CARLOS ALBERTO DA SILVA QUEIROZ

CARLOS ALBERTO DA SILVA QUEIROZ

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Preparation of lanthanum acetate from a mixed rare earths concentrate
2023 - QUEIROZ, CARLOS A. da S.
A simple and economical chemical process to obtaining lanthanum acetate of high purity was studied. The raw material in the form of mixed rare earths carbonate 24% La2O3 comes from commercial Brazilian monazite. It is used the technique of strong cationic exchange resin, proper to water treatment to the lanthanum''s fractionation and it is achieved a purity of 99.9% La2O3 and yield greater than or equal 90%, with the elution of rare earths by EDTA solution at pH 4.0. The complex of EDTA-La is transformed in La2O3 , subsequently the lanthanum oxide is dissolved in acetic acid to obtain the cerium acetate. The solid salt then is characterized via chemical analysis, thermal analysis, X ray diffraction, infrared spectroscopy and mass spectrometry to certify the lanthanum acetate purity. The analytical data collected allowed to conclude that the stechiometric formula for the compound is La (CH3COO)3.1.5 H2O.
Production of high purity samarium acetate for use in nuclear area
2021 - QUEIROZ, CARLOS A. da S.; PEDREIRA FILHO, WALTER dos R.
Samarium is currently used in many applications, such as catalysts, lasers and metal alloys. Samarium is also employed to absorb neutrons in nuclear reactors. In medicine, samarium is used in the form of radioactive 153Sm to produce radiopharmaceuticals. A simple process for the preparation of pure samarium acetate was studied. The raw material, which was used in the form of rare earth carbonates was produced industrially from the chemical treatment of Brazilian monazite. Ion exchange chromatography was performed using a strong cationic resin to fractionate rare earth elements (REE). Under these conditions, 99.9% pure Sm2O3 and yield greater than or equal 60% was eluted by ammonium salt of ethylenediaminetetraacetic acid (EDTA) solution in con-trolled pH. The EDTA-samarium complex was transformed into samarium oxide, which was subsequently dis-solved in acetic acid to obtain the samarium acetate. Molecular absorption spectrophotometry was used to moni-tor the samarium and sector field inductively coupled plasma mass spectrometry was used to certify the purity of the samarium acetate. The solid salt was characterized by chemical analysis, thermal analysis, infrared spectros-copy and X ray diffraction. The analytical data collected allowed to conclude that stoichiometric formula for the samarium acetate obtained is Sm(CH3COO)3.4.H2O.
Synthesis and characterization of praseodymium acetate for use in nanotechnology
2019 - QUEIROZ, CARLOS A. da S.
A simple and economical chemical process to obtaining praseodymium acetate of high purity is studied. The raw material in the form of mixed rare earths carbonate comes from an industrial separation of rare earths, thorium and uranium in the Brazilian monazite. It is used the technique of strong cationic 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 80%, with the elution by EDTA solution in pH controlled. The complex of EDTApraseodymium is transformed in praseodymium oxide, subsequently the oxide is dissolved in acetic acid to obtain the praseodymium acetate. The solid salt was characterized via chemical analysis, thermal analysis, X ray diffraction and infrared spectroscopy. In summary the analytical data collected allowed to conclude that stoichiometric formula for the praseodymium acetate obtained is Pr(CH3COO)3.1.5H2O. The molecular absorption spectrophotometry technique 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 contain the followings contaminants in micrograms per gram: Y( 20 ), Sc ( 18 ), La ( 6 ), Ce ( 26 ), Nd ( 3 ), Sm ( 18 ), Eu ( 17 ), Gd (19 ), Tb ( 16 ), Dy (17 ), Ho ( 18 ), Er (18 ), Tm ( 16 ),Yb ( 17 ), Lu ( 17.0), Lu ( 17 ).
Preparation of high purity cerium precursors for use in automotive catalysts
2018 - QUEIROZ, CARLOS A. da S.
Starting with a fraction of mixed rare earths chloride with 47% in CeO2 , high pure cerium oxide and acetate was prepared. The mixed rare earths chloride solution was treated by fractionated precipitation technique. Cerium (III) was oxidized to cerium (IV) by addition of hydrogen peroxide. The acidity liberated in the hydrolytic process was neutralizes with NH3 stream generated by compressed air injected into the 1M NH4OH solution and bubbled into the rare chlorides solution. The temperature was maintained at 60oC. After the complete cerium hydroxide precipitation, it was separated by filtration. This hydroxide precipitate enriched in cerium (90% in CeO2) was dissolved in hydrochloric acid and the cerium chloride solution was used as the feeling solution to a strong cationic ion exchanger resin system. After loading the resin with de cerium, it was rinsed with water and eluted the ions by complexation with ammonium salt of EDTA adjusted to pH 4,0. Free EDTA acid was precipitated by addition of chloride acid to the cerium complex eluted and it was separated by filtration. The ultimate cerium chloride solution was treated with oxalic acid and the cerium oxalate separated, dried and fired to cerium oxide. The highly pure cerium oxide prepared (99.9%) was directly dissolved with hot concentrated acetic acid.The typical cerium acetate obtained contain the followings contaminants in micrograms per gram: Y(4.1 ), Sc (15.4 ), La (32.4), Pr (14.6), Nd (6.5), Sm (9.7), Eu (5.3), Gd (9.2), Tb (6.2), Dy (5.4), Ho (0.08) Er(0.9), Tm (0.2),Yb ( 20.5), Lu (2.3).
Synthesis and characterization of neodymium acetate for use in nanotechnology
2018 - QUEIROZ, CARLOS A. da S.
A simple and economical chemical process to obtaining neodymium acetate of high purity was studied. The raw material in the form of mixed rare earths carbonate comes from Brazilian monazite. It was used the technique of strong cationic exchange resin, proper to water treatment to the neodymium''s fractionation and it is achieved a purity of 99.9% in Nd2O3 and yield greater than or equal 80%, with the elution of rare earths by EDTA solution in pH controlled. The complex of EDTA-neodymium is transformed in neodymium oxide, subsequently the oxide is dissolved in acetic acid to obtain the neodymium acetate. The solid salt was characterized via chemical analysis, thermal analysis, X ray diffraction, infrared spectroscopy and inductively coupled plasma mass spectrometry to certify the purity.The analytical data collected allowed to conclude that the stoichiometric formula for the compound is Nd(CH3COO)3.1.5H2O. The typical neodymium acetate obtained (purity ≥ 99.9%) contain the followings contaminants in micrograms per gram: Y(0.9), Sc (5.1), La (1.0), Pr (3.4), Sm (12.8), Eu (1.1), Gd (15.4), Tb (2.9), Dy (5.3), Ho (7.4) Er(1.5), Tm (0.3),Yb ( 2.5), Lu (1.0).
Preparation of neodymium acetate for use in nuclear area and nanotechnology
2017 - QUEIROZ, C.A.S.; PEDREIRA FILHO, W.R.; SENEDA, J.A.
Neodymium and its compounds are being increasingly applied in the manufacture of new materials. In nuclear area neodymium isotopes are used in a variety of scientific applications. Nd-142 has been used to produce short-lived Tm and Yb isotopes. Nd-146 has been suggested to produce Pm-147 and Nd-150 has been used to study double beta decay. Due to the several modern applications using nanomaterials, more and more highly rare earth compounds have been demanded. The researches at IPEN uses the experience gained in rare earth separation for the preparation of some pure acetates, purity > 99.9% for application in nanotechnology research. A simple and economical chemical process to obtaining neodymium acetate of high purity is studied. The raw material in the form of mixed rare earths carbonate comes from Brazilian monazite. It is used the technique of strong cationic exchange resin, proper to water treatment, to the neodymium's fractionation and it is achieved a purity of 99.9% in Nd2O3 and yield greater than or equal 80%, with the elution of rare earths by EDTA solution in pH controlled. The complex of EDTA-neodymium is transformed in neodymium oxide, subsequently the oxide is dissolved in acetic acid to obtain the neodymium acetate. The solid salt was characterized via molecular absorption spectrophotometry, mass spectrometry, thermal analysis, chemical analysis and X ray diffraction. In summary the analytical data collected allowed to conclude that the stoichiometric formula for the neodymium acetate prepared is Nd(CH 3COOH)3.1.5H2O.
Conditions for the ion exchange separation of gadolinium and samarium from a mixed rare earths carbomates
1985 - QUEIROZ, CARLOS A. da S.; ABRAO, ALCIDIO
Trace amounts of rare elements in high pure gadolinium oxide by sector field inductively coupled plasma mass spectrometry (SF ICP-MS)
2003 - PEDREIRA, W.R.; QUEIROZ, C.A.S.; ABRAO, A.; PIMENTEL, M.M.
Preparacao de nitrato de cerio de alta pureza
1995 - AVILA, D.M.; QUEIROZ, C.A.S.; MUCCILLO, E.N.S.
Sintese e caracterizacao de Lnsub(2)Osub(3) (Ln=Ce e Gd) de alta pureza
1999 - AVILA, D.M.; MUCCILLO, E.N.S.; QUEIROZ, C.A.S.