Synthesis Of Amidoxime Functionalized Hyper-Crosslinked Porous Polymer And Its Application In Uranium Adsorption

Nuclear fission of uranium is an important way to develop nuclear energy.Its enrichment is of great strategic significance to the sustainable development of our society.Adsorption is the most suitable method for enriching uranium.The existing porous aromatic skeleton polymer adsorbent for uranium extraction have poor adsorption performance,require harsh synthesis conditions and high synthesis cost.In view of the above problems,porous adsorbents were prepared by post-crosslinking of polymer precursors,and then the material synthesis steps were further simplified.The adsorbents were prepared by“knitting”method.The effects of various factors on the adsorption properties of adsorbents were studied.The target polymer HCR-AO was prepared by amidoximation reaction and Friedel-crafts alkylation reaction.The adsorbent showed good thermodynamic and chemical stability.The adsorbent has rich micropore and high porosity.The best ratio of solid to liquid is 0.8 g/L.The synergistic effect of porous structure and amidoxime group can accelerate the diffusion rate of uranium ions from the outer layer to the channel.Under the interference of other metal ions,HCR-AO still exhibited a high removal rate of about 91.6%of uranium ions,and the polymer had high ion selectivity.The main way of adsorption is the complex of amidoxime group and uranium ion in the form of 2:1η~2,and mainly occurs in the form of chemisorption in the inner-sphere surface.The amidoxime based porous aromatic framework polymer HCPA was synthesized by one pot method using BP-AO and biphenyl as reactants and dimethoxymethane as a external crosslinker.The specific surface area,porosity and amidoxime group content of the adsorbent can be controlled by the ratio of the monomers.The specific surface area can be adjusted from948 m~2/g to 246 m~2/g,and the mesoporous content gradually moves to the microporous region with the increase of amidoxime monomer ratio.The adsorption capacity of HCPA-2 with low amidoxime group content is higher than that of other materials due to the combined effect of specific surface area and functional group content of adsorbent.Under the interference of other metal ions,HCPA-2 still maintained a high uranium removal rate of about 80%,the partition coefficient of uranium ions was 695.94 m L/g,and the polymer had high ion selectivity.The adsorption mechanism is the adsorption of uranium ion on the adsorbent and the inner-sphere surface complexation of amidoxime group with uranium ion in the form ofη~2.