Study On The Synthesis Of Polyacrylonitrile Amidoxime And Its Adsorpion To Uranyl Ion

In order to realize the sustainable development of energy,nuclear energy has become the main energy development goal of the world.However,with the development of nuclear energy industry,whether it is in the nuclear power operation,or in the front-end of nuclear fuel cycle,spent fuel reprocessing,military nuclear facilities decommissioning process will inevitably produce a large number of uranium waste.It is very urgent and important to properly handle and dispose of the waste liquid.In this paper,homogeneous solution method has been adopted.In an organic solvent N,N’-dimethylformamide（DMF）,the polyacrylonitrile powder reacts with hydroxylamine,for preparation of amidoxime polyacrylonitrile adsorption material.The prepared adsorbent was characterized by Fourier transform infrared spectroscopy（FT-IR）and the specific surface area and pore size analyzer.The adsorption of uranyl ions on the adsorbent was studied by using uranyl nitrate solution with initial concentration of 100 ppm.The effects of adsorption time,pH value of uranium solution and adsorption temperature on adsorption were investigated.The results showed that the morphology of the adsorption material was different from that of the preparation conditions,such as reaction time,reaction solute ratio,reaction temperature and so on.At room temperature（25℃）reaction,nitrile and hydroxylamine molar ratio of 1:1,the adsorption material can be granulated by different degrees of yellow flat round solid particles,and nitrile and hydroxyl amine molar ratio of 1:2 can not be obtained by granulation of the fixed form of the product,and only an amorphous white solid powder can be obtained.The reaction was carried out at a high temperature（90℃）,and when the nitrile group and hydroxylamine molar ratio was 1:2,the product was a yellow solid powder.The results of FT-IR show that the nitrile group（-C≡N）of polyacrylonitrile has reacted with hydroxylamine（NH₂·OH）,resulting in a new functional group:amidoxime group（-C（=NOH）NH₂）.And-C≡N has been substantially all converted to-C（=NOH）NH₂ for 7 days.The results of adsorption experiments show that the adsorption capacity of uranium is the highest at room temperature,n（nitrile）:n（hydroxylamine）=1:1,and the preparation time is 3d.And when the pH value of 3.0,the adsorption capacity of up to 158.90mg/g.Under the same adsorption conditions,the adsorption capacity of the prepared materials prepared at room temperature,n（nitrile）:n（hydroxylamine）=1:2andtheadsorptionofn（nitrile）:n（hydroxylamine）=1:2 prepared by high temperature is similar.It was about half of the adsorption capacity of the adsorbent material prepared at room temperature,n（nitrile）:n（hydroxylamine）=1:1.Under different conditions,the optimum pH value of the adsorption material was different,but the adsorption rate and adsorption capacity increased with the increase of adsorption temperature.The adsorption isotherm conforms to the Langmuir isothermal model,and the adsorption of uranyl ions on the adsorbent is uniform monolayer adsorption.