Síntese e Caracterização de nanopartículas de maghemita revestidas com ácido oléico para obtenção de fluidos magnéticos a base de óleos isolantes

Detalhes bibliográficos
Ano de defesa: 2009
Autor(a) principal: VIALI, Wesley Renato lattes
Orientador(a): SARTORATTO, Patrícia Pommé Confessori lattes
Banca de defesa: Não Informado pela instituição
Tipo de documento: Dissertação
Tipo de acesso: Acesso aberto
Idioma: por
Instituição de defesa: Universidade Federal de Goiás
Programa de Pós-Graduação: Mestrado em Química
Departamento: Educação em Química
País: BR
Palavras-chave em Português:
Fluido magnético, nanopartículas, oxido de ferro
Palavras-chave em Inglês:
Magnetic fluid, naoparticles, iron oxide
Área do conhecimento CNPq:
CNPQ::CIENCIAS EXATAS E DA TERRA::QUIMICA
Link de acesso: http://repositorio.bc.ufg.br/tede/handle/tde/1059
Resumo: In this work maghemite nanoparticles were synthesized by co-precipitating Fe2+ and Fe3+ in alkaline medium. The freshly prepared magnetite was oxidized by two different routes: by bubbling O2 through an acid suspension of magnetite nanoparticles or by hydrothermal treatment of magnetite with ferric nitrate/nitric acid solution. After oxidation, the nanoparticles were covered with oleic acid and the grafting coefficient was evaluated according to the oxidation method and pH employed in the adsorption experiments. The covered particles were dispersed in mineral and vegetable insulating oils, resulting in magnetic fluids whose colloidal stability was investigated in regard to the following parameters: dilution, heating, water content, chemical composition of insulating oils and addition of oleic acid. The nanoparticles were characterized by X-ray diffratometry, thermogravimetric and differential thermal analyses and infrared spectroscopy. The Fe3+/Fe2+ molar ratio in the solids was determined by UV-Vis spectrometry. The magnetic fluids were characterized regarding the volume fraction of nanoparticles, the water content, and their colloidal stability was monitored by dynamic light scattering measurements and visual observations. The results obtained from the analyses indicated that the oxidized magnetite nanoparticles (5 to 10 nm) have inverse spinel structure and Fe3+/Fe2+ molar ratio varied from 20 to 70, depending on the oxidation method and employed conditions. The grafting coefficient varied from 2,1 to 4,8, reflecting the oleic acid adsorption conditions, and the further treatments. It was also observed that by controlling the experimental conditions, a grafting coefficient very close to a Langmuir s monolayer can be achieved, together with a decrease in the amount of physisorbed species which contribute negatively to the colloidal stability. The study of colloidal stability showed that dilution, heating and XVII water content have a great influence in the sedimentation of diluted magnetic fluids, when they are diluted with minerals insulating oils. It was verified that the magnetic fluids diluted with vegetable insulating oil showed very high colloidal stability in the accelerated thermal aging experiment
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spelling SARTORATTO, Patrícia Pommé Confessorihttp://lattes.cnpq.br/9777959525393785http://lattes.cnpq.br/8783679369399364VIALI, Wesley Renato2014-07-29T15:12:48Z2009-12-092009-03-18VIALI, Wesley Renato. Synthesis and characterization of oleic acid coated maghemite nanoparticles to obtain insulating oil based magnetic fluids. 2009. 100 f. Dissertação (Mestrado em Educação em Química) - Universidade Federal de Goiás, Goiânia, 2009.http://repositorio.bc.ufg.br/tede/handle/tde/1059In this work maghemite nanoparticles were synthesized by co-precipitating Fe2+ and Fe3+ in alkaline medium. The freshly prepared magnetite was oxidized by two different routes: by bubbling O2 through an acid suspension of magnetite nanoparticles or by hydrothermal treatment of magnetite with ferric nitrate/nitric acid solution. After oxidation, the nanoparticles were covered with oleic acid and the grafting coefficient was evaluated according to the oxidation method and pH employed in the adsorption experiments. The covered particles were dispersed in mineral and vegetable insulating oils, resulting in magnetic fluids whose colloidal stability was investigated in regard to the following parameters: dilution, heating, water content, chemical composition of insulating oils and addition of oleic acid. The nanoparticles were characterized by X-ray diffratometry, thermogravimetric and differential thermal analyses and infrared spectroscopy. The Fe3+/Fe2+ molar ratio in the solids was determined by UV-Vis spectrometry. The magnetic fluids were characterized regarding the volume fraction of nanoparticles, the water content, and their colloidal stability was monitored by dynamic light scattering measurements and visual observations. The results obtained from the analyses indicated that the oxidized magnetite nanoparticles (5 to 10 nm) have inverse spinel structure and Fe3+/Fe2+ molar ratio varied from 20 to 70, depending on the oxidation method and employed conditions. The grafting coefficient varied from 2,1 to 4,8, reflecting the oleic acid adsorption conditions, and the further treatments. It was also observed that by controlling the experimental conditions, a grafting coefficient very close to a Langmuir s monolayer can be achieved, together with a decrease in the amount of physisorbed species which contribute negatively to the colloidal stability. The study of colloidal stability showed that dilution, heating and XVII water content have a great influence in the sedimentation of diluted magnetic fluids, when they are diluted with minerals insulating oils. It was verified that the magnetic fluids diluted with vegetable insulating oil showed very high colloidal stability in the accelerated thermal aging experimentNeste trabalho foram preparadas nanopartículas de maghemita pelo método da coprecipitação de íons Fe3+ e Fe2+ em meio básico. A magnetita inicialmente obtida foi oxidada utilizando-se gás oxigênio ou solução de nitrato férrico/ácido nítrico. Após a oxidação, as nanopartículas foram revestidas com ácido oleico e a eficiência deste processo foi avaliada em função do método de oxidação e do pH de adsorção. As partículas revestidas foram dispersas em óleos isolantes dos tipos naftênico, parafínico ou vegetal, resultando em fluidos magnéticos cujas estabilidades coloidais foram avaliadas em função dos seguintes parâmetros: diluição, aquecimento, teor de água, natureza do meio dispersante e adição de ácido oleico. As nanopartículas foram caracterizadas por difratometria de raios X, análise termogravimétrica e térmica diferencial e espectroscopia de infravermelho. A razão Fe3+/Fe2+ nos sólidos foi determinada por espectrofotometria no visível. Os fluidos magnéticos foram caracterizados quanto à fração volumétrica de nanopartículas e ao teor de água, e sua estabilidade coloidal foi acompanhada por espalhamento dinâmico de luz e por medidas visuais de turbidez. Os resultados das análises e experimentos indicaram que as nanopartículas de magnetita oxidada (5 a 10 nm) apresentaram estrutura espinélio inverso e razão Fe3+/Fe2+ desde 20 até 70, dependendo do método e condições de oxidação empregadas. O coeficiente de revestimento variou de 2,1 a 4,8, refletindo tanto as condições utilizadas nos procedimentos de adsorção do ácido oleico, como também os tratamentos subseqüentes. Demonstrou-se que através do controle das condições experimentais pode-se obter um revestimento muito próximo ao de uma monocamada de Langmuir, bem como reduzir a quantidade de XV espécies moleculares fisissorvidas que contribuem negativamente para a estabilidade coloidal. O estudo da estabilidade coloidal mostrou que a diluição, o aquecimento e o teor de água favorecem a sedimentação dos fluidos magnéticos quando estes são diluídos em óleos isolantes naftênico e parafínico. Verificou-se que os fluidos magnéticos em óleo vegetal quando em frações volumétricas baixas apresentaram alta estabilidade coloidal em experimentos de envelhecimento aceleradoMade available in DSpace on 2014-07-29T15:12:48Z (GMT). No. of bitstreams: 1 Dissertacao - Wesley Renato Viali.pdf: 3929545 bytes, checksum: b4e900de56f7f751a05beaeb0b326f0b (MD5) Previous issue date: 2009-03-18application/pdfhttp://repositorio.bc.ufg.br/TEDE/retrieve/3528/Dissertacao%20-%20Wesley%20Renato%20Viali.pdf.jpgporUniversidade Federal de GoiásMestrado em QuímicaUFGBREducação em QuímicaFluido magnético, nanopartículas, oxido de ferroMagnetic fluid, naoparticles, iron oxideCNPQ::CIENCIAS EXATAS E DA TERRA::QUIMICASíntese e Caracterização de nanopartículas de maghemita revestidas com ácido oléico para obtenção de fluidos magnéticos a base de óleos isolantesSynthesis and characterization of oleic acid coated maghemite nanoparticles to obtain insulating oil based magnetic fluidsinfo:eu-repo/semantics/publishedVersioninfo:eu-repo/semantics/masterThesisinfo:eu-repo/semantics/openAccessreponame:Biblioteca Digital de Teses e Dissertações da UFGinstname:Universidade Federal de Goiás (UFG)instacron:UFGORIGINALDissertacao - Wesley Renato Viali.pdfapplication/pdf3929545http://repositorio.bc.ufg.br/tede/bitstreams/941e9045-a001-461d-9353-b7e9b19c4590/downloadb4e900de56f7f751a05beaeb0b326f0bMD51THUMBNAILDissertacao - Wesley Renato Viali.pdf.jpgDissertacao - Wesley Renato Viali.pdf.jpgGenerated Thumbnailimage/jpeg4418http://repositorio.bc.ufg.br/tede/bitstreams/89cc7d10-64e8-4c80-95f4-c470a13fc73d/downloadd9c4607332576e91e3704d37ac55e593MD52tde/10592014-07-30 03:06:13.485open.accessoai:repositorio.bc.ufg.br:tde/1059http://repositorio.bc.ufg.br/tedeBiblioteca Digital de Teses e Dissertaçõeshttp://repositorio.bc.ufg.br/PUBhttps://repositorio.bc.ufg.br/tede_oai/requesttesesdissertacoes.bc@ufg.br ||tesesdissertacoes.bc@ufg.bropendoar:32082014-07-30T06:06:13Biblioteca Digital de Teses e Dissertações da UFG - Universidade Federal de Goiás (UFG)false
dc.title.por.fl_str_mv Síntese e Caracterização de nanopartículas de maghemita revestidas com ácido oléico para obtenção de fluidos magnéticos a base de óleos isolantes
dc.title.alternative.eng.fl_str_mv Synthesis and characterization of oleic acid coated maghemite nanoparticles to obtain insulating oil based magnetic fluids
title Síntese e Caracterização de nanopartículas de maghemita revestidas com ácido oléico para obtenção de fluidos magnéticos a base de óleos isolantes
spellingShingle Síntese e Caracterização de nanopartículas de maghemita revestidas com ácido oléico para obtenção de fluidos magnéticos a base de óleos isolantes
VIALI, Wesley Renato
Fluido magnético, nanopartículas, oxido de ferro
Magnetic fluid, naoparticles, iron oxide
CNPQ::CIENCIAS EXATAS E DA TERRA::QUIMICA
title_short Síntese e Caracterização de nanopartículas de maghemita revestidas com ácido oléico para obtenção de fluidos magnéticos a base de óleos isolantes
title_full Síntese e Caracterização de nanopartículas de maghemita revestidas com ácido oléico para obtenção de fluidos magnéticos a base de óleos isolantes
title_fullStr Síntese e Caracterização de nanopartículas de maghemita revestidas com ácido oléico para obtenção de fluidos magnéticos a base de óleos isolantes
title_full_unstemmed Síntese e Caracterização de nanopartículas de maghemita revestidas com ácido oléico para obtenção de fluidos magnéticos a base de óleos isolantes
title_sort Síntese e Caracterização de nanopartículas de maghemita revestidas com ácido oléico para obtenção de fluidos magnéticos a base de óleos isolantes
author VIALI, Wesley Renato
author_facet VIALI, Wesley Renato
author_role author
dc.contributor.advisor1.fl_str_mv SARTORATTO, Patrícia Pommé Confessori
dc.contributor.advisor1Lattes.fl_str_mv http://lattes.cnpq.br/9777959525393785
dc.contributor.authorLattes.fl_str_mv http://lattes.cnpq.br/8783679369399364
dc.contributor.author.fl_str_mv VIALI, Wesley Renato
contributor_str_mv SARTORATTO, Patrícia Pommé Confessori
dc.subject.por.fl_str_mv Fluido magnético, nanopartículas, oxido de ferro
topic Fluido magnético, nanopartículas, oxido de ferro
Magnetic fluid, naoparticles, iron oxide
CNPQ::CIENCIAS EXATAS E DA TERRA::QUIMICA
dc.subject.eng.fl_str_mv Magnetic fluid, naoparticles, iron oxide
dc.subject.cnpq.fl_str_mv CNPQ::CIENCIAS EXATAS E DA TERRA::QUIMICA
description In this work maghemite nanoparticles were synthesized by co-precipitating Fe2+ and Fe3+ in alkaline medium. The freshly prepared magnetite was oxidized by two different routes: by bubbling O2 through an acid suspension of magnetite nanoparticles or by hydrothermal treatment of magnetite with ferric nitrate/nitric acid solution. After oxidation, the nanoparticles were covered with oleic acid and the grafting coefficient was evaluated according to the oxidation method and pH employed in the adsorption experiments. The covered particles were dispersed in mineral and vegetable insulating oils, resulting in magnetic fluids whose colloidal stability was investigated in regard to the following parameters: dilution, heating, water content, chemical composition of insulating oils and addition of oleic acid. The nanoparticles were characterized by X-ray diffratometry, thermogravimetric and differential thermal analyses and infrared spectroscopy. The Fe3+/Fe2+ molar ratio in the solids was determined by UV-Vis spectrometry. The magnetic fluids were characterized regarding the volume fraction of nanoparticles, the water content, and their colloidal stability was monitored by dynamic light scattering measurements and visual observations. The results obtained from the analyses indicated that the oxidized magnetite nanoparticles (5 to 10 nm) have inverse spinel structure and Fe3+/Fe2+ molar ratio varied from 20 to 70, depending on the oxidation method and employed conditions. The grafting coefficient varied from 2,1 to 4,8, reflecting the oleic acid adsorption conditions, and the further treatments. It was also observed that by controlling the experimental conditions, a grafting coefficient very close to a Langmuir s monolayer can be achieved, together with a decrease in the amount of physisorbed species which contribute negatively to the colloidal stability. The study of colloidal stability showed that dilution, heating and XVII water content have a great influence in the sedimentation of diluted magnetic fluids, when they are diluted with minerals insulating oils. It was verified that the magnetic fluids diluted with vegetable insulating oil showed very high colloidal stability in the accelerated thermal aging experiment
publishDate 2009
dc.date.available.fl_str_mv 2009-12-09
dc.date.issued.fl_str_mv 2009-03-18
dc.date.accessioned.fl_str_mv 2014-07-29T15:12:48Z
dc.type.status.fl_str_mv info:eu-repo/semantics/publishedVersion
dc.type.driver.fl_str_mv info:eu-repo/semantics/masterThesis
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status_str publishedVersion
dc.identifier.citation.fl_str_mv VIALI, Wesley Renato. Synthesis and characterization of oleic acid coated maghemite nanoparticles to obtain insulating oil based magnetic fluids. 2009. 100 f. Dissertação (Mestrado em Educação em Química) - Universidade Federal de Goiás, Goiânia, 2009.
dc.identifier.uri.fl_str_mv http://repositorio.bc.ufg.br/tede/handle/tde/1059
identifier_str_mv VIALI, Wesley Renato. Synthesis and characterization of oleic acid coated maghemite nanoparticles to obtain insulating oil based magnetic fluids. 2009. 100 f. Dissertação (Mestrado em Educação em Química) - Universidade Federal de Goiás, Goiânia, 2009.
url http://repositorio.bc.ufg.br/tede/handle/tde/1059
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dc.publisher.none.fl_str_mv Universidade Federal de Goiás
dc.publisher.program.fl_str_mv Mestrado em Química
dc.publisher.initials.fl_str_mv UFG
dc.publisher.country.fl_str_mv BR
dc.publisher.department.fl_str_mv Educação em Química
publisher.none.fl_str_mv Universidade Federal de Goiás
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