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Previous issue date: 2015-12-14 / Conselho Nacional de Desenvolvimento Cient?fico e Tecnol?gico (CNPq) / Coordena??o de Aperfei?oamento de Pessoal de N?vel Superior (CAPES) / Neste trabalho foram produzidas membranas de quitosana reticuladas ionicamente, utilizando o ?cido sulf?rico como agente de reticula??o para serem aplicadas no tratamento de ?guas residuais da ind?stria do petr?leo. Duas metodologias de reticula??o das membranas foram desenvolvidas: homog?nea e heterog?nea. No processo homog?neo a vari?vel analisada foi a raz?o molar de SO42-/ NH3+ (1:6 e 1:4), enquanto, no processo heterog?neo o tempo de imers?o das membranas em ?cido sulf?rico foi a vari?vel em estudo, sendo utilizado tempos de 5 e 30 minutos. Os resultados de FTIR-ATR evidenciaram a forma??o de liga??es i?nicas entre os grupos NH3+protonados da quitosana e os ?ons sulfato do agente reticulante. Apenasnas membranas heterog?neas indicando um grau de reticula??o bastante pequeno para as homog?neas.As an?lises de TG/DTG e DRX confirmaram a forma??o dessas intera??es, como tamb?m demonstraram que houve a forma??o de uma nova estrutura na regi?o superficial das membranas CS5 e CS30 em rela??o ?s membranas de CS, CS16 e CS14. Os ensaios de intumescimento em meio aquoso evidenciaram que os processos de reticula??o reduziram a capacidade de sor??o das membranas. Enquanto que em meio ?cido as membranas de CS16 e CS14 aumentaram a capacidade de sor??o at? um percentual m?ximo de aproximadamente 140%, e as de CS5 e CS30 atingiram um m?ximo de 60%. As propriedades mec?nicas indicaram o comportamento r?gido e d?ctil das membranas reticuladas. Atrav?s dos experimentos de sor??o de solu??o de CuCl2, foi determinado que o m?ximo de efici?ncia foi obtido para as membranas CS16 com 73% de remo??o de cobre em pH 5,0 e 87% em pH 4,0. Os experimentos realizados com CuSO4 tamb?m resultaram em 80% de remo??o de ?ons de Cu2+ para as membranas de CS16. Tamb?m foi verificado que o aumento da concentra??o e da temperatura refletiram na diminui??o da capacidade de adsor??o para todas as membranas. Os resultados de cin?tica evidenciaram que as membranas foram melhor caracterizadas pela equa??o de pseudo-segunda-ordem. E, osEstudos de equil?brio demonstraram que as membranas de CS, CS16 e CS14 seguem o modelo de Langmuir, enquanto que as membranas de CS5 e CS30 seguem o modelo de Freundlich. Os experimentos de filtra??o resultaram em m?ximo de reten??o de ?ons de Cu2+ para as membranas de CS16 e CS5, atingindo 92 e 98% respectivamente. / In this work a chitosan (CS) ionically crosslinked were manufactured by treatment with
sulfuric acid solution for application in the treatment of wastewater from oil industry. Two
crosslinking process were developed: homogeneous and heterogeneous. In the homogeneous
process the ratio molar of SO42-/ NH3+ (1:6 and 1:4) were the variable analyzed, denominated
CS16 and CS14 respectively. In the heterogeneous process the soaking time of the membranes in
sulfuric acid solution were the variable studied, being used times of 5 (CS5) and 30 (CS30)
minutes. FTIR-ATR results indicated no changes in the characteristics of chitosan after
homogeneous crosslinking process, while heterogeneous crosslinking showed formation of ionic
bonds between protonated groups from chitosan and the crosslinking agent sulfate ions. TG/DTG
and XRD analysis confirmed the formation of these interactions, as also shown the new structure
on the surface region of CS5 and CS30 membranes compared to CS, CS16 e CS14. Swelling test
in aqueous medium have shown that crosslinking process reduced the membrane sorption
capacity. Swelling test in acid medium demonstrated that CS16 and CS14 membranes increasing
the adsorption capacity up to a maximum percentage of 140% approximately, whereas the CS5 e
CS30 reached a maximum of 60%. The mechanical properties indicated the stiff and ductile
behavior of crosslinked membrane. Adsorption experiments of CuCl2 results that CS16
membranes reached the efficiency maximum with 73% of copper removal at pH 5.0 and 87% at
pH 4.0. The experiments with CuSO4 also obtained efficiency maximum to the CS16 membrane
and 80% to the removal of Cu2+ ions. Also was verified that the increase of concentration and
temperature cause a decrease in the adsorption capacity for all membranes. Kinetics study
indicated that pseudo-second-order obtained characterized better the membranes. Equilibrium
studies demonstrated that the CS, CS16 and CS14 follow the Langmuir model, whereas CS5 and
CS30 follows Freundlich model. Filtration experiments results with rejection maximum to the
CS16 and CS5 membranes, reaching 92 and 98% respectively.
| Identifer | oai:union.ndltd.org:IBICT/oai:repositorio.ufrn.br:123456789/21136 |
| Date | 14 December 2015 |
| Creators | Marques, J?ssica Souza |
| Contributors | 83115951787, http://lattes.cnpq.br/2860689190271698, Silva, Djalma Ribeiro da, 13893734449, http://lattes.cnpq.br/2791074318745945, Pergher, Sibele Berenice Castella, 50942611004, http://lattes.cnpq.br/5249001430287414, Alc?ntara, Ana Cl?cia Santos de, 83221018568, http://lattes.cnpq.br/3149929057352643, Ferreras, Jes?s Maria Arsuaga, 00000000000, Pereira, M?rcia Rodrigues |
| 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/doctoralThesis |
| 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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