Facile Synthesis Of An Environment-friendly Cyclodextrin-based Polycarboxylic Acid Polyer Effcient Removal Of U(?)and Eu(?)

As a kind of clean energy,nuclear energy characterized by high energy density and abundant reserves.At present,it is continuously developed and applied by various countries to response the global energy crisis.However,the various radionuclides produced in this process,if improperly handled,would cause long-term damage to the ecological environment,which made the disposal of nuclear waste aroused great concern around the world.As a class of adsorbent material,polycarboxylic acid polymers with better stability and abundant active sites could be obtained by modification of polycarboxylic acid on various substrate materials.It had exhibited excellent adsorption capacity in the treatment of organics,heavy metal ions and radionuclides in solution.In our research,a green and facile method was used to esterify and cross-link?-cyclodextrin(?-CD)and 1,2,3,4-butanetetracarboxylic acid(BTCA)to prepare a cyclodextrin-based polycarboxylic acid polymer(BTCA-?-CD),and then showed effective adsorption of radionuclide ions U(?)/Eu(?),expanding its potential performance in radioactive wastewater treatment.In detail,the polymer materials were characterized by Fourier Transform Infrared Spectroscopy(FT-IR),Thermogravimetric analysis(TGA),Scanning electron microscopy(SEM)and X-ray diffraction(XRD)to analyze its structure,morphology and performance.It had been systematically studied the effects of cross-linking ratio(?-CD:BTCA),solution pH,contact time,initial concentration,temperature,interfering ions and cycles to the uptake of U(?)/Eu(?).The FT-IR and X-ray photoelectron spectroscopy(XPS)of the material before and after adsorption were used to characterize and analyze the possible mechanism.SEM and energy dispersive X-ray spectroscopy mapping analysis(EDS mapping)were used to observe the morphology and element distribution of the material after adsorption.The results revealed that the obtained maximum adsorption value of BTCA-?-CD for U(?)was 175.5 mg/g,when the experimental conditions were 303 K,?-CD:BTCA=1:5,pH=5.0,t=75 min,C₀=80 mg/L.Under the experimental conditions of 303 K,?-CD:BTCA=1:5,solution pH=6.0,t=90min,C₀=90mg/L,the maximum adsorption capacity for Eu(?)was165.4 mg/g.And two adsorption kinetics results were in line with the pseudo-second-order kinetic model,indicating that it was a chemical adsorption process.Differently,The fitting data of there models of adsorption isotherm showed that the former conformed to the Freundlich model and the latter conformed to the Temkin model.The thermodynamic results exhibited that the former was a spontaneous endothermic reaction while the latter was a spontaneous exothermic reaction.Then,FT-IR and XPS analysis indicated that the oxygen-containing functional groups(including carboxyl and hydroxyl groups)of the polymer worked mainly as binding sites during the adsorption process,and EDS data was confirmed the authenticity of the batch adsorption results on side.Moreover,rapid adsorption rate and better reproducibility also indicated that this polymer could be seen as a promising adsorbent in nuclear treatment.