Blow Spinning Of Pre-Acid-Activated Polyamidoxime/Chitosan Composite Nanofibers And Their Performance For Uranium Extraction From Seawater

Extraction of Uranium(U)from seawater and wastewater is very important for the sustainable development of nuclear energy,ecological environment protection and human health.Scientists have started the research on the extraction uranium from seawater and achieved many outstanding achievements.However,the acquisition of uranium adsorbents with high adsorption capacity,low cost and excellent antibacterial properties is still a great challenge to be solved in the research of extracting uranium from seawater.Chitosan is a kind of natural antibacterial material,which can chelate metal ions,and has the advantages of low cost,good biodegradability and non toxicity.All these advantages contribute to the application of chitosan in the extraction of uranium from seawater.Amidoxime is considered to be the most efficient group due to its significant affinity andselectivity to the uranyl ions.It has outstanding performance in extracting uranium from seawater.By dissolving PAO in an acidic solution,the pre-acid activated PAO(PA-PAO)has a higher uranium capture capacity(>1825 mg/g),and it does not have to be soaked in a hot alkaline solution to increase its adsorption capacity.The main contents are as follows:(1)Based on the good adsorption capacity and antibacterial activity of chitosan(CS)to uranyl ions,a solution gas spinning and glutaraldehyde crosslinked chitosan nanofibers(CS NFs)were designed and prepared.Compared with chitosan hydrogels,CS NFs have a larger specific surface area and more exposed adsorption active sites.CS NFs can reached a saturated adsorption capacity of 202mg/g in 5L of 16 ppm simulated seawater after 36 hours,indicating that it has good adsorption capacity.(2)On the basis of the CS NFs research,a new kind of PAO-based NFs were developed via aqueous solution blow spinning of pre-acid-activated PAO(PA-PAO)and chitosan(CS)mixed solution.The dissolved PA-PAO exhibits high U capture ability(>1825 mg/g),which is even better than that treated by conventional‘hot alkali activation.’This may be the first report on such high U capture efficiency of acid-activated PAO.The saturation uranium extraction capacity of PA-PAO/CS-NFs reached 913.13mg/g in the simulated seawater with uranium concentration of 16 ppm with 48 hours.In natural seawater,PA-PAO/CS-NFs realized a uranium extraction capacity of 4.91mg/g within a short field test of 10 days,which is higher than that of other amidoxime-based adsorbents,such as hydrogel,membrane,etc.Moreover,after four cycles of adsorption-desorption,the structure of NFs was still well preserved,indicating the excellent mechanical property and good recyclability of the covalently crosslinked PA-PAO/CS-NFs.In addition,PA-PAO/CS NFs yielded obvious antibacterial effect for E.coli,S.aureus and P.aeruginosa,which was of great significance for the sustained and efficient adsorption of uranium-absorbing materials in the ocean with complex biological environment.The features of the PA-PAO/CS NFs,including high-efficiency adsorption,recyclability,and good antibacterial effect,indicated that PA-PAO/CS NFs had unique advantages in the industrial field of extracting uranium from seawater and nuclear wastewater.