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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
1

Desenvolvimento de materiais comp?sitos porosos de PE-g-MA/fibra de coco/quitosana e aplica??o como materiais adsorventes na remo??o de cromo (III). / Development of PE-g-MA/coconut fiber/chitosan porous composite materials and application as adsorbents for the removal of chromium (III).

Wysard Junior, Mauro Meliga 15 October 2013 (has links)
Submitted by Sandra Pereira (srpereira@ufrrj.br) on 2017-01-20T13:13:06Z No. of bitstreams: 1 2013 - Mauro Meliga Wysard Junior.pdf: 3560905 bytes, checksum: 2826a580c7e2ec9ebe3a9e07daacb4f7 (MD5) / Made available in DSpace on 2017-01-20T13:13:06Z (GMT). No. of bitstreams: 1 2013 - Mauro Meliga Wysard Junior.pdf: 3560905 bytes, checksum: 2826a580c7e2ec9ebe3a9e07daacb4f7 (MD5) Previous issue date: 2013-10-15 / Coordena??o de Aperfei?oamento de Pessoal de N?vel Superior - CAPES / The need to reduce environmental impacts while maintaining economic efficiency of various processes has motivated research to develop cheaper and sustainable technologies, to replace those already employed in the industrial sectors. Thus, recycling and utilization of natural materials such as coconut fiber or marine animal shells, is envisioned as an alternative to reduce the environmental impact and at the same time the use of these components in industrial processes reduces operational costs. In this context the biosorbents are included, such as coconut fibers and chitosan, which have high applicability to processes for removing metal ions, and are widely available at low cost. In addition, the problem found in the recovery of these adsorbents and adsorbate after the adsorption process can be bypassed by setting biosorbents in polymeric matrixes, obtaining larger parts, which facilitates the separation steps. Thus, this work aims to develop porous composite adsorbent properties, from the physical mixture of maleic anhydride polyethylene (PE-g-MA), coconut fiber (FC), chitosan (Q), and sodium chloride (NaCl) used as porogen agent), and assess the capacity of these new porous composite in the removal of metallic chromium (III) Ion, since this is a residue present in large industrial activities such as electroplating. The porosity of this material was obtained by leaching of NaCl, present in the composition of composite material. For this assessment, we conducted a trial planning, where could be evaluate the influence of particle size of coconut fiber and the amount of chitosan on adsorption process efficiency, as well as the pH of an aqueous solution containing the chromium (III) adsorbate. With the results could be concluded that the model used in planning was valid for the evaluation of the significance of these variables, as well as the trend of better removal of chromium (III), which took place in the higher pH values (between 6 and 7) and in the presence of increased amounts of chitosan (7.5-8.6 g). The granulometric size range of coconut fiber that was more favorable was between 0.097-0.142 mm. Analyzing these porous composites by spectroscopy in the infrared (FTIR), X-ray diffraction (XRD), water absorption and scanning electron microscopy (SEM), you can see and confirm the strong interaction between the components of the mixture, possibly by interfering in the process efficiency of adsorption of chromium / A necessidade de reduzir impactos ambientais e ao mesmo tempo manter a efici?ncia econ?mica de diversos processos, vem motivando o meio acad?mico a realizar pesquisas voltadas para o desenvolvimento de novas tecnologias mais baratas e sustent?veis, que possam substituir as j? empregadas nos setores industriais. Desta forma, a reciclagem e a utiliza??o de mat?rias-primas naturais como a casca de coco e carapa?as de animais marinhos ? vislumbrada como uma alternativa para a redu??o do impacto ambiental, e ao mesmo tempo, pela utiliza??o desses componentes em processos industriais com a finalidade de reduzir custos operacionais. Neste contexto encontram-se os biossorventes naturais, como a fibra de coco e a quitosana, que apresentam alta aplicabilidade em processos de remo??o de ?ons met?licos, e uma grande disponibilidade a baixo custo. Al?m disso, o problema encontrado na recupera??o desses adsorventes e do adsorvato ap?s o processo de adsor??o pode ser contornado pela fixa??o dos biossorventes em matrizes polim?ricas, obtendo-se pe?as de maior volume, o que facilita as etapas de separa??o. Assim, este trabalho teve como objetivo desenvolver comp?sitos porosos com propriedades adsorventes, a partir da mistura f?sica de polietileno graftizado com anidrido maleico (PE-g-MA), fibra de coco (FC), quitosana (Q) e cloreto de s?dio (NaCl) utilizado como agente porog?nico), e avaliar a capacidade de adsor??o desses novos comp?sitos porosos na remo??o do ?on met?lico cromo (III), j? que este, ? um res?duo presente em grandes atividades industriais, como a galvanoplastia. Com esta finalidade, foi realizado um planejamento experimental, onde foi avaliada a influ?ncia do tamanho das part?culas de fibra de coco e da quantidade de quitosana na efici?ncia do processo de adsor??o, assim como o pH da solu??o aquosa contendo o adsorvato cromo (III). Com os resultados pode-se concluir que o modelo usado no planejamento experimental foi v?lido para a avalia??o da signific?ncia dessas vari?veis, como para as melhores condi??es de remo??o do cromo (III), as quais aconteceram nos valores mais elevados de pH (entre 6 e 7) e na presen?a de maiores quantidades de quitosana (7,5-8,6 g). A faixa granulom?trica da fibra de coco que se mostrou mais favor?vel foi de 0,097-0,142 mm. Analisando esses comp?sitos porosos por espectroscopia na regi?o do infravermelho (FTIR), difra??o de raios-X (DRX), absor??o de ?gua e microscopia eletr?nica de varredura (MEV), p?de-se constatar e confirmar a forte intera??o ocorrida entre os componentes da mistura, possivelmente, interferindo na efici?ncia do processo de adsor??o do cromo (III).

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