Preparation Of Functionalized Polyacrylonitrile Nanofibers By Electrospinning And The Sorption Of U(?)

Due to the rapid development of nuclear energy,the recovery/removal of uranium from the aqueous phase has become a hot issue.Therefore,the search for new functionalized adsorbents with good sorption performance,strong regeneration ability and low preparation cost has become a key problem to be solved.In this paper,an electrospinning device was built independently,and polyacrylonitrile nanofiber(PAN)with diameters between 200 and 300 nm was successfully prepared by electrospinning.The amidoxime-based polyacrylonitrile nanofiber(AO-PAN)was synthesized with PAN as the framework material,and the synthesis conditions were optimized.The synthetic method was modified,and the amidoxime-based polyacrylonitrile nanofiber(PAO)was directly prepared by electrospinning.The acid-hydrolyzed bifunctional polyacrylonitrile nanofiber(A-PAO)and the alkali-hydrolyzed bifunctional polyacrylonitrile nanofiber(B-PAO)were synthesized by two different methods:acid hydrolysis and alkali hydrolysis.The synthesized materials were characterized by Scanning Electron Microscopy(SEM),Fourier Transform Infrared Spectroscopy(FT-IR),X-ray Photoelectron Spectroscopy(XPS)and elemental analysis to obtain the morphology and structure of the materials.The sorption behavior of U(?)on AO-PAN,PAO,A-PAO and B-PAO nanofibers was studied in detail by static batch method,including the effects of solid-liquid ratio,ionic strength,contact time,pH,initial concentration of U(?),temperature and coexisting ions on the sorption of U(?)and the desorption of U(?)on these materials.The experimental results show that the U(?)sorption capacity changes with the increasing of pH and ionic strength,which is related to the change of morphology of U(?)in the solution system,the protonation and deprotonation behavior of the surface functional groups of the materials,and the complexation modes between the materials and U(?).Under the same experimental conditions,B-PAO has the shortest time for U(?)sorption to reach equilibrium.A-PAO and B-PAO have better sorption capacity for U(?)than AO-PAN and PAO,which indicates that the introduction of carboxyl groups is beneficial to improve the sorption performance of U(?)on materials.The sorption of U(?)by AO-PAN,PAO,A-PAO and B-PAO is a spontaneous endothermic process,and it accords with pseudo-second-order kinetic model and Langmuir isotherm model,which indicates that their sorption of U(?)is monolayer surface chemisorption.The maximum sorption capacity of B-PAO for U(?)is 3.33 mmol/g,which is about 8 times that of PAO and 1.5 times that of A-PAO.PAO,A-PAO and B-PAO have good sorption selectivity for U(?),and they can be reused more than 3 times after treatment with 2 mol/L Na2CO3 solution,which indicates that they were economical and practical adsorbents for U(?).