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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.
11

Ozonização catalítica de efluente de laticínio em processo semi-batelada com reciclo / Catalytic ozonation of dairy effluent in semi-batch process with recycle

Messias, Raquel de Aquino 20 July 2015 (has links)
O efluente lácteo é caracterizado pelo elevado teor de matéria orgânica. Os principais impactos ambientais causados pelas indústrias de laticínios estão relacionados ao lançamento dos efluentes líquidos, geralmente com ineficiente controle ou tratamento, sendo de fundamental importância a implementação de técnicas de tratamento eficazes e de baixo custo. Dentro desta proposta, os chamados Processos Oxidativos Avançados (POAs) são tecnologias eficientes para a oxidação (parcial ou total) de compostos orgânicos de difícil degradação. O presente trabalho de pesquisa objetivou a avaliação da potencialidade da ozonização catalítica, para a redução da carga orgânica do efluente proveniente da indústria de laticínio Cia de Alimentos Glória da cidade de Guaratinguetá, oriundos do processamento de beneficiamento de leite, utilizando-se Fe2+ como catalisador em processo semi-batelada com reciclo. A caracterização do efluente lácteo in natura foi realizada empregando-se métodos estabelecidos e otimizados de alguns parâmetros elencados nas legislações ambientais, destacando-se: DQO, COT, DBO5, Nitrogênio (orgânico e amoniacal), Fósforo total, Ferro, Sólidos (ST, STF, STV), surfactantes aniônicos, óleos e graxas e elementos metálicos. Através de planejamento fatorial fracionado 24-1, determinaram-se as melhores condições entre as variáveis potência do ozonizador, vazão de O2, concentração de Fe2+ e pH para a etapa de tratamento com POA, tendo como fator de resposta a redução da DQO e COT. Avaliou-se também uma nova configuração de reator em função de uma espuma formada durante o processo de tratamento. Os resultados obtidos para o conjunto de experimentos mostraram-se promissores, sendo que a redução média de COT com 63,95 % e de DQO com 70,50 % para o ensaio com as variáveis da reação otimizada, com o custo no valor de R$ 0,056 / L de efluente. Após o processo de ozonização catalítica, a amostra do melhor experimento: pH 4,0, concentração de Fe2+ 1,0 g L-1, potência 86 W, vazão de O2 0,5 L min-1, tendo como vazão mássica de O3 3,10 mg min-1, foi tratada por um processo biológico - Sistema Lodo Ativado (SLA), a fim de verificar a eficiência de degradação da matéria orgânica do efluente estudado através do sistema conjugado (POA - SLA). Os resultados para o tratamento híbrido apresentou percentuais de reduções para COT de 82,95 %, DQO de 95,60 % e DBO de 93,09 %. / Dairy effluent is characterized by the high content of organic material. The major environmental impacts caused by dairy industries are related to the release of liquid effluents, generally with an inefficient control or treatment, which makes it essential to implement effective treatment techniques, at a low cost. Within this proposal, Advanced Oxidation Processes (AOPs) are efficient technologies for oxidation (partial or total) of organic compounds of difficult degradation. This research study aimed at assessing the potential of catalytic ozonation for reduction of the effluent organic load from the dairy industry Cia de Alimentos Glória located in the city of Guaratinguetá, State of São Paulo, Brazil, derived from milk processing, using Fe2+ as catalyst in a semi-batch process with recycle. The characterization of milky effluent in natura was performed by using established and optimized methods of some parameters listed in environmental legislation, among them: COD, TOC, BOD5, Nitrogen (organic and ammoniacal), total Phosphorus, Iron, Solids (TS, FTS, VTS), anionic surfactants, oils and greases and metallic elements. Through fractional factorial design 24-1, the best conditions among the power variables of the power ozonator, O2 flow, Fe2+ concentration and pH were determined for the treatment stage with AOP, with a response factor of COD and TOC reduction. A new configuration of reactor was also assessed due to the presence of foam during the treatment process. The obtained results for the set of experiments were found to be promising, with an average reduction of TOC of 63.95 % and of 70.50 % for COD for the test with optimized reaction variables, with a cost of U$$ 0.02 / L of effluent. After the catalytic ozonation process, the sample of the best experiment was: pH 4.0, concentration of Fe2+ 1.0 g L-1, power of 86 W, flow of O2 0.5 L min-1, with mass flow of O3 3.10 mg min-1, was treated by a biological process in order to verify to verify the efficiency of degradation of the organic matter of the effluent studied through the conjugated (AOP - AS) system.The results for the hybrid treatment showed percentages of reductions for TOC of 82.95 %, COD of 95.60 % and BOD5 of 93.09 %.
12

Preparação de catalisadores magnéticos para aplicação em fotocatálise heterogênea e ozonização catalítica heterogênea de poluentes emergentes / Preparation of magnetic catalysts for application in heterogeneous photocatalysis and heterogeneous catalytic ozonation of emerging pollutants

Ciccotti, Larissa 28 May 2014 (has links)
O presente trabalho descreve a preparação de catalisadores magnéticos para aplicação nos processos de fotocatálise heterogênea e ozonização catalítica heterogênea, visando a degradação de poluentes emergentes. Primeiramente buscou-se preparar nanopartículas magnéticas para posterior aplicação no preparo de catalisadores magnéticos de TiO2. Diversas variáveis experimentais foram avaliadas na preparação das nanopartículas magnéticas, tais como: temperatura de reação, tempo de agitação, tempo no ultrasom, velocidade de agitação, velocidade de agitação da base, tempo de agitação do estabilizante, concentração da base e do estabilizante. A influência destes parâmetros de preparação no diâmetro hidrodinâmico e distribuição de tamanho das partículas foi avaliada por meio de um planejamento estatístico. Dependendo das condições experimentais, obteve-se materiais com um tamanho médio variando entre 11 e 36 nm e entre 23% e 77% de distribuição de tamanho. Na condição otimizada, obteve-se partículas com um tamanho médio, obtido pela técnica de espalhamento de luz dinâmico, de 18 nm e 21% de distribuição. O nanomaterial magnético foi utilizado para preparar os catalisadores híbridos Fe3O2@TiO2 e Fe3O4@SiO2@TiO2. Os materiais foram caracterizados por difratoemtria de raios-X (XRD), microscopia de varredura (MEV) e transmissão (TEM), espectroscopia no infravermelho (FT-IR), análise térmica (TG e DTA), espectrometria de emissão óptica (ICP-OES), medidas de área superficial (BET) e espalhamento dinâmico de luz (DLS). Os catalisadores magnéticos foram empregados na degradação dos poluentes emergentes paracetamol; 4-metilaminoantipirina (4-MAA); ibuprofeno; 17 β-estradiol; 17 α-etinilestradiol, e do fenol. Nos processos de degradação também variou-se o efeito do pH nas respostas dos sistemas. De maneira geral, o material Fe3O4@TiO2 apresentou atividade catalítica nos processos de degradação fotoquímica e de ozonização, com desempenho similar ou, em alguns casos, superior ao TiO2. Em relação a 4-MAA, obteve-se, em 60 minutos de tratamento, 25% de mineralização para o processo de fotólise e 66% para o processo de fotocatálise empregando Fe3O4@TiO2. Para o processo de ozonização em pH 3, obteve-se, em 180 minutos de tratamento, 40 e 60% de mineralização para o processo não catalítico e o processo catalítico empregando Fe3O4@TiO2, respectivamente. Os resultados utilizando-se TiO2 foram semelhantes à ozonização não catalítica, o que demonstra o efeito positivo do núcleo magnético para a atividade do material. Assim, o material híbrido multifuncional Fe3O4@TiO2 mostrou-se eficiente para a degradação de poluentes emergentes empregando-se os processos de fotocatálise e de ozonização catalítica heterogênea, possibilitando uma adicional praticidade de separação do meio de tratamento. / The present work describes the preparation of magnetic catalysts for application in heterogeneous photocatalysis and heterogeneous catalytic ozonation processes, aiming the degradation of emerging pollutants. Magnetic nanoparticles were prepered as substratum of magnetic TiO2 catalysts. Several experimental variables were evaluated in the preparation of the magnetic nanoparticles, such as temperature, stirring time, sonication time, precipitation reaction stirring speed, base addition rate, dispersion stirring time, base concentration and stabilizer percentage. The influence of these parameters on particle hydrodynamic diameter and size distribution were measured by a statistical design. Depending on the experimental conditions, materials with an average size ranging between 11 nm and 35 nm and distribution between 23% and 77% were obtained. In the optimum preparation conditions, Fe3O4 magnetic particles with a hydrodynamic diameter of 18 nm and 21% distribution were obtained. The magnetic nanomaterial was used to prepare the hybrid catalysts Fe3O4@TiO2 and Fe3O4@SiO2@TiO2. The prepared materials were characterized by X-ray diffraction (XRD), field-emiss ion scanning electron microscopy (FEG-SEM), transmission electron microscopy (TEM), Fourier transform infrared spectroscopy (FT-IR), thermogravimetric (TG), differential thermal analysis (DTA), inductively coupled plasma optical emission spectrometry (ICP-OES), BET specific surface area and dynamic light scattering (DLS). The magnetic catalysts were employed in the degradation of the emerging pollutants paracetamol; 4-methylaminoantipyrin (4-MAA); ibuprofen; 17 β-estradiol; 17 α-ethinyl estradiol, and phenol. In the treatment processes the effect pH on the systems was also varied. In general, the material Fe3O4@TiO2 showed catalytic activity in the processes of photochemical degradation and ozonation, with performance similar or, in some cases, superior to TiO2. For example, the 4-MAA mineralization, after 60 minutes of treatment, by the photolysis process reached a m aximum value of 25%. In the same treatment time by the photocatalytic process using Fe3O4@TiO2 it was obtained 66% of 4-MAA mineralization. For the ozonation process, in pH 3, after 180 minutes of treatment, 40% of 4-MAA mineralization was achieved by non-catalytic method. On the other hand, in the same treatment time employing Fe3O4@TiO2, 60% of 4-MAA mineralization was obtained. In addition, for the ozonation process using TiO2 similar results to non-catalytic ozonation were observed, which demonstrates the positive effect of the magnetic core for the activity of the catalyst. Thus, the hybrid material Fe3O4@TiO2 was efficient for the degradation of emerging pollutants employing the photocatalysis and heterogeneous catalytic ozonation processes, allowing an additional practicality for separating the catalyst from the treatment medium.
13

Ozonização catalítica de efluente de laticínio em processo semi-batelada com reciclo / Catalytic ozonation of dairy effluent in semi-batch process with recycle

Raquel de Aquino Messias 20 July 2015 (has links)
O efluente lácteo é caracterizado pelo elevado teor de matéria orgânica. Os principais impactos ambientais causados pelas indústrias de laticínios estão relacionados ao lançamento dos efluentes líquidos, geralmente com ineficiente controle ou tratamento, sendo de fundamental importância a implementação de técnicas de tratamento eficazes e de baixo custo. Dentro desta proposta, os chamados Processos Oxidativos Avançados (POAs) são tecnologias eficientes para a oxidação (parcial ou total) de compostos orgânicos de difícil degradação. O presente trabalho de pesquisa objetivou a avaliação da potencialidade da ozonização catalítica, para a redução da carga orgânica do efluente proveniente da indústria de laticínio Cia de Alimentos Glória da cidade de Guaratinguetá, oriundos do processamento de beneficiamento de leite, utilizando-se Fe2+ como catalisador em processo semi-batelada com reciclo. A caracterização do efluente lácteo in natura foi realizada empregando-se métodos estabelecidos e otimizados de alguns parâmetros elencados nas legislações ambientais, destacando-se: DQO, COT, DBO5, Nitrogênio (orgânico e amoniacal), Fósforo total, Ferro, Sólidos (ST, STF, STV), surfactantes aniônicos, óleos e graxas e elementos metálicos. Através de planejamento fatorial fracionado 24-1, determinaram-se as melhores condições entre as variáveis potência do ozonizador, vazão de O2, concentração de Fe2+ e pH para a etapa de tratamento com POA, tendo como fator de resposta a redução da DQO e COT. Avaliou-se também uma nova configuração de reator em função de uma espuma formada durante o processo de tratamento. Os resultados obtidos para o conjunto de experimentos mostraram-se promissores, sendo que a redução média de COT com 63,95 % e de DQO com 70,50 % para o ensaio com as variáveis da reação otimizada, com o custo no valor de R$ 0,056 / L de efluente. Após o processo de ozonização catalítica, a amostra do melhor experimento: pH 4,0, concentração de Fe2+ 1,0 g L-1, potência 86 W, vazão de O2 0,5 L min-1, tendo como vazão mássica de O3 3,10 mg min-1, foi tratada por um processo biológico - Sistema Lodo Ativado (SLA), a fim de verificar a eficiência de degradação da matéria orgânica do efluente estudado através do sistema conjugado (POA - SLA). Os resultados para o tratamento híbrido apresentou percentuais de reduções para COT de 82,95 %, DQO de 95,60 % e DBO de 93,09 %. / Dairy effluent is characterized by the high content of organic material. The major environmental impacts caused by dairy industries are related to the release of liquid effluents, generally with an inefficient control or treatment, which makes it essential to implement effective treatment techniques, at a low cost. Within this proposal, Advanced Oxidation Processes (AOPs) are efficient technologies for oxidation (partial or total) of organic compounds of difficult degradation. This research study aimed at assessing the potential of catalytic ozonation for reduction of the effluent organic load from the dairy industry Cia de Alimentos Glória located in the city of Guaratinguetá, State of São Paulo, Brazil, derived from milk processing, using Fe2+ as catalyst in a semi-batch process with recycle. The characterization of milky effluent in natura was performed by using established and optimized methods of some parameters listed in environmental legislation, among them: COD, TOC, BOD5, Nitrogen (organic and ammoniacal), total Phosphorus, Iron, Solids (TS, FTS, VTS), anionic surfactants, oils and greases and metallic elements. Through fractional factorial design 24-1, the best conditions among the power variables of the power ozonator, O2 flow, Fe2+ concentration and pH were determined for the treatment stage with AOP, with a response factor of COD and TOC reduction. A new configuration of reactor was also assessed due to the presence of foam during the treatment process. The obtained results for the set of experiments were found to be promising, with an average reduction of TOC of 63.95 % and of 70.50 % for COD for the test with optimized reaction variables, with a cost of U$$ 0.02 / L of effluent. After the catalytic ozonation process, the sample of the best experiment was: pH 4.0, concentration of Fe2+ 1.0 g L-1, power of 86 W, flow of O2 0.5 L min-1, with mass flow of O3 3.10 mg min-1, was treated by a biological process in order to verify to verify the efficiency of degradation of the organic matter of the effluent studied through the conjugated (AOP - AS) system.The results for the hybrid treatment showed percentages of reductions for TOC of 82.95 %, COD of 95.60 % and BOD5 of 93.09 %.
14

Preparação, caracterização e avaliação da atividade catalítica de óxidos de lantanóides incorporados em sílica mesoporosa ordenada na degradação de compostos orgânicos poluentes via ozonização catalítica heterogênea / Preparation, characterization and evaluation of the catalytic activity of lanthanide oxides incorporated on ordered mesoporous silica for the degradation of organic pollutants via heterogeneous catalytic ozonation

Soeira, Luciana Serra 28 November 2012 (has links)
Neste trabalho realizou-se a síntese e caracterização de materiais contendo óxidos de lantanóides incorporados em sílica mesoporosa ordenada, os quais foram utilizados como catalisadores no processo de ozonização de compostos orgânicos poluentes. Empregando-se o método de impregnação úmida, realizou-se a incorporação de óxido de cério e óxido de lantânio no suporte mesoporoso, do tipo SBA-15. Utilizaram-se diferentes precursores dos óxidos metálicos, a fim de verificar a influência que a fonte do cátion metálico exerça tanto nas características estruturais, texturais e morfológicas dos materiais quanto na atividade catalítica. A caracterização destes materiais mostrou que em todas as amostras não houve colapso da estrutura ordenada de mesoporos da SBA-15. Porém nos materiais incorporados observou-se a diminuição da área superficial específica e o volume de poro, devido à presença do CeO2 ou do La2O3 tanto na superfície do suporte quanto no interior dos mesoporos. Também foi possível identificar as fases cristalinas destes óxidos após a etapa de incorporação. Os catalisadores foram empregados na degradação de um azocorante, Preto Remazol B. Para todos os materiais verificou-se que a ozonização catalítica heterogênea proporcionou o aumento da mineralização em relação ao processo de ozonólise. Para os catalisadores que continham CeO2, os melhores resultados de mineralização do azocorante foram obtidos para os catalisadores cujos precursores eram complexos metálicos. Para estes materiais obteve-se um incremento de 65% em comparação com a ozonólise, sem que houvesse um grande aumento no consumo de ozônio. Para os materiais que continham La2O3, o catalisador cujo precursor do óxido foi um dos sais inorgânicos utilizados (nitrato de lantânio hidratado) apresentou o melhor teor de mineralização, sendo 72% superior em relação à ozonólise, ao final de 60 minutos. Os catalisadores contendo óxido de cério incorporado à SBA-15 também foram empregados no processo de ozonização catalítica de mais duas espécies orgânicas de grande relevância ambiental: fenol e ácido salicílico. Para o primeiro, houve um incremento mínimo na remoção da matéria orgânica de 70%, para todos os catalisadores testados, em relação à ozonólise, após 60 minutos. Entretanto, apenas dois deles (SBA-Ce(Gly) e SBA-Ce(Cl)) apresentaram um consumo de ozônio semelhante à ozonólise, o que indica que estes eram os mais eficientes. Na degradação do ácido salicílico a sinergia entre o suporte mesoporoso ordenado de elevada área superficial com o óxido de cério mais uma vez mostrou-se eficiente na mineralização da espécie orgânica, sendo obtidos teores de mineralização superiores a 90% para a ozonização catalítica contra 60% para a ozonólise, ao final de 60 minutos de tratamento / The aim of this work was the synthesis and characterization of materials with lanthanide oxides incorporated in ordered mesoporous silica, which were used as catalysts on the ozonation of organic pollutants. The incorporation of cerium and lanthanum oxides on the mesoporous support, SBA-15 type, was made by wet impregnation method. Different metal oxides precursors were used in order to investigate the influence in structural, textural and morphological characteristics of the materials and in catalytic activity. No collapse in the ordered mesopores structure of SBA-15 was observed after lanthanide oxides incorporation. However the hybrid compounds presented lower specific surface area and pore volume. It was observed the presence of CeO2 and La2O3 in the external support surface and in the interior of the mesopores. It was also possible to identify crystalline phases of these oxides after the incorporation step. The catalysts were employed on the degradation of an azo dye, Remazol Black B. For all samples it was found that the heterogeneous catalytic ozonization provided an increase in the mineralization levels of this organic species compared with the results of the ozonolysis. For the CeO2-based materials, the best results were achieved for the catalysts whose precursors were the metal complexes. For these materials the mineralization of the Remazol Black B was, at least, 65% superior to ozonolysis alone, without a great increase in the consumption of ozone. For the La2O3-based materials, the best result was obtained for the catalyst which oxide precursor was one of the inorganic salt (lanthanum nitrate hydrate). The mineralization was 72% higher than the ozonolysis alone after 60 minutes of treatment. The catalysts containing cerium oxide incorporated into the SBA-15 were also employed in the catalytic ozonization of two other organic species of great environmental importance: phenol and salicylic acid. For the first, there was a minimal increase in the removal of the organic matter when compared with ozonolysis alone. However, only two of them (SBA-Ce(Gly) e SBA-Ce(Cl)) showed a consumption of ozone similar to ozonolysis, indicating that these were the most efficient. In salicylic acid degradation, the mineralization achieved was greater than 90% for the catalytic ozonation versus 60% for the ozonolysis alone, after 60 minutes of treatment
15

Catalytic Ozonation Of Dye Solutions In A Semi-batch Reactor

Pirgalioglu, Saltuk 01 December 2008 (has links) (PDF)
Treatment of textile wastewaters containing dye materials using the conventional methods based on biological treatment is not possible. In order to overcome this problem, ozonation based on the oxidation of organic pollutants with ozone gas dissolved in aqueous phase have been studied widely. Catalytic ozonation and advanced oxidation processes (AOP) are also used in order to increase the efficiency of sole ozonation In this work, catalytic ozonation processes in the presence of Copper Sulfide (CuS) powder and a synthesized catalyst by the impregnation of iron on alumina (Fe/Al2O3) were studied separately in the treatment of dye solutions, namely Remazol Brilliant Blue-R (RBBR) and Reactive Black-5 (RB-5). Besides catalytic ozonation runs, ozonation parameters and ozonation mechanism were also studied and a model was developed for the semi-batch ozonation. Both catalysts increased the oxidation of side products measured by the decrease in the amount of total organic carbon (TOC) in the treated dye solutions. Dye removal rates were also enhanced in the treatment of RB-5 dye solutions while no significant effect was observed on dye removal rates of RBBR solutions. TOC removals above 90% were observed in the catalytic ozonation using CuS for both of the dye solutions at pH =10 having initial dye concentration of 100 mg/L. The most significant effect of the catalyst addition was observed at pH = 3 where the TOC removals of non-catalytic ozonation were the lowest. CuS addition increased percent TOC removal at the end of the reaction period of 80 min by 123% in the treatment of 100 mg/L RBBR solution, and by 65% in the treatment of 100 mg/L RB-5 solution at pH = 3. On the other hand, addition of Fe/Al2O3 catalyst increased TOC removal of 100 mg/L RB-5 solution by 52 % at pH = 3. In addition, volumetric mass transfer coefficients (kLa) of ozone in the absence and in the presence of a chemical reaction between dye and ozone were estimated from modeling. A correlation for the enhancement factor of ozone absorbed into dye solutions in terms of initial dye concentration was obtained and reported.
16

Preparação de catalisadores magnéticos para aplicação em fotocatálise heterogênea e ozonização catalítica heterogênea de poluentes emergentes / Preparation of magnetic catalysts for application in heterogeneous photocatalysis and heterogeneous catalytic ozonation of emerging pollutants

Larissa Ciccotti 28 May 2014 (has links)
O presente trabalho descreve a preparação de catalisadores magnéticos para aplicação nos processos de fotocatálise heterogênea e ozonização catalítica heterogênea, visando a degradação de poluentes emergentes. Primeiramente buscou-se preparar nanopartículas magnéticas para posterior aplicação no preparo de catalisadores magnéticos de TiO2. Diversas variáveis experimentais foram avaliadas na preparação das nanopartículas magnéticas, tais como: temperatura de reação, tempo de agitação, tempo no ultrasom, velocidade de agitação, velocidade de agitação da base, tempo de agitação do estabilizante, concentração da base e do estabilizante. A influência destes parâmetros de preparação no diâmetro hidrodinâmico e distribuição de tamanho das partículas foi avaliada por meio de um planejamento estatístico. Dependendo das condições experimentais, obteve-se materiais com um tamanho médio variando entre 11 e 36 nm e entre 23% e 77% de distribuição de tamanho. Na condição otimizada, obteve-se partículas com um tamanho médio, obtido pela técnica de espalhamento de luz dinâmico, de 18 nm e 21% de distribuição. O nanomaterial magnético foi utilizado para preparar os catalisadores híbridos Fe3O2@TiO2 e Fe3O4@SiO2@TiO2. Os materiais foram caracterizados por difratoemtria de raios-X (XRD), microscopia de varredura (MEV) e transmissão (TEM), espectroscopia no infravermelho (FT-IR), análise térmica (TG e DTA), espectrometria de emissão óptica (ICP-OES), medidas de área superficial (BET) e espalhamento dinâmico de luz (DLS). Os catalisadores magnéticos foram empregados na degradação dos poluentes emergentes paracetamol; 4-metilaminoantipirina (4-MAA); ibuprofeno; 17 β-estradiol; 17 α-etinilestradiol, e do fenol. Nos processos de degradação também variou-se o efeito do pH nas respostas dos sistemas. De maneira geral, o material Fe3O4@TiO2 apresentou atividade catalítica nos processos de degradação fotoquímica e de ozonização, com desempenho similar ou, em alguns casos, superior ao TiO2. Em relação a 4-MAA, obteve-se, em 60 minutos de tratamento, 25% de mineralização para o processo de fotólise e 66% para o processo de fotocatálise empregando Fe3O4@TiO2. Para o processo de ozonização em pH 3, obteve-se, em 180 minutos de tratamento, 40 e 60% de mineralização para o processo não catalítico e o processo catalítico empregando Fe3O4@TiO2, respectivamente. Os resultados utilizando-se TiO2 foram semelhantes à ozonização não catalítica, o que demonstra o efeito positivo do núcleo magnético para a atividade do material. Assim, o material híbrido multifuncional Fe3O4@TiO2 mostrou-se eficiente para a degradação de poluentes emergentes empregando-se os processos de fotocatálise e de ozonização catalítica heterogênea, possibilitando uma adicional praticidade de separação do meio de tratamento. / The present work describes the preparation of magnetic catalysts for application in heterogeneous photocatalysis and heterogeneous catalytic ozonation processes, aiming the degradation of emerging pollutants. Magnetic nanoparticles were prepered as substratum of magnetic TiO2 catalysts. Several experimental variables were evaluated in the preparation of the magnetic nanoparticles, such as temperature, stirring time, sonication time, precipitation reaction stirring speed, base addition rate, dispersion stirring time, base concentration and stabilizer percentage. The influence of these parameters on particle hydrodynamic diameter and size distribution were measured by a statistical design. Depending on the experimental conditions, materials with an average size ranging between 11 nm and 35 nm and distribution between 23% and 77% were obtained. In the optimum preparation conditions, Fe3O4 magnetic particles with a hydrodynamic diameter of 18 nm and 21% distribution were obtained. The magnetic nanomaterial was used to prepare the hybrid catalysts Fe3O4@TiO2 and Fe3O4@SiO2@TiO2. The prepared materials were characterized by X-ray diffraction (XRD), field-emiss ion scanning electron microscopy (FEG-SEM), transmission electron microscopy (TEM), Fourier transform infrared spectroscopy (FT-IR), thermogravimetric (TG), differential thermal analysis (DTA), inductively coupled plasma optical emission spectrometry (ICP-OES), BET specific surface area and dynamic light scattering (DLS). The magnetic catalysts were employed in the degradation of the emerging pollutants paracetamol; 4-methylaminoantipyrin (4-MAA); ibuprofen; 17 β-estradiol; 17 α-ethinyl estradiol, and phenol. In the treatment processes the effect pH on the systems was also varied. In general, the material Fe3O4@TiO2 showed catalytic activity in the processes of photochemical degradation and ozonation, with performance similar or, in some cases, superior to TiO2. For example, the 4-MAA mineralization, after 60 minutes of treatment, by the photolysis process reached a m aximum value of 25%. In the same treatment time by the photocatalytic process using Fe3O4@TiO2 it was obtained 66% of 4-MAA mineralization. For the ozonation process, in pH 3, after 180 minutes of treatment, 40% of 4-MAA mineralization was achieved by non-catalytic method. On the other hand, in the same treatment time employing Fe3O4@TiO2, 60% of 4-MAA mineralization was obtained. In addition, for the ozonation process using TiO2 similar results to non-catalytic ozonation were observed, which demonstrates the positive effect of the magnetic core for the activity of the catalyst. Thus, the hybrid material Fe3O4@TiO2 was efficient for the degradation of emerging pollutants employing the photocatalysis and heterogeneous catalytic ozonation processes, allowing an additional practicality for separating the catalyst from the treatment medium.
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Preparação, caracterização e avaliação da atividade catalítica de óxidos de lantanóides incorporados em sílica mesoporosa ordenada na degradação de compostos orgânicos poluentes via ozonização catalítica heterogênea / Preparation, characterization and evaluation of the catalytic activity of lanthanide oxides incorporated on ordered mesoporous silica for the degradation of organic pollutants via heterogeneous catalytic ozonation

Luciana Serra Soeira 28 November 2012 (has links)
Neste trabalho realizou-se a síntese e caracterização de materiais contendo óxidos de lantanóides incorporados em sílica mesoporosa ordenada, os quais foram utilizados como catalisadores no processo de ozonização de compostos orgânicos poluentes. Empregando-se o método de impregnação úmida, realizou-se a incorporação de óxido de cério e óxido de lantânio no suporte mesoporoso, do tipo SBA-15. Utilizaram-se diferentes precursores dos óxidos metálicos, a fim de verificar a influência que a fonte do cátion metálico exerça tanto nas características estruturais, texturais e morfológicas dos materiais quanto na atividade catalítica. A caracterização destes materiais mostrou que em todas as amostras não houve colapso da estrutura ordenada de mesoporos da SBA-15. Porém nos materiais incorporados observou-se a diminuição da área superficial específica e o volume de poro, devido à presença do CeO2 ou do La2O3 tanto na superfície do suporte quanto no interior dos mesoporos. Também foi possível identificar as fases cristalinas destes óxidos após a etapa de incorporação. Os catalisadores foram empregados na degradação de um azocorante, Preto Remazol B. Para todos os materiais verificou-se que a ozonização catalítica heterogênea proporcionou o aumento da mineralização em relação ao processo de ozonólise. Para os catalisadores que continham CeO2, os melhores resultados de mineralização do azocorante foram obtidos para os catalisadores cujos precursores eram complexos metálicos. Para estes materiais obteve-se um incremento de 65% em comparação com a ozonólise, sem que houvesse um grande aumento no consumo de ozônio. Para os materiais que continham La2O3, o catalisador cujo precursor do óxido foi um dos sais inorgânicos utilizados (nitrato de lantânio hidratado) apresentou o melhor teor de mineralização, sendo 72% superior em relação à ozonólise, ao final de 60 minutos. Os catalisadores contendo óxido de cério incorporado à SBA-15 também foram empregados no processo de ozonização catalítica de mais duas espécies orgânicas de grande relevância ambiental: fenol e ácido salicílico. Para o primeiro, houve um incremento mínimo na remoção da matéria orgânica de 70%, para todos os catalisadores testados, em relação à ozonólise, após 60 minutos. Entretanto, apenas dois deles (SBA-Ce(Gly) e SBA-Ce(Cl)) apresentaram um consumo de ozônio semelhante à ozonólise, o que indica que estes eram os mais eficientes. Na degradação do ácido salicílico a sinergia entre o suporte mesoporoso ordenado de elevada área superficial com o óxido de cério mais uma vez mostrou-se eficiente na mineralização da espécie orgânica, sendo obtidos teores de mineralização superiores a 90% para a ozonização catalítica contra 60% para a ozonólise, ao final de 60 minutos de tratamento / The aim of this work was the synthesis and characterization of materials with lanthanide oxides incorporated in ordered mesoporous silica, which were used as catalysts on the ozonation of organic pollutants. The incorporation of cerium and lanthanum oxides on the mesoporous support, SBA-15 type, was made by wet impregnation method. Different metal oxides precursors were used in order to investigate the influence in structural, textural and morphological characteristics of the materials and in catalytic activity. No collapse in the ordered mesopores structure of SBA-15 was observed after lanthanide oxides incorporation. However the hybrid compounds presented lower specific surface area and pore volume. It was observed the presence of CeO2 and La2O3 in the external support surface and in the interior of the mesopores. It was also possible to identify crystalline phases of these oxides after the incorporation step. The catalysts were employed on the degradation of an azo dye, Remazol Black B. For all samples it was found that the heterogeneous catalytic ozonization provided an increase in the mineralization levels of this organic species compared with the results of the ozonolysis. For the CeO2-based materials, the best results were achieved for the catalysts whose precursors were the metal complexes. For these materials the mineralization of the Remazol Black B was, at least, 65% superior to ozonolysis alone, without a great increase in the consumption of ozone. For the La2O3-based materials, the best result was obtained for the catalyst which oxide precursor was one of the inorganic salt (lanthanum nitrate hydrate). The mineralization was 72% higher than the ozonolysis alone after 60 minutes of treatment. The catalysts containing cerium oxide incorporated into the SBA-15 were also employed in the catalytic ozonization of two other organic species of great environmental importance: phenol and salicylic acid. For the first, there was a minimal increase in the removal of the organic matter when compared with ozonolysis alone. However, only two of them (SBA-Ce(Gly) e SBA-Ce(Cl)) showed a consumption of ozone similar to ozonolysis, indicating that these were the most efficient. In salicylic acid degradation, the mineralization achieved was greater than 90% for the catalytic ozonation versus 60% for the ozonolysis alone, after 60 minutes of treatment
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Optimisation d'un procédé de traitement des eaux par ozonation catalytique / Optimization of a wastewater treatment process by catalytic ozonation

Abouzlam, Manhal 10 January 2014 (has links)
Le principal objectif de la thèse est l'optimisation d'un procédé d'oxydation avancée par la mise en œuvre des outils de l'automatique moderne.Le procédé considéré concerne l'ozonation catalytique utilisé pour traiter les eaux résiduaires industrielles. L'optimisation de ce procédé consiste à contrôler l'abattement des polluants tout en minimisant le coût de fonctionnement du procédé. La mesure en ligne de la concentration en polluant est fournie par l'absorbance, grandeur corrélée à la DCO. Le procédé est alors considéré comme un système à une entrée, la puissance du générateur d'ozone, et deux sorties, l'ozone dans les évents et l'absorbance.L'identification du procédé a mené à l'estimation d'un modèle linéaire pour construire les lois de commande et d'un modèle non-linéaire, de type modèle de Wiener, pour tester les correcteurs en simulation avant les essais expérimentaux.Les trois commandes testées, la commande par modèle interne, la commande optimale et la commande H∞, permettent de rejeter des perturbations sur la concentration en polluant dans les effluents à traiter. Des analyses de stabilité du système bouclé, vis-à-vis de retards sur la commande, ont été menées.Les résultats expérimentaux obtenus ont permis de conclure sur les gains significatifs apportés par ces développements.La méthodologie développée pour cette application peut être étendue à d'autres procédés afin de faciliter le développement industriel des procédés d'oxydation avancée. / The main goal of the PhD thesis focuses on the optimization of an advanced oxidation process by implementing the modern control tools.The considered process is a lab-scale pilot of industrial wastewater treatment by catalytic ozonation. The optimization of this process is achieved by controlling the pollutant abatement while minimizing the high operating costs. The online measurement of the pollutant concentration is provided by the absorbance which is correlated with COD. Therefore, the process is considered as a system with one input, the ozone generator power, and two outputs, the ozone gas concentration at the top of the reactor and the absorbance.A linear model of the process was identified. It allowed calculating the control laws. And a nonlinear model, with a so-called Wiener model structure, was also identified to test the controllers in simulation before the experiments.The three control methods applied, the internal model control, the optimal control and the H∞ control, allow rejecting disturbance on the pollutant concentration of the effluent to be treated.The stability of closed-loop system with delayed control input was analyzed.The experimental results show the significant benefits provided by this closed-loop system.The methodology developed for this application can be extended to other processes to facilitate the industrial development of advanced oxidation processes.
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Présence, devenir et traitement des biocides dans les rejets d'un établissement hospitalier / Occurence, fate and treatment of biocides from a University Hospital wastewater network

Lasek, Florence 11 December 2018 (has links)
L’objectif de ce travail a été d’étudier la présence, le devenir et le traitement de biocides dans les rejets d’un établissement hospitalier. Pour cela, 3 substances biocides, représentatives d’une activité de soins (i.e. didécylmethylammonium (DDAC), digluconate de chlorhexidine (CHD) et bis(aminopropryl)laurylamine (BAPLA)) ont été ciblées et 5 campagnes de prélèvements réalisées sur l’ensemble du réseau de collecte des eaux usées du CHU de Poitiers ont été menées. Dans ces conditions, une émission continue de biocides sur 24 h, avec des quantités rejetées en journée plus importantes du fait de la plus forte activité de soins et de nettoyage durant cette période a été montrée. Des concentrations de l’ordre de quelques mg/L pour le DDAC et de quelques dizaines de µg/L pour le CHD et le BAPLA ont été observées. En termes de flux massiques, la comparaison des quantités retrouvées dans les rejets aux quantités utilisées par le CHU a permis de préciser la nature des sources d’émission ainsi que les usages et/ou les pratiques les plus propices à ces rejets.Parallèlement, une étude laboratoire de la stabilité et du devenir des biocides dans les eaux résiduaires a été menée. Une première estimation des quantités adsorbées sur les matières en suspension a été obtenue. De même, les produits de dégradation susceptibles d’être générés lors du rejet de biocides en présence d’un résiduel de chlore ont été identifiés et l’évolution de l’écotoxicité vis-à-vis de Vibrio fisheri a été évaluée.Enfin, la possibilité d’un traitement à la source utilisant l’ozone pour limiter les rejets de biocides a été envisagée et une étude pilote sur le terrain a été menée. / The objectives of this study was to study the presence, the fate and the treatment of some biocides in the wastewaters from a hospital. 3 biocidal substances specific to healthcare activities (i.e. didecylmethylammonium chloride (DDAC), chlorhexidine digluconate (CHD) and bis(aminopropryl)laurylamine (BAPLA)) were selected and 5 sampling campaigns were conducted throughout the entire Poitiers University Hospital sewage system. Under these conditions, a continuous biocide discharges over 24 h was shown, with higher quantities discharged during the day. This was pointing out the greater healthcare and facility cleaning activities taking place during this period. Concentrations of a few mg/L for DDAC and a few dozens of µg/L for CHD and BAPLA were detected. In terms of mass flows, the comparison of the quantities found in the discharges with the quantities used by the university hospital made it possible to specify the nature of the sources of emission as well as the uses and / or the practices most favorable to these discharges.In parallel, a laboratory study of the stability and fate of biocides in wastewater was conducted. A first estimate of the amounts adsorbed on suspended solids was obtained. Similarly, the degradation products likely to be generated during the release of biocides in the presence of a chlorine residual have been identified and the evolution of the ecotoxicity towards Vibrio fisheri has been evaluated.Finally, the proposal of an ozone based treatment at source was carried out to limit biocide discharges and a pilot study was conducted on the hospital wastewaters.
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Etude d'un procédé d'ozonation catalytique pour l'élimination des micropolluants dans les effluents urbains / Etude d’un procédé d’ozonation catalytique pour l’élimination des micropolluants dans les effluents urbains

Crousier, Claire 10 December 2015 (has links)
Les travaux menés au cours de cette thèse ont pour objectif d’étudier l’applicabilité du procédé d’ozonation catalytique TOCCATA® au traitement avancé d’eaux résiduaires urbaines pour le contrôle des émissions en micropolluants. Ce travail couvre la détermination des propriétés physico-chimiques, structurelles et de réactivité de deux catalyseurs et l’optimisation de leur conditionnement pour le procédé d’ozonation catalytique. La caractérisation hydrodynamique du réacteur à co-courant ascendant triphasique en lit fixe utilisé pour la mise en œuvre du procédé a été également réalisée. Les processus élémentaires impliqués dans le procédé ont ensuite été étudiés séparément : transfert gaz-liquide, adsorption, ozonation simple et interaction ozone/matériau. Enfin l’ozonation catalytique a été étudiée vis-à-vis de l’élimination de la matière organique des eaux usées réelles. L’ozonation catalytique se montre moins sélective que l’ozonation simple et améliore le procédé en termes de transfert d’ozone et d’élimination du carbone organique. Des mécanismes et des lois cinétiques pour chacun des processus élémentaires ont été déterminés et une loi de vitesse globale de premier ordre pour le procédé d’ozonation catalytique est proposée. L’étude de l’influence de différentes variables opératoires a été effectuée en vue de l’optimisation du procédé. L’investigation a ensuite été élargie à l’élimination de micropolluants spécifiques (carbamazépine, diuron, kétoprofène, diclofénac, naphtalène) appliquée à des eaux synthétiques, ainsi qu’à des eaux résiduaires urbaines réelles. La plupart des composés sont dégradés après application d’une faible dose d’ozone par le procédé. L’étude de leurs propriétés et de leur affinité avec le système d’ozonation catalytique a permis d’expliquer leurs comportements. / This thesis aimed to study the application of the TOCCATA® catalytic process to urban wastewaters treatment in order to control micropolluant emissions. This work first focused on physico-chemical, structural and reactional properties of two catalysts and on the optimization of their conditioning for the use in the catalytic process. The hydrodynamic characterisation of the fixed bed triphasic co-current upflow reactor used for this study was realized. Elementary processes involved in the process were studied separately: gas-liquid transfer, adsorption, single ozonation, ozone/catalyst interactions. Catalytic ozonation was then investigated for the elimination of organic matter contained in real urban wastewaters. Catalytic ozonation appeared to be less selective than single ozonation and to improve the process in terms of ozone transfer and organic carbon removal efficiency. Mechanisms and kinetic laws were determined for each elementary process and a global first order kinetic law was proposed for catalytic ozonation. The study of various operating conditions (liquid and gas flows, ozone dose …) was conducted in order to optimize the process efficiency.Investigations were then extended towards specific micropollutants elimination (carbamazepine, diuron, ketoprofen, diclofenac, naphtalene) onto synthetic waters as well as real urban wastewaters. Most of the compounds were eliminated with low dose ozonation by the TOCCATA® catalytic ozonation process. The properties of the micropollutants and their affinities with the catalytic ozonation system were studied in order to explain their behaviours.

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