SORAYA MARIA RIZZO DA ROCHA

SORAYA MARIA RIZZO DA ROCHA

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Obtaining pure praseodymium acetate to use in researches and development
2010 - QUEIROZ, CARLOS A. da S.; ROCHA, SORAYA M.R. da; PEDREIRA, WALTER R.; SENEDA, JOSE A.; LOBO, RAQUEL M.; S. FILHO, WALTER
This paper presents a simple and economical procedure to obtain high purity praseodymium acetate. The raw material in the form of mixed rare earths carbonate comes from a industrial separation of rare earths, thorium and uranium in the brasilian monazite. It is used the tecnique of strong cation exchange resin, proper to water treatment, to the praseodymium's fractionation and it is achieved a purity of 99.9% in Pr6O11 and yield greater than or equal 60%, with the elution of rare earths by EDTA solution in pH controlled. The complex of EDTA-praseodymium is transformed in praseodymium oxide, subsequently the oxide is dissolved in acetic acid to obtain the praseodymium acetate. The molecular absorption spectrophotometry tecnique is used to monitoring the praseodymium content during the process and mass spectrometry to certification the purity of the praseodymium acetate. The typical praseodymium acetate obtained presents the followings contaminants in micrograms per gram: Sc(18.20±0.22); Y (20.20 ± 0.20); La (6.75 ± 0.81); Ce (26.10 ± 0.70); Nd (3.31 ± 0.63); Sm (18.30 ± 0.80); Eu (17.00 ± 0.90); Gd (19.40 ± 0.40); Tb (16.30 ± 0.50); Dy (16.90 ± 0.50), Ho(17.90 ± 0.10); Er (18.40 ± 0.70); Tm (16.90 ± 0.10); Yb (17.60 ± 0.60); Lu (17.70 ± 0.50). The high purity praseodymium acetate comes being applied, replacing the imported product, in research and development area on rare earth catalysts.
Advanced mass spectrometric applied to determinated of composition in lead (Pb-208) from residues of thorium facilities
2007 - SENEDA, JOSE A.; QUEIROZ, CARLOS A. da S.; RIZZO, SORAYA M. da R.; DIAS, MAURO S.; KAKAZU, MAURICIO H.; ABRAO, ALCIDIO
Obtencao experimental de acetato de praseodimio de alta pureza a partir de carbonatos mistos de terras raras
2010 - QUEIROZ, C.A. da S.; ROCHA, S.M.R. da; PEDREIRA, W.R.; SENEDA, J.A.; LOBO, R.M.; FILHO, W.S.
Sintese e caracterizacao de precursores a base de lantanio para aplicacao em catalisadores
2002 - ROCHA, S.M.R.; QUEIROZ, C.A.S.; ABRAO, A.
Synthesis and characterization of lanthanum acetate for application as a catalyst
2001 - ROCHA, S.M.R.; QUEIROZ, C.A.S.; ABRAO, A.
Study on radiogenic lead recovery from residues in thorium facilities using ion exhange anb electrochemical process
2007 - SENEDA, JOSE A.; FORBICINI, CHRISTINA A.L.G. de O.; QUEIROZ, CARLOS A. da S.; VASCONCELLOS, MARI E. de; FORBICINI, SERGIO; RIZZO, SORAYA M. da R.; ABRAO, ALCIDIO
Synthesis and characterization of lanthanum acetate for application as a catalyst
2002 - ROCHA, S.M.R.; QUEIROZ, C.A.S.; ABRAO, A.
Síntese e caracterização de precursores à base de lantânio para aplicação em catalisadores
2002 - ROCHA, S.M.R.; QUEIROZ, C.A.S.; ABRAO, A.
A partir dos carbonatos mistos de terras raras empobrecidos em cério, separa-se o lantânio em sistema de colunas de troca iônica, preenchidas com resina catiônica forte. Obtém-se óxido de lantânio com pureza igualou superior a 99,9% em uma única operação, por eluição com EDTA amoniacal. Acetato de lantânio é, então, sintetizado para obtenção do precursor catalítico com alta área específica. O uso de precursores à base de terras raras, como o acetato de lantânio, é de grande interesse no desenvolvimento de catalisadores. Os estudos nesta área apontam que a pureza do material inicialmente empregado fornece precursores com alta área específica, melhorando o desempenho de vários sistemas catalíticos.
Study on radiogenic lead recovery from residues in thorium facilities using ion exchange and electrochemical process
2010 - SENEDA, J.A.; FORBICINI, C.A.L.G. de O.; QUEIROZ, C.A. da S.; VASCONCELLOS, M.E. de; FORBICINI, S.; RIZZO, S.M. da R.; SALVADOR, VERA L.R.; ABRÃO, A.
Brazil has one of the biggest mineral thorium reserves, enabling the use of this material in its nuclear reactors. Consequently, this cycle of the fuel would need an initial purification stage of the natural thorium, generating residues from chemical treatment. This work provides operational parameters for the recovery of existing values in these residues, especially the radiogenic lead, that is a radioisotope of thorium decay chain, using ionic exchange technique associated to the electrochemical one. The treatment by ionic exchange in anionic resin and hydrochloric acid medium, provides about 33.4% of radiogenic lead. At the electrochemical process, lead was reduced to a metal in nitric acid medium, presenting a recovery of 98%. The electrochemical process presents an increase in the cost, nevertheless the technological importance of the radiogenic lead in the production of new elements, besides being a strategic material, justifies its use.