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Efici?ncia de extra??o de cobre e n?quel utilizando sistemas microemulsionados bif?sicos e trif?sicosOliveira, M?nica Rodrigues de 23 January 2014 (has links)
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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
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Desenvolvimento de metodologia de extra??o e pr?-concentra??o utilizando sistema microemulsionado para determina??o de Cd, Co, Cu, Ni, Pb e Tl em ?guas naturais e produzidas por HR-CS AASCosta, Emily Cintia Tossi de Ara?jo 23 September 2013 (has links)
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Previous issue date: 2013-09-23 / A contamina??o de ?guas naturais por metais tornou-se assunto de interesse p?blico mundial por serem considerados biocumulativos. A determina??o e o monitoramento de contaminantes met?licos em ?guas ? uma tarefa que deve ser cont?nua e por isto a import?ncia do desenvolvimento, modifica??o e otimiza??o de metodologias anal?ticas capazes de realizar a determina??o dos v?rios contaminantes met?licos em ambientes naturais, pois em muitos casos, a instrumenta??o dispon?vel n?o apresenta sensibilidade anal?tica suficiente para a determina??o de tra?os. Neste estudo, um m?todo de extra??o e pr?-concentra??o utilizando um sistema microemulsionado, no equil?brio de Winsor II foi testado e otimizado para a determina??o dos metais Co, Cd, Pb, Tl, Cu e Ni por Espectrometria de absor??o at?mica de alta resolu??o com fonte cont?nua e atomiza??o em forno de grafite e chama (HR-CS AAS). A otimiza??o do programa de temperatura para o forno de grafite foi realizada atrav?s de curvas de pir?lise e atomiza??o para cada analito sem e com o uso de diferentes modificadores qu?micos. Cd e Pb tiveram condi??es ?timas com modificador permanente Ru, pir?lise em 700?C e atomiza??o em 1700?C, para Tl solu??o Pd/Mg foi o melhor modificador, temperaturas 600?C e 1700?C de pir?lise e atomiza??o, respectivamente e para o Co pir?lise em 800?C e atomiza??o ? 2400?C sem uso de modificador qu?mico, por?m W foi empregado como modificador permanente a fim de se prolongar o tempo de vida ?til do forno. Cu e Ni foram analisados na chama ap?s pr?-concentra??o. Avaliou-se tamb?m fatores que influenciam a efici?ncia de extra??o, atrav?s do efeito salting out. Como compromisso, 6 g L-1 de Na e 1% de HNO3 (v/v) foi definido. Para determina??o do ponto ?timo de extra??o, um planejamento centroide-simplex foi aplicado, sendo escolhido como compromisso as seguintes propor??es: 70% fase aquosa, 10% fase ?leo e 20% Cotensoativo/Tensoativo (C/T = 4). Ap?s extra??o, os metais foram determinados e as Figuras de m?rito obtidas para o m?todo proposto foi: 0,1 a 10 ?g L-1 de faixa linear, LOD 0,094, 0,011, 0,057 e 0,050 ?g L-1 para Pb, Cd, Tl e Co, respectivamente. Testes de adi??o e recupera??o na amostra certificada apresentaram valores de recupera??o ap?s extra??o de 105 e 101% para Pb e Cd, respectivamente, e nas amostras fortificadas a recupera??o para os analitos ficou entre 107 e 108% comprovando que o m?todo proposto pode ser utilizado na extra??o, possibilitou a separa??o dos metais de matrizes complexas, e ainda com bom fator de pr?-concentra??o. / The determination and monitoring
of metallic contaminants in water is a task that must
be continuous, leading to the importance of
the development, modification and optimization
of analytical methodologies capab
le of determining the various
metal contaminants in natural
environments, because, in many cases, the ava
ilable instrumentation does not provide enough
sensibility for the determination of trace values
. In this study, a method of extraction and pre-
concentration using a microemulsion system with
in the Winsor II equilibrium was tested and
optimized for the determination of Co, Cd, P
b, Tl, Cu and Ni through the technique of high-
resolution atomic absorption spectrometry
using a continuum source (HR-CS AAS). The
optimization of the temperature program for
the graphite furnace (HR-CS AAS GF) was
performed through the pyrolysis and atomization
curves for the analytes Cd, Pb, Co and Tl
with and without the use of different chemical
modifiers. Cu and Ni we
re analyzed by flame
atomization (HR-CS F AAS) after pre-concentr
ation, having the sample introduction system
optimized for the realization of discrete sampling. Salinity and pH levels were also analyzed
as influencing factors in the efficiency
of the extraction. As final numbers, 6 g L
-1
of Na (as
NaCl) and 1% of HNO
3
(v/v) were defined. For the determination of the optimum extraction
point, a centroid-simplex statistical plan was a
pplied, having chosen as the optimum points of
extraction for all of the analytes, the follo
wing proportions: 70%
aqueous phase, 10% oil
phase and 20% co-surfactant/surfactant (C/S
= 4). After extraction, the metals were
determined and the merit figures obtained
for the proposed method were: LOD 0,09, 0,01,
0,06, 0,05, 0,6 and 1,5 ?g L
-1
for Pb, Cd, Tl, Co, Cu and Ni, re
spectively. Line
ar ranges of ,1-
2,0 ?g L
-1
for Pb, 0,01-2,0 ?g L
-1
for Cd, 1,0 - 20 ?g L
-1
for Tl, 0,1-5,0 ?g L
-1
for Co, 2-200
?g L
-1
and for Cu e Ni 5-200 ?g L
-1
were obtained. The enrichment factors obtained ranged
between 6 and 19. Recovery testing
with the certified sample show
ed recovery values (n = 3,
certified values) after extraction of 105
and 101, 100 and 104% for Pb, Cd, Cu and Ni
respectively. Samples of sweet waters of lake
Jiqui, saline water from Potengi river and water
produced from the oil industry (PETROBRAS) were
spiked and the recovery (n = 3) for the
analytes were between 80 and 112% confirming th
at the proposed method
can be used in the
extraction. The proposed method enabled the sepa
ration of metals from complex matrices,
and with good pre-concentration factor, consistent with the MPV (allowed limits) compared
to CONAMA Resolution No. 357/2005 which regulat
es the quality of fresh surface water,
brackish and saline water in Brazil.
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