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Previous issue date: 2014-01-23 / The environmental impact due to the improper disposal of metal-bearing industrial
effluents imposes the need of wastewater treatment, since heavy metals are nonbiodegradable
and hazardous substances that may cause undesirable effects to humans and
the environment. The use of microemulsion systems for the extraction of metal ions from
wastewaters is effective when it occurs in a Winsor II (WII) domain, where a
microemulsion phase is in equilibrium with an aqueous phase in excess. However, the
microemulsion phase formed in this system has a higher amount of active matter when
compared to a WIII system (microemulsion in equilibrium with aqueous and oil phases
both in excess). This was the reason to develop a comparative study to evaluate the
efficiency of two-phases and three-phases microemulsion systems (WII and WIII) in the
extraction of Cu+2 and Ni+2 from aqueous solutions. The systems were composed by:
saponified coconut oil (SCO) as surfactant, n-Butanol as cosurfactant, kerosene as oil
phase, and synthetic solutions of CuSO4.5H2O and NiSO4.6H2O, with 2 wt.% NaCl, as
aqueous phase. Pseudoternary phase diagrams were obtained and the systems were
characterized by using surface tension measurements, particle size determination and
scanning electron microscopy (SEM). The concentrations of metal ions before and after
extraction were determined by atomic absorption spectrometry. The extraction study of
Cu+2 and Ni+2 in the WIII domain contributed to a better understanding of microemulsion
extraction, elucidating the various behaviors presented in the literature for these systems.
Furthermore, since WIII systems presented high extraction efficiencies, similar to the ones
presented by Winsor II systems, they represented an economic and technological
advantage in heavy metal extraction due to a small amount of surfactant and cosurfactant
used in the process and also due to the formation of a reduced volume of aqueous phase,
with high concentration of metal. Considering the reextraction process, it was observed
that WIII system is more effective because it is performed in the oil phase, unlike
reextraction in WII, which is performed in the aqueous phase. The presence of the metalsurfactant
complex in the oil phase makes possible to regenerate only the surfactant present
in the organic phase, and not all the surfactant in the process, as in WII system. This fact
allows the reuse of the microemulsion phase in a new extraction process, reducing the
costs with surfactant regeneration / O impacto ambiental gerado pelo descarte de efluentes industriais carregados de metais
pesados imp?e a necessidade do tratamento desses rejeitos, uma vez que s?o t?xicos e n?o
biodegrad?veis, podendo causar s?rios danos ? popula??o e ao meio ambiente. O processo
de extra??o de c?tions met?licos utilizando microemuls?es ? eficaz quando acontece em
WII, onde a fase microemulsionada encontra-se em equil?brio com uma fase aquosa em
excesso. No entanto, a microemuls?o formada nesse sistema possui uma maior quantidade
de mat?ria ativa quando comparada ao equil?brio de WIII (microemuls?o em equil?brio com
fases aquosa e oleosa, ambas em excesso), ainda pouco estudado, motivando, assim, o
desenvolvimento de um estudo comparativo da efici?ncia de extra??o dos ?ons Cu2+ e Ni2+
por sistemas microemulsionados bif?sicos e trif?sicos (WII e WIII). Os constituintes
utilizados nos sistemas de extra??o foram: ?leo de coco saponificado - OCS (Tensoativo), n-
Butanol (Cotensoativo), querosene (Fase Oleosa) e solu??es sint?ticas de CuSO4.5H2O e
NiSO4.6H2O com NaCl 2% (fases aquosas). Foram obtidos os diagramas de fases
pseudotern?rios e os sistemas microemulsionados foram caracterizados atrav?s das t?cnicas
de tens?o superficial, tamanho de part?culas e microscopia eletr?nica de varredura (MEV). A
concentra??o dos ?ons foi determinada por espectrometria de absor??o at?mica. O estudo da
extra??o dos c?tions met?licos Cu2+ e Ni2+ na regi?o de WIII contribuiu para um melhor
entendimento dos processos de extra??o por microemuls?o, elucidando os v?rios
comportamentos apresentados na literatura para esses sistemas. Al?m disso, uma vez que
houve uma alta efici?ncia de extra??o, similar aos sistemas de Winsor II, o sistema trif?sico
(WIII), por apresentar uma menor quantidade de tensoativo e cotensoativo, e um menor
volume de fase aquosa ap?s a extra??o, levou a uma maior concentra??o do metal,
representando uma vantagem econ?mica e tecnol?gica do processo. Assim, a extra??o em
sistema trif?sico ? vi?vel e, apesar dos percentuais de extra??o em WII e WIII serem
semelhantes, o sistema de WIII leva a uma maior concentra??o do metal na fase extrato. O
presente trabalho mostrou, ainda, que a etapa de reextra??o para os sistemas em WIII ? mais
eficaz pois, diferentemente da extra??o em Winsor II, ela ? realizada na fase oleosa, onde
est? depositado o complexo metal/tensoativo, regenerando somente o tensoativo que
complexa com o metal na fase org?nica, e n?o todo o tensoativo utilizado, como ? o caso do
equil?brio em Winsor II. Este fato viabiliza a reutiliza??o da fase microemuls?o no processo
de extra??o, diminuindo os custos de regenera??o do tensoativo
| Identifer | oai:union.ndltd.org:IBICT/oai:repositorio.ufrn.br:123456789/17785 |
| Date | 23 January 2014 |
| Creators | Oliveira, M?nica Rodrigues de |
| Contributors | CPF:07286937391, http://lattes.cnpq.br/0676872399141537, Silva, Djalma Ribeiro da, CPF:13893734449, http://lattes.cnpq.br/2791074318745945, Barros Neto, Eduardo Lins de, CPF:59545844434, http://lattes.cnpq.br/2811639726261017, Peres, Ant?nio Eduardo Clark, CPF:04457641634, http://lattes.cnpq.br/8666548473150908, Lucena Neto, Marciano Henrique de, CPF:32288514434, http://lattes.cnpq.br/4809804711785369, Dantas, Tereza Neuma de Castro |
| 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/doctoralThesis |
| 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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