Investigation of the Actinide Enrichment by Rhabdophane Precipitation Using Cerium as a Surrogate
In response to the enrichment and separation of actinide nuclides in radioactive waste liquid,Ce was used to simulate actinide nuclides,and CePO4·nH2O was prepared by chemical precipitation method.The effects of temperature,pH value on Ce3+removal,precipitate phase composition,microstructure,and dehydration heat behavior were studied.The results show that the chemical formula of the precipitation product rhabdophane is CePO4·0.667H2O.The precipitation process of CePO4·0.667H2O can be divided into the homogeneous rapid nucleation stage(less than 2 hours)and the grain growth stage influenced by ion deposition.Compared with the grain growth stage,the nucleation stage is more suscepti-ble to the influence of pH value,and increasing pH value is conducive to the rapid removal of Ce3+.In a solution with a temperature of 90℃ and a pH of 3.0-5.0,the removal rate of Ce3+is over 99％after a 2 hour precipitation reaction.The separated CePO4·0.667H2O transforms into the monazite phase,which is an ideal host for incorporating actinides.Hydrated rhabdophane is a highly promising material for separating and solidifying actinide nuclides.
RhabdophaneActinide nuclidePrecipitation methodSeparation and enrichmentSolidification
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