Preparation Of Functional Uranium Adsorption Fiber Material And Study On Uranium Adsorption Properties

Uranium resources are the basic resources for the sustainable development of nuclear industry.However,due to the limited land uranium resources,the proven uranium resources are only enough for human use for 120 years,and the uranium resources in seawater are rich.Therefore,it is of great strategic significance to carry out seawater uranium extraction.Adsorption method is most widely used in seawater uranium extraction,and the development of efficient adsorbent is the key of adsorption method.Fiber adsorbents are widely used in the field of adsorption because of their large surface area,mature modification means,braidable molding and corrosion resistance.At present,there are many problems in extracting uranium from real seawater by adsorbent.The content of uranyl ion in concentrated water after seawater desalination is high,the environment is relatively simple compared with real seawater,and the adsorbent is easy to recover in extracting uranyl ion from concentrated water after seawater desalination.In this paper,sponge gourd complex fiber and polyacrylonitrile fiber were used as base materials to prepare oxime/guanidine co modified sponge gourd complex（WGLC）and guanidine/amidoxime functionalized polyacrylonitrile fiber composite（PAN-G-AO）by two-step method,and the adsorption of uranyl ions by adsorbents in seawater desalination concentrated water was studied.The functional groups of oxime and guanidine were grafted onto the surface of loofah,and the composite materials of loofah（WGLC）co-modified by oxime and guanidine was prepared.According to the fitting results of adsorption isotherm model,the adsorption process of uranyl ions on WGLC composites was mainly monolayer adsorption process,and the theoretical maximum adsorption capacity reached 429.18 mg L^-1at 25°C and p H=6.0.In the uranyl solution containing other competing ions,the WGLC adsorption material showed good selective adsorption ability for uranyl ions,and the desorption rate decreased to 79.68%after6 cycles of adsorption and desorption experimentsits.In the simulated seawater experiment,the WGLC adsorption material showed good adsorption ability for uranyl ions in low concentration solution.Using polyacrylonitrile fiber as the base material,guanidine and amidoxime functional groups were grafted on polyacrylonitrile fiber by two steps.Static adsorption experiments showed that p H=6.0 was the optimal adsorption p H value,and the adsorption process of uranyl ions on PAN-G-AO composites was mainly monolayer adsorption process.At 25°C and p H=6.0,the theoretical maximum adsorption capacity was 490.20 mg L^-1,and it reached adsorption equilibrium within 15 min.After six cycles of adsorption and desorption experiment,it was only reduced by 5.14%.In the experiments of competitive ions and simulated seawater,it was found that PAN-G-AO still had good selectivity and adsorption capacity for uranyl ions in complex water environment.In order to investigate the adsorption of uranyl ions in seawater desalination concentrated water,WGLC,PAN-G-AO and PAN-PEI adsorption materials were placed in uranyl solution containing scale inhibitor/flocculant（Fe Cl₃）respectively,and the adsorption capacity of uranyl ions decreased to different degrees.The scale inhibitor 2-nitrobutane-1,2,4-tricarboxylic acid had the greatest effect on the adsorbent.The concentration of Fe Cl₃added to uranyl solution increased from 0 mg L^-1to 3 mg L^-1,and the adsorption capacity of uranyl ions adsorbed by the adsorption materials decreased from 94.20 mg g^-1,58.53 mg g^-1and 99.15 mg g^-1to 16.08mg g^-1,9.88 mg g^-1and 46.73 mg g^-1respectively.The higher the concentration,the more pronounced the effect.The three adsorbents were adsorbed in real seawater desalination water samples（original seawater,flocculation filtration seawater,reverse osmosis seawater,reverse osmosis seawater and seawater desalination concentrated water）for 30 days,the adsorption capacity of the three adsorption materials is 18.43μg g^-1,18.60μg g^-1and 18.36μg g^-1respectively,which is higher than that in other stages.It shows that it is feasible to extract uranium from seawater desalination concentrated water.