Study On Adsorption Of Radionuclide By Functionalized Two-dimensional Transition Metal Carbide

The rapid development of nuclear energy causes the disposal of radioactive nuclear waste to be of great significance to the spent fuel cycle and environmental safety.The effective removal of radionuclides using functionalized nanomaterials has proven to be an effective means.As a nanosheet material,two-dimensional transition metal carbide(MXene)has large specific surface area,excellent radiation stability,and abundant active sites have shown excellent performance in the removal of radionuclides.In this thesis,amidoxime-functionalized MXene(F-TC)and carboxyl-functionalized MXene(TCCH)were prepared,respectively,to achieve effective removal of radionuclides in aqueous solution,which is of great significance for radioactive pollution control.(1)MXene was modified by the diazonium salt of p-aminobenzonitrile to obtain amidoxime-functionalized MXene nanomaterial,and it was prepared as an electroadsorption electrode.Morphology and structural were characterized by Scanning electron microscope(SEM),X-ray diffraction(XRD),.transmission electron microscope(TEM),atomic force microscope(AFM),Fourier transform infrared spectrometer(FT-IR),and thermogravimetric analyzer(TGA).U(?)adsorption was studied using a batch experiment system.The maximum adsorption capacity was 294 mg/g,and the adsorption capacity increased to 626 mg /g after 24 hours of application of a pulse potential.X-ray photoelectron spectroscopy(XPS)and Extended X-ray absorption spectroscopy fine structure(EXAFS)were used to analyze the coordination structure of the five-membered ring formed by amidoxime and uranyl ion.(2)Functionalizing with diazonium salt of p-aminobenzoic acid to obtain carboxy-modified MXene.The materials were characterized by XRD,SEM,TEM,TGA and so on.The batch adsorption experiments showed that the adsorption capacities of U(?)and Eu(?)for TCCH reached 344.8 mg/g and 97.1 mg/g,respectively,and both met the Langmuir adsorption model.90% of U(?)and Eu(?)removal could be achieved in simulated groundwater.Ionic strength experiments,XPS and EXAFS analyses were conducted to assess the detailed adsorption mechanism.The results reveal that the adsorption of U(?)on TCCH follows an inner-sphere configuration,whereas the adsorption of Eu(?)is determined by both inner-sphere complexation and electrostatic interaction.