Novel Sn-doped Ammonium Phosphomolybdate: Preparation, Characterization and Adsorption Properties of Cs

摘要: With the development of nuclear power, a significant amount of radioactive waste liquid has been generated, among which cesium posed high radioactivity and a long half-life, which necessitated its removal from waste liquids. In this study, a series of Sn-doped ammonium phosphomolybdate adsorbents were synthesized through chemical coprecipitation for the adsorption of cesium. The incorporation of stannum ions replaced one-third of the inert ammonium ions in ammonium phosphomolybdate, which resulted in an increase in the volumetric charge density between molecules and enhanced the performance of the adsorbent. Transmission electron microscopy, scanning electron microscopy, and energy dispersive spectroscopy analyses revealed that while the face-centered cubic crystal structure of the material remained unchanged, the morphology of the microparticles transitioned from cubic to spherical. According to the results from X-ray diffraction, Fourier transform infrared spectroscopy, and thermogravimetric analysis, as well as adsorption capacity and stability tests, the adsorbent SnII0.5SnIV0.5(NH4)2[P(Mo3O10)4] (add Fe), which exhibited the best performance was selected for further investigation. This included X-ray photoelectron spectroscopy, adsorption selectivity, adsorption–desorption cycles, thermodynamics, isotherms, and kinetics experiments. The results indicated that SnII0.5SnIV0.5(NH4)2[P(Mo3O10)4] (add Fe) exhibited excellent selectivity for cesium, with the adsorption process characterized as an exothermic ion exchange reaction, which achieved a saturated adsorption capacity of 115 mg/g and maintained over 85% adsorption efficiency after three cycles. Additionally, density functional theory was used to further analyze the changes in the unit cell dimensions and energy of the material. The results demonstrated that this study successfully developed a novel adsorbent based on the ammonium phosphomolybdate matrix, which was capable of efficiently and rapidly extracting Cs from radioactive waste liquids. This study also provided a new idea for the design and development of inorganic materials.