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Previous issue date: 2013-12-17 / Coordena??o de Aperfei?oamento de Pessoal de N?vel Superior / In this work it was synthesized and characterized the cobalt ferrite (CoFe2O4) by
two methods: complexation combining EDTA/Citrate and hydrothermal investigating the
influence of the synthesis conditions on phase formation and on the crystallite size. The
powders were mainly characterized by x-ray diffraction. In specific cases, it was also used
scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), x-ray
fluorescence (XRF) and isotherms of adsorption and desorption of nitrogen (BET method).
The study of the crystallite size was based on the interpretation of x-ray diffractograms
obtained and estimated by the method of Halder-Wagner-Scherrer and Langford. An
experimental design was made in order to assist in quantifying the influence of synthesis
conditions on the response variables. The synthesis parameters evaluated in this study were:
pH of the reaction medium (8, 9 and 10), the calcination temperature (combined complexation
method EDTA/Citrate 600?C, 800?C and 1000?C), synthesis temperature (hydrothermal
method 120?C, 140?C and 160?C), calcination time (combined complexation method
EDTA/Citrate - 2, 4 and 6 hours) and time of synthesis (hydrothermal method 6, 15 and 24
hours). By the hydrothermal method was possible to produce mesoporous powders with high
purity, with an average crystallite size up to 7 nm, with a surface area of 113.44 m?/g in the
form of pellets with irregular morphology. By using the method of combined complexation
EDTA/Citrate, mesoporous powders were produced with greater purity, crystallite size up to
22nm and 27.95 m?/g of surface area in the form of pellets with a regular morphology of
plaques. In the experimental design was found that the hydrothermal method to all the studied
parameters (pH, temperature and time) have significant effect on the crystallite size, while to
the combined complexation method EDTA/Citrate, only temperature and time were
significant / Neste trabalho foi sintetizada e caracterizada a ferrita de cobalto (CoFe2O4)
atrav?s dos m?todos complexa??o combinada EDTA/Citrato e hidrot?rmico, investigando a
influ?ncia das condi??es de s?ntese na forma??o da fase e no tamanho m?dio de cristalito. Os
p?s foram caracterizados principalmente por difra??o de raios-x. Em casos espec?ficos,
tamb?m foi utilizado microscopia eletr?nica de varredura (MEV), espectroscopia de energia
dispersiva (EDS), fluoresc?ncia de raios-x (FRX) e isotermas de adsor??o e dessor??o de
nitrog?nio (M?todo BET). O estudo do tamanho de cristalito foi baseado na interpreta??o dos
difratogramas de raios-x obtidos e estimado atrav?s do m?todo de Halder-Wagner-Langford
(HWL) e de Scherrer. Um planejamento experimental foi realizado com a finalidade de
auxiliar na quantifica??o da influ?ncia das condi??es de s?ntese nas vari?veis-resposta. Os
par?metros de s?ntese avaliados neste trabalho foram: pH do meio reacional (8, 9 e 10),
temperatura de calcina??o (m?todo de complexa??o combinando EDTA/Citrato 600?C,
800?C e 1000?C), temperatura de s?ntese (m?todo hidrot?rmico 120?C, 140?C e 160?C),
tempo de calcina??o (m?todo de complexa??o combinando EDTA/Citrato 2, 4 e 6 hrs) e
tempo de s?ntese (m?todo hidrot?rmico 6, 15 e 24 hrs). Pelo m?todo hidrot?rmico foi
poss?vel produzir p?s mesoporosos com elevado grau de pureza, com tamanho m?dio de
cristalito de at? 7nm, com ?rea superficial de 113,44m?/g e na forma de aglomerados com
morfologia irregular. Ao se utilizar o m?todo de complexa??o combinando EDTA/Citrato
foram produzidos p?s mesoporosos com maior pureza, cristalitos com at? 22nm de tamanho,
27,95m?/g de ?rea superficial e na forma de aglomerados com morfologia regular de placas.
No planejamento experimental foi constatado que no caso do m?todo hidrot?rmico todos os
par?metros estudados (pH, Temperatura e tempo) apresentam efeito significativo no tamanho
de cristalito, enquanto que, para o m?todo de complexa??o combinando EDTA/Citrato,
apenas a temperatura e o tempo foram significativos / 2020-01-01
| Identifer | oai:union.ndltd.org:IBICT/oai:repositorio.ufrn.br:123456789/15848 |
| Date | 17 December 2013 |
| Creators | Medeiros, Indira Aritana Fernandes de |
| Contributors | CPF:13681389420, http://buscatextual.cnpq.br/buscatextual/visualizacv.do?id=K4781094H3, Santos, Andarair Gomes dos, CPF:02813010421, http://lattes.cnpq.br/3470634368296605, Silva, Gilson Garcia da, CPF:56634161453, http://lattes.cnpq.br/8681275097040450, Souza, Carlson Pereira de |
| Publisher | Universidade Federal do Rio Grande do Norte, Programa de P?s-Gradua??o em Engenharia Qu?mica, UFRN, BR, Pesquisa e Desenvolvimento de Tecnologias Regionais |
| Source Sets | IBICT Brazilian ETDs |
| Language | Portuguese |
| Detected Language | English |
| Type | info:eu-repo/semantics/publishedVersion, info:eu-repo/semantics/masterThesis |
| Format | application/pdf |
| Source | reponame:Repositório Institucional da UFRN, instname:Universidade Federal do Rio Grande do Norte, instacron:UFRN |
| Rights | info:eu-repo/semantics/embargoedAccess |
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