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Previous issue date: 2005-11-25 / Gallium is an important material used in the electronic industry whose demand in the world market is increasing in view of its potential applications. A selective technique is required to allow for the production of the metal, separated from aluminium. Due to the fact that microemulsions constitute an attractive alternative to metal extraction procedures, microemulsified systems have been employed as gallium-selective extraction agents. Two surfactants have been synthesized: sodium 12-N,N-diethylamino-9,10-dihydroxyestearate (AMINE) and saponified coconut oil (SCO), both produced from raw materials readily available in Northeastern Brazil. Also, the commercial extraction agent KELEX-100, conventionally used with the same purpose, has been used in this work for comparison. The optimization of the extraction process with microemulsions was carried out by investigating the influence of some parameters, namely the type of cosurfactant, the cosurfactant/surfactant (C/S) ratio, the pH and concentration of metals in the aqueous phase. Pseudoternary diagrams, which are representative of the microemulsified systems under study, have been constructed in order to establish the boundaries of the regions where the several Winsor systems are formed. An experimental planning methodology (Scheff? Net) has been used to optimize the extraction. The extraction percentage values were as high as 100% for gallium and 99.99% for aluminium for the system with KELEX-100; 96.6% for gallium and 98.8% for aluminium for the system containing AMINE; and 88% for gallium and 85% for aluminium for the system with SCO. The microemulsified system chosen for presenting the best results in gallium extraction was composed by SCO/isoamyl alcohol/kerosene/Bayer licquor with a C/S ratio of 28 and pH of the original aqueous phase of 6.0. The selectivity that has not been observed in the extraction stage was accomplished in the reextraction process using HCl. For the KELEX-100 system, gallium was reextracted at 100% with 6M HCl and aluminium was reextracted at 100% with 0.8M HCl. For the AMINE system, the reextraction percentages were also 100% for both metals, using 6M HCl for gallium and 0.5M HCl for aluminium. On the other hand, the reextraction percentages for the system with SCO were as high as 84% for gallium and 92% for aluminium, with HCl in the same concentrations as those used in the AMINE system. Finally, an optimized system was applied in the gallium extraction process employing a reciprocating perforated-plates extractor. As a result, the metal content was extracted at a recovery rate of 95% for gallium and 97% for aluminium / O g?lio ? um importante material utilizado na ind?stria eletr?nica, cuja demanda no mercado mundial est? crescendo em raz?o de suas aplica??es. A obten??o do metal necessita de um m?todo seletivo para separ?-lo do alum?nio. Sendo as microemuls?es uma alternativa atrativa para a extra??o de metais, decidiu-se utilizar sistemas microemulsionados como extratantes seletivos ao g?lio. Dois tensoativos foram sintetizados; o 12-N,Ndietil-amino-9,10-dihidroxiestearato de s?dio (AMINADO) e o ?leo de coco saponificado (OCS), obtidos de mat?rias-prima dispon?veis na regi?o Nordeste do Brasil. O extratante comercial KELEX-100, convencionalmente utilizado com essa mesma finalidade, foi usado neste trabalho para compara??o. A otimiza??o do processo de extra??o por microemuls?es foi realizada atrav?s do estudo da influ?ncia de par?metros, tais como: tipo de cotensoativo, raz?o C/T, pH e concentra??o de metais na fase aquosa. Os diagramas pseudotern?rios, representativos dos sistemas microemulsionados em estudo, foram estabelecidos no sentido de delimitar as regi?es de exist?ncia dos sistemas de Winsor. Uma metodologia de planejamento experimental (Rede Scheff?) foi usada para otimizar a extra??o. O percentual de extra??o atingiu valores de at? 100 % para o g?lio e 99,99% para o alum?nio para o sistema com o KELEX-100; 96,6 % para o g?lio e 98,8 % para o alum?nio no sistema contendo AMINADO; 88 % para o g?lio e 85 % para o alum?nio no sistema com OCS. O sistema microemulsionado selecionado por apresentar os melhores resultados na extra??o do g?lio foi composto de: OCS/?lcool isoam?lico/querosene/licor de Bayer a uma raz?o C/T igual a 28 e pH da fase aquosa igual a 6. A seletividade que faltou ? extra??o foi atingida na etapa de reextra??o utilizando-se solu??es de HCl. Para o sistema com o KELEX-100, reextraiu-se g?lio a 100% com HCl 6M e alum?nio a 100% com HCl 0,8M. No caso do sistema com AMINADO, os percentuais de reextra??o de ambos os metais tamb?m foram de 100%, usando-se HCl 6M para g?lio e HCl 0,5 M para o alum?nio. Por outro lado, para o sistema com OCS, os percentuais de reextra??o foram tais que 84% do g?lio e 92% do alum?nio foram recuperados com HCl nas mesmas concentra??es empregadas no caso do AMINADO. Um sistema otimizado foi, finalmente, aplicado na extra??o do g?lio em um extrator de pratos perfurados rec?procos (EPPR) e permitiu a extra??o deste metal com uma taxa de recupera??o de g?lio a 95% e alum?nio a 97%
| Identifer | oai:union.ndltd.org:IBICT/oai:repositorio.ufrn.br:123456789/15932 |
| Date | 25 November 2005 |
| Creators | Lucena Neto, Marciano Henrique de |
| Contributors | CPF:07286937391, http://buscatextual.cnpq.br/buscatextual/visualizacv.do?id=K4783139Z0&dataRevisao=null, Dantas Neto, Afonso Avelino, CPF:05641284491, http://buscatextual.cnpq.br/buscatextual/visualizacv.do?id=K4783215D9, Barros Neto, Eduardo Lins de, CPF:59545844434, http://buscatextual.cnpq.br/buscatextual/visualizacv.do?id=K4798645D3, Gurgel, Alexandre, CPF:59721421472, http://lattes.cnpq.br/5266735277153768, Garnica, Alfredo Ismael Curbelo, CPF:05227790779, http://lattes.cnpq.br/0257037690238235, Peres, Ant?nio Eduardo Clark, CPF:04457641634, http://lattes.cnpq.br/8666548473150908, Dantas, Tereza Neuma de Castro |
| 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/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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