Synthesis Of Aminooxime-based Polyacrylonitrile Coating Material And Its Adsorption Behavior To U(?)

With the rapid development of nuclear energy applications,the radioactive uranium-containing wastewater and the decreasing uranium resources will become a stumbling block to Chinese nuclear energy development.The concentration of uranium in uranium-containing wastewater is larger than that of seawater,and the enrichment is easier.Recycling can not only alleviate the tension of uranium resources,but also reduce the impact of nuclear energy development on the natural environment.In this paper,polyacrylonitrile powder is first modified by amidoximation by homogeneous method.Dimethyl sulfoxide is used as solvent,polyacrylonitrile powder is used as solute,hydroxylamine hydrochloride is contacted with it to make amidoximation homogeneous modification.With this as coating solution,artificial zeolite and activated carbon are put into it.At the same time,ultrasonic and vacuum treatment are carried out,and amidoximated polyacrylonitrile is coated on artificial zeolite.Adsorptive materials for practical engineering applications are prepared on activated carbon and activated carbon.Homogeneous modification of Amidoxime of polyacrylonitrile is more uniform and sufficient,and the conversion of Amidoxime is higher.The coated material is easier to be loaded into a column for dynamic adsorption and is easy to be applied in engineeringBy using Fourier transform infrared spectroscopy(FT-IR),specific surface area and porosity measurement,scanning electron microscopy(SEM),X-ray diffraction(XRD),thermogravimetric analysis(TGA)and other characterization methods before and after coating,and adsorption The artificial zeolite and activated carbon before and after are analyzed and tested.The results show that the amidoxime modification of the coating liquid is successful,and the amidoxime polyacrylonitrile is applied to the surface and interior of the artificial zeolite and activated carbon during the coating processThe adsorption behaviors of the two adsorbent materials under different conditions are also studied.The main factors are:adsorbent solid-liquid ratio.pH,ionic strength,time,initial uranium concentration,temperature versus U(VI)coating of artificial zeolite and coating.The experimental results show that the adsorption equilibrium of coated artificial zeolite and coated activated carbon is reached at 72h and 48h.The experimental results show that increasing the solid-liquid ratio,temperature,and initial concentration of uranium will increase the adsorption performance of the two adsorbents within a certain range,but will eventually become stable.The coated artificial zeolite pH=6.3-8.1 has the best adsorption performance at pH=6.3-8.1,and the coated activated carbon has the best adsorption performance at pH=4.0-6.0.The ionic strength has little effect on the adsorption results of the two adsorbents.Finally,the adsorption kinetics and adsorption thermodynamics fitting analysis were carried out,and the adsorption mechanism of coated artificial zeolite and coated activated carbon was studied.The pseudo-first-order kinetic model,the presudo-second-order kinetic model and the intra-particle diffusion model were selected to fit and analyze the adsorption kinetics of uranyl ions coated with artificial zeolite and coated activated carbon.The fitting results showed adsorption.Process is more consistent with the intraparticle diffusion model and the presudo-secondary dynamic model.The Freundlich,Langmuir models are selected to fit the adsorbent isotherm process of the two adsorbents.The fitting results show that the Freundlich model can better describe the adsorption process.The thermodynamic results of the adsorption process show that the adsorption process of uranyl ions by coated artificial zeolite and coated activated carbon is composed of both chemical adsorption and physical adsorption,and the spontaneous endothermic process controlled by entropy increaseIt is found that the adsorption capacity of activated carbon coated with amidoxime polyacrylonitrile(69.1mg/g)is higher than that of zeolite coated with amidoxime polyacrylonitrile(51.3mg/g).