No description available.

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

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Les problèmes de pollution chimique de l'eau sont devenus une source de préoccupation importante et un enjeu prioritaire pour les industriels du nucléaire. L'objectif principal de cette thèse est d'étudier certains minéraux échangeurs ioniques utilisables pour une décontamination liquide en strontium (radioisotope toxique pour l'homme). Mais également de relier les propriétés physico-chimiques de ces matériaux avec leurs propriétés de rétention du radioisotope. Ce mémoire présente donc la synthèse de deux matériaux choisis pour leurs propriétés de sorption spécifique et quantitative du strontium : le nonatitanate de sodium et la zéolithe A. Une seconde partie du travail est dédiée à l'étude des capacités d'échange spécifique de ces matériaux vis-à-vis du strontium en présence d'autres éléments comme le sodium et le calcium. Le nonatitanate de sodium et la zéolithe A ont également été testés sur des effluents réels. Les performances d'un monolithe de zéolithe A ont été évaluées pour un procédé de traitement en colonne. Ce matériau semble prometteur pour la décontamination d'effluents car il permet de cumuler les avantages de la poudre de zéolithe A avec ceux d'un transfert de matière sans perte de charge du solide. / The problems of chemical pollution of water have become a major concern and a priority for the nuclear industry.The aim of this work is to study some ion exchangers used for the removal of strontium ions because 90Sr is one of a major pollutant in nuclear liquid wastes. This study allows linking the physical and chemical properties of these materials and their sorption properties. This work presents therefore the synthesis of two materials - sodium nonatitanate and zeolite A - selected for their specific sorption properties of strontium: A second part of this work is dedicated to the study of specific exchange capacities of these materials for the strontium in presence of other elements such as sodium and calcium. Batch experiments were performed and kinetic and ion exchange models have been applied to understand the selectivity of the materials for strontium removal. Sodium nonatitanate and zeolite A are also studied in actual effluents.Monoliths of zeolite A have been also tested in dynamic ion exchange process. This material is promising for the treatment of radioactive effluents in continuous flow because it joins the sorption properties of the zeolite powder with the advantage of a solid with a macroporous network.

The aim of master's thesis is separation rubidium from cement bypass dust by columns based od hexacyanoferric and resins

No description available.

Activated Carbon was produced from strong cation-exchange resins, sulphonated styrene divinylbenzene copolymers originally in H+ form, by means of carbonization and steam activation in an electrical furnace. One macroporous resin produced by BAYER Chemicals Inc., Lewatit MonoPlus SP 112 H, was used in the research. Products of carbonization and activation were characterized by using BET, Mercury Porosimetry, Helium Pycnometry and SEM techniques. The effect of carbonization time and temperature on the BET surface areas of the resins were also investigated. Two sets of carbonization experiments (Set 1 and 2) were performed in which time and temperature were varied in order to study their effects on the BET surface areas of the products. In activation experiments (Set 3), carbonized ion-exchangers (600 oC, 1 hr) were activated with steam at 900&deg / C, changing the time of activation and the steam flow rate. The temperatures of the water bath used for steam generation were selected as 60&deg / C, 80&deg / C and 90&deg / C. The pore structures of activated carbons were determined by proper techniques. The volume and area of macropores in the pore diameter range of 8180-50 nm were determined by mercury intrusion porosimetry. Mesopore (in the range of 50-2 nm) areas and volumes were determined by N2 gas adsorption technique at -195.6oC, BET surface areas of the samples were also determined, in the relative pressure range of 0.05 to 0.02, by the same technique. The pore volume and the area of the micropores with diameters less than 2 nm were determined by CO2 adsorption measurements at 0oC by the application of Dubinin Radushkevich equation. In the experiments of Sets 1 and 2, the BET surface area results of the six different carbonization times ranging from 0.5 to 3 hours gave almost the same value with a maximum deviation of 5% from the average showing almost no effect on the areas of the products. In the experiments of Set 3 , the sample activated at 800&deg / C for 6 hrs had the highest BET area, 2130 m2/g, and the one activated at 800&deg / C for 1 hr had the lowest BET area 636 m2/g. N2 adsorption/ desorption isotherms showed no distinct hysteresis indicating a cylindrical geometry of the pores. Adsorption isotherms further indicated that the pores are both highly microporous and mesoporous. N2 (BET) and CO2 (D-R) surface areas of the samples were in the range of 636-2130m2/g and 853-1858 m2/g, respectively. Surface areas of the samples consisted of about 8-53% mesopores and 47-92% micropores.