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D.Sc. / The ion exchange properties of a number of synthetic inorganic ion exchangers and the natural zeolite, clinoptilolite, were evaluated with respect to the elements Na, Cs, Sr, Ba, Ce(III), Eu, Zr, U(VI), Np(V), PU(IV) and Am(III). The role of the structure of crystalline exchangers in determining the selectivity thereof, especially in the case of clinoptilolite, was also investigated. Hydrated antimony pentoxide and antimonic acid showed high sorption of a number of ions over a wide pH range (2 - 10). The selectivity order of hydrous oxides for the actinides was as follows: PU(IV) > Am(III) > U(VI) > Np(V). Titanium phosphate, zirconium phosphosilicate and sodium titanate, however, preferred U to Am. To predict the selectivity order of crystalline inorganic ion exchangers, the Eisenman theory could be used, but other factors such as ion sieve effects had to be taken into account. In such cases the parameters contributing to the change in free energy during ion exchange plays a major role. Samples containing clinootilolite from two deposits in South Africa were evaluated with respect to chemical composition, conversion to the sodium, calcium and cesium forms, as well as the sorption of Cs and Sr from various media. Similar trends to those:reported for clinoptilolite from other parts of the world were found. Rietveld refinement of the structure of Cs-exchanged clinoptilolite was carried out using powder diffraction data and the computer program WYRIET. The zeolite was not isolated from the natural matrix, which meant that a number of phases had to be included in the refinement process. The refinement confirmed the...

Thesis (Ph. D.)--Lehigh University, 1999. / Includes vita. Bibliography: leaves 243-258.

Thesis (Ph. D., Chemical Engineering)--University of Idaho, May 2006. / Major professor: Vivek Utgikar. Includes bibliographical references (leaves 99-107). Also available online (PDF file) by subscription or by purchasing the individual file.

Made available in DSpace on 2014-10-09T12:23:06Z (GMT). No. of bitstreams: 0 / Made available in DSpace on 2014-10-09T13:56:09Z (GMT). No. of bitstreams: 1 00622.pdf: 2326364 bytes, checksum: 665ea383abf1ee58d4ae5e2198a0bebb (MD5) / Dissertacao (Mestrado) / IEA/D / Escola Politecnica, Universidade de Sao Paulo - POLI/USP

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Made available in DSpace on 2014-10-09T12:23:06Z (GMT). No. of bitstreams: 0 / Made available in DSpace on 2014-10-09T13:56:09Z (GMT). No. of bitstreams: 1 00622.pdf: 2326364 bytes, checksum: 665ea383abf1ee58d4ae5e2198a0bebb (MD5) / Dissertacao (Mestrado) / IEA/D / Escola Politecnica, Universidade de Sao Paulo - POLI/USP

Made available in DSpace on 2014-10-09T12:53:26Z (GMT). No. of bitstreams: 0 / Made available in DSpace on 2014-10-09T13:58:38Z (GMT). No. of bitstreams: 0 / Este trabalho apresenta a síntese, caracterização e estudos de adssorção de trocadores iônicos inorgânicos a base de óxidos mistos estanho-titânio para recuperação dos metais cádmio e níquel de efluentes aquosos, descartados no meio ambiente principalmente através de baterias de Ni-Cd. Os trocadores foram sintetizados via método sol-gel modificado da mistura de cloreto de estanho(IV) e cloreto de titânio(III) com hidróxido de amônio. Os materiais obtidos: SnO2/TiO2 e SnO2/TiO2:Eu3+ foram caracterizados via espectroscopia de infravermelho, análise térmica, microscopia eletrônica de varredura (MEV), difração de raios-X (DRX) (método do pó) e espectroscopia eletrônica (excitação e emissão) para o trocador dopado com európio. Os mesmo materiais também foram sintetizados em matriz polimérica para a sua utilização em coluna, devido os materiais sintetizados apresentarem tamanho de cristalito na escala nanométrica. Determinaram-se as razões de distribuição dos metais, tomando-se como parâmetros a influência do pH, da concentração dos metais (determinando-se as isotermas de adsorção) e do tempo de contato (determinando-se a cinética de adsorção). Os trocadores apresentaram alta capacidade de troca, com porcentagens de adsorção acima de 90%, cinética rápida, superfícies de troca energeticamente heterogenias, adsorção física e processo de troca espontâneo. Para o trocador dopado foram estudadas as propriedades espectroscópicas e calculado os parâmetros de intensidade também se obteve um rendimento quântico satisfatório. / Dissertação (Mestrado) / IPEN/D / Instituto de Pesquisas Energeticas e Nucleares - IPEN-CNEN/SP

Made available in DSpace on 2014-10-09T12:46:03Z (GMT). No. of bitstreams: 0 / Made available in DSpace on 2014-10-09T13:59:45Z (GMT). No. of bitstreams: 1 07536.pdf: 5663211 bytes, checksum: 0b68204c0f6a1c7f09e9308ae2274961 (MD5) / Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP) / Dissertacao (Mestrado) / IPEN/D / Instituto de Pesquisas Energeticas e Nucleares - IPEN/CNEN-SP / FAPESP:97/07964-0