• JoomlaWorks Simple Image Rotator
  • JoomlaWorks Simple Image Rotator
  • JoomlaWorks Simple Image Rotator
  • JoomlaWorks Simple Image Rotator
  • JoomlaWorks Simple Image Rotator
  • JoomlaWorks Simple Image Rotator
  • JoomlaWorks Simple Image Rotator
  • JoomlaWorks Simple Image Rotator
  • JoomlaWorks Simple Image Rotator
  • JoomlaWorks Simple Image Rotator
 
  Bookmark and Share
 
 
Master's Dissertation
DOI
10.11606/D.44.1995.tde-21102015-144107
Document
Author
Full name
Mirian Chieko Shinzato
Institute/School/College
Knowledge Area
Date of Defense
Published
São Paulo, 1995
Supervisor
Committee
Hypólito, Raphael (President)
Carvalho, Adilson
Valarelli, José Vicente
Title in Portuguese
Estudo experimental de retenção de ions metálicos em vermiculita
Keywords in Portuguese
Mineralogia
Vermiculita
Abstract in Portuguese
A vermiculita é um mineral secundário resultante da alteração de micas; geralmente encontrada na forma de placas centimétricas (vermiculita macroscópica), ou na fração argila de solos. Neste trabalho, a vermiculita macroscópica proveniente da jazida de Massapé-Paulistana, localizada no município de Paulistana, sudeste do Estado de Piauí, foi utilizada nas formas natural e piroexpandida, com o objetivo de estudar sua propriedade de reter metais em solução. Análises químicas e mineralógicas permitiram definir a seguinte fórmula estrutural para o mineral estudado: ('Ca IND. 0.256' 'K IND. 0.159' 'Na IND. 0.058') ('Mg IND. 2.56' ''Fe POT. 3+' IND. 0.255' ''Fe POT. 2+' IND. 0.092' 'Ti IND. 0.042' 'Mn IND. 0.005' 'Li IND. 0.005') [ ('Si IND. 3.043' 'Al IND. 0.848' ''Fe POT. 3+' IND. 0.109') 'O IND. 10'] . '(OH) IND. 2' . 4.16 'H IND. 2'O A vermiculita de Massapé-Paulistana apresenta superfície específica (SE) e capacidade de troca catiônica (CTC) elevadas, quando micronizadas (< 200 mesh). A sua forma piroexpandida apresenta, no entanto, uma SE maior que a amostra natural, porém a sua CTC é mais baixa. A pequena CTC apresentada pela amostra expandida decorre da perda de água interfoliar durante o processo piroexpansão, dificultando, desta forma, a mobilidade dos cátions na posição interfoliar. Experiências realizadas com a amostra natural micronizada utilizando soluções salinas de natureza diversas ('Na POT. +', 'K POT. +', 'Ba POT. 2+', 'Mg POT. 2+', 'H IND. 3''O POT. +') permitiram verificar que a facilidade de troca catiônica está diretamente relacionada com as características dos íons: quanto maior o grau de hidratação do cátion interfoliar do mineral, em relação ao do cátion da solução, maior é sua facilidade de troca. Por este motivo, procurou-se utilizar, para os ensaios de troca iônica com metais pesados ('Pb POT. 2+', 'Cu POT. 2+', 'Ni POT. 2+'), amostras de vermiculita natural e aquelas saturadas previamente com cátions altamente hidratáveis ('H IND. 3''O POT. +', 'Mg POT. 2+'). Obteve-se para a vermiculita com 'H IND. 3''O POT. +' resultados satisfatórios em ensaios de troca com os íons cobre, chumbo e níquel. A amostra natural e aquela saturada com magnésio mostraram-se eficientes na troca com chumbo, entretanto, exibiram eficiências razoáveis na troca com níquel e cobre. A recuperação destes metais pesados retidos na estrutura das vermiculitas foi efetuada utilizando-se soluções de EDTA para acelerar o processo de troca.
Title in English
Not available.
Keywords in English
Not available.
Abstract in English
Vermiculite is a secondary mineral derived from mica weathering and is found generally as centimetric flakes (macroscopic vermiculite) or as a clay mineral in soil. In this work macroscopic vermiculite from the Massapé-Paulistana deposit, near Paulistana, southeast Piauí, was employed in its natural and expanded forms to study its property in exchanging metals in solution. Chemical and mineralogical analyses of natural vermiculite defined its structural formula as: ('Ca IND. 0.256' 'K IND. 0.159' 'Na IND. 0.058') ('Mg IND. 2.56' ''Fe POT. 3+' IND. 0.255' ''Fe POT. 2+' IND. 0.092' 'Ti IND. 0.042' 'Mn IND. 0.005' 'Li IND. 0.005') [ ('Si IND. 3.043' 'Al IND. 0.848' ''Fe POT. 3+' IND. 0.109') 'O IND. 10'] . '(OH) IND. 2' . 4.16 'H IND. 2'O When in fine grains (< 200 mesh), the Massapé-Paulistana macroscopic vermiculite has both high surface area (SA) and cation exchange capacity (CEC). The expanded form has a higher SA than the natural samples, which, in turn, also have higher CEC. However, because the expanded form has lost some interlayer water during expansion by heating, cation movement in the interlayer space becomes more difficult. Experiments performed with 200-mesh fractions of natural sample using different cations in solution ('Na POT. +', 'K POT. +', 'Ba POT. 2+', 'Mg POT. 2+', 'H IND. 3''O POT. +') showed that the CEC of each ion is directly related to ionic characteristics: the higher the hydration of the interlayer cation, the higher its CEC. For this reason, samples of natural vermiculite and others saturated with 'H IND. 3''O POT. +' and with 'Mg POT. 2+' were employed to exchange some heavy metals ('Pb POT. 2+', 'Cu POT. 2+', 'Ni POT. 2+') in solution. Vermiculite with 'H IND. 3''O POT. +' yielded the most satisfactory results, allowing lead, nickel and copper exchange. Both natural vermiculite and those saturated with 'Mg POT. 2+' were very efficient in exchanging lead but not much nickel and copper. The recovery of these heavy metals from the vermiculite structure was also studied; in this case EDTA solution was employed to accelerate the exchange process.
 
WARNING - Viewing this document is conditioned on your acceptance of the following terms of use:
This document is only for private use for research and teaching activities. Reproduction for commercial use is forbidden. This rights cover the whole data about this document as well as its contents. Any uses or copies of this document in whole or in part must include the author's name.
Publishing Date
2015-10-26
 
WARNING: Learn what derived works are clicking here.
All rights of the thesis/dissertation are from the authors
Centro de Informática de São Carlos
Digital Library of Theses and Dissertations of USP. Copyright © 2001-2021. All rights reserved.