Preparation Of Amidoxime Group/imidazole Copolymer Fibers And Their Adsorption Behavior For U(Ⅵ)

With the improvement of people’s living standards and the progress of science and technology,China’s energy demand pressure is increasing.The energy structure mainly composed of coal is facing increasing problems in terms of energy supply level and environmental protection.At present,nuclear power technology is quite mature,and it can efficiently and stably provide energy and achieve extremely low greenhouse gas emissions.Therefore,the proportion of nuclear energy in future energy utilization will gradually increase.China’s terrestrial uranium reserves are relatively small,and the mining technology is not yet mature.However,there are abundant uranium resources in seawater,with a reserve of approximately 4.5 billion tons.If economic and efficient materials for extracting uranium from seawater can be developed,the shortage of uranium resources in China will be effectively alleviated.However,the concentration of uranium in seawater is very low（3.3 ppb）,and the composition is complex,not only contains a large number of coexisting ions,but also many Marine microorganism.The main task we face is how to design uranium extraction materials with high adsorption capacity,high selectivity,strong antibacterial properties,and reusability.In response to these situations,this paper introduces imidazole cations into amidoxime based materials,aiming to improve the material’s ability to adsorb uranium through the synergistic effect of amidoxime groups and imidazole cations.At the same time,it is hoped that the introduction of imidazole groups can improve the material’s antibacterial performance.The main research content of this paper is as follows:Firstly,P（AN/VEIMBr）and P（AN/VEIMBF₄）were synthesized through free radical polymerization and subjected to hydroxylamination to obtain amidoxime acrylonitrile ethyl imidazole bromide（P（AO/VEIMBr））and amidoxime acrylonitrile ethyl imidazole tetrafluoroborate（P（AO/VEIMBF4））.Then,P（AO/VEIMBr）fibers and P（AO/VEIMBF4）fibers were obtained through electrospinning technology.The synthesized materials were characterized in a series of ways by FTIR,¹H NMR,and SEM.Study the adsorption performance of materials through static adsorption experiments,and test the antibacterial performance of fibers through antibacterial zone experiments and oscillation experiments.The adsorption behavior of uranium on P（AO/VEIMBr）₈ and P（AO/VEIMBF₄）₆fibers was studied using static adsorption experiments.The experimental results show that the adsorption of U（VI）by both materials conforms to a quasi second-order kinetic model,with chemical adsorption dominating;According to the fitting results of the thermodynamic model,it was found that the linear correlation coefficient of the two materials to the Langmuir model is closer to 1,indicating that the adsorption of U（VI）on the material is monolayer adsorption,and the maximum adsorption amounts obtained by fitting are 77 mg-U/g-Ads and 82 mg-U/g-Ads,respectively;In the coexisting ion experiment,the two materials exhibited good ion selectivity for U（VI）;When conducting desorption experiments,0.2 mol/L（NH₄）₂CO₃ and 1.0 mol/L NH₄HCO₃ solutions were selected as desorption agents for the two materials,which were able to elute more than 90%of U（VI）from the materials and still maintain good adsorption performance after being reused five times;The antibacterial properties of the two fibers were tested through the inhibition zone and shaking test.It was found that P（AO/VEIMBF₄）₆ fiber had a certain antibacterial effect.Under the solid-liquid ratio of 10 g/L,the antibacterial rates against Staphylococcus aureus and Escherichia coli were 85.3%and 71.6%,respectively.The experiment provided a certain idea for improving the antibacterial materials,and then improving the adsorption performance;The adsorption mechanism of U（VI）on two materials was analyzed through XPS:the amino nitrogen in the amidoxime functional group coordinated with oxime oxygen and uranyl ions;Finally,DFT theoretical calculation was used to analyze the reason for the difference in the adsorption performance of the two materials,that is,the anions contained in the two materials were different,so that the binding energy of P（AO/VEIMBF₄）and uranyl ion was lower than P（AO/VEIMBr）,thus showing better adsorption performance.