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Previous issue date: 2014-05-21 / Chemical modification of clays has been extremely studied in the search for
improvements of their properties for use in various areas, such as in combating
pollution by industrial effluents and dyes. In this work, the vermiculite was chemically
modified in two ways, characterized and evaluated the adsorption of methylene blue
dye. First was changed with the addition of a surfactant
(hexadecyltrimethylammonium bromide, BHTA) making it an organophilic clay and
then by adding an acid (HCl) by acid activation. Some analyzes were performed as
X-ray fluorescence (FRX), X-ray diffraction (DRX), adsorption isotherms of methylene
blue dye, infrared (FTIR) , scanning electron microscopy (SEM), thermal gravimetric
analysis and spectroscopy energy dispersive (EDS). Analysis by FRX of natural
vermiculite indicates that addition of silicon and aluminum, clay presents in its
structure the magnesium, calcium and potassium with 16 % organic matter cations.
The DRX analyzes indicated that the organic vermiculite was an insertion of the
surfactant in the space between the lamellae, vermiculite and acid partial destruction
of the structure with loss of crystallinity. The adsorption isotherms of methylene blue
showed that there was a significant improvement in the removal of dye to the
vermiculite with the addition of cationic surfactant hexadecyltrimethylammonium
bromide and treatment with acid using HCl 2 mol/L. In acid vermiculites subsequently
treated with surfactant, the adsorption capacity increased with respect to natural
vermiculite, however was much lower compared vermiculite modified with acid and
surfactant separately. Only the acidic vermiculite treated with surfactant adjusted to
the Langmuir model. As in the infrared spectrometry proved the characteristics of
natural vermiculite. In the organic vermiculite was observed the appearance of
characteristic bands of CH3, CH2, and (CH3)4N. Already on acid vermiculite, it was
realized a partial destruction with decreasing intensity of the characteristic band of
vermiculite that is between 1074 and 952 cm-1. In the SEM analysis, it was observed
that there was partial destruction to the acid treatment and a cluster is noted between
the blades caused by the presence of the surfactant. The TG shows that the higher
mass loss occurs at the beginning of the heating caused by the elimination of water
absorbed on the surface between layers. In the organic vermiculite also observed a
loss of mass between 150 and 300 ?C caused decomposition of the alkylammonium
molecules (surfactants) / A modifica??o qu?mica de argilas tem sido extremamente estudada na busca por
melhorias de suas propriedades para seu uso em diversas ?reas, como por exemplo,
no combate a polui??o ocasionada por efluentes industriais como corantes. Neste
trabalho, a vermiculita foi modificada quimicamente de duas maneiras, caracterizada
e avaliada na adsor??o do corante azul de metileno. Primeiro foi alterada com adi??o
de um surfactante (brometo de hexadeciltrimetilam?nio, BHTA) tornando-a uma
argila organof?lica e depois pela adi??o de um ?cido (HCl) por ativa??o ?cida .
Algumas an?lises foram realizadas como fluoresc?ncia de raios-X (FRX), difra??o de
raios-X (DRX), isotermas de adsor??o do corante azul de metileno, infravermelho
(FTIR), microscopia eletr?nica de varredura (MEV), an?lise termogravim?trica e
Espectroscopia de energia dispersiva (EDS). An?lise por FRX da vermiculita natural
indica que al?m do sil?cio e do alum?nio, a argila apresenta em sua estrutura os
c?tions magn?sio, c?lcio e pot?ssio com 16 % de mat?ria org?nica. As an?lises por
DRX indicam que na vermiculita org?nica houve uma inser??o do surfactante no
espa?o entre as lamelas, e na vermiculita ?cida uma destrui??o parcial da estrutura
com perda de cristalinidade. As isotermas de adsor??o do azul de metileno
mostraram que houve uma melhora significativa na remo??o do corante para a
vermiculita com a adi??o do surfactante cati?nico brometo de
hexadeciltrimetilam?nio, bem como com tratamento ?cido utilizando HCl 2 mol/L.
Nas vermiculitas ?cidas tratadas posteriormente com o surfactante, a capacidade de
adsor??o aumentou em rela??o a vermiculita natural, porem foi bem menor em
rela??o as vermiculitas modificadas com o ?cido e com o surfactante
separadamente. S? as vermiculitas ?cidas tratadas com surfactante se ajustaram ao
modelo de Langmuir. A espectrometria na regi?o do infravermelho comprovou as
caracter?sticas da vermiculita natural. Na vermiculita org?nica observou-se o
aparecimento de bandas caracter?sticas de grupos CH3, CH2, al?m de (CH3)4N. J?
na vermiculita ?cida, percebeu-se uma destrui??o parcial com a diminui??o de
intensidade da banda caracter?stica das vermiculitas que ? entre 1074 e 952 cm-1.
Na an?lise de MEV, observou-se que houve destrui??o parcial com no tratamento
?cido e nota-se um aglomerado entre as l?minas causado pela presen?a do
surfactante. As curvas TG mostram que a maior perda de massa ocorre no come?o
do aquecimento ocasionado pela elimina??o de ?gua absorvida na superf?cie entre
camadas. Na vermiculita org?nica tamb?m observa uma perda de massa entre 150 e
300 ?C ocasionada pela decomposi??o das mol?culas de alquilam?nio (surfactante)
| Identifer | oai:union.ndltd.org:IBICT/oai:repositorio.ufrn.br:123456789/17755 |
| Date | 21 May 2014 |
| Creators | Maia, Francisco Alexis Dantas |
| Contributors | CPF:16225422404, http://lattes.cnpq.br/3511004608337461, Lima, Francisco Jos? Santos, CPF:42429625415, http://lattes.cnpq.br/1295841954027018, Pergher, Sibele Berenice Castella, CPF:50942611004, http://lattes.cnpq.br/5249001430287414, Silva J?nior, Umberto Gomes da, CPF:16233719453, http://lattes.cnpq.br/3952943964796396, Silva, Ademir Oliveira da |
| Publisher | Universidade Federal do Rio Grande do Norte, Programa de P?s-Gradua??o em Qu?mica, UFRN, BR, F?sico-Qu?mica; Qu?mica |
| 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/openAccess |
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