| Molybdenum disulfide has become a research hotspot for radionuclide adsorption materials in aqueous solutions due to its good chemical stability,diversity of preparation methods,and richness of active sites.In this dissertation,Mo S2 adsorbents were prepared by molten salt electrolysis,and Mn O2/Mo S2 and Ag3PO4/Mo S2 adsorbents were further prepared by compounding.The micro-morphology,surface potential,and synergistic adsorption effects of uranyl ions and iodide ions on Mo S2,Mn O2/Mo S2 and Ag3PO4/Mo S2adsorbents were mainly studied.The specific research content is as follows:Using Li Cl-KC-(NH4)6Mo7O24-KSCN molten salt system as the electrolyte,Mo S2 can be controlled by adjusting different electrolytic parameters.The prepared molybdenum disulfide was compounded with manganese dioxide and silver phosphate,respectively,to prepare Mn O2/Mo S2 and Ag3PO4/Mo S2 adsorbents.The morphology and properties of the materials were characterized by SEM,FT-IR,Raman,XRD,Zeta potential and XPS.The characterization results show that Mo S2,Mn O2/Mo S2 and Ag3PO4/Mo S2 were successfully prepared,and the composite materials were applied to the removal of U(VI)and I(I)in aqueous solution,respectively.The influence of p H value,reaction time,reaction temperature and initial concentration of radionuclides on the adsorption property of the material was studied by static adsorption experiment.The effects of these factors on the adsorption performance of the materials were investigated.The quasi-first-order and quasi-second-order kinetic models,Langmuir and Freundlich adsorption isotherms were used to study the adsorption mechanism of Mo S2 and Mn O2/Mo S2 on U(VI).The results show that the optimal p H of U(VI)for Mo S2 and Mn O2/Mo S2 is 5.5,and the equilibrium time is 300 min and 90 min,respectively.The results of kinetic studies show that the adsorption of U(VI)by Mo S2 and Mn O2/Mo S2 conforms to a quasi-second-order kinetic model,and the adsorption is mainly controlled by chemical action.The results of the isothermal adsorption model study show that the Langmuir adsorption isotherm model is more consistent with its adsorption process,indicating that the adsorption of U(VI)by Mo S2 and Mn O2/Mo S2 is monolayer adsorption,and the maximum saturated adsorption capacities are 48.9 mg/g and 163.8 mg/g.Thermodynamic studies show that the adsorption process is a spontaneous endothermic process.Using HCl solution can effectively elute uranium on the surface of the adsorbent.After repeated use,the adsorption of U(VI)by Mn O2/Mo S2 has only decreased by 15%.The experimental results of Mo S2 and Ag3PO4/Mo S2 on I(I)show that the optimal adsorption p H is 7.0,and the equilibrium times are 180 min and 120 min,respectively.The adsorption conforms to the quasi-second-order kinetic model and Langmuir adsorption isotherm model.The saturated adsorption capacities are 40.3 mg/g and 335.7 mg/g,respectively.Adsorption is a spontaneous endothermic process.When HCl solution is used as the eluent,the elution effect is the best.After repeated use,Ag3PO4/Mo S2 reacts with I(I)The amount of adsorption decreased by only 20%.The research results show that the chemical properties of Mn O2/Mo S2 and Ag3PO4/Mo S2 composite materials are stable,and the performance of Mo S2 in removing U(VI)and I(I)in aqueous solution can be effectively improved,indicating that composite adsorbents have good application prospect.In this paper,the adsorption properties of molybdenum disulfide composite for radionuclides are studied,which can provide theoretical research and experimental support for the removal of radioactive waste liquid. |
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