Remo??o de bisfenol-A por silicatos modificados com cobalto

Autor: Cruz, Alenice Ferreira
Jazyk: portugalština
Rok vydání: 2016
Předmět:
Zdroj: Repositório Institucional da UFVJMUniversidade Federal dos Vales do Jequitinhonha e MucuriUFVJM.
Druh dokumentu: masterThesis
Popis: Submitted by Jos? Henrique Henrique (jose.neves@ufvjm.edu.br) on 2017-03-23T19:40:24Z No. of bitstreams: 2 license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) alenice_ferreira_cruz.pdf: 3398178 bytes, checksum: 4f7c2c8ff0a3c9856be63b637e43306b (MD5)
Approved for entry into archive by Rodrigo Martins Cruz (rodrigo.cruz@ufvjm.edu.br) on 2017-04-20T16:59:10Z (GMT) No. of bitstreams: 2 license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) alenice_ferreira_cruz.pdf: 3398178 bytes, checksum: 4f7c2c8ff0a3c9856be63b637e43306b (MD5)
Made available in DSpace on 2017-04-20T16:59:11Z (GMT). No. of bitstreams: 2 license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) alenice_ferreira_cruz.pdf: 3398178 bytes, checksum: 4f7c2c8ff0a3c9856be63b637e43306b (MD5) Previous issue date: 2016
O bisfenol-A ? um importante produto qu?mico, amplamente utilizado em ind?strias para a produ??o de policarbonatos, resinas epoxi e outros pl?sticos. Existe uma car?ncia em desenvolver m?todos eficazes para remov?-lo de efluentes. Uma vez que, o mesmo faz parte dos chamados poluentes emergentes, pois ? um contaminante prejudicial para os organismos, mesmo em baixas concentra??es, devido ao seu efeito nocivo sobre sa?de. Neste trabalho, buscou-se avaliar o desempenho de dois silicatos mesoporosos (MCM-41 e Co-silicato) frente ? adsor??o do bisfenol-A. Os perfis de difra??o de raio-X dos materiais confirmaram a forma??o da MCM-41 e o material modificado (Co-silicato) demonstrou alterar ao ?nico elemento de ordem estrutural, que ? a disposi??o dos canais paralelos (2?=2). As imagens de MEV mostraram que os materiais n?o apresentaram morfologia definida. Dados indicaram que ambos os materiais apresentam elevada ?rea espec?fica, sendo 988 m2g-1 para MCM-41 e 729 m2g-1 para Co-silicato. O material Co-silicato mostrou elevado potencial como adsorvente, frente ? MCM-41. A elevada ?rea superficial, aliada ao tamanho dos poros, juntamente com a presen?a de ?ons met?licos (cobalto) favoreceram o processo de adsor??o. A forma??o de s?tios ativos no silicato, ap?s a inser??o de cobalto, favoreceu a adsor??o do contaminante. A partir dos testes de adsor??o realizados em pH 3, 6 e 9 foi poss?vel notar que o material que teve uma melhor capacidade de adsor??o foi o material Co-silicato. Diante dos testes de cin?tica, o material Co-silicato nas faixas de pH analisadas demonstrou maior potencial de adsor??o do bisfenol-A, em rela??o ao resultados de remo??o obtidos com o material MCM-41. Os modelos utilizados para os ajustes matem?ticos da adsor??o foram as isotermas de Langmuir, Freundlich, e Redlich-Peterson. O valor do coeficiente de correla??o (R2) 0,9641 pH 3; (R2) 0,9834 pH 6 e (R2) 0,9959 pH 9 dos par?metros de Redlich-Peterson sugeriram que o modelo de Redlich-Peterson descreve melhor o comportamento de adsor??o de bisfenol-A no material Co-silicato, j? que apresenta maior valor do coeficiente de correla??o em pH testados, comparando com os valores de correla??o (R2) de Langmuir e Freundlich. Os dados revelaram que a modifica??o da MCM-41 com ?tomos de cobalto alteraram as propriedades f?sico-qu?mica do material, e potencializou o adsorvente para adsor??o da mol?cula de bisfenol-A.
Disserta??o (Mestrado) ? Programa de P?s-Gradua??o em Qu?mica, Universidade Federal dos Vales do Jequitinhonha e Mucuri, 2016.
Bisphenol-A is an important chemical, widely used in industries for the production of polycarbonates, epoxy resins and other plastics. There is a lack of effective methods to remove it from effluents. Since it is part of so-called emerging pollutants, it is a harmful contaminant for organisms, even in low concentrations, because of its harmful effect on health. This work aimed to evaluate the performance of two mesoporous silicates (MCM-41 and Co-silicate) against the adsorption of bisphenol-A. The X-ray diffraction profiles of the materials confirmed the formation of MCM-41 and the modified material (Co-silicate) was shown to change to the only structural element, which is the arrangement of the parallel channels (2? = 2). The SEM images showed that the materials did not present definite morphology. Data indicated that both materials presented a high specific area, being 988 m2g- 1 for MCM-41 and 729 m2g-1 for Co-silicate. Co-silicate material showed high adsorbent potential compared to MCM-41. The high surface area, together with the pore size, together with the presence of metallic ions (cobalt) favored the adsorption process. The formation of active sites in the silicate, after the insertion of cobalt, favored the adsorption of the contaminant. From the adsorption tests carried out at pH 3, 6 and 9 it was possible to observe that the material with the best adsorption capacity was the Co-silicate material. Due to the kinetic tests, the Co-silicate material in the analyzed pH ranges showed a higher adsorption potential of bisphenol-A in relation to the removal results obtained with the MCM-41 material. The models used for the mathematical adjustments of the adsorption were the isotherms of Langmuir, Freundlich, and Redlich-Peterson. The value of the correlation coefficient (R2) 0.9641 pH 3; (R2) 0.9834 pH 6 and (R2) 0.9959 pH 9 of the Redlich-Peterson parameters suggested that the Redlich-Peterson model better describes the adsorption behavior of bisphenol-A in the Co-silicate material, since it presents Higher value of the pH correlation coefficient tested, compared with the Langmuir and Freundlich correlation values (R2). The data revealed that the modification of MCM-41 with cobalt atoms altered the physicochemical properties of the material and potentiated the adsorbent for adsorption of the bisphenol-A molecule.
Databáze: Networked Digital Library of Theses & Dissertations
Externí odkaz: