azul de metileno utilizando o material com Egap de 4,17 eV indicam que o p? testado apresenta influ?ncia na diminui??o da concentra??o do corante para os testes realizados em pH 2 e 5 obtendo aproximadamente 95% e 24% de convers?o respectivamente, e para os teste em pH 9 observou-se que a fot?lise direta ? mais efetiva na redu??o da concentra??o do corante alcan?ando em torno 67% de convers?o, por?m o processo reacional necessita ser mais estudado para melhor compreens?o dos resultados. / This work describes the 2? experimental design with center point in triplicate for the production of strontium molybdate (SrMoO4) through complexation combined Citrate/EDTA method where investigated the influence of pH (6, 7,5 and 9), time calcination (3, 4 and 5 h) and heating rate (5, 7 and 10?C min-1) in some of its chemical and physical parameters. Based on thermogravimetric curve of SrMoO4 powders were calcined at 650?C. The synthesized materials were characterized by TG/DSC, XRD, EDX, SEM and ERD. The lattice parameters of the crystal structure were obtained from the Rietveld refinement method. All the XRD patterns were indexed according to JCPDS 01-085-0586 record with tetragonal structure and space group I41/a and the residual parameter structure refinement ranged from 1.035 to 1.292, secondary phases and impurities not being identified. It was found that there are differences between the average relative intensities of the diffraction peaks of X-rays. Using statistical tools, it was found that the rate of heating was the independent variable showed the greatest influence on this difference. The EDX analysis showed the presence of deviations between the theoretical and experimental composition for strontium and molybdenum components; the percentage deviation ranged from 0.027 to 3.67% depending on the conditions of synthesis. According to the SEM micrographs, the synthesized powders are composed of agglomerates of particles with irregular and spherical morphology bipiramidal. According to the analysis of the experimental design, with the dependent variable bandgap energy, the lowest values (4.18 and 4.17 eV to pH 6 and 9, respectively) were the samples calcined for 3 hours at the same heating rate 10 C min-1 compared to the calcined material in other conditions of synthesis and the statistical models generated have been shown to describe the observed phenomena. Exploratory testing photodegradation of the synthetic solution of methylene blue dye using the material bandgap of 4.17 eV indicate that the tested powder has influence on the reduction of dye concentration for tests carried out in pH 2 and 5 getting approximately 95% and 24 % conversion respectively, and the test at pH 9 it was noted that direct photolysis is more effective in reducing the dye concentration reached around 67% conversion, but the reaction process needs more study to better understand the results.