Study On The Synthesis,Phosphorylated And Uranium Adsorption Performance Of Defect-rich MoS₂

With the development of nuclear power,the shortage of uranium resources and the hazards of uranium-containing wastewater have become increasingly prominent.Therefore,high-efficiency uranium adsorption materials have important economic and social significance.Molybdenum disulfide is a graphene-like two-dimensional material,which has a unique two-dimensional layered structure and excellent chemical stability,become one of the most promising matrix materials for adsorption and separation.This work provides a new insight to solve the problems of low adsorption capacity and weak selectivity of U（Ⅵ）for MoS₂.The molten salt electrolysis method and defect engineering strategy were prepared defect MoS₂ with high-density edge S active sites through Zr and Pd doping.Based on the high activity of the edge S site,phosphorylated molybdenum disulfide（MoS₂-PO₄）,phosphorylated zirconium doped Molybdenum disulfide（Zr-MoS₂-PO₄）and phosphorylated palladium-doped molybdenum disulfide（Pd-MoS₂-PO₄）were prepared by in-situ phosphorylation technology,these adsorbents have the characteristics of large adsorption capacity,fast speed,strong selectivity and high stability.The microstructure and surface chemical properties of defect-rich molybdenum disulfide before and after phosphorylation modification were characterized by XRD,Raman,SEM,TEM,AFM,XPS,FT-IR,Zeta potential and other technical means.Study the influence of molten salt electrolysis and phosphoric acid functionalization process parameters on the microstructure and adsorption performance of molybdenum disulfide nanosheets.And combine advanced spectroscopy analysis methods（XPS）and adsorption data to study the preparation mechanism of molten salt electrolysis and the function of phosphoric acid at the atomic level mechanism of chemical and adsorption of uranium.In this work,systematically studied the effects of solution pH,ionic strength（Na Cl O₄）,solid-liquid ratio,contact time,initial concentration and temperature on the adsorption performance of MoS₂-PO₄,Zr-MoS₂-PO₄,and Pd-MoS₂-PO₄.The results show that the optimal adsorption pH value of MoS₂-PO₄,Zr-MoS₂-PO₄ and Pd-MoS₂-PO₄ was 5.5,and the adsorption capacity depends on the pH value of the solution,the ionic strength has little effect on the adsorption capacity.The adsorption rate of U（Ⅵ）by these adsorbents very fast,the adsorption equilibrium time was reached at 3 min.The adsorption processes of three adsorbents for uranium more conform to the pseudo-second-order kinetics model and Langmuir isothermal model.It shows that the adsorption process is a monolayer chemical adsorption,and the maximum theoretical adsorption capacity was 353.35 mg·g^-1,458.72 mg·g^-1and416.62 mg·g^-1,respectively.Exploring the influence of temperature on the adsorption process shows that the adsorption process is a spontaneous endothermic process.The adsorption of U（VI）by the three adsorbents has good selectivity,and the selectivity can reach 64.4%,59.1%and 67.3%respectively.Moreover,the reusability showed that 1.0 mol·L^-1 HCl solution can effectively elute the uranium on the surface of MoS₂-PO₄,Zr-MoS₂-PO₄ and Pd-MoS₂-PO₄,and the elution rates are 96.3%,97.2%,and 97.0%,respectively.In addition,after five consecutive adsorption-desorption experiments,the amount of the adsorption decreased slightly.Three adsorbents are complexed with uranyl ions through O on the surface P=O and P-O.In summary,the research results would provide theoretical and technical support for the design,preparation and functionalization of defects-rich MoS₂.This work would play an important role in promoting the application of MoS₂ in the treatment of uranium-containing radioactive waste and has great economic and social significance.