CARLOS ALBERTO DA SILVA QUEIROZ
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Artigo IPEN-doc 14211 Quantification of trace amounts of rare earth elements in high purity gadolinium oxide by sector field inductively coupled plasma mass spectrometry (ICP-MS)2004 - PEDREIRA, W.R.; QUEIROZ, C.A. da S.; ABRAO, A.; PIMENTEL, M.M.Artigo IPEN-doc 10222 Sequential separation of the yttrium-heavy rare earths by fractional2004 - VASCONCELLOS, M.E.; QUEIROZ, C.A.S.; ABRAO, A.Artigo IPEN-doc 10226 Synthesis and thermoanalytical characterization of samarium peroxocarbonate2004 - QUEIROZ, C.A.S.; VASCONCELLOS, M.E.; ROCHA, S.M.R.; SENEDA, J.A.; PEDREIRA, W.R.; MATOS, J.R.; ABRAO, A.Artigo IPEN-doc 12977 Solubility behavior of rare earths with ammonium carbonate and ammonium carbonate plus ammonium hydroxide: precipitation of their peroxicarbonates2008 - VASCONCELLOS, MARI E. de; ROCHA, S.M.R.; PEDREIRA, W.R.; QUEIROZ, CARLOS A. da S.; ABRAO, ALCIDIOThe purpose of this work is to report the significant behavior of the rare earths when treated with ammonium carbonate and with a binary mixture of ammonium carbonate plus ammonium hydroxide. The carbonates of some rare earths are completely soluble in ammonium carbonate or in ammonium carbonate plus ammonium hydroxide, while others are only partially soluble and finally some are completely insoluble. Addition of hydrogen peroxide to the soluble complexed rare earth carbonates results in the precipitation of a series of a new compounds described as rare earth peroxicarbonates. The rare earths have some different precipitation behavior in the carbonate–peroxide system. Some are completely and immediately precipitated, others are completely precipitated after an aging period, and finally other are not precipitated at all. These different behaviors open a new possibility for the separation chemistry of the rare earths. Sm, Gd, Dy, Y, Yb and Tm are fast and completely soluble in ammonium carbonate. Ho, Eu and Tb are completely soluble in ammonium carbonate but slowly dissolved. La, Ce, Pr and Nd are only partially soluble in ammonium carbonate. While Ce, Pr, Nd, Sm, Eu and Dy are completely and easily soluble in the ammonium carbonate plus ammonium hydroxide mixture, La is only partially soluble and Tb is completely insoluble in the same mixture. Concerning the peroxicarbonates, La, Ce, Pr, Nd, Sm, Eu, Gd, Dy and Ho are quantitatively precipitated. The precipitation of the Er peroxicarbonate is quantitative, but after an aging period of 24 h. Y is not precipitated at all. The process is very easy, simple and economically attractive. Although proved in bench scale, its scale-up is easily feasible.