Study On The Preparation Of Functionalized Biomass Carbon Composite And Its Removal Of Uranium

In order to meet the increasing global energy needs,nuclear power has developed rapidly in recent years due to its high efficiency.At the same time,a large amount of uranium is inevitable to release a large amount of uranium into the environment through nuclear fuel cycle activities.Uranium exists in two stable oxidation states,U(IV)and U(?).The latter form is more harmful to organisms and can damage the normal functions of the brain,liver and kidneys and eventually lead to death.In addition,limited uranium resources also limit the development of the nuclear industry.Therefore,the removal and extraction of U(?)from uranium wastewater is very important for human health,environmental protection and resource recovery.Adsorption technology has been widely used for its advantages of rapid balance,high capacity,diversity,low cost,recyclability and simplicity.In this paper,two functionalized biomass carbon composite materials are prepared and used for the removal of uranium.The two composite materials have good removal effects and are easy to separate and recover.The morphology,structure,composition,specific surface area,magnetic properties,characteristic functional groups and chemical bonds were characterized and analyzed by SEM,TEM,XRD,BET,VSM,FT-IR and XPS techniques.The effects of p H,contact time,initial concentration of uranium,temperature of uranium solution and interfering ions on uranium removal were investigated.The mechanism of uranium removal was also studied.(1)Preparation of magnetic carbon aerogel(MWCA)and its removal of uranium in solution:Using wax gourd as carbon source,MWCA was prepared by carbonization/magnetization process to remove U(?).MWCA reached adsorption equilibrium within 120 min at a p H of6 and a temperature of 303K,and the maximum removal amount is288.2mg/g.MWCA has good magnetic properties and can be easily separated from the solution by applying a magnetic field.The adsorption isotherm data is more in line with the Langmuir isotherm model,and the kinetic data can fit the quasi-secondary kinetic model well.The thermodynamic parameters?H⁰,?S⁰,?G⁰indicate that the adsorption process is endothermic and spontaneous.Through coexisting ion experiments,it is found that MWCA has good selectivity to U(?).XPS and FT-IR analysis show that MWCA removes U(?)through the synergistic effect of adsorption and reduction.(2)Preparation of aminated biochar loaded with nanoscale zerovalent iron sulfide(Sn ZVI-BC-NH₂)and its removal of uranium in solution:Biochar was prepared with watermelon peel as a carbon source,and 3-aminopropyltriethoxysilane was used to modify the biochar to prepare aminated biochar(BC-NH₂).Sn ZVI-BC-NH₂was prepared by liquid-phase reduction method with sodium borohydride as reducing agent and sodium hydrosulfite as vulcanizing agent and used for the removal of U(?).Sn ZVI-BC-NH₂reaches adsorption equilibrium within180 min at 298 K and p H value of 6,and the maximum removal amount was 502.5mg/g.The kinetic data of Sn ZVI-BC-NH₂removal of U(?)can fit the quasi-secondary kinetic model well,and the adsorption isotherm data is more in line with the Langmuir isotherm model.The thermodynamic parameters?H⁰,?S⁰,?G⁰indicate that the removal process of U(?)is endothermic and spontaneous.XPS and FT-IR analysis showed the synergistic effect between adsorption and reduction in the U(?)removal process.The experimental results of coexisting ions show that Sn ZVI-BC-NH₂has good selectivity to U(?).XPS analysis and anti-oxidation experiments show that the Fe Sx shell not only protects the n ZVI particles,but also participates in the removal of U(?).