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Previous issue date: 2015-07-15 / Conselho Nacional de Desenvolvimento Cient?fico e Tecnol?gico (CNPq) / Coordena??o de Aperfei?oamento de Pessoal de N?vel Superior (CAPES) / Com o crescente desenvolvimento cient?fico e tecnol?gico, o homem passa a explorar os recursos naturais de forma mais agressiva, gerando diariamente grandes quantidades de res?duos que s?o descartados no meio ambiente sem nenhum tratamento pr?vio. As institui??es de ensino e pesquisa v?m ganhando destaque como poluidoras do ambiente, j? que ignoram sua condi??o de geradoras de efluentes e descartam seus res?duos qu?micos de forma inadequada. Dentre os principais contaminantes ambientais, os corantes ganham destaque, pois se tratam de subst?ncias altamente t?xicas para a fauna e flora aqu?tica, podendo causar s?rios danos ? sa?de humana. Muitas t?cnicas no tratamento de efluentes contendo corantes v?m sendo apresentados na literatura, dentre as quais se destaca a adsor??o que vem sendo utilizada de forma eficaz no tratamento desses efluentes. O baba?u, palmeira nativa da Am?rica latina ? amplamente encontrada em alguns estados do norte, nordeste e centro-oeste do Brasil, produz um fruto que possui uma vasta potencialidade, dentre as quais se destaca a produ??o de carv?o. Assim, este trabalho tem como objetivo utilizar o carv?o de coco de baba?u modificado com ?cido c?trico (CCBMod) para tratar o efluente real gerado a partir do uso do corante azul de metileno (AM). Para caracterizar o CCBMod utilizou-se as t?cnicas de Espectroscopia de absor??o molecular na regi?o do Infravermelho (IV), Difra??o de raios-X (DRX), Termogravimetria e An?lise T?rmica Diferencial (TG/DTA) e Microscopia Eletr?nica de Varredura (MEV). O IV mostrou a presen?a de grupos OH, CH2, CH3 e C=O tanto no material modificado quando no material sem modifica??o, grupos estes caracter?sticos da lignina, no entanto n?o se verificou nenhuma incorpora??o do ?cido c?trico no material, dados que foram comprovados pelas demais t?cnicas. Assim infere-se que o ?cido usado na modifica??o foi eficiente na ativa??o dos s?tios dispon?veis do carv?o, melhorando o processo de adsor??o no decorrer do tempo. Na varia??o da concentra??o inicial do adsorvente, observou-se que o percentual de remo??o da cor do AM aumenta com a diminui??o da concentra??o inicial, onde nas concentra??es de 14, 12, 10, 8, 6, 4 e 2 mg L-1 apresentou valores m?dios de remo??o correspondendo respectivamente a 56,13; 62,43; 62,70; 70,00; 87,00; 93,83 e 100 %. Para a varia??o do pH da solu??o, observou-se que com o aumento do pH aumenta-se o percentual de remo??o da cor, assim para os potenciais hidrogeni?nicos 3,0; 6,0 e 10,0 obteve-se respectivamente, 39,73; 62,69 e 92,74 % de remo??o do AM. O modelo de cin?tica de adsor??o que melhor se ajustou aos dados experimentais foi o de pseudo-segunda-ordem, apresentando um valor de r2 igual 0,9965 e valores de qe,exp de 1,5424 mg g-1 e qe,teor de 1,5625 mg g-1. O modelo isot?rmico que melhor se ajustou aos dados experimentais foi o de Langmuir indicando uma natureza de adsor??o em monocamada. O efluente real proposto apresentou uma decomposi??o do AM de 7,20 % no decorrer de 14 dias e a remo??o desse efluente real pelo CCBMod foi de 57,86%. Concluindo-se que o CCBMod ? um material adsorvente eficaz na remo??o do AM de solu??es aquosas. / With the growing scientific and technological development, the man begins to exploit natural resources more aggressively, generating daily huge amounts of waste that are discarded into the environment without any prior treatment. Higher educational and research institutions have been gaining emphasis as environmental polluters, since ignore their condition waste generators and discard their chemical waste improperly. Among the main environmental contaminants, the dyes gain prominence, because they are highly toxic substance to aquatic plants and animals, causing serious damage to human health. Many techniques for the treatment of wastewater containing dyes have been reported in the literature, among them the adsorption has been used of way effective in the treatment of these effluents containing dyes. The babassu, palm tree native of Latin America is widely found in some northern, northeast and center-west states of Brazil, produces a fruit that has a vast potential, among which stands out the production of coal. This work aims to use the babassu coconut carbon (BCC) modified with citric acid to treat real effluent generated from methylene blue (MB) dye. In order to characterize the BCC modified were used the techniques of molecular absorption spectroscopy in infrared region (IR), X-ray Diffraction (XRD), thermal analysis (TG/ DTA) and Scanning Electron Microscopy (SEM). The IR showed the presence of groups OH, CH2, CH3 and C=O in both the materials modified and without modification, these groups are characteristic of lignin. It is also noted that the acid treatment promoted a modified on carbon surface, decreasing the heterogeneity of the same. Data were confirmed by other techniques. Thus it is inferred that the acid used in the modification was effective in activation of the available carbon sites, improving adsorption process over time. Varying the initial concentration of the adsorbent, it was observed that the removal percentage of MB color increases with decreasing initial concentration, where the concentrations from 14 to2 mg L-1 showed maximum removal points corresponding respectively to 62,43; 62,70; 70,00; 87,00; 93,83 e 100 %. For the change in pH of the solution was observed that with an increase in pH increases the percentage of the MB removal color, so to pH 3.0; 6.0 and 10.0 was obtained respectively 93,60; 67.29 and 42.15% removal AM. The adsorption kinetics model that best fit the experimental data was the pseudo-second-order, with a r2 value of 0.9965 and qe,exp 1.5424 mg g-1 and qe,teor 1.5625 mg g-1. The isothermal model that best fit the experimental data was the Langmuir indicating adsorption in monolayer. Concluding the modified BCC was presented as an effective adsorbent material in the MB removal from aqueous solutions. The real effluent proposed presented a decomposition to AM of 7.20% over 14 days and the removal of this real effluent by CCBMod was 57.86%. Concluding CCBMod is an effective adsorbent material in the removal of AM from aqueous solutions.
| Identifer | oai:union.ndltd.org:IBICT/oai:repositorio.ufrn.br:123456789/20436 |
| Date | 15 July 2015 |
| Creators | Silva, Isabel do Nascimento |
| Contributors | 44420773472, http://lattes.cnpq.br/9563490368583906, Guedes, Ana Paula de Melo Alves, 03330987499, http://lattes.cnpq.br/5738717177200782, Huitle, Carlos Alberto Martinez, 01139059980, http://lattes.cnpq.br/2485073932883264, Pimentel, Patricia Mendon?a, 77858239449, http://lattes.cnpq.br/9303372770390061, Fernandes, Nedja Suely |
| Publisher | Universidade Federal do Rio Grande do Norte, PROGRAMA DE P?S-GRADUA??O EM 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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