A novel layered zirconium molybdate as a precursor to a ceramic zirconomolybdate host for lanthanide bearing radioactive waste

作者：Vereshchagina Tatiana A^*; Fomenko Elena V; Vasilieva Nataly G; Solovyov Leonid A; Vereshchagin Sergei N; Bazarova Zhibzema G; Anshits Alexander G

来源：Journal of Materials Chemistry, 2011, 21(32): 12001-12007.

DOI：10.1039/c1jm11202c

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.

• 出版日期2011