The Study Of The Solidification And Separation Of Tlhorium

A large number of minerals are associated with radioactive thorium?Th?and uranium?U?,so the removal and purification of radioactive pollutants in the mine is particularly important.At the same time,potential nuclear accidents in nuclear power plants have some impact on the surrounding ecological environment and human beings.Actinides are the key nuclides in nuclear energy,and it is important to carry out their related basic coordination chemistry research to explore the stability of nuclear spent fuel in natural environment or extreme environment,as well as applicability of actinide coordination compounds as chemical storage forms for nuclear waste.In this study,a series of iodate and selenite comounds with varied structure were prepared by hydrothermal method and characterized by X-ray single crystal diffraction,absorption spectrum,fluorescence spectrum,SEM-EDS,and X-ray powder diffraction.Their structural novelty and environmental stability were studied as well.The specific research contents are as follows:1)ThIOCl with a novel two-dimensional structure was successfully prepared by hydrothermal method by adjusting the reaction temperature.The structural analysis shows that this structure is a rare inorganic cation framework structure in which every six Th^?in the crystalline material are connected into a hexanuclear thorium cluster by?₃-oxo and?₃-hydroxo bridges,forming cationic networks bridged with IO₃^-and the distribution of chlorine ions between the cationic networks.In addition,this compound has good thermal stability and acid-base stability.Due to the weak hydrogen bonding and the interaction of halogen atoms around each Cl^-in the structure,the chloride ions can not be interchanged because of the chloride ions firmly locked in the networks.Therefore,the material is a new type of actinide solid material constructed from halogen-halogen bonds with high stability.2)By adjusting the amount of selenite,five lanthanide selenides compounds and thorium selenite with five different 3D structures were prepared by the traditional hydrothermal method.A new set of the periodic trend of lanthanides was noticed.In this regard,study on crystallization separation between the lanthanides???and actinides???,and multi-element crystallization separation has been carried out by simulating the compositions of REE and thorium elements in monazite—one of the three major rare earth minerals.It was found that when lanthanides???present together with thorium???,the solid phase crystalline products are actinide/lantanide???selenite,and the lanthanide???ions remain in the solution phase.Owing to the presence of selenite,the reaction system is highly oxidizing,so the cerium???was oxidized to cerium???and crystallized with thorium???in the form of solid solution simultaneously,the remaining lanthanide???ions existed in the solution phase.The separation between lantanides???and actinide???/Ce???was successfully realized.