Made available in DSpace on 2014-12-17T15:01:26Z (GMT). No. of bitstreams: 1
JosilmaFF_DISSERT_Parcial.pdf: 436034 bytes, checksum: 128f71801f48233150a514d2629a577b (MD5)
Previous issue date: 2011-02-11 / Conselho Nacional de Desenvolvimento Cient?fico e Tecnol?gico / The constant search for biodegradable materials for applications in several fields
shows that carnauba wax can be a viable alternative in the manufacturing of
biolubricants. Carnauba wax is the unique among the natural waxes to have a
combination of properties of great importance. In previous studies it was verified the
presence of metals in wax composition that can harm the oxidative stability of
lubricants. Considering these factors, it was decided to develop a research to evaluate
iron removal from carnauba wax, using microemulsion systems (Me) and perform the
optimization of parameters, such as: extraction pH, temperature, extraction time, among
others. Iron concentration was determined by atomic absorption and, to perform this
analysis, sample digestion in microwave oven was used, showing that this process was
very efficient. It was performed some analysis in order to characterize the wax sample,
such as: attenuated total reflectance infrared spectroscopy (ATR-IR), thermogravimetry
(TG), differential scanning calorimetry (DSC), energy dispersive X-ray fluorescence
(EDXRF), scanning electron microscopy (SEM) and melting point (FP). The
microemulsion systems were composed by: coconut oil as surfactant, n-butanol as
cosurfactant, kerosene and/or heptanes as oil phase, distilled water as water phase. The
pH chosen for this study was 4.5 and the metal extraction was performed in finite
experiments. To evaluate Me extraction it was performed a factorial design for systems
with heptane and kerosene as oil phase, also investigating the influence of temperature
time and wax/Me ratio, that showed an statistically significant answer for iron
extraction at 95% confidence level. The best result was obtained at 60?C, 10 hours
contact time and 1: 10 wax/Me ratio, in both systems with kerosene and heptanes as oil
phase. The best extraction occurred with kerosene as oil phase, with 54% iron removal / Em virtude da constante busca por materiais biodegrad?veis para diversas
aplica??es, a cera de carna?ba pode ser uma alternativa vi?vel na fabrica??o de
biolubrificantes. A carna?ba ? a ?nica entre as ceras a possuir uma combina??o de
propriedades de grande import?ncia. Em estudos preliminares verificaram-se na
composi??o da cera alguns metais que podem prejudicar a estabilidade oxidativa do
lubrificante. Diante desses fatores, decidiu-se desenvolver um trabalho sobre a remo??o
de ferro, da cera de carna?ba, atrav?s de sistemas microemulsionados (Me) e realizar
uma otimiza??o de par?metros, como: ajuste de pH, temperatura, tempo de extra??o,
entre outros. A concentra??o de ferro foi determinada por absor??o at?mica e, para essa
an?lise, a digest?o da amostra em forno de micro-ondas se mostrou bastante eficiente.
Foram realizadas algumas an?lises de caracteriza??o da amostra como: espectroscopia
de infravermelho por reflet?ncia total atenuada (IV-ATR), termogravimetria (TG),
calorimetria explorat?ria diferencial (DSC), fluoresc?ncia de raios-X por energia
dispersiva (EDXRF), microscopia eletr?nica de varredura (MEV) e ponto de fus?o
(PF). O sistema de microemuls?o utilizado teve como tensoativo: ?leo de coco
saponificado, cotensoativo: n-butanol, fase ?leo: querosene e/ou heptano, fase aquosa:
?gua destilada. O pH escolhido para o estudo foi de 4,5 e a extra??o do metal foi
realizada em banho finito. Para tanto, foi realizado um planejamento experimental
fatorial para o sistema com fase ?leo heptano e fase ?leo querosene. Em ambos os
planejamentos foram investigadas as vari?veis temperatura, tempo e raz?o
cera/microemuls?o, que se mostraram estatisticamente significativas para a resposta
extra??o de ferro a 95% de confian?a. Tanto para o sistema em que a fase ?leo foi o
heptano quanto para o querosene, o melhor resultado obtido foi em 60?C, 10 horas e
raz?o cera/Me 1:10. A melhor extra??o se deu com sistemas microemulsionados com
fase ?leo querosene, extraindo cerca de 54% de ferro / 2020-01-01
| Identifer | oai:union.ndltd.org:IBICT/oai:repositorio.ufrn.br:123456789/15816 |
| Date | 11 February 2011 |
| Creators | Fontana, Josilma F?tima |
| Contributors | CPF:05641284491, http://buscatextual.cnpq.br/buscatextual/visualizacv.do?id=K4783215D9, Leite, Ricardo Henrique de Lima, CPF:52264343400, http://lattes.cnpq.br/3801476460958779, Melo, Keila Rejane de Oliveira, CPF:03411704454, Moura, Maria Carlenise Paiva de Alencar, CPF:21414130368, http://buscatextual.cnpq.br/buscatextual/visualizacv.do?id=K4702157Y9, Dantas, Tereza Neuma de Castro, Dantas Neto, Afonso Avelino |
| 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 |
Page generated in 0.0027 seconds