Preparation Of Functionalized Hollow Porous Carbon For Uranium Adsorption

The fossil energy crisis and radionuclide pollution have increased people's attention to the utilization and management of uranium resources.The mankind facing the energy and environmental crisis.The development and utilization of uranium resources has important strategic significance in seawater or uranium-containing wastewater.Nano Hollow Porous Carbon(NHPC)materials have low density,high specific surface area,high porosity,excellent stability and conductivity,and have a wide range of applications in the fields of catalysis,batteries,energy storage and environment.It is composed of metal organic frameworks(MOFs).The derivative porous carbon has become one of the hot research topics.Carbonization retains the various advantages of MOFs through pyrolysis,such as the high conductivity and good stability,which makes up the shortcomings of MOFs in practical applications.However,the NHPC prepared by high temperature pyrolysis has fewer functional groups on the surface,poor hydrophilicity,and lack of selectivity to adsorption metal ions,which limit its application in radionuclide adsorption.Aiming at this problems,this paper uses the template method to prepare nano hollow porous carboncage(NHPC)with a hollow structure,and uses the acid oxidation method to modify the surface,prepared highly hydrophilic NHPC-OH,and further introduces functional group on the surface of the material.Phosphate-based nanoporous carbon(NHPC-PO4)and amidoximated nanoporous carbon composite(NHPC-AO)are prepared with affinity phosphoric acid group and amidoxime group,which are used for the adsorption of U(VI).The structure and composition of NHPC,NHPC-OH,NHPC-PO4,and NHPC-AO were characterized by XRD,SEM,TEM,N2 adsorption-desorption isotherm,FT-IR and other methods.The basic characteristics of NHPC,NHPC-OH,NHPC-PO4,NHPC-AO adsorption of U(VI)were studied by batch adsorption method,such as the influence of the solution p H,U(VI)initial concentration,contact time and other factors on the adsorption,and clarified the kinetics and isotherms of U(VI)adsorption.The elution and regenerate performance and selectivity were investigated.The effect of functionalized porous carbon materials was discussed for extracting uranium in seawater.SEM,FT-IR and XPS characterization were used to explore the possible mechanism of material adsorption of U(VI).The matching results indicates that the NHPC has successfully introduced phosphoric acid groups or amidoxime groups on the surface of the material after surface modification.The adsorption experiment shows that the optimal p H range of the material for uranium adsorption is between about 5.0 and 6.0.The kinetic curves of U(VI)adsorption on the four functionalized carbon materials synthesized by fitting calculations are all consistent with the pseudo-second-order kinetic adsorption model,indicates that the process of material adsorption is chemical adsorption,and conforms to the Langmuir adsorption isotherm model.The selectivity is increased by introducing functional groups on the surface of the hollow carbon,and the adsorption material has good reusability.Our research work provides a new idea for the selective enrichment of uranium from seawater.