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Previous issue date: 2017-03-30 / Conselho Nacional de Desenvolvimento Cient?fico e Tecnol?gico (CNPq) / O esgotamento das reservas minerais e a preocupa??o crescente da sociedade com o meio ambiente e a sustentabilidade traz perspectivas animadoras nas ?reas de reciclagem de res?duos de equipamentos eletroeletr?nicos (REEE). Diante disso, este trabalho tem como objetivo desenvolver uma rota para reciclar metais presentes nas placas de circuito impresso (PCI) de computadores desktops obsoletos. Para isso foram feitos ensaios de lixivia??o utilizando diferentes ?cidos (n?trico, ?gua r?gia, clor?drico e sulf?rico) variando os par?metros de temperatura e de concentra??o molar do ?cido seguindo um planejamento experimental fatorial completo do tipo 2? com repeti??es no ponto central avaliou-se a efici?ncia do processo atrav?s do percentual de massa lixiviada obtida por an?lise gravim?trica. As amostras antes e depois dos ensaios de lixivia??o foram analisadas por FRX, MEV e EDS para que fossem identificados e quantificados os principais elementos qu?micos existentes, bem como determinar a morfologia das amostras de PCI utilizadas. Os melhores resultados alcan?ados em termos percentuais de massa lixiviada foram obtidos para ?gua r?gia e ?cido n?trico. J? os resultados de menor rendimento alcan?ados foram obtidos para o ?cido clor?drico e sulf?rico. O estudo estat?stico do ?cido n?trico demonstrou que a concentra??o molar do ?cido foi o ?nico fator que apresentou efeito significativo sobre a vari?vel resposta, n?o houve falta de ajuste e o coeficiente de correla??o (R?) estimado foi de 0,99111, indicando que o modelo de primeira ordem testado ? preditivo e significativo. J? para a ?gua r?gia, a concentra??o molar do ?cido e a intera??o temperatura/concentra??o foram os dois fatores que apresentaram efeito significativo sobre a vari?vel resposta e o modelo que melhor se adequou foi o de segunda ordem (R? de 0,99914). Por fim, as an?lises por FRX demonstraram quais elementos foram ou n?o lixiviados por cada ?cido. A ?gua r?gia apresentou facilidade em dissolver praticamente todos os metais. O ?cido n?trico dissolveu cobre, chumbo e c?lcio. Os ?cidos clor?drico e sulf?rico foram eficientes na lixivia??o do estanho, ferro e n?quel. De maneira geral, cada ?cido foi seletivo para diferentes elementos qu?micos presentes na composi??o das PCI, possibilitando assim desenvolver uma rota de reciclagem vi?vel baseado nesse estudo. / The reduction of mineral reserves and the growing concern of society with the environment and sustainability brings exciting prospects in the areas of recycling of waste electrical and electronic equipment (WEEE). Therefore, this paper aims to develop a route to recycle metals present on the printed circuit boards (PCB) of obsolete desktops computers. For this, leaching tests were performed using different acids (nitric, regal water, hydrochloric and sulfuric), varying the parameters of temperature and molar concentration of the acid following a complete factorial experimental design of the type 2? with repetitions at the central point was evaluated the process through the percentage of leached mass obtained by gravimetric analysis. The samples before and after the leaching tests were analyzed by FRX, MEV and EDS to identify and quantify the main chemical elements as well as the morphology of the PCB samples used. The best results obtained in percentage terms of leached mass were obtained for royal water and nitric acid. On the other hand, the results of lower yields were obtained for hydrochloric and sulfuric acid. The statistical study of nitric acid showed that the molar concentration of the acid was the only factor that had a significant effect on the response variable, there was no lack of fit and the estimated coefficient of correlation (R?) estimated was 0.99111, indicating that the first order model tested is predictive and significant. However, for the royal water the acid molar concentration and the temperature/concentration interaction were the two factors that had a significant effect on the response variable and the model that best suitable was the second order (R? of 0,99914). Finally, the FRX reviews demonstrated which elements were or were not leached by each acid. Regal water has shown ease in dissolving practically all metals. The nitric acid dissolved copper, lead and calcium. The hydrochloric and sulfuric acid were efficient in the leaching of tin, iron and nickel. In general, each acid was selective for different chemical elements present in the composition of the PCB and for this reason a viable recycling route based on this study is possible.
| Identifer | oai:union.ndltd.org:IBICT/oai:repositorio.ufrn.br:123456789/23395 |
| Date | 30 March 2017 |
| Creators | Melo, Raffael Andrade Costa de |
| Contributors | 13681389420, http://lattes.cnpq.br/1030834608582624, Moriyama, Andr? Luis Lopes, 06663278401, http://lattes.cnpq.br/5552878900145656, Silva, Gilson Garcia da, 56634161453, http://lattes.cnpq.br/8681275097040450, Souza, Carlson Pereira de |
| Publisher | PROGRAMA DE P?S-GRADUA??O EM ENGENHARIA QU?MICA, UFRN, Brasil |
| Source Sets | IBICT Brazilian ETDs |
| Language | Portuguese |
| Detected Language | English |
| Type | info:eu-repo/semantics/publishedVersion, info:eu-repo/semantics/masterThesis |
| 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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