Тип публикации: статья из журнала
Год издания: 2011
Идентификатор DOI: 10.1039/c1jm11202c
Ключевые слова: Actinide immobilization, Crystalline structure, Crystallization process, Hydrothermal treatments, Oxide systems, Phase formations, Spent nuclear fuels, Structural type, Thermochemical Conversion, Zirconium molybdate, Anoxic sediments, Bearings (structural), Ceramic materials, Crystallization, Effluents, Ion exchange, Lanthanum, Loading, Molybdenum oxide, Neodymium, Radioactive elements, Radioactive wastes, Radioactivity, Rare earths, Sodium, Sorption, Structural ceramics, Surface structure, Thermoanalysis, Uranium, Waste treatment, X ray diffraction, X ray diffraction analysis, Zirconium alloys, Zirconium
Аннотация: Novel layered zirconium molybdates (Mo/Zr = 2) in Na(+)- and NH(4)(+)-exchanged forms with a defective crystalline structure and a specific surface area of up to 100 m(2) g(-1) were synthesized under mild hydrothermal treatment conditions (150 degrees C, 3 days) without structure-directing reagents. The NH(4)(+)-zirconomolybdate material was tested for its ability to immobilise aqueous radioactive waste containing rare earth elements by a sorption/impregnation-crystallization process using simulant Nd(3+)/Ln(3+) bearing solutions. The motivation for tailoring (Ln, Zr, Mo)-ceramics was the utilization of sediment-forming components of spent nuclear fuel processing solutions, such as Mo and Zr, for immobilization of transuranium radionuclides or an actinide-lanthanide (An-Ln) fraction of high-level effluents. The target (Ln, Zr, Mo)-phase acceptable for incorporation of actinides and lanthanides, Ln(2)Zr(3)(MoO(4))(9) (Ln = La-Tb), was selected on the basis of studying the phase formation in triple oxide systems Ln(2)O(3)-ZrO(2)-MoO(3) (Ln = La-Lu, Y, Sc) and analysis of the known promising host phases being developed in the world for the actinide immobilization. X-ray diffraction and thermal analysis methods were used in the study of the thermochemical conversion of the Nd(3+)/Ln(3+)-zirconomolybdates resulting from loading the layered NH(4)(+)-zirconomolybdate precursor with different quantities of Nd(3+)/Ln(3+). The results on Nd(3+) immobilization by the sorption-crystallization route reflected the influence of the acidity of the simulant solutions on the content of the target phase in the solidified (Nd, Zr, Mo)-ceramics. The impregnation/sorption-crystallization procedure provided polyphase composites including Nd(2)Zr(3)(MoO(4))(9), Zr(x)Nd(y)(MoO(4))(2) and ZrO(2), the quantity of the target phase depending on the Nd(3+) loading. The solidification of the Ln bearing simulant solution at 16% Me(n+) loading resulted in nearly mono-phase ceramics of the Nd(2)Zr(3)(MoO(4))(9) structural type.
Журнал: JOURNAL OF MATERIALS CHEMISTRY
Выпуск журнала: Vol. 21, Is. 32
Номера страниц: 12001-12007
ISSN журнала: 09599428
Место издания: CAMBRIDGE
Издатель: ROYAL SOC CHEMISTRY
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