Preparation Of Poly(Amidoxime) Nanofibers And Alg/PAO Gel And Their Adsorption Behavior Of U(Ⅵ)

With the progress of society and the vigorous development of the economy,energy problems have become increasingly prominent.As a clean energy that has developed rapidly in the past few decades,nuclear energy is facing unprecedented opportunities and challenges.There are 4.5 billion tons of uranium reserves in the ocean,which is several thousand times that of terrestrial uranium reserves.Therefore,it is particularly important to extract U（VI）from seawater in a low-cost and efficient method.At present,amidoxime-based adsorbent materials are the most promising materials for extracting uranium.However,the seawater environment is more complicated,with a large number of coexisting ions and competing ions.Although powder-based adsorbents have the advantage of large specific surface area,there are great disadvantages in recycling.The purpose of this thesis is to synthesize an adsorbent material that can be used to extract uranium from seawater.Through electrospinning and self-assembly methods,two solid adsorption materials containing amidoxime-based nanofibers（PAO Nano Fibers）and gel spheres（semi IPN Alg/PAO Gel spheres）were successfully prepared,respectively.Through FTIR,SEM,A series of characterizations were carried out on the material by element analysis.Then the adsorption properties of the two materials for Uranium under different conditions were studied.By the method of orthogonal experiment,the scanning electron microscope is used.Analyzing the morphology and diameter of the PAO nanofiber adsorbent material,the result shows the best conditions for electrospinning:the concentration of the spinning solution is 8%,the applied voltage is 25k V,the distance between the needle and the collecting plate is 10cm,and the spinning solution flows out.The speed is 0.7μL/min;We successfully prepared PAO NFs with good morphology and good adsorption performance;the adsorption behavior of PAO NFs and Alg/PAO gel was studied through static batch adsorption experiments.The effects of solid-liquid ratio,ionic strength,p H,equilibrium time,and temperature on the adsorption of uranium are mainly studied.According to the fitting parameters of the thermodynamic model,it is found that the correlation coefficient of the Langmuir model is closer to 1,and the maximum adsorption obtained by the fitting is 113.6mg-U/g-Ads.When eluting U（VI）,a mixed solution of 0.1mol/L Na₂CO₃ solution and 0.1mol/L H₂O₂ is used the desorbent.By semi IPN Alg/PAO gel spheres,the adsorption of U（VI）conforms to the Langmuir model in terms of thermodynamics.The maximum adsorption obtained by fitting is 186.6mg-U/g-Ads.0.8mol/L nitric acid selected can be eluted U（VI）.The semi IPN Alg/PAO gel spheres can maintain the adsorption rate of uranium by more than 60%in the spiked-uranium seawater experiment,showing a excellent adsorption capacity for uranium.The adsorption U（VI）mechanism of the two materials is discussed by X-ray photoelectron spectroscopy,and it is found that amido nitrogen and oxime oxygen in amidoxime functional group of PAO NFs coordinate with uranyl ion.The amidoxime groups in the semi IPN Alg/PAO gel spheres and the carboxyl groups that are not involved in structural cross-linking in the gel spheres participate in the coordination of uranyl ions.According to the experiment of ion selectivity,two kinds of adsorption materials have good selectivity to U（Ⅵ）,and the materials have good reusability.They are very promising for the extraction of uranium in real seawater.