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Master's Dissertation
Full name
Paulo Cesar Ocheuze Trivelin
Date of Defense
Piracicaba, 1976
Title in Portuguese
Enriquecimento isotópico de 15N por cromatografia de troca iônica
Keywords in Portuguese
Abstract in Portuguese
O método cromatográfico de troca iônica, em colunas de resina, foi empregado no estudo do enriquecimento isotópico de 15N. Inicialmente, foram feitas determinações da constante de separação de troca dos isótopos 15N e 14N, no equilíbrio envolvendo hidróxido de amônio na fase solução e iônios NH+4 adsorvidos em resinas catiônicas: Dowex 50W-X8 e X12, 100-200 ?mesh?. Foram descritos três sistemas de enriquecimento isotópico de nitrogênio, constituídos de colunas de resinas catiônicas, onde se desenvolveram experimentos sobre o fracionamento de 15N e 14N, deslocando-se bandas de NH+4 adsorvidos, estabelecidos com solução de hidróxido de amônio, por eluição com hidróxido de sódio. Foram também conduzidos experimentos para produção de sulfato de amônio enriquecido a 5 átomos % em 15N, que tiveram por objetivos verificar sua viabilidade econômica. Finalmente, ainda foram feitas, determinações de altura de placas teóricas, em situações de equilíbrio para a banda de NH+4 onde se procurou avaliar as condições experimentais empregadas. As análises isotópicas de nitrogênio nos estudos sobre o enriquecimento de 15N foram realizadas por espectrometria de massa.
Abstract in English
The chromatographic ion exchange method in resin columns was employed in the study of 15N isotopic enrichment. Initially the constant for the exchange of 15N and 14N isotopes was investigated in the equilibrium between ammonium hydroxide, in solution phase, and NH+4 ion adsorbed in the cationic resins: Dowex 50W-X8 and X12, 100-200 mesh. Three systems for nitrogen isotopic enrichment were described. They consisted of cationic resin columns, in which experiments of 15N and 14N fractionation were developed displacing adsorbed ammonium bands set up with hydroxide solution by elution with sodium hydroxide. Experiments of ammonium sulphate production enriched to the level of 5 atoms % in 15N, were also developed, which had the objective of verifying its economic viability. Finally, determinations of the heights of theoretical plates were made under stead state conditions for NH+4 bands, in which the employed experimental conditions were evaluated. The isotopic nitrogen analysis in the 15N enrichment studies were made by mass spectrometry.
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