Thermoanalytical characterization of neodymium peroxicarbonate

Queiroz, Carlos Alberto da Silva; Matos, J. R.; Vasconcellos, Mari E. de; Abrão, A.

doi:10.1016/s0925-8388(02)00300-6

Cited by 12 publications

(10 citation statements)

References 4 publications

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“…In accordance with recent published data [24,25], rare earth elements may form stable peroxy-carbonate compounds in peroxide-containing aqueous environments. Hence, the existence of a peroxy-carbonate species La 2 O 2 (CO 3 ) 2 also in a basic molten carbonate, where peroxide ions are abundant, is worth to be examined.…”

Section: Discussionsupporting

confidence: 91%

“…On the other hand, there could be a possibility that a different basic dissolution path would be also operating in a decreasing basic carbonate where larger amounts of superoxide ions are present: (24) In this case, the theoretical CO 2 dependence of the La solubility is predicted to be higher (i.e., -1.0 ) than in the previous case. A study of the La solubility as a function of CO 2 ( and also of O 2 ) should allow to precise whether superoxide ions are effectively involved in the basic dissolution of 3 …”

mentioning

confidence: 90%

“…As the thermal stability of rare earth peroxy-carbonates is reported to decrease rapidly above 873 K (600°C) [24], the involvement of this reaction in the La 2 O 3 dissolution process is expected to be more relevant at decreasing melt temperatures.…”

mentioning

confidence: 99%

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Lux-Flood Basicity of Mixed La2O3-Alkali Molten Carbonates Determined by Analysis of their Oxygen Solubility Properties

Frangini¹

2009

TOPCJ

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Abstract:The Lux-Flood basicity of La 2 O 3 -containing alkali molten carbonate mixtures has been quantitatively estimated by a gas solubility method based on the use of acidic gaseous O 2 for the titration of the oxide concentration in the melt. The amount of gaseous oxygen dissolved in the melt in form of peroxide ion has been taken as a quantitative probe for the carbonate basicity. Results demonstrate that addition of a 0.5 mol % of La 2 O 3 to alkali carbonates is able to dramatically increase the melt basicity and that the degree of this basicity change mostly depends on the melt composition in terms of the average cation size of the alkali carbonate mixture. Plausible dissolution paths of La 2 O 3 in molten carbonates under both acidic and basic regimes are also discussed.

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Section: Discussionsupporting

confidence: 91%

mentioning

confidence: 90%

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Lux-Flood Basicity of Mixed La2O3-Alkali Molten Carbonates Determined by Analysis of their Oxygen Solubility Properties

Frangini¹

2009

TOPCJ

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“…The oxide was dissolved and cerium assayed by iodometry. 11 Total Rare Earth concentrations in the filtrate, depleted in cerium, were analyzed after their conversion to nitrates, precipitation with oxalic acid and subsequent calcination to the oxides. Cerium in this oxide was also assayed by iodometry.…”

Section: Analytical Experimentsmentioning

confidence: 99%

“…Cerium in this oxide was also assayed by iodometry. 11 The final cerium oxide samples, purified by the process described above, were analyzed for the other accompanying Rare Earths as contaminants by ICP-MS and neutron activation analyzes (NAA). For neutron activation analyzes the oxides were irradiated directly in the IEA-R1 Nuclear Reactor, S.Paulo.…”

Section: Analytical Experimentsmentioning

confidence: 99%

Pure cerium dioxide preparation for use as spectrochemical standard and analysed by inductively coupled plasma mass spectrometry (SF ICP-MS)

Queiroz¹,

Pedreira²,

Abrão³

et al. 2005

J. Braz. Chem. Soc.

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Ao longo dos anos, o Instituto de Pesquisas Energéticas e Nucleares (IPEN/CNEN-SP) tem realizado diversas pesquisas na produção de Terras Raras (RE) de alta pureza. A metodologia apresentada neste trabalho refere-se à produção econômica e de baixo custo de óxido de cério. O cério produzido pode ser utilizado como um padrão espectroquímico. A obtenção desse padrão está associada à precipitação fracionada pelo sistema RECl 3 /NH 4 OH/Ar/H 2 O 2 , para enriquecer o óxido de cério de 90% a 99,99% em CeO 2 . O controle de qualidade do padrão produzido é feito através da técnica da espectrometria de massas com fonte de plasma (ICP-MS) e confirmado pela técnica da ativação de nêutrons. Os valores das impurezas de Terras Raras no óxido, em ppm são: La(36), Pr(19), Nd(161), Sm(11), Eu(5,3), Gd(113), Tb(89), Dy(2), Ho(0,05), Er(1), Tm(<0,05), Yb(11), Lu(19) e Y(2,1), respectivamente. Os valores encontrados das impurezas são comparados aos padrões internacionais e confirmam o alto nível de pureza do óxido de cério produzido no IPEN.For several years, IPEN/CNEN-SP has been working in the separation of the Rare Earth (RE) elements. A simple and economic procedure for the purification of technical grade cerium concentrate is described. The highly pure cerium dioxide is designed to be used as spectrochemical standard. It is obtained by association of the fractional precipitation technique, in the system RECl 3 /NH 4 OH/ Air/H 2 O 2 , to enrich the cerium up to 90% and then it is upgraded by ion exchange technique to 99.99% CeO 2 . The quality control warranty was accomplished by inductively coupled mass spectrometry (ICP-MS) and neutron activation analysis. The collected values for the accompanying Rare Earth elements in a CeO 2 sample are the following (ppm):

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